Epiqa Demo Manual Version 2.2.1 Final

January 12 PN EP-00101-6

User Guide for Demo Mode

Epiqa: EPID Dosimetry

For Quality Assurance

Epiqa Reference Guide

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This page is left blank intentionally.

General Information Epiqa Reference Guide

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Abstract This document provides information about the installation, configuration,

calibration and instructions for use of EpiqaTM program.

Manufacturer EPIdos s.r.o.

Lesná 7

900 28 Ivanka pri Dunaji

Slovak Republic

Notice Information in this document is subject to change without notice and

does not represent a commitment on the part of EPIdos. EPIdos is not

liable for errors contained in this document or for incidental or

consequential damages in connection with the furnishing or use of this

material.

This document contains proprietary information protected by copyright.

No part of this document may be reproduced, translated, or transmitted

without the express written permission of EPIdos s.r.o..

Trademarks EpiqaTM is a trademark of EPIdos s.r.o.

IDLTM is a trademark of ITT Corporation.

PortalVisionTM, EclipseTM, RapidArc, Clinac, TrueBeamTM are

trademarks or registered trademarks of Varian Medical Systems Inc.

Microsoft, Windows and Windows Vista are registered trademarks

of Microsoft Corporation.

All other trademarks or registered trademarks are the property of their

respective owners.

Contacting Support For support with the Epiqa product, go on-line to

http://epidos.eu/helpdesk or write an e-mail to [email protected].

Please always state Epiqa serial number and software version in the

request.

Updates For updates to this document please send e-mail to

[email protected].

http://epidos.eu/helpdesk

Document History Epiqa Reference Guide

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Document History .

Version Date Changes, Remarks Reason

0.1 Jan 15, 2009 Initial version.

0.2 Jan 31, 2009 Adopted for IDL 7.0 use. Adoption of the GLA feedback, reflecting new IDL version

0.3 March 06, 2009

Adopted for Epiqa 1.1.0.2 version, finished Chapter 4. Modifications to reflect Epiqa changes

0.4 March 23, 2009

Inserting IFU part for Epiqa.

0.5 March 25, 2009

Section 3.4 adapted to version 1.2. Minor corrections of the installation process. Configuration section 4 enhanced. RapidArc commissioning section added.

First version released for customer feedback

1.0 April 15, 2009

Final version for commercial use.

1.1 August 20, 2009

Section 5.5.1 – Plan preparation - inserted information about support for (0,0,0) geometry. Section 5.7 – Disk drive file data organisation – explained Automove function. Section 5.14.1 – Preferences – inserted information about new functions. Appendix 6.4 – DICOM Export – enhanced DICOM filter settings to support Automove.

Included updates reflecting changes in software version 1.2.5

1.2.6 October 1, 2009

Updated information on contacting Epiqa support.


1.3.0 January 15, 2010

Section 4.1.1 , 4.1.3 – Removed information about the need to disable CU calibration, added section about support of CU calibrated images.


Added Section 4.6.5 – Diagonal profile definition.

1.3.2 February 02, 2010

Section 4.6.2 – Added information about network location of param folder.


1.3.3 March 14, 2010

No changes Updating manual version to match 1.3.3 release

2.0.10

February 23, 2011

Section 2.5 – Added GLAaS algorithm description.

Section 3.1- Updated operating system and hardware requirements. Section 3.4 – Updated information about licensing. Section 4.1.1 – Added graphics to set up geometry, the whole section substantially updated. Section 4.2. – Added graphics describing process. Section 4.2.2 – Added graphics to set up. Section 5 – Epiqa data preparation introduced


Document History Epiqa Reference Guide

January 12 - 5 - PN EP-00101-6

Document History - continued

Version Date Changes, Remarks Reason

2.0.10 Cont.

February 23, 2011

Section 6 – Introduced (was Section 5) and updated : Section 6.3 – added description of the new toolbar. Section 6.4 – replacement of section 5.8. updated. Section 6.5 – replacement of section 5.9 updated. Section 6.6 – replacement of section 5.11 Section 6.7 – replacement of section 5.14 updated Section 6.8 – replacement of section 5.12 Section 6.9 – replacement of section 5.13 updated


2.1.0 March 8, 2011

Section 3.1 - Updated operating system and hardware requirements. Section 4.1.2 – Included information about support of TrueBeam accelerator. Section 6.9.4 – Corrected information about density of energy phantom material.

Update to reflect changes in software version 2.1.0.

2.1.1 April 4, 2011

Section 3.1 – Added information on installation on Windows 7 operating system. Section 3.2 & 3.3 – Updated and enhanced by Windows 7 installation specifics.

Included updates reflecting installation on Windows 7 operating system.

2.1.2 April 30, 2011

No changes Updating manual version to match 2.1.2 release

2.2.1 January 3, 2012

Section 6.7.4 – Inserted manual alignment chapter.

Section 6.7.6 – Inserted manual alignment and auto centring preferences description.

Update to reflect changes in software version 2.2.1.

Contents Epiqa Reference Guide

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1 CONTENTS

DOCUMENT HISTORY ................................................................................................................... 4

DOCUMENT HISTORY - CONTINUED ........................................................................................... 5

1 CONTENTS .............................................................................................................................. 6

2 INTRODUCTION ...................................................................................................................... 9

2.1 Hera - IMRT QA Module ................................................................................................... 9

2.2 Artemis - RapidArc QA Module .......................................................................................... 9

2.3 Athena - Machine QA Module ............................................................................................ 9

2.4 Hermes - TPS QA Module ................................................................................................. 10

2.5 The Engine - GLAaS Algorithm .................................................................................... 10

3 EPIQA INSTALLATION .......................................................................................................... 12

3.1 General Information on Epiqa ...................................................................................... 12

3.2 Installation on Windows XP or Windows 7 computer with UAC off ........................... 13

3.2.1 IDL Run Time Module Installation ............................................................................. 13

3.2.2 Epiqa Software Suite Installation ............................................................................... 13

3.3 Installation on Windows 7 operating system with UAC enabled ............................... 14

3.3.1 IDL Run Time Module Installation ............................................................................. 14

3.3.2 Epiqa Software Suite Installation ............................................................................... 15

3.4 Requesting a License for Epiqa ................................................................................... 16

3.5 Verifying the installation and applying the license file ............................................... 16

4 EPIQA CONFIGURATION PROGRAM .................................................................................. 17

4.1 Before you start - Preliminary steps before measuring configuration data .............. 18

4.1.1 Set-up for portal dosimetry verification using Epiqa ................................................... 18

4.1.2 Set-up requirements .................................................................................................. 21

4.2 Calibration Data for Primary Radiation Configuration ................................................ 22

4.2.1 Integrated images required for Primary Radiation Configuration ............................... 22

4.2.2 Ion chamber measurements ...................................................................................... 23

4.3 Calibration Data for Transmitted Radiation Configuration ......................................... 25

4.3.1 Integrated images required for Transmitted Radiation Configuration ......................... 25

4.3.2 MLC transmission factor measurement ..................................................................... 25

5 EPIQA - INPUT DATA PREPARATION ................................................................................. 26

5.1 Epiqa Workflow and Data Preparation ......................................................................... 26

6 EPIQA - INSTRUCTIONS FOR USE ...................................................................................... 27

6.1 Introductory information ............................................................................................... 27

6.2 Epiqa Main Screen ........................................................................................................ 27

6.3 Toolbar ........................................................................................................................... 28

6.4 Using Epiqa for the first time ....................................................................................... 29

6.4.1 Data Loading – General Information.......................................................................... 29

6.4.2 Data Loading – Working Instructions ......................................................................... 30

6.4.3 Calculating results ..................................................................................................... 33


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6.5 Analysing results - Evaluation tools ............................................................................ 34

6.5.1 Analysis settings – Set-up geometry ......................................................................... 34

6.5.2 Main analysis ............................................................................................................ 34

6.5.3 Analysis mode Absolute Dose Difference .................................................................. 35

6.5.4 Analysis mode Percentage Dose Difference ............................................................. 35

6.5.5 Analysis mode Gamma evaluation ............................................................................ 36

a. Global gamma analysis approach ................................................................................ 37

b. Local gamma analysis approach .................................................................................. 37

c. Gamma options ........................................................................................................... 38

6.5.6 Complementary analysis ........................................................................................... 39

6.5.7 Reset collimator = 0 for PV ...................................................................................... 39

6.5.8 Gaussian convolution ................................................................................................ 39

6.6 View menu options ........................................................................................................ 40

6.6.1 CIAO Edge ................................................................................................................ 40

6.6.2 Graticule ................................................................................................................... 40

6.6.3 PV dimension ............................................................................................................ 40

6.6.4 Color scale ................................................................................................................ 40

6.6.5 Gamma Color ............................................................................................................ 40

6.6.6 MI .............................................................................................................................. 41

6.6.7 White background ..................................................................................................... 41

6.6.8 Zoom ......................................................................................................................... 41

6.6.9 Pan ........................................................................................................................... 41

6.6.10 Reset Geometry ........................................................................................................ 41

6.7 Tool menu options ........................................................................................................ 42

6.7.1 Histogram area ......................................................................................................... 42

6.7.2 Enable profiles .......................................................................................................... 44

6.7.3 Export profiles ........................................................................................................... 44

6.7.4 Manual Alignment ..................................................................................................... 45

6.7.5 Point dose ................................................................................................................. 46

6.7.6 Preferences ............................................................................................................... 46

a. General 1 ..................................................................................................................... 46

b. General 2 ..................................................................................................................... 47

c. Percentage difference analysis .................................................................................... 47

d. Gamma analysis .......................................................................................................... 48

e. Protocol ....................................................................................................................... 48

f. Profiles ........................................................................................................................ 48

g. Eclipse dose geometry................................................................................................. 48

h. Epiqa parameter file ..................................................................................................... 49

i. Histogram .................................................................................................................... 50

j. View............................................................................................................................. 50

6.7.7 The Protocol .............................................................................................................. 50

6.7.8 Field properties ......................................................................................................... 51

6.8 RapidArc commissioning tests analysis in Artemis module ........................................ 52

6.8.1 Test 0.1: dMLC Dosimetry ......................................................................................... 54

6.8.2 Test 0.2: Picket Fence test versus gantry angle ........................................................ 55

6.8.3 Test 1.1: Picket Fence test during RapidArc .............................................................. 56


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6.8.4 Test 1.2: Picket fence test during RapidArc with intentional errors ............................ 57

6.8.5 Test 2: Accurate control of Dose Rate and Gantry Speed during RapidArc delivery .. 58

6.8.6 Test 3: Accurate control of Leaf Speed during RapidArc delivery .............................. 59

6.8.7 RapidArc commissioning test report .......................................................................... 60

6.9 Complementary analysis menu in Athena module for Machine QA ............................ 61

6.9.1 Output Factor ............................................................................................................ 61

6.9.2 Wedge Factor ........................................................................................................... 62

6.9.3 Profile analysis .......................................................................................................... 63

6.9.4 Percentage Depth Dose (PDD) ................................................................................. 65

7 REFERENCES ....................................................................................................................... 67

Introduction Epiqa Reference Guide

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2 INTRODUCTION

Epiqa is a comprehensive tool for Quality Assurance with Electronic Portal Imaging Devices

(EPID).

The main core of the package is the conversion algorithm, which converts the readings into

absorbed dose at a certain depth using EPID images. The algorithm is widely and detailed

published, and user can refer to the original papers (references 1 to 5). Dose matrices, either

converted from EPID images or computed by the treatment planning system can be easily

compared in a quantitative way through dose difference or gamma matrices. Epiqa is designed for

IMRT and RapidArc Quality Assurance usage as well as for standard linac Quality Assurance

procedures.

The Epiqa software consists of four different modules. Those modules are:

2.1 Hera - IMRT QA Module

Hera for IMRT QA is designed to compare the calculation and delivery of sliding window or step-

and-shoot IMRT fields, in particular for pre-treatment QA.

It includes comparison of the acquired Portal Vision integrated images with the calculated IMRT

fields using dose to water conversion. Reference dose matrix is calculated to water phantom at any

depth using the same calculation algorithm as for patient plan. Each field is delivered while

acquiring integrated image at the treatment gantry angle. Analysis workspace supports dose

difference, gamma analysis using user selectable ROI.

2.2 Artemis - RapidArc QA Module

Artemis for RapidArc QA supports analysis of the RapidArc dose distribution calculation and its

delivery, in particular for pre-treatment QA.

It compares acquired Portal Vision integrated image over the whole arc with the calculated dose

distribution using dose to water conversion. Reference dose matrix is calculated to water phantom

at any depth using the same calculation algorithm as for patient plan and resetting all calculated

segments to zero gantry angle. RapidArc is delivered under normal treatment conditions while

acquiring integrated image. Analysis workspace supports dose difference, gamma analysis using

user selectable ROI.

2.3 Athena - Machine QA Module

Athena for linac QA is designed to analyse open fields, hard and Enhanced Dynamic Wedge

fields, and to check the beam parameters.

It offers conversion of the Portal Vision integrated images to dose to water matrix and its analysis

comparing measured versus measured (or calculated) dose matrices.

Following beam parameters are analysed: symmetry, flatness, output factors, wedge angles and

factors, beam energy using additional build up step phantom


January 12 - 10 - PN EP-00101-6

2.4 Hermes - TPS QA Module

Hermes for treatment planning system QA supports comparison and quantitative analysis of

calculated dose matrices of any treatment modality.

It supports Eclipse QA procedures by comparison of the calculated dose matrices of any beam

type – open fields, IMRT or RapidArc. This module is also useful to compare different dose

calculation algorithms.

Note: Epiqa currently supports only Eclipse calculated dose matrices.

2.5 The Engine - GLAaS Algorithm

EpiqaTM is a program that allows to convert a dosimetric image acquired by an EPID into a dose

map and to compare the dose map with a reference dose distribution. It is possible to utilize Epiqa

for a verification of static as well as intensity modulated fields, including RapidArc® fields.

The conversion of a dosimetric image into a dose map is only possible if a response of the imager

to a beam is known. The EPID‟s response shows very good linearity, but exhibits rather strong

energy dependence, which causes a difference in response to primary and MLC transmitted

radiation. Epiqa overcomes this limitation by the calibration process that takes the energy

dependence of the detector into account. For the purpose of calibration, a set of integrated images

for open and transmission fields of different field sizes are acquired and consequently imported into

Epiqa together with the output factor table (measured by a conventional detector such as ionization

chamber) to establish basic algorithm configuration data.

Based on the knowledge of jaws position and the trajectory of MLC leafs (for an IMRT field), a

calibration factor can be determined for every pixel of an EPID by weighting the contribution of

primary and transmitted radiation and by applying an interpolation among the data of the

calibration dataset.

The pixel based calibration relates the readout of a pixel to a dose at the depth of dmax in water

equivalent homogenous medium. By applying the conversion to all pixels of the EPID, a planar

dose distribution at the dmax in water is obtained.

The image-to-dose conversion algorithm (GLAaS) is often confused with portal dose image

prediction algorithms (PDIP). As described in the previous paragraphs, the GLAaS derives

calibration factors for EPID‟s pixels using empirically measured dataset. The obtained dose map is

compared against dose distribution calculated by clinically used dose algorithm. It is therefore an

independent method of verification of the dose distribution calculated by a treatment planning

system and verification of the delivery device performance. The PDIP estimates a response of the

imager for the theoretical incidental fluence. In other words, the algorithm predicts a pattern that

will be created on the imager and a user has then a possibility to compare it with the real one. This

method checks the reproducibility in delivery of the incidental fluence, meaning it verifies the

technical accuracy of the delivery (which is usually very good) and not the dose distribution/dose

calculation algorithm itself.

A detailed description of the GLAaS image-to-dose algorithm can be found in [1].


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Figure 1 - Epiqa QA principle

Epiqa Installation Epiqa Reference Guide

January 12 - 12 - PN EP-00101-6

3 EPIQA INSTALLATION

3.1 General Information on Epiqa

The Epiqa software is based on the IDL version 7.0 (Interactive Data Language, Copyright © ITT)

scripting language using DICOM (-RT) as the input standard. Further details on IDL are available

on the Web site: http://www.ittvis.com/.

The Epiqa software consists of three executable IDL .sav files:

1. Epiqa_license_request.sav: contains the code to request the license for your Epiqa

software.

2. Epiqa_configuration.sav: is used configure and calibrate the GLAaS algorithm.

3. Epiqa.sav: main software code consisting of four independent modules.

a) IMRT QA module

b) RapidArc QA module

c) Machine QA module

d) Treatment Planning System QA module

To use Epiqa software delivered as an executable .sav files the run time module installation of the

IDL software is required. This run time module installation doesn‟t require license and can be freely

installed on any PC.

Operating System Requirements:

Microsoft Windows XP (32-bit & 64-bit) Service Pack 3.

Microsoft Windows 7 (32-bit & 64-bit).

Note: Windows 7 is supported by Epiqa version 2.1 and higher.

Windows 64-bit operating systems are only supported by Epiqa version 2.1 and higher.

Windows Vista is not supported.

Installation on Windows 7 computer has some specifics, which are related to the safety feature of

this operating system, called User Account Control. More information about this feature can be

found on the web - http://windows.microsoft.com/en-US/windows7/What-is-User-Account-Control.

The installation steps and also start up of the Epiqa program differ depending on the settings of the

user account control (UAC) and Windows 7 edition.

To install and use Epiqa on a PC it is recommended to turn off UAC by setting the UAC level to

“Never notify”. Please see more details on UAC settings on the web -

http://windows.microsoft.com/en-US/windows7/What-are-User-Account-Control-settings.

If turning off UAC is not possible due to hospital policy, it is still possible to install and use Epiqa on

such computer. Follow the steps described in paragraph 3.3.

Minimal hardware requirements:

PC Intel/AMD x86 32-bit

1 Gbyte RAM.

400 Mbyte of free hard disc space.

http://www.ittvis.com/ProductServices/IDL.aspx

http://windows.microsoft.com/en-US/windows7/What-is-User-Account-Control

http://windows.microsoft.com/en-US/windows7/What-are-User-Account-Control-settings


January 12 - 13 - PN EP-00101-6

3.2 Installation on Windows XP or Windows 7 computer with UAC off

To install Epiqa on Windows XP or Windows 7 computer with UAC off login as user with

administrator rights.

3.2.1 IDL Run Time Module Installation

Insert Epiqa USB drive into the USB port.

a) Open Windows Explorer application and navigate to your Epiqa USB drive – the drive name

is EPIQA – double click IDL_setup.exe and click OK.

b) The IDL 7.0 Install Shield Wizard window appears, click Next.

c) Click Yes to accept IDL license agreement displayed in the next window.

d) The Choose Destination Location dialog appears. The default destination directory

C:\Program Files\ITT\ is suggested. Select the installation directory and click Next to accept

the directory.

e) The Select Features dialog appears. Accept the default features and click Next.

f) The File Type Associations dialog appears. Accept the default associations and click Next.

g) The Start Copying Files dialog appears. Click Next.

h) The Setup Status dialog appears and shows the installation progress.

i) When the software installation is complete the IDL Licence Wizard starts, click No as there

is no need for the license in case IDL is used in run time mode which is needed for Epiqa

use.

j) A dialog box notifies you that the installation was successful. Click Finish. Your IDL

installation is now complete.

3.2.2 Epiqa Software Suite Installation



is EPIQA – double click Epiqa_setup.exe and click OK.

b) The Epiqa Install Shield Wizard window appears, click Next.

c) Review the license agreement, select “I accept the terms in the license agreement” and

click Next.

d) The Destination Folder dialog appears. The default destination directory C:\Program

Files\EPIdos\Epiqa\ is suggested. Select the installation directory and click Next to accept

the directory.

e) The Installing Epiqa dialog appears and shows the installation progress. Final Install Shield

Wizard window offers to run license request and to open this manual file. Click Finish. Your

Epiqa installation is now complete.


January 12 - 14 - PN EP-00101-6

3.3 Installation on Windows 7 operating system with UAC enabled

Installation on the computer running Windows 7 with User Account Control active has some

specifics, which differ depending on the Windows 7 edition. Login to computer as a user with

administrative rights. In order to successfully run the installation of both IDL runtime module and

Epiqa software you need to run setup executables with the elevated user rights, which are

accessible by right mouse click over the installation file and selecting “Run as administrator”.

The limitations of Epiqa installation depend on the Windows 7 edition:

a) Windows 7 Home and Professional – do not install Epiqa in default directory

C:\Program Files\EPIdos. Epiqa licensing system does not work if running from this

directory which accessibility is controlled by UAC and displays Error 113 – Permission

denied. Use any other installation directory such as C:\Epiqa.

b) Windows 7 Enterprise and Ultimate – it is possible to install Epiqa also in default

directory C:\Program Files\EPIdos or any other directory. Upon launching Epiqa software

user must always confirm the message from UAC to allow launching IDLRT.EXE run time

module. Refer to Figure 2.

Figure 2 - UAC confirmation when running Epiqa on Windows 7 Ultimate

3.3.1 IDL Run Time Module Installation



is EPIQA.

b) Right mouse click on IDL_setup.exe and select Run as administrator.

c) Confirm that you want to make changes to your computer by clicking on Yes button in User

Account Control window. Refer to Figure 3.


January 12 - 15 - PN EP-00101-6

Figure 3 - IDL setup UAC information window

d) The IDL 7.0 Install Shield Wizard window appears, click Next.

e) Click Yes to accept IDL license agreement displayed in the next window.

f) The Choose Destination Location dialog appears. The default destination directory

C:\Program Files\ITT\ is suggested. Keep this installation directory and click Next to accept

the directory.

g) The Select Features dialog appears. Accept the default features and click Next.

h) The File Type Associations dialog appears. Accept the default associations and click Next.

i) The Start Copying Files dialog appears. Click Next.

j) The Setup Status dialog appears and shows the installation progress.

k) When the software installation is complete the IDL Licence Wizard starts, click No as there

is no need for the license in case IDL is used in run time mode which is needed for Epiqa

use.

l) A dialog box notifies you that the installation was successful. Click Finish. Your IDL

installation is now complete.

3.3.2 Epiqa Software Suite Installation



is EPIQA.

b) Right mouse click on Epiqa_setup.exe and select Run as administrator.

c) Confirm that you want to make changes to your computer by clicking on Yes button in User

Account Control window.

d) The Epiqa Install Shield Wizard window appears, click Next.

e) Review the license agreement, select “I accept the terms in the license agreement” and

click Next.

f) The Destination Folder dialog appears. The default destination directory C:\Program

Files\EPIdos\Epiqa\ is suggested. Select the installation directory and click Next to accept

the directory.

g) The Installing Epiqa dialog appears and shows the installation progress. Final Install Shield

Wizard window offers to run license request and to open this manual file. Click Finish. Your

Epiqa installation is now complete.


January 12 - 16 - PN EP-00101-6

3.4 Requesting a License for Epiqa

There is no need to request EPIdos for license if running Epiqa in demo mode. Although all

functionalities of Epiqa are accessible user can only use DICOM data provided with the

installation package.

3.5 Verifying the installation

There is no need to apply any license file if you run Epiqa in demo mode.

At the end of the installation, in case you used default installation directory, you should have the

directory structure related to Epiqa as shown in Figure 4.

Figure 4 - Epiqa Installation Directory Structure

Epiqa directory contains three executable binary files to run Epiqa software and its configuration

program, license request result file and following subdirectories:

a) Demo_data directory contains the DICOM RT plans, calculated dose matrices and

measured integrated image files for product training and trial period. Before you receive the

license file you can use those data to test Epiqa functionalities for IMRT, RapidArc QA and

machine QA,. Without the license file, Epiqa is restricted for use only with provided

demonstration data.

b) Doc directory contains this manual.

c) Import directory contains DICOM RT plans necessary for Epiqa configuration.

d) Lib directory contains program libraries.

e) License directory - here you need to copy the supplied license.dat file.

f) Log directory contains program diagnostic information which may help to solve problems

with the program. Diagnostic log writing can be turned on or off in Options menu.

g) Param folder is empty upon the installation. After you completely run Epiqa configuration

program parameter files will be stored in this location.

Epiqa configuration program Epiqa Reference Guide

January 12 - 17 - PN EP-00101-6

4 EPIQA CONFIGURATION PROGRAM

The operative main steps to obtain the input data for the configuration program are illustrated in the

following Figure 5.

Figure 5 - Configuration data, preparation steps

Preliminary steps

Decide for your

set-up geometry

PV aSi

image calibration

Data for Primary Beam

Import

RP_Epiqa_Conf_Primary.dcm

PV aSi

image acquisition

Ion Chamber

measurements

RT-plan export

PV images export

text file

Data for Transmitted Beam

Import

RP_Epiqa_Conf_Transm.dcm

PV aSi

image acquisition

Ion Chamber

MLC transm. fact.

RT-plan export

PV images export

value

Preliminary steps

Decide for your

set-up geometry

PV aSi

image calibration

Data for Primary Beam

Import

RP_Epiqa_Conf_Primary.dcm

PV aSi

image acquisition

Ion Chamber

measurements

RT-plan export

PV images export

text file

Data for Transmitted Beam

Import

RP_Epiqa_Conf_Transm.dcm

PV aSi

image acquisition

Ion Chamber

MLC transm. fact.

RT-plan export

PV images export

value


January 12 - 18 - PN EP-00101-6

4.1 Before you start - Preliminary steps before measuring configuration data

4.1.1 Set-up for portal dosimetry verification using Epiqa

The Epiqa program allows performing portal dosimetry measurements according to three different

configurations:

a. „mix‟ configuration: Measured PV images are acquired without adding any build-up on the

top of the cassette. This is most popular configuration. The measurement depth is 0.8 cm,

which is the intrinsic water equivalent thickness of the EPID device, but matrices are

converted into dose at dmax. Measurements are then compared with doses computed by the

TPS at dmax. This configuration relates PV acquisitions performed without adding any build-

up material on the top of the PV cassette with doses calculated/measured at dmax, where

the dose calculation is more reliable. This procedure is similar to what is usually applied

when in-vivo dosimetry is performed with solid state diodes without sufficient build-up

material.

Example for 6MV: Source Detector Distance; SDD = 100 cm, this corresponds to the

detector vertical position reading 0.0 cm.

Source Surface Distance; SSD = SDD – dmax = 98,5 cm, this a

correct SSD set in Eclipse for this example.

dmax (in water) = 1.5 cm.

d(Portal Vision) = 1.2 cm, this is the real depth of the aSi layer inside of

Portal Vision detector. Equivalent water thickness of the material

above aSi layer is 0,8 cm as mentioned above.

Figure 6 - Geometry set up for mix configuration

Note: In case of RapidArc, the “mix” configuration is recommended.


January 12 - 19 - PN EP-00101-6

b. „dmax‟ configuration: Measured PV images are acquired by adding build-up on the top of the

cassette in a way that SDD-SSD=dmax (SDD = source to detector distance, SSD = source to

surface distance) for each specific energy. The water equivalent slabs thickness used must

consider the 0.8 cm of the intrinsic water equivalent thickness of the EPID device.

Measurements are then compared with doses computed by the TPS at dmax. This is the also

correct configuration to choose if user desires to calibrate the whole system at any depth

different from dmax. Calibration, measurements and calculations have to be coherently set-

up at the desired depth as displayed in Figure 7.

Example for 18MV: Source Detector Distance; SDD = 100 cm, this corresponds to the


Source Surface Distance; SSD = SDD – dmax = 96,8 cm, this a

correct SSD set in Eclipse for this example.

dmax (in water) = 3.2 cm.

Build-up thickness: dmax – 0.8 cm = 2.4 cm.

Figure 7 - Geometry set up for Dmax configuration


January 12 - 20 - PN EP-00101-6

c. „no build-up‟ configuration: Measured PV images are acquired without adding any build-up

on the top of the cassette. The measurement depth is 0.8 cm, which is the intrinsic water

equivalent thickness of the EPID device. Measurements are then compared with „doses‟

computed by the TPS at 0.8 cm depth. Limits of this method have been described in the

original publication [1].

Example: Source Detector Distance; SDD = 100 cm, this corresponds to the


Source Surface Distance; SSD = SDD – d = 99.2 cm, this a correct

SSD set in Eclipse for this example.

d(Portal Vision) = 1.2 cm, this is the real depth of the aSi layer inside of

Portal Vision detector. Equivalent water thickness of the material

above aSi layer is 0,8 cm as mentioned above.

Figure 8 – Geometry set up for no-build up configuration

In case Varian‟s Portal Dosimetry is also being used, it is possible to keep the CU calibration and

intensity profile entered during the Portal Dosimetry calibration. No extra steps are required to use

CU calibrated images with Epiqa software in preliminary phase. If you choose to disable CU

dosimetry calibration and use raw integrated images see Appendix 7 to find out how to disable CU

dosimetry calibration.


January 12 - 21 - PN EP-00101-6

4.1.2 Set-up requirements

The configuration procedure must be performed for each single machine (linac and detector),

energy and SDD separately.

The suggested SDD for the detector is closest possible to the isocenter (Exact-arm SDD=100cm

(vert=0.0), R-arm SDD=105 cm (vert= -5.0)) to maximize effective measurable field size.

In case of using Epiqa for several different dose rates only the standard imager calibration (Section

4.1.3) is mandatory for each dose rate.

The Epiqa parameters obtained by the dedicated configuration (Chapter 4.2 & 4.3) are valid for the

nominal dose rate used for the configuration data acquisition and are automatically extended to

any lower dose rate. For this reason, it is recommended to perform data acquisition for

calibration using the highest dose rate considered for clinical use.

Varian‟s Portal Vision exhibits some saturation problems when used for portal dosimetry. The

detector saturation depends on the model of the Portal Vision acquisition electronics and the

detector model. There are several combinations of the acquisition electronics and the detector

(IDU) possible:

a) IAS2 with IDU 11 – commercial model name PV aS500, resolution 512x384 pixels

b) IAS2 with IDU 20 – commercial model name PV aS500, resolution 512x384 pixels

c) IAS3 with IDU 20 working in binned mode – commercial mode name PV aS500-II,

resolution 512x384 pixels

d) IAS3 with IDU 20 working in full mode – commercial model name PV aS1000, resolution

1024x768 pixels

e) XI with IDU 20 working in full mode – this is a MV imaging system implemented in the

TrueBeam accelerator.

The saturation depends on the fluence of the beam entering the detector and so positioning of the

detector to larger distance will solve the saturation problem for high dose rates, of course for the

price of the smaller field of view. The systems a) and b) are most prone to saturation problems

while system d) does not exhibit saturation problems. More about detector saturation can be found

in van Esch at all [7] and Nicolini et al [3]. For Portal Vision with IAS2 acquisition electronics it is

recommended not to exceed the dose rate higher than 300 MU/min when measuring close to

isocenter. If dose rate 600 MU/min is desired it is recommended to use SDD=140 cm for this type

of Portal Vision.


January 12 - 22 - PN EP-00101-6

4.2 Calibration Data for Primary Radiation Configuration

Simplified and schematic explanation of this configuration step is depicted in the diagram in Figure

9. For detailed description, refer to fundamental paper by Nicolini et al [1]

Figure 9 - Primary Radiation Calibration Schema

4.2.1 Integrated images required for Primary Radiation Configuration

To determine detector‟s response to primary radiation it is necessary to measure a minimal set of

open fields (at least the suggested 8 square fields: 30x30, 25x25, 20x20, 15x15, 12x12, 10x10,

5x5, 3x3). For each field a minimum of three images with different MUs have to be acquired.

For each field size, acquire three images with 10, 20 and 50 MU to evaluate detector parameters

according to the selected set-up condition. The entire procedure is automated using an appropriate

DICOM RT-plan with the recommended 24 image acquisitions (8 fields x 3 different MUs), provided

with the Epiqa software, named RP_Epiqa_Conf_primary.dcm and located in

<Epiqa Installation directory>\import\RT_plan\Epiqa_configuration\primary\.

IMPORTANT: To acquire the calibration images, it is mandatory to import plan provided with

Epiqa into your Eclipse or ARIA system. During this process import filter will convert generic

machine ID to your machine ID. See Appendix 7 for help on how to configure Import filter of

Eclipse or ARIA system to accept DICOM RT Plan with different Machine ID. Configuration

program stores and assigns calibration data together with the machine ID and so the plan used to

acquire calibration images MUST HAVE correct machine ID; the same as it was entered in the

license request.

See Appendix 7 how to import plan in ARIA and how to prepare it for measurements.

IMRT image for

a static open field

(X,Y)

PV_ reading (RPV)

The EwwF is calculated as

EwwF=2 X*Y/(X+Y)

According to FIT 2,

from EwwF the OF is derived

According to FIT 3,

from OF the mpr is derived(the value of qpr is shown in

the parameter output file)

D [Gy]= mpr * RPV + qpr

DOSE


January 12 - 23 - PN EP-00101-6

If you are user of ARIA or VARiS/Vision system, you may use the system support for image

acquisition. In RT Chart attach Integrated Image sequence template and load the plan from the

Queue using 4D Treatment Console.

4.2.2 Ion chamber measurements

For each previously acquired calibration image it is necessary to determine the dose calibration

factor expressed in terms of MU/Gy. A set of measurements with an ion-chamber in a water

equivalent phantom is suggested. The ion chamber set up (measurement depth) needs to match

image calibration method (i.e. depth=dmax for dmax and mix modes, depth=0.8 cm for no-build-up

mode) as displayed in Figure 10.

Figure 10 - Geometry for OF measurements

As an alternative, the same values can be derived from Eclipse calculation in a water phantom.

The results have to be saved in a text file („IC.dat‟) according to the following format:


January 12 - 24 - PN EP-00101-6

IC MEASUREMENTS

[Treatmentmachinename:]

6EX

[Energy:Low/High]

6

[Data MU/Gy]

[XY],3,5,8,10,12,15,18,20,25,30

3,94.76,,,,,,,,,

5,,86.46,,87.49,,,,86.50,,86.12

8,,,86.70,,,,,,,

10,,88.23,,85.58,,,,84.19,,83.62

12,,,,,84.78,,,,,

15,,,,,,84.34,,,,

18,,,,,,,83.18,,,

20,,87.55,,84.57,,,,82.82,,82.08

25,,,,,,,,,,

30,,87.40,,84.29,,,,82.36,,81.60

[ENDDATA]

Treatment machine name must correspond to your linac ID for which the table is being

constructed.

The 1st row in the file contains values for Y jaw; 1st column contains values for X jaw.


January 12 - 25 - PN EP-00101-6

4.3 Calibration Data for Transmitted Radiation Configuration

To assess the detector response to transmitted radiation the calibration process requires

acquisition of several images with beam shielded by MLC leaves. The original approach as

described by Nicolini et al [1] has been preserved but the set of experimental measurements has

been revised in Epiqa software.

It consists of following measurements:

a) Open square field (X=10.0cm,Y=10.0cm), 50 MU.

b) Square field (X=10.0cm,Y=10.0cm), closed by MLC with 3 different MUs

(50,100,200 MU).

c) Measurement of the MLC transmission factor in the set-up configuration condition for

the selected square field (X=10.0cm,Y=10.0cm).

4.3.1 Integrated images required for Transmitted Radiation Configuration

Similarly as for primary radiation, you have to acquire the integrated images for all fields as

described above. The entire procedure is automated using an appropriate DICOM RT-plan

provided with the Epiqa software, named RP_Epiqa_Conf_Transm.dcm and located at

<Epiqa Installation directory>\import\RT_plan\Epiqa_configuration\transmission\.

To acquire the calibration images, it is mandatory to import plan provided with Epiqa into your

Eclipse or ARIA system. During this process import filter will convert generic machine ID to your

machine ID. See Appendix 7 for help on how to configure Import filter for Eclipse or ARIA system

to accept DICOM RT Plan with different Machine ID. Configuration program stores and assigns

calibration data together with the machine ID and so the plan used to acquire calibration images

MUST HAVE correct machine ID; the same as it was entered in the license request.

See Appendix 7 how to import plan in ARIA and how to prepare it for measurements.

If you are user of ARIA or VARiS/Vision system, you may use the system support for image

acquisition. In RT Chart attach Integrated Image sequence template and load the plan from the

Queue using 4D Treatment Console.

4.3.2 MLC transmission factor measurement

The value of the MLC transmission factor is required for the Epiqa configuration. It is suggested to

measure it with an ion chamber according to your selected experimental set-up for a 10x10 field.

You may use provided DICOM RT plan (“RP_Epiqa_Conf_Transm.dcm”) located at

<Epiqa Installation directory>\import\RT_plan\Epiqa_configuration\transmission\.

Epiqa - input data preparation Epiqa Reference Guide

January 12 - 26 - PN EP-00101-6

5 EPIQA - INPUT DATA PREPARATION

Every Epiqa installation also includes DICOM data ready to be used for software functions

evaluation.

If you run Epiqa in demo mode please use data located at

C:\Program Files\EPIdos\Epiqa\demo_data.

5.1 Epiqa Workflow and Data Preparation

In order to use Epiqa software for quality assurance analysis you need to supply the program with

only three items:

a) Treatment plan in DICOM RT format

b) 1st data set of images - Eclipse dose matrices or PV images.

c) 2nd data set of images - Eclipse dose matrices or PV images.

Example of pre-treatment patient QA flow with Epiqa for Eclipse versus PV comparison is shown in

Figure 11.

Figure 11 - Data flow when using Epiqa

Preparation of the reference dose matrix for comparison with the dose measured by Portal Vision

and calculated by Epiqa includes several steps. Some of those steps are specific for use with

Epiqa.

Epiqa - instructions for use Epiqa Reference Guide

January 12 - 27 - PN EP-00101-6

6 EPIQA - INSTRUCTIONS FOR USE

6.1 Introductory information

Epiqa package includes four main modules:

a) Hera for IMRT QA

b) Artemis for RapidArc QA

c) Athena for Machine QA

d) Hermes for TPS QA

Epiqa‟s main functionality is to compare the planar dose matrices. The following pairing of dose

matrices types can be loaded and compared:

a) Hera : PV versus PV, TPS versus PV

b) Artemis : PV versus PV, TPS versus PV

c) Athena : PV versus PV, TPS versus PV

d) Hermes : TPS versus TPS

Epiqa automatically launches appropriate module according to the type of data loaded.

6.2 Epiqa Main Screen

Figure 12 - Epiqa Main Screen

4

5 6 7

8 9 10

3

11

10 2


January 12 - 28 - PN EP-00101-6

1. Title Bar

2. Menu Bar

3. Toolbar

4. Context window

5. Dose matrix window, 1st data set (Eclipse or Portal Vision)

6. Analysis matrix window according to the selected analysis mode (gamma evaluation or

dose difference)

7. Dose matrix, 2nd data set (Eclipse or Portal Vision)

8. Profile display in x direction (left-right) for both dose matrices

9. Profile display in y direction (feet-head) for both dose matrices

10. Display of histogram and statistics for the analysis matrix window

11. Point dose Bar

6.3 Toolbar

Figure 13 - Toolbar description

1. Open

2. Measurement setup

3. Analysis type

4. Set gamma parameters

5. Set percentage dose difference parameters

6. Reset collimator to 0 for measured image

7. Calculate all selected fields

8. Histogram: select histogram area

9. Profiles: click on image

10. Select profile type

11. Cross-hair

12. Point dose: move on image

13. Additional gamma analysis

14. Zoom in

15. Zoom out

16. Pan

17. Reset geometry

18. Protocol

19. Select field

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19


January 12 - 29 - PN EP-00101-6

6.4 Using Epiqa for the first time

In case the software is not licensed it is possible to run Epiqa in demo mode, however the data

loading is limited to pre-defined demo cases that are distributed to the user in the folder

<Epiqa Installation Directory>\demo_data\ .

6.4.1 Data Loading – General Information

Epiqa‟s main functionality is to compare the planar dose matrices. The following pairing of dose

matrices types can be loaded and compared:

a) Hera : PV versus PV, Eclipse versus PV

b) Artemis : PV versus PV, Eclipse versus PV

c) Athena : PV versus PV, Eclipse versus PV

d) Hermes : Eclipse versus Eclipse

Epiqa automatically enters in the proper module according to the type of data loaded.

Refer to example of the data-loading dialog in Figure 14.

Figure 14 - Epiqa data loading start

Depending on the selected type of analysis program requires following data to perform an analysis:

a) DICOM RT plan file (mandatory)

b) Set of images/dose matrices related to the RT-plan:

Eclipse calculated dose matrices (one dose image per field)

Portal Vision images (one image per field, see note below)

c) For PV images also a reference PV image (10x10 cm field, 50 MU) is needed.

Note: Hera for IMRT QA module manages comparison between one single Eclipse dose plane

matrix and 2 portal images belonging to the delivered sub-fields in case of split IMRT field. The

subfield image summing is performed automatically.

Large Field IMRT plans and images are currently not supported.


January 12 - 30 - PN EP-00101-6

6.4.2 Data Loading – Working Instructions

With the introduction of version 2.0 Epiqa includes a possibility to load all data in one step.

Activating the “Load all data in one step” option in window „Get Files‟, after the selection of the RT-

plan file, both the test and references image files are automatic loaded. In order for this option to

work, Epiqa needs that patient data are organized according the standard Epiqa patient folders

tree. This folder structure is automatically created when the “Create New” function is used.

Described steps assume using Hera IMRT QA data loading with Eclipse dose as reference and PV

Integrated Image.

a. Click File Open and select desired comparison mode. For this example, select Eclipse vs

PV. Refer to Figure 14.

b. Window Get Files opens. Click „Get RTPLAN file‟ button and load the DICOM RT plan file.

Figure 15 - Get Files window

c. Upon plan loading Epiqa enters in the proper module indicated in the uppermost icon. All field

names according to the DICOM RT plan data (names and order) are displayed. In case of an

erroneous selection click on „Delete‟ button for a new file loading. If only a subset of fields has

to be analysed deselect the unwanted fields.

Figure 16 - Get Files - Plan loaded

d. Click „Get Eclipse Files‟ and select the dose matrices exported from Eclipse and click Open.

Epiqa automatically opens the „eclipse‟ subfolder. The number of loaded dose matrices must

correspond to number of fields selected for analysis otherwise, Epiqa displays warning.


January 12 - 31 - PN EP-00101-6

Figure 17 - Eclipse Images loading

e. Because DICOM exported dose matrices do not contain Field ID, Epiqa uses file names to

align fields with the corresponding dose matrix. This however works only if the naming is

consistent. It is therefore suggested to name dose matrices with increasing field sequential

numbers during the export as described in 6. If the correspondence between plan fields and

Eclipse dose matrices is incorrect, move the files up and down with the arrow buttons.

Figure 18 - Get Files - Eclipse files loaded

f. Click „Get PV Files‟ and load the exported PV images including the 10x10 reference PV image.

The number of loaded dose matrices must correspond to number of fields selected for analysis

otherwise, Epiqa displays warning. If the correspondence between plan fields and Eclipse dose

matrices is incorrect, move the files up and down with the arrow buttons.


January 12 - 32 - PN EP-00101-6

Figure 19 - Integrated images loading

For a split field two acquired PV images are expected, while only one Eclipse dose matrix can be

loaded. Figure 20 shows an example of split field number 1 and automatic sorting of acquired

subfields.

Figure 20 - Single field versus split field loading

g. Click „OK‟ or „OKCalculate‟ button to proceed.

Figure 21 - Get Files - data loading finished


January 12 - 33 - PN EP-00101-6

6.4.3 Calculating results

a. Click „Calculate All Selected Fields‟ button to start calculation of the dose file matrices

and the analysis results on the settings defined in preferences. Refer to paragraph 6.7.6 -

Preferences for description. This calculation is rather processor intensive. Be patient waiting for

the results.

b. Images and results are displayed in the six windows (described in paragraph 6.2) progressively

for all the fields as the system processes the data. The calculation phase is finished when the

last field is displayed. You can switch between the fields and see the results by using the scroll

bar next to toolbar.

Figure 22 - Epiqa main window - data loaded and results calculated


January 12 - 34 - PN EP-00101-6

6.5 Analysing results - Evaluation tools

Epiqa provides three analysis modes to compare dose matrices for each field:

a) Dose difference: pixel by pixel absolute difference

b) Percentage dose difference: pixel by pixel relative difference

c) GAMA: gamma analysis with user configurable values for distance to agreement

(DTA) and delta dose (Delta D[%]).

Linac output and detector stability are accounted for by a analysing static 10x10 field which is

mandatory for every measurement.

For each results calculation an output file output.xls is created (or updated) in the patient directory

with a summary of the analysis results. Profile plots are always displayed in absolute dose [Gy];

the profiles along the main axes are displayed by default.

6.5.1 Analysis settings – Set-up geometry

Click on Analysis in menu bar. Options available in the Analysis menu are listed in

Figure 23.

Figure 23 - Analysis menu options

Selection of the correct set-up geometry is crucial to obtain correct results. The selected geometry

for analysis must be equal to the geometry selected for measurement and reference dose

calculation. Epiqa configuration must be performed for selected geometry prior to using it. Refer to

paragraph 4.1.1 for more details.

There are three possible configurations:

1. No build-up: PV acquisition without adding build-up material on the detector and reference

dose calculation at 8 mm depth.

2. Dmax: PV acquisition with additional build-up material on the cassette to reach dmax depth

and reference dose calculation at dmax.

3. Mix: PV acquisition without adding build-up material on the detector and reference dose

calculation at dmax.

6.5.2 Main analysis

In the menu Analysis Main analysis, select the analysis mode for comparison of both dose

matrices:

1. Absolute dose difference: pixel by pixel dose difference in Gy.

2. Percentage dose difference: pixel by pixel relative difference.

3. Gamma: gamma analysis with user configurable values for distance to agreement (DTA)

and delta dose (Delta D[%]).


January 12 - 35 - PN EP-00101-6

Figure 24 - Analysis parameters definition

6.5.3 Analysis mode Absolute Dose Difference

The resulting analysis matrix is determined as an absolute difference between calculated and

measured dose distribution in Gy. The difference levels are displayed according to scale set

automatically between maximum and minimum difference value. It is possible to change this scale

by clicking Analysis Absolute dose difference option Scale range.

Figure 25 - Example of dose difference analysis in Hera module - Eclipse dose

versus measured dose for an IMRT field

6.5.4 Analysis mode Percentage Dose Difference

This mode allows performing analysis with global or local approach.

For global approach, the maximum significant dose is used as a reference for calculation of the

relative difference in all pixels. The resulting analysis matrix is determined as percentage

difference (∆D%):

100max_

),(),(),%(D 12

signif

jiMjiMji

Where:

1. ∆D% is the difference value

2. M1 is the 1st data set dose map (left side of the screen)

3. M2 is the 2nd data set dose map (right side of the screen)


January 12 - 36 - PN EP-00101-6

4. max_signif is the maximum significant dose as set in the menu Analysis Percentage dose

difference option Parameters.

For local approach, the local dose of each pixel in reference image is used as a reference. The

resulting analysis matrix is determined as percentage difference (∆D%):

100),(

),(),(),%(D

2

12

jiM

jiMjiMji

The difference levels are displayed according to scale set automatically between maximum and

minimum difference value. It is possible to change this scale by clicking Analysis Absolute dose

difference option Scale range.

Figure 26 - Example of percentage dose difference analysis in Athena module -

Eclipse dose versus measured dose for an Open field.

6.5.5 Analysis mode Gamma evaluation

Select Analysis Main Analysis Gamma to activate this evaluation mode. The gamma index

method is implemented as described by Low et al. [10]. Distance to agreement (DTA) and dose

difference (D%) values acceptance criteria can be set by the user in the menu AnalysisGamma

Option. Refer to Figure 27.

Figure 27 - Gamma evaluation options


January 12 - 37 - PN EP-00101-6

Similar as with percentage dose difference, this mode allows performing analysis with global or

local approach.

a. Global gamma analysis approach

D% is referred to the maximum significant dose per field of the reference image, test image or

any value defined by user. Maximum significant dose is defined as the maximum dose value in the

histogram of pixel values in the field minus the highest 5% (default) pixel values in the histogram.

The user can set this cut off value differently. This definition was introduced to avoid bias in the

analysis due to presence of high dose peaks in the measured data (e.g. due to faulty pixel in the

detector or due to extremely narrow high dose areas).

Figure 28 - Maximum significant dose definition

Figure 28 displays dose matrix of head & neck field with highlighted high dose peaks and

corresponding pixel dose histogram.

b. Local gamma analysis approach

For local approach, the local dose of each pixel in reference image is used as a reference.

The values are displayed according to a predefined colour scale where green is used for pixels

with <1 and red with >1.5.

Figure 29 displays and example of gamma analysis in Artemis module. Analysis window header

indicates the parameters of the evaluation including local or global approach. The bottom of the

analysis window contains more detailed information about the selected mode and its parameters. If

you performed analysis several times with different settings or modes, focus window contains the

history of all analyses. To return to any of the previous analyses, click on its header, drag, and

drop it in the graphics window.


January 12 - 38 - PN EP-00101-6

Figure 29 - Example of gamma analysis in Artemis module - Eclipse dose

versus measured dose for a RapidArc field.

c. Gamma options

Select Analysis Gamma options Parameters to open window allowing for detailed parameter

set up. Selecting Analysis Gamma options Colour scale allows user to customise the

graphics displaying the gamma analysis. Refer to Figure 30.

Figure 30 - Gamma options window


January 12 - 39 - PN EP-00101-6

6.5.6 Complementary analysis

This menu option is only active when performing analysis of the non-modulated fields. Its

functionality is explained in the dedicated Chapter 6.9 – Complementary analysis menu in Athena

module for Machine QA.

6.5.7 Reset collimator = 0 for PV

In case of Eclipse versus PV comparison; in case that dose calculation matrix was performed with

collimator angle equal to zero but PV images are acquired with the planned angle, toggle this

option before calculating the results.

If the treatment field has a collimator angle different from zero user can:

1. Calculate dose and acquire PV-images with the planned angle.

2. Calculate dose with collimator angle equal to zero (higher calculation sampling in the

leaves direction movement), and acquire PV-images with the planned angle.

3. Calculate dose and acquire PV-images with collimator angle equal to zero (higher

calculation sampling in the leaves direction movement and better use the PV detector size).

In this case RT-plan export needs collimator angle set to zero.

Note: For RapidArc demo cases “Reset coll=0 for PV” option is used and automatically

toggled on.

6.5.8 Gaussian convolution

With the Gaussian convolution option, the dose matrix computed by Epiqa is convolved with a

Gaussian distribution with a predefined sigma value. By default the Gaussian convolution is turned

off.

Figure 31 - Gaussian convolution parameters


January 12 - 40 - PN EP-00101-6

6.6 View menu options

Menu View allows user to customize the screen of the Epiqa programme. Click View Draw

Options to access list of objects. Click on the object name to change its status. Refer to Figure 32.

Figure 32 – Draw Options

6.6.1 CIAO Edge

Activate/deactivate the display of the intersections of the profile with the CIAO edges in the profile

plots.

Figure 33 - CIAO edge display in profile window

6.6.2 Graticule

Activate/deactivate the display of the graticule in the images.

6.6.3 PV dimension

Activate/deactivate the display of the PV cassette dimension on the analysis image.

6.6.4 Color scale

Activate/deactivate the display of the dose, gamma and dose difference colour scale.

6.6.5 Gamma Color

Activate/deactivate the display of the dedicate gamma colour scale.


January 12 - 41 - PN EP-00101-6

6.6.6 MI

Activate/deactivate the display of the Modulation Index value for reference and test dose matrices.

The concept of the modulation index as described for fluence in Webb S.: Phys Med Biol 2003,

48:2051-2062, was extended to dose matrices to evaluate the modulation of the dose matrices.

The Modulation Index, MI, is computed according to:

MI(F) = F

dffZ0

)( with F= 1.0

where Z(f) is the fraction of changes among adjacent pixels (in the two-dimensional frame) that

exceed a certain fraction (f) of the SD.

6.6.7 White background

The background of the profile and histogram windows is turned from black to white.

6.6.8 Zoom

Selecting View Zoom provides to user an option to zoom-in or zoom-out the display of the

results. Select desired function and click on the image in the area of interest.

6.6.9 Pan

With activation of pan function user can move zoomed images on the screen to review entire

zoomed dose matrix.

6.6.10 Reset Geometry

Clicking this menu option will reset all geometry changes and reload default view settings.


January 12 - 42 - PN EP-00101-6

6.7 Tool menu options

In the Tool menu, the following options are available.

Figure 34 - Tools menu

6.7.1 Histogram area

According to the selected analysis mode, histogram and statistics for the analysis matrix are

displayed. Refer to

Figure 35.

Figure 35 – Histogram area menu


January 12 - 43 - PN EP-00101-6

The field area as defined by the linac jaws is taken into account for histogram calculations by

default. Other calculation areas are selectable; the new active area contour is shown in blue in all

the three images, and related histogram is updated. Refer also to Figure 36.

Figure 36 - Example of Histogram tool: Eclipse dose versus

measured dose for an IMRT field.

The following options are available:

1. Field: field area as defined by the linac jaws

2. Field+1cm: field area as defined by the main jaws plus 1 cm in each direction

3. CIAO: Completely Irradiated Area Outline as defined by the “extreme” MLC positions for

each leaf

4. ROI rect: rectangular ROI - click left mouse button in any of the three windows (1st or 2nd

dose data set, analysis image) and draw desired rectangle, click again to finish.

5. ROI irr: irregular ROI - free draw ROI can be defined in any of the three windows (1st or 2nd

dose data set, analysis image); click each point of the desired contour and close it with a

right mouse click.

The statistics parameters proposed in the histogram window are:

a. According to the select analysis mode, in Gy or in % or as gamma value

1. mean

2. standard deviation

3. median

4. maximum

5. minimum

b. The correlation coefficient between 2nd data set (M2) and 1st data set (M1) dose matrices:


January 12 - 44 - PN EP-00101-6

correlation 12

121,2

),cov(

MM

MM

MM

that results in 11 1,2 MM

Refer to Nicolini et al [5] for detailed description.

c. Number of tested points.

d. For gamma method:

1. % of points in the defined area with >1 ( points failing the acceptance criteria)

2. % of points in the defined area with 1< <1.5

3. % of points in the defined area with >1.5

4. Gamma agreement index (GAI [%] ) = 100% - % of points with >1 in the defined area.

6.7.2 Enable profiles

Profile plots are always displayed in absolute dose [Gy]; solid red line for 1st data set, cyan dashed

line for 2nd data set. Profiles are displayed along the main axes through the field isocenter by

default.

A light-grey line shows the intersection with corresponding orthogonal profile; white lines display

CIAO edges at the profile position. By clicking the „Profiles‟ button in the analysis options toolbar

you can activate interactive x and/or y profiles. You can define the profiles position(s) in any of the

three windows (1st or 2nd data set dose, analysis image). The new coordinates are shown in the

graph titles. Refer also to Figure 37.

Figure 37 - Example of Profile tool: Eclipse dose versus measured

dose for a RA field.

6.7.3 Export profiles

Profiles parallel to the main axes can be exported in ASCII format. The coordinates of the

intersection of two profiles can be set to the beam central axis, the centre of mass of the field or by

x

y


January 12 - 45 - PN EP-00101-6

coordinates. The profiles are computed by averaging of n adjacent pixel lines, as defined by the

user in the “Average export profile over n contiguous profiles”. Refer to Figure 38.

Figure 38 - Export profiles definitions

6.7.4 Manual Alignment

Epiqa software performs auto centring of the reference (measured) image isocenter based on the

information about image position from DICOM file and 10x10 reference field. After initial calculation

of the results user may shift reference image vs. calculated by choosing menu function „Manual

alignment tool‟. Click „Up‟, ‟Down‟, ‟Left‟ or „Right‟ button for desired shift by one pixel. Programme

will instantly recalculate the gamma analysis results. The pixel size displayed in the window

depends on the type of the imager used and cannot be changed. Maximum allowed shift is 10 mm.

Refer to Figure 39.


January 12 - 46 - PN EP-00101-6

Figure 39 - Manual alignment tool

6.7.5 Point dose

Click the „Point Dose‟ button in the analysis options toolbar and move the mouse on one of the

three images (1st, 2nd data set or analysis image). According to the mouse position (shown with a

cross), the following information is displayed underneath the colour scale window:

1. x and y point position coordinates (respect to the isocenter)

2. Absolute point dose values for both data set matrices (in Gy)

3. Point value of the analysis matrix (according to the selected analysis mode)

Figure 40 - Point dose analysis

6.7.6 Preferences

User definable preferences can be set. Menu Preferences is separated into 10 different tabs.

a. General 1

This part of the preferences allows user to select default main analysis parameters

1. Measurement Set-up condition – no build-up, dmax or mix (refer to paragraph 4.1.1).

2. Analysis mode – Dose difference, Percentage dose difference, GAM (refer to paragraph

6.5.2).

3. Calculation area – additional margin of 4 cm, 8 cm, 10 cm, 15 cm to the field size or whole

detector area (40x30 cm2) can be set as default.


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Figure 41 - General options

4. Automatic activation of the option to reset collimator rotation to 0 - for module Hera and

Artemis.

5. Set up of default for automatic activation of Gaussian convolution tool with desired sigma

value.

6. Autocenter parameters – define the maximum shift of the reference image (in x and y

direction) that the system can use during the automatic centring procedure (minimization of

punctual difference between test and reference image). Max settable value is 5mm.

b. General 2

1. Debugging log file – Enable (On) the generation of complete debugging file. By default the

debugging log is disabled and only the error log file is generated.

2. Default open folder – Default folder for data file loading.

3. Automatic move DICOM folders – automation of the patient input data management. Using

function File Create new user can create file data structure for new patient. Automove

patient data functionality allows for automatic data transfer from DICOM export directories

to patient working directories. Epiqa recognizes patient data according to the file names

and moves all relevant data to appropriate folders even if the DICOM export folders contain

data of several patients. In order for this transfer to work, DICOM Export filter must be

properly configured to include Patient ID in the exported file name.

The DICOM export folders must have different names; e.g. RTP plan, Eclipse dose and

images must be exported into its own directories. See example in Figure 41.

4. Option to set loading of all data in one step – Activating the ‟Load all data in one step‟

option after selection of the RT-plan file, both the test and references image files are

automatic loaded too. This option needs that patient data are organized according the


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standard Epiqa patient folders tree. This folder structure is automatically created when the

„Create new patient‟ function is used.

c. Percentage difference analysis

A wide number of setting options for Percentage Difference Analysis is introduced and user can

save his own specific setting in the preference menu. User has option to choose from global or

local analysis. Refer also to paragraph 6.5.4.

Figure 42 - Dose percentage difference and gamma analysis preference settings

d. Gamma analysis

The set DTA criteria in mm is converted in a integer number of pixels for maximum search distance

purposing; this means that the actual value in mm for the search rounding depends on the

resolution of the analyzed matrices. A wide number of setting options for gamma analysis was

introduced. User can save his own specific setting in the preference menu and choose from global

or local analysis.

e. Protocol

Institution logo for protocol – allows adding hospital‟s logo to printed protocol.

f. Profiles

This part of preferences settings allows customising the profiles display. User has option to set

static or dynamic profiles display, colour, and appearance of the profiles on the screen.

g. Eclipse dose geometry

Set the geometry of the reference TPS dose calculation. For geometry (0,0) the user must export

frontal dose plane; for geometry (90,90) the export of transversal slice is needed.


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Figure 43 - Epiqa preferences selection

h. Epiqa parameter file

Using this tab user can define the current working Epiqapar.dat file location. In case that other then

default location was selected during the data configuration process, it is mandatory to specify

where the program should look for the calibration data. It is possible to use multiple parameter files

and switch between them, such as clinical and experimental calibration. Refer to Figure 44. Epiqa

supports the network location of parameter file. Using shared location on the network allows for

sharing of the configuration parameters in case of running Epiqa at several workstations

Figure 44 - Selecting Epiqa parameter file location


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i. Histogram

This selection provides user with the option to set preferred area at which is histogram analysis

calculated. Bin parameter defines the gamma values step in the histogram.

j. View

View tab allows user to specify which graphical objects are displayed as default. Refer to

paragraph 6.6 - View menu options for more details.

6.7.7 The Protocol

The protocol generated in html format contains the results of the gamma analysis (if other analysis

modes are set, the protocol is currently not available).

A text can be added for comment or description before creating the protocol. A file in html format is

saved in the patient directory and opened with the user-associated program (e.g. Internet Explorer

Browser).

The information available in the protocol includes:

1. Institution name

2. Patient information: name, ID, date of birth, sex (from RT-plan)

3. Plan information: plan ID, Machine, dose prescription

4. Acquisition information: detector model (aS500/aS1000), acquisition date, patient directory

name for the QA, Epiqa calibration date and depth.

5. QA results: field characteristics (name, jaw setting, MU, split or not), gamma analysis

results according to the selected calculation area.

Figure 45 - Example of protocol generated by Artemis for RapidArc QA


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6.7.8 Field properties

For each field the geometric and dosimetric field properties are shown.

Figure 46 - Field Properties


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6.8 RapidArc commissioning tests analysis in Artemis module

To check the linac accuracy in delivery RapidArc plans, Artemis offers a dedicated analysis tool

which allows the user verifying linac performance following pre-defined tests on MLC, dose rate

and gantry speed accuracy. Those tests are based on the official Varian tests for RapidArc

commissioning and described in Ling et al [8]. It is expected that all tests are performed by utilising

Integrated Image acquisition during the test field delivery.

The RapidArc commissioning tests are accessible by selecting File RapidArc commissioning.

Figure 47 – RapidArc commissioning access.

A window opens where user can select the QA tests to for which he desires to perform results

analysis. Refer to Figure 48.

Figure 48 – RapidArc commissioning selection.

The tests are grouped in prerequisite tests and RapidArc specific commissioning tests. The tests

numbers and names relate to original Varian‟s document “RapidArc commissioning” [9].

Prerequisite tests:

1. Test 0.1: dMLC Dosimetry - Measure the linac output at gantry angles 0°, 180°, 90° and

270° for a 4x10 cm DMLC sliding window field with a 0.5 cm slit to test the effect of the

gravity on leaf position and linac dosimetry system.

2. Test 0.2: Picket Fence test versus gantry angle - Picket fence test at stationary gantry

angles – for subsequent comparison with tests during RapidArc.


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RapidArc commissioning tests:

1. Test 1.1: Picket Fence test during RapidArc - To test the effect of gantry rotation on the

MLC positional accuracy.

2. Test 1.2: Picket fence test during RapidArc with intentional errors - To demonstrate

that test 1.1 can detect sub-millimetre errors during RapidArc.

3. Test 2: Accurate control of Dose Rate and Gantry Speed during RapidArc delivery -

This test uses seven combinations of dose-rate, gantry range and gantry speed to give

equal dose to seven 1.8 cm wide strips in a single RapidArc field.

4. Test 3: Accurate control of Leaf Speed during RapidArc delivery - This test uses four

combinations of leaf speed and dose-rate to give equal dose to four strips in a single

RapidArc field.

After user selects test to perform, Epiqa will proceed from one test another, allowing user to

accept, or not, the results and to record results in a protocol. The type of MLC equipment

(Millennium 120 or Millennium HD 120) must be defined before starting the tests.

Each test opens specific data entry window to load the acquired images. Title bar of each window

informs user about expected number of images to load and the test type.

Figure 49 – Get files window for Test 0.1.

Upon successful image loading, Artemis displays acquired images for analysis. Each specific test

window provides a toolbar on the right side. Refer to Figure 50 for the button function explanation

Figure 50 – RapidArc commissioning toolbar.

Load images

Profiles: click on image

Add results to report and go to next test

Go to next test

Reload images

Restart RapidArc commissioning from beginning


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6.8.1 Test 0.1: dMLC Dosimetry

For the test 0.1 the values (in a.u.= arbitrary units) of a central ROI are displayed, as well as the

deviation from the reference value, defined as the average over the four images ROI value.

Profiles are not available for this test. Refer to Figure 51.

Figure 51 – Test 0.1: results.

Click on button to add the results to protocol and proceed to the next test. Provide acceptance

information and comment in the next window. Refer to Figure 52.

Figure 52 – Test 0.1, Test 2, Test 3: acceptance window.


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6.8.2 Test 0.2: Picket Fence test versus gantry angle

Load four Picket Fence test patterns acquired in all four main gantry angles. The analysis window

displays the picket fence pattern. Refer to Figure 53.


In Test 0.2 the profile button is active. Click on the button and choose X-prof in the related pop-up

(refer to Figure 54). This tool allows the user to scroll, leaf per leaf, on all loaded images; the leaf

number is displayed in the plot title. In case the ASCII profile export is desired click File Expprof.

Program allows to export profile of single or all MLC leaf pairs in Excel format. An .xls file

containing the current or all profiles is saved in the folder containing the test images.

Figure 54 - X profile selection




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Figure 55 – Test 0.2, Test 1.1: acceptance window.

6.8.3 Test 1.1: Picket Fence test during RapidArc

In Test 1.1, similarly to Test 0.2, Artemis manages the profiles across the acquired image. Green

profile corresponds to the green line position in the left window; two previous leave profiles are

displayed in cyan, and two next ones in red colour. Refer to Figure 56.





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6.8.4 Test 1.2: Picket fence test during RapidArc with intentional errors

In Test 1.2, similarly to Test 1.1, Artemis manages the profiles across the acquired image. Green

profile corresponds to the green line position in the left window; two previous leave profiles are

displayed in cyan, and two next ones in red colour. Refer to Figure 57.




Figure 58 – Test 1.2: acceptance window.


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6.8.5 Test 2: Accurate control of Dose Rate and Gantry Speed during RapidArc delivery

To analyse linac performance in delivering correct dose with variable dose rate and gantry speed

Test 2 suggests to acquire also open field image to compensate for beam profile (refer to [9]).

Artemis is capable to perform this correction for exact dose delivery analysis. Upon entering Test

2, a window opens allowing user to browse for both image files that have to be used; the RapidArc

test image (called T2_DR_GS) and the open field image. Refer to Figure 59.

Figure 59 – Test 2: get two different files.

In Test 2, both acquired images are displayed, as well as the ratio of the two. In the upper right

image, pre-defined ROIs are displayed together with their values (in a.u.). Deviations from the

reference value, defined as the average value of all the ROIs are shown with the recommended

tolerance value of 2%. Profiles managed by Artemis are displayed in the lower right image. Refer

to Figure 60.

Figure 60 – Test 2: results.




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6.8.6 Test 3: Accurate control of Leaf Speed during RapidArc delivery

To analyse linac and MLC performance in delivering correct dose with variable leaf speed and

dose rate. Test 3 suggests to acquire also open field image to compensate for beam profile (refer

to [9]). Artemis is capable to perform this correction for exact dose delivery analysis. Upon entering

Test 3, a window opens allowing user to browse for both image files that have to be used; the

RapidArc test image (T3MLCSpeed) and the open field image. Refer to Figure 61.

Figure 61 – Test 3: get two different files.

In Test 3, both acquired images are displayed, as well as the ratio of the two. In the upper right

image, pre-defined ROIs are displayed together with their values (in a.u.). Deviations from the

reference value, defined as the average value of all the ROIs are shown with the recommended

tolerance value of 2%. Profiles managed by Artemis are displayed in the lower right image. Refer

to Figure 62.

Figure 62 – Test 3: results.




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6.8.7 RapidArc commissioning test report

Concluding all the test, if a reporting was selected is user asked to select desired saving directory

and has the possibility to add a report comment. A file in html format is saved and opened with the

user-associated program (e.g. Internet Explorer Browser).

Figure 63 – RapidArc commissioning

tests report.


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6.9 Complementary analysis menu in Athena module for Machine QA

In addition to the 2D dose matrices analysis tools, Athena module offers a set of dedicated

analysis tools and protocols for radiation beam QA. There are four options available in Analysis

Complementary Analysis menu, which are active according to the RT-plan properties that are

automatically detected by Epiqa:

1. Output factor (Open – Hard wedge – Enhance Dynamic Wedge fields)

2. Wedge factor (Hard wedge – Enhance Dynamic Wedge fields)

3. Profile analysis (Open – Hard wedge – Enhance Dynamic Wedge fields)

4. PDD: percentage dose depth (Open and dedicated phantom)

User definable parameters are calculated for the two loaded data set (Eclipse-PV, PV-PV, Eclipse-

Eclipse).

6.9.1 Output Factor

In menu bar select Analysis Complementary Analysis Output factor. Select the ROI

characteristics for the average dose reading (DFn = dose for the Field n) and the reference Field

(Fr). Refer to Figure 64.

Figure 64 - Output factor calculation parameters

The output factor is derived as: OF = DFn / DFr. These parameters can also be changed in the

results windows by selecting Options Set parameter.

A table showing the results for all the fields in the RT-plan and for both data sets is displayed.

Figure 65 - Output Factor results table in Epiqa: Eclipse dose versus

PV measured dose for square and rectangular fields

.


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A report can be generated by clicking File Report. The report file in html format is saved in the

patient directory and directly opened with the user-associated program (e.g. Internet Explorer

Browser).

Figure 66 - Example of Output Factor Report

6.9.2 Wedge Factor

From menu bar select Analysis Complementary Analysis Wedge factor. The wedge factor is

derived as:

Wedge Factor = DFn / DFr

where DFn is the dose of Field n and DFr is the open field reference dose.

A table showing the results for all the fields in the RT-plan and for both data sets is displayed.

Figure 67 - Example of Wedge Factor results table: Eclipse dose versus

PV measured dose for Enhance Dynamic Wedges Fields


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User can set ROI characteristics for the average dose reading and the reference field by selecting

Options Set parameter.

A report can be generated by clicking File Report. The report file in html format is saved in the

patient directory and directly opened with the user-associated program (e.g. Internet Explorer

Browser).

6.9.3 Profile analysis

From menu bar, select Analysis Complementary Analysis Profile analysis. X-Y profiles and a

table of related parameters is displayed; you can switch between the fields using the scroll bar.

Use View menu to activate or deactivate X and/or Y profiles in any data set.

The profiles can be renormalized by selecting Options Normalization. Refer to Figure 68.

Figure 68 - Profile normalization options

Figure 69 - Example of Profiles analysis: Eclipse dose versus

PV measured dose for an open field.

The profile analysis parameters and their definition are user configurable according to pre-defined

options in. Select Options Set Parameters.


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Figure 70 - Profile analysis parameters definition

A report can be generated by clicking File Export Report. The report file in html format is

saved in the patient directory and directly opened with the user-associated program (e.g. Internet

Explorer Browser).

Figure 71 - Example of the profile report


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6.9.4 Percentage Depth Dose (PDD)

For a RT-plans containing open static fields, the PDD option becomes active.

The depth dose analysis tool implemented in Athena module requires calculating and acquiring

square field using a plastic (PMMA) phantom with four different thicknesses, which is delivered

together with the software.

Figure 72 - Plastic phantom for beam energy verification

The L shaped phantom geometry creates four sectors of different dose levels (see BEV in Figure

73). Thickness, density and centre of each sector are user configurable. It is recommended to keep

one sector corresponding to the set-up configuration in use; this means no phantom material for

“no build-up” and “mix” configuration and additional build up to reach depth of maximal dose for

“dmax” configuration. (e.g. sector D in Figure 73).

Figure 73 - Percentage Depth Dose analysis

The PV image is acquired with the PDD phantom placed on the PV cassette. The Eclipse dose

matrix is computed for an analogous PDD phantom.

The nominal density of the phantom material supplied with Epiqa software is 1.19 g/cm3. However

it is suggested to verify the density of the phantom before first use using precise scales.

Figure 74 provides an example of the results for 6 MV X-rays.


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Figure 74 - Example of PDD analysis

References Epiqa Reference Guide

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7 REFERENCES

1. Nicolini G, Fogliata A, Vanetti E, Clivio A, Cozzi L: GLAaS - an absolute dose calibration

algorithm for an amorphous silicon portal imager. Applications to IMRT verification. Med Phys

2006; 33: 2839-2851.

2. Nicolini G, Fogliata A, Vanetti E, Clivio A, Vetterli D, Cozzi L: Testing the GLAaS algorithm for

dose measurements on an amorphous silicon portal imager on low and high energy photon

beams. Med Phys 2008; 35: 464-472.

3. Nicolini G, Vanetti E, Clivio A, Fogliata A, Boka G, Cozzi L: Testing the portal imager GLAaS

algorithm for machine quality assurance. Radiation Oncology 2008; 3:14

4. Nicolini G., Vanetti E., Clivio A., Fogliata A., Korreman S., Bocanek J., Cozzi L: The GLAaS

algorithm for portal dosimetry and quality assurance of RapidArc, an intensity modulated

rotational therapy, Radiation Oncology 2008, 3:24

5. Nicolini G, Fogliata A, Vanetti E, Clivio A, Ammazzalorso F, Cozzi L: What is an acceptably

smoothed fluence? Dosimetric and delivery considerations for dynamic sliding window IMRT.

Radiation Oncology 2007; 2:42

6. Webb S: Use of a quantitative index of beam modulation to characterize dose conformality:

illustration by a comparison of full beamlet IMRT, few-segment IMRT and conformal

unmodulated radiotherapy. Phys Med Biol 2003, 48:2051-2062

7. Ann Van Esch, Tom Depuydt, Dominique Pierre Huyskens: The use of an aSi-based EPID for

routine absolute Dosimetric pre-treatment verification of dynamic IMRT fields. Radiotherapy

and Oncology 71 (2004) 223–234

8. Ling CC, lZhang P, Archambault Y, Bocanek J, Tang G, LoSasso T: Commissioning and

Quality Assurance of RapidArc™ Radiotherapy Delivery System. Int J Radiat Oncol Biol Phys

2003, 72: 575–581

9. Varian Medical Systems: RapidArc commissioning, procedure. Education Department

customer support document, available at my.varian.com

10. Low DA, Harms WB, Mutic S, Purdy JA. A technique for the quantitative evaluation of dose

distribution. Med Phys 1998, 25: 656-660

http://www.ro-journal.com/content/3/1/14#refs

http://www.ro-journal.com/content/2/1/42

http://my.varian.com/

Epiqa Reference Guide

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Documents

Epiqa Demo Manual Version 2.2.1 Final