ICRU Recommended Dose and Volume Specification for ... · PDF fileICRU Recommended Dose and Volume Specification for Reporting Interstitial Brachytherapy ICRU Recommended Dose and

ICRU Recommended Dose and Volume Specification for Reporting Interstitial

Brachytherapy

ICRU Recommended Dose and Volume Specification for Reporting Interstitial

Brachytherapy

Ali S. Meigooni, Ph.D.

University of Kentucky Medical Center, Department of Radiation Medicine

Lexington, KY

Ali S. Meigooni, Ph.D.

University of Kentucky Medical Center, Department of Radiation Medicine

Lexington, KY

Table of ContentsTable of ContentsIntroductionDefinitions of Terms and Concepts

Temporary and Permanent ImplantsSource SpecificationDescription of Source PatternsTotal Reference Air KermaVolume and PlanesDescription of Dose Distribution

Time Dose FactorsDefinition of Quantities

Absorbed doseThe Kerma (Kinetic Energy Released in MatterThe activityThe air kerma-rate constant, ΓδRelationship Between the QuantitiesReference Air Kerma Rate

IntroductionIntroductionDefinitions of Terms and ConceptsDefinitions of Terms and Concepts

Temporary and Permanent ImplantsSource SpecificationDescription of Source PatternsTotal Reference Air KermaVolume and PlanesDescription of Dose Distribution

Time Dose FactorsDefinition of QuantitiesDefinition of Quantities

Absorbed doseThe Kerma (Kinetic Energy Released in MatterThe activityThe air kerma-rate constant, ΓδRelationship Between the QuantitiesReference Air Kerma Rate

Table of Contents (continue)Recommendations For Recording and Recommendations For Recording and ReportingReporting

Parameters Required for Recording and ReportingPriority

Practical Applications of the Practical Applications of the RecommendationsRecommendations

Temporary ImplantsPermanent ImplantSingle Stationary Source LineMoving SourcesSurface Applicators

IntroductionIntroductionWith the introduction of miniaturized

brachytherapy sources, the sophisticated 3-D source localization methods have been introduced, which can be linked to computerized methods for dose calculation. Therefore, a common language is valuable to provide a method of dose specification and reporting which can be used for implants of all types of interstitial brachytherapy procedures.

With the introduction of miniaturized brachytherapy sources, the sophisticated 3-D source localization methods have been introduced, which can be linked to computerized methods for dose calculation. Therefore, a common language is valuable to provide a method of dose specification and reporting which can be used for implants of all types of interstitial brachytherapy procedures.

Introduction (continue)Introduction (continue)1985: ICRU Report 38,

Was written regarding the Dose and volume specification as well as reporting intracavitary Brachytherapyin GYN.

1997: ICRU Report 58,

Was written to generate a guideline about the dose specification and reporting for interstitial Brachytherapy


Was written regarding the Dose and volume specification as well as reporting intracavitary Brachytherapyin GYN.


Was written to generate a guideline about the dose specification and reporting for interstitial Brachytherapy

Introduction (continue)Introduction (continue)The aim of the report 58 was to develop a common language that was based on the presently existing concepts.

In this presentation, the ICRU-58 recommended concepts and procedures for dose specifications and reporting of the interstitial brachytherapy implants will be reviewed.

The aim of the report 58 was to develop a common language that was based on the presently existing concepts.

In this presentation, the ICRU-58 recommended concepts and procedures for dose specifications and reporting of the interstitial brachytherapy implants will be reviewed.

Definitions of Terms and ConceptsDefinitions of Terms and ConceptsTemporary

The radioactive sources are removed from the tissue after the treatment is completed

Permanent ImplantsThe brachytherapy sources remain in the patient, and they will not be removed.

Temporary The radioactive sources are removed from the tissue after the treatment is completed

Permanent ImplantsThe brachytherapy sources remain in the patient, and they will not be removed.

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Definitions of Terms and Concepts(Continue)


Traditionally, the temporary implants were performed with the linear (wires) radioactive sources or seeds arranged in a linear fashion (i.e. ribbons, etc.). However, in a permanent implants, multiple loose sourceswere distributed in random orientations.

Traditionally, the temporary implants were performed with the linear (wires) radioactive sources or seeds arranged in a linear fashion (i.e. ribbons, etc.). However, in a permanent implants, multiple loose sourceswere distributed in random orientations.

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With the design of the low energy radioactive sources in the form of stranded seeds or radioactive wires, now the permanent implant can also be performed with linear or pre-arranged ribbons. The loose seed implants are considered separately in this report.

With the design of the low energy radioactive sources in the form of stranded seeds or radioactive wires, now the permanent implant can also be performed with linear or pre-arranged ribbons. The loose seed implants are considered separately in this report.

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Planning temporary implants, The total time of implantation depends on

a. Number of sources, b. Strengths and source c. Pattern of distribution of sources

Planning temporary implants, The total time of implantation depends on

a. Number of sources, b. Strengths and source c. Pattern of distribution of sources

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Planning permanent implants, The number of sources depends on

a. Their initial strength, b. Type of the radioisotope.

Planning permanent implants, The number of sources depends on

a. Their initial strength, b. Type of the radioisotope.

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Planning Boost permanent and temporary implants,The number of seeds and the initial activity of the seeds are adjusted upon the external beam radiation dose.

Planning Boost permanent and temporary implants,The number of seeds and the initial activity of the seeds are adjusted upon the external beam radiation dose.

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Definition of QuantitiesDefinition of Quantities

Absorbed dose

The mean energy imparted by the radiation to a unit mass of medium

The Kerma (Kinetic Energy Released in Matter

The sum of the initial kinetic energies of all the ionizing charged particles liberated by uncharged ionizing particles.

Absorbed dose

The mean energy imparted by the radiation to a unit mass of medium

The Kerma (Kinetic Energy Released in Matter

The sum of the initial kinetic energies of all the ionizing charged particles liberated by uncharged ionizing particles.

dmd

D ε= 1Gy = 1J/Kg

dmdE

K tr= 1Gy = 1J/Kg1Gy = 1J/Kg

Definition of Quantities (continue)Definition of Quantities (continue)The activity

Number of disintegration of a radioactive nucleus per second (dps).

The air kerma-rate constant, Γδ,

The activity

Number of disintegration of a radioactive nucleus per second (dps).

The air kerma-rate constant, Γδ, dtd

A Ν= The SI unit : s-1

The SI unit : J.kg-1m2The SI unit : J.kg-1m2

Aδ =Γ Kδ&2

l

Where is the air kerma rate due to photons of energy greater than δ, at a distance, , from a point source, with activity of A.

δK&

l

Definition of Quantities (continue)Definition of Quantities (continue)Relationship Between the Quantities

Where:

g = part of the kerma that is lost to bremsstrahlung in medium.

(μtr) = energy transfer coefficient for the medium

Reference Air Kerma Rate Reference Air Kerma Rate = Air Kerma Rate at a reference point of 1

cm or 1 m

1U = 1 μGy m2 h-1 = 1 cGy cm2 h-1

Relationship Between the Quantities

Where:

g = part of the kerma that is lost to bremsstrahlung in medium.

(μtr) = energy transfer coefficient for the medium

Reference Air Kerma Rate Reference Air Kerma Rate = Air Kerma Rate at a reference point of 1

cm or 1 m

1U = 1 μGy m2 h-1 = 1 cGy cm2 h-1

KD trairm

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Source Strength Specification Source Strength Specification ),,()(

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Pre-1995

a. App. mCi (Aapp)

b. mgRaEq.

Post-1995 (TG-43 recommendation)

a. air kerma strength μGy . h-1. m-1 or cGy . h-1. cm-1 (U)

Total Reference Air Kerma(TRAK)

Total Reference Air Kerma(TRAK)

Where;

Si = Reference air kerma rate for each source

ti = Irradiation time for each source

Where;

Si = Reference air kerma rate for each source

ti = Irradiation time for each source

iiS.tTRAK ∑=

This quantity is analogous to mg.hThis quantity is analogous to mg.h

Description of Source PatternsDescription of Source Patterns),,()(

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single plane: implant is defined as an implant containing two or more sources, which lie in the same plane

two-plane (double-plane): implant contains two planes, which are generally parallel to each other

Multi-plane: implant, contains three or more planes

non-planer: sphere or cylinder

single plane: implant is defined as an implant containing two or more sources, which lie in the same plane

two-plane (double-plane): implant contains two planes, which are generally parallel to each other

Multi-plane: implant, contains three or more planes

non-planer: sphere or cylinder

GTV

CTV

PTV

TV

IV

Volume and Planes (ICRU 50)Volume and Planes (ICRU 50)

Volume and PlanesVolume and Planes

Gross Tumor Volume (GTV)The palpable or visible/demonstrable extent

and location of the malignant growth.

Clinical Volume (CTV)The volume of the tissue that contains a gross tumor volume and/or subclinical microscopic malignant disease which has to be eliminated.

Volume and Planes (continue)Volume and Planes (continue)Planning Target Volume (PTV)

The volume of tissue receiving the prescribed irradiation.

For an interstitial brachytherapy, the PTV is, in general, identical to the CTV.

Treatment Volume (TV)The volume of tissue, which is encompassed by an isodose surface that has been specified by the radiation oncologist.The dose value at this isodose surface is the minimum target dose

Planning Target Volume (PTV)The volume of tissue receiving the prescribed irradiation.

For an interstitial brachytherapy, the PTV is, in general, identical to the CTV.

Treatment Volume (TV)The volume of tissue, which is encompassed by an isodose surface that has been specified by the radiation oncologist.The dose value at this isodose surface is the minimum target dose

CTVCTV

The maximum diameters measured in three orthogonal directions must be reportedThe maximum diameters measured in three orthogonal directions must be reported

Central PlaneCentral Plane

The plane that is perpendicular to the main direction of the linear sources and passing through the estimated center of the implant.


Central Plane (continue)Central Plane (continue)The plane that is perpendicular to the main

direction of the linear sources and passing through the estimated center of the implant.


Description of Dose DistributionDescription of Dose DistributionInterstitial Brachytherapy Implants:Interstitial Brachytherapy Implants:

Non Homogeneous dose distribution

High Regions around the sources

Regions of plateau doseor local minimum doses

Dose Distribution in One or More Planes Through the Implant

Dose Distribution in One or More Planes Through the Implant

The minimum information needed for the dose distribution of an implant is,

The isodose curves in at least one plane either in tabular form or by graphical presentation

The central plane of the implant should be used, If only one plane is chosen.

The minimum information needed for the dose distribution of an implant is,

The isodose curves in at least one plane either in tabular form or by graphical presentation

The central plane of the implant should be used, If only one plane is chosen.

Prescription Dose Prescription Dose

The prescribed dose is defined as the dose, which the physician intends to give, and enters in the patient’s treatment chart.

Minimum Target Dose (MTD):The minimum dose at the periphery of the CTV = Minimum dose decided upon by the clinician as adequate to treat the CTV (minimum peripheral dose).

MTD ≅ 90% of the prescribed dose in the Manchester system for interstitial therapy

The prescribed dose is defined as the dose, which the physician intends to give, and enters in the patient’s treatment chart.

Minimum Target Dose (MTD):The minimum dose at the periphery of the CTV = Minimum dose decided upon by the clinician as adequate to treat the CTV (minimum peripheral dose).

MTD ≅ 90% of the prescribed dose in the Manchester system for interstitial therapy

Prescription Dose (continue) Prescription Dose (continue) Mean Central Dose (MCD) : Dm

The minimum dose at the periphery of the CTV

= Arithmetic mean of the local minimum doses between sources, in the central planes.

Mean Central Dose (MCD) : Dm

The minimum dose at the periphery of the CTV

= Arithmetic mean of the local minimum doses between sources, in the central planes.

Prescription Dose (continue) Prescription Dose (continue) Mean Central Dose (MCD) : Dm

Prescription Dose (continue) Prescription Dose (continue) High Dose Volume

The volume of tissue that is encompassed that will receive more than 150% of the mean central dose be reported.

Low Dose VolumeA low dose volume should be defined as a volume within the clinical target volume, encompassed by an isodose corresponding to 90% of the prescribed dose. The maximum dimension of the low dose volume in any plane calculated should be reported.

High Dose VolumeThe volume of tissue that is encompassed that will receive more than 150% of the mean central dose be reported.

Low Dose VolumeA low dose volume should be defined as a volume within the clinical target volume, encompassed by an isodose corresponding to 90% of the prescribed dose. The maximum dimension of the low dose volume in any plane calculated should be reported.

Prescription Dose (continue) Prescription Dose (continue) Dose Uniformity Parameters

ICRU defines the following two methods for the dose uniformity

i. The spread of the individual minimum doses used to calculate the mean central dose in the central plane (expressed as a percentage of the mean central dose).

ii. The dose homogeneity index; defined as the ratio of minimum target dose to the mean central dose.

Dose Uniformity ParametersICRU defines the following two methods for the dose uniformity

i. The spread of the individual minimum doses used to calculate the mean central dose in the central plane (expressed as a percentage of the mean central dose).

ii. The dose homogeneity index; defined as the ratio of minimum target dose to the mean central dose.

Time Dose Factors Time Dose Factors Time and Dose Rates for Temporary Implants

Time = Prescribed dose/initial dose rateTime Dose Pattern for Temporary Implants

a. Continuous irradiation

b. Non-continuous irradiation

c. Pulsed irradiation

Time and Dose Rates for Temporary Implants

Time = Prescribed dose/initial dose rateTime Dose Pattern for Temporary Implants

a. Continuous irradiation

b. Non-continuous irradiation

c. Pulsed irradiation

Recommendations for Recording and Reporting

Recommendations for Recording and Reporting

Parameters Required for Recording and Reporting

Description of Volumes : GTV, PTV, ….

Description of Sources :

Radioisotope and filtration

Pattern of source distribution

Description of Technique and Source pattern

Parameters Required for Recording and Reporting

Description of Volumes : GTV, PTV, ….

Description of Sources :

Radioisotope and filtration

Pattern of source distribution

Description of Technique and Source pattern

Practical Applications of the Recommendations

Practical Applications of the Recommendations

Temporary Implants : Table 1.

Permanent Implant: Table 2

Single Stationary Source Line: Table 3

Moving Sources: Table 4

Surface Applicators : Table 5

Temporary Implants : Table 1.

Permanent Implant: Table 2

Single Stationary Source Line: Table 3

Moving Sources: Table 4

Surface Applicators : Table 5

Parameters for reporting temporary interstitial implants

Prioritya Levelb of computation

Description of Volume (3.A.i):Gross Tumor VolumeClinical Target VolumeTreated Volume (2.6.4)

111

113

Description of Source and Technique (3.A.ii, 3.A.iii)

Radionuclide, type of sourcSource size and shape, source patternReference air Kerma rateInactivity vector (applicator), if any

1 1

Description of Time Pattern (3.A.iv) 1 1Total Reference Air Kerma (3.A.v) 1 1

Table 1: Levels of priority for reporting temporary interstitial implants

Parameters for reporting temporary interstitial implants


Description of Dose (3.A.vi):a. Prescribed dose including point or surface

of prescriptionc.Reference Dose in Central Plane

a. Mean Central Doseb. Minimum Target Dos

1

11

1

22

Description of High and Low Dose volume (2.F.vi,2.F.vii)

2 3

Uniformity Parameters (2.6.8) 3 3Alternative Representation of Dose Distribution (2.F.ix)

3 3

Dose Rates at point or surface of prescription (2.G.ii, 2.G.iii)

3 3

Table 1: Levels of priority for reporting temporary interstitial implants (Cont.)

a. Priority1 Concerned with doses in the central plan2 Required calculations outside the central plan. If this is

not available, then a more detailed description of source pattern under priority 1 is required.

3 Additional information mostly of clinical research interest

b. Level of computation

1. No computer needed2. Hand calculation and/or computer calculation in central

plane.3. 3-D computation needed

c. Essential to establish consistent reporting and related to past experience, necessary for comparison of brachytherapy data and for relating outcome to treatment. If a classical system is used, the system should be identified.

Parameters for reporting permanent interstitial implants


Description of Volume (3.A.i):

Gross Tumor VolumeClinical Target VolumeTreated Volume (2.6.4)

111

113

Description of Source and Technique (3.A.ii, 3.A.iii)Radionuclide, type of sourceSource size and shape, source patternReference air Kerma rateInactivity vector (applicator), if any

1 1

Total Reference Air Kermac (3.A.v) 1 1

Description of Dose (3.A.vi):Prescribed dose including method of prescription.Reference Dose in Central Planea. Mean Central Doseb. Minimum Target Dose

1

11

1

22

Description of High and Low Dose volume (2.F.vi,2.F.vii) 2 3

Uniformity Parameters (2.F.viii) 3 3

Alternative Representation of Dose Distribution (2.F.ix) 3 3

Table 2: Levels of priority for reporting permanent interstitial implants.

Parameters for reporting implants with a single stationary source line


Description of Volume (3.B.1):

Gross Tumor VolumeClinical Target VolumeTreated Volume

111

113

Description of Source and Technique (3.A.ii, 3.A.iii)RadioNuclideLength and Shape (Straight/Curved)Reference air Kerma rate

Strength distribution (uniform linear strength is assumed, if not, distribution must be specified.)

Diameter of inactive vector (applicator)

1 1

Description of Time Pattern (3.A.iv) 1 1

Total Reference Air Kerma (3.A.v) 1 1

Description of Dose and Prescription point (Distance from the source line position along the source line)

1 1

Minimum target dose if different from prescribed dose 1 1

Dose at 1 cm from axis of the source line at its center 1 1

Dose at the surface of applicator in contact with tissue 3 3

Additional representation of dose distribution (2.F.ix) 3 3

Dose Rate: Average overall treated dose rate at the point or surface of dose prescription (2.G.II, 2.G.III) 3 1

Table 3: Levels of priority for reporting implants with a single stationary source line.

Parameters for reporting temporary interstitial implants Prioritya Levelb of computation

Description of Volume (3.A.i):

Gross Tumor VolumeClinical Target VolumeTreated Volume (2.F.iv)

111

113

Description of Source and Technique (3.A.ii, 3.A.iii)Radionuclide, source type and sourceType of movementRange of motion (effective length of source)Applicator-including diameter of inactive vector.Number of inactive vectorsReference air kerma rate

1 1

Description of Time Pattern (2.G.iii)

Intervals between fractionsIrradiation time per fraction

1 1


Description of Dose (3.A.vi): Prescribed doseMinimum target doseFor single source line or bifurcation, dose at 1 cmFor complex implant, mean central dose

1111

1222

Method of dose optimization, if applicable 2 3

Description of high and low dose volume (2.F.vi, 2.F.vii) 2 2

Uniformity Parameters Additional representation of dose distribution (2.F.ix) 3 3

Alternative Representation of Dose Distribution (2.F.ix) 3 3

Dose Rates at point or surface of prescription (2.G.ii, 2.G.iii) 3 3

Table 4: Levels of priority for reporting implants with a moving source.

Parameters for reporting use of surface applicators


Description of Clinical Target Volume (3.A.i):Treated Volume (2.F.iv)

1 1

1 3

Description of Applicator ( 3.A.iii)

Shape (flat/curved, round/square, etc.)Size

1 1

Description of source (3.A.ii)

Radionuclide and chemical formConcentration (seeds/tubes/plated)c

1 1

Description of Time Pattern (2.G.iii)

Intervals between fractionsIrradiation time per fraction

1 1


Description of Dose (3.A.vi):Prescription Dose and point of dose prescriptionDose at 5 mm in tissue at the center of the applicatord

Minimum target dosee

Description of high dose at tissue surface in contact with applicator, usually near the –center of the applicator.

111

2

122

2Uniformity Parameters

Additional representation of dose distribution (2.F.ix) 3 3

Dose Rates:Average dose rate at the point of dose prescription (2.G.II) 3 3

Table 5: Levels of priority for reporting implants with a surface applicators.

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ICRU Recommended Dose and Volume Specification for ... · PDF fileICRU Recommended Dose and Volume Specification for Reporting Interstitial Brachytherapy ICRU Recommended Dose and