Localization of radioactive fragments in the human body ... · Master of Science Thesis 2010 7 Fig 1. Basic design and operating principle of a semiconductor detector Cadmium telluride

UNIVERSITY OF GOTHENBURG

Master of Science Thesis

Localization of radioactive fragments in the

human body using surgical detectors

Afrah Mamour

SUPERVISOR: Mats Isaksson

Assoc. Prof.

DEPARTMENT OF RADIATION PHYSICS

2010

Master of Science Thesis 2010

2

Abstract

Intraoperative probes have been employed to aid in the detection and removal of tumors for

more than 50 years. For a period of about 40 years, fundamentally every detector type that

could be invented had been tested or at least suggested for use as an intraoperative probe.

These detectors included such as scintillation detectors (NaI(Tl)) and semiconductor detectors

(CdTe, CdZnTe and HgI2). Intraoperative probes are now established as clinical devices for

example these have been utilized in breast cancer, where surgeons should locate the first

lymph node (sentinel lymph node, SLN). The technology can also be used to locate

radioactive fragments that have penetrated the skin. For this reason one must be aware of the

detector properties if a survey should be necessary in the case if contaminated patients found

in the hospital. It is very important to remove the radioactive fragments as soon as possible.

Contamination could be by radioactive fragments which emit radiation with high energies, i.e.

these haven’t similar energy such as radiopharmaceuticals utilized at surgery, and then these

must be tested. Several moments was performed in this work to study properties of the

detector such as efficiency, angular sensitivity and line spread function and a computer

simulation was also carried out to estimate radiation dose rates to those who will work at the

detector, if the patient is contaminated. The localization of radioactive sources was also

executed in the cavities in the phantom to study the localization.


3

Table of contents

ABSTRACT ..........................................................................................................................2

1. INTRODUCTION ............................................................................................................5

1.1 SENTINEL LYMPH NODE ...................................................................................5

1.2 MICROSHIELD ....................................................................................................6

2. THEORY ..........................................................................................................................6

2.1 DETECTOR ...........................................................................................................6

2.2 DEFINITION ..........................................................................................................8

3. STATISTICS ....................................................................................................................9

4. MATERIAL AND METHOD ........................................................................................ 10

4.1 MICROSHIELD SIMULATION ..........................................................................10

4.2 EXPRIMENTAL ..................................................................................................12

4.2.1 EFFICIENCY ...............................................................................................12

4.2.2 ANGULAR SENSITIVITY..........................................................................16

4.2.3 PHANTOM ..................................................................................................17

4.2.4 LINE PROFILE ...........................................................................................18

5. RESULTS .......................................................................................................................19

5.1 SIMULATION......................................................................................................19

5.2 EXPRIMENTAL .................................................................................................. 21

5.2.1 EFFICIENCY .................................................................................................. 21

5.2.2 ANGULAR SENSITIVITY .................................................................................. 22

5.2.3 PHANTOM .................................................................................................. 22

5.2.4 LILNE PROFILE ......................................................................................... 24

6. DISCUSSION ................................................................................................................. 27

6.1 SIMULATION .................................................................................................... 27

6.2 EFFICIENCY ..................................................................................................... 27

6.3 ANGULAR SENSITIVITY ......................................................................................... 27

6.4 PHANTOM ............................................................................................................ 28

6.5 LINE PROFILE .................................................................................................. 28

6.6 STATISTICS ...................................................................................................... 28

6.7 DETECTOR ....................................................................................................... 29

7. CONCLUSIONS ............................................................................................................. 30

8. ACKNOWLEGEMENT ................................................................................................. 30

Appendix 1 .......................................................................................................................... 31

Appendix 2 .......................................................................................................................... 36

Appendix 3 .......................................................................................................................... 41


4

Appendix 4 ..........................................................................................................................42

Appendix 5 ..........................................................................................................................43

References ........................................................................................................................... 52


5

1. Introduction

When an accident in which radioactive material is involved, there must be a rapid procedure

that determines whether people are contaminated or not. At a first stage to perform a

contamination measurement on all involved, a radiation protection instrument is required.

Because the presence of radiation is not detectable by human senses, it is notable to check the

operability of any instrument before its use.

At many hospitals today, small detectors are used in conjunction with surgical procedures to

detect the uptake of radionuclides. One example is breast cancer, where surgeons should

locate the first lymph node (sentinel lymph node, SLN). The technology can also be used to

locate radioactive fragments that have penetrated the skin. If the fragments have high activity,

it is necessary that they can be removed as quickly as possible. At localization and removal of

radioactive fragments existing equipment should be used at the current hospital by the people

who normally use such equipment. The proposed method of application of the National

Radiological Protection preparedness is primarily to provide a compilation of available

resources.

The purpose of this work was to quantify the characteristics of the detector (efficiency,

spatial resolution, angular sensitivity, etc.) in the detection of different radionuclides with

different energies.

Additionally, the microshield simulation was performed in this work to estimate DDER (Deep

dose equivalent rate, [µSv h-1

]). The aim of this was to illustrate how much radiation dose is

for those who will work at the detector, if the patient is contaminated. The fact is that the

damage will be taken care of first before those start with decontamination.

1.1 Sentinel Lymph Node

The concept was proposed by Cabanas in 1977 [1]. The first lymph node to receive lymphatic

drainage from a tumor site is the sentinel node, and if there has been lymphatic spread, the

sentinel node is the first node to have metastatic involvement. Further, the concept implies

that sampling the sentinel node is sufficient for assessing a lymphatic bed. The sentinel node

concept applies to the spread of several types of cancer including breast cancer and

melanoma. It was first applied in the management of cancer by Cabanas in 1977 and it was

first applied in the management of melanoma in 1992 by Morton et al. [2].

Thurston et al [3] reported the basic criteria for the choice of a radionuclide to be used for

lymphoscintigraphy. The 99m

Tc labeled nanocolloid particles are pre-operatively injected

around the primary tumor with a specific activity. Due to the size of the molecules, 99m

Tc

labeled nanocolloid can be transported only to the node, the first or sentinel node, which will

demonstrate the highest node activity in the axilla. Several hours to one day after injection,

allowing for the lymphatic transport of the nanocolloid, the patient undergoes surgery,

followed by histological examination of the sentinel node. The role of the surgical gamma

probe is to localize the sentinel node intra-operatively.


6

1.2 MicroShield

This is a broad gamma ray shielding and dose estimation program that is commonly used for

designing shields, estimating source strength from radiation measurements, minimizing

exposure to people, and teaching shielding principles. It is fully interactive and utilizes wide

input error checking. Integrated tools provide graphing of results; material and source file

creation, source inference with decay, projection of exposure rate versus time as a result of

decay, access to material and nuclide data, and decay heat calculations. In some cases, such as

the calculation of absorbed dose, additional tools may be needed to complete an assessment

[4].

2. Theory

2.1 Detector

In general all semiconductor detectors for ionizing radiation will, through some interaction in

the detector volume, create a charge pulse that can be detected. This charge pulse consists of

electrons and holes, which are separated under the influence of an applied electric field, and

the current is detected by an external circuit. Therefore, in view of detector operation the

factors of concern that must be concerned is the nature of the interaction between the incident

radiation and the volume of the detector material where the charge is created, the efficiency of

the excitation process, the efficiency of the charge collection process, the external circuit that

detects the charge pulse that has been created, and finally the background noise of the device.

In a semiconductor material the incident radiation can create a very large number of electron-

hole pairs since the energy necessary to produce one electron-hole pair is about 3 to 6 eV,

depending on the bandgap and other properties of the material being employed. The electron-

hole pairs are created either directly, as might be the case if the incident radiation is a charged

particle such as an electron, or indirectly where the incident radiation undergoes any number

of the processes and secondary particles produced lose their energy through the production of

electron-hole pairs (see Fig 1). The relatively small energy required to produce electron- hole

pairs in semiconductors and the high quantum efficiencies are two advantages of

semiconductor nuclear detectors [5].


7

Fig 1. Basic design and operating principle of a semiconductor detector

Cadmium telluride (CdTe) is a type of semiconductor detector which combines high atomic

numbers, Cd and Te have atomic numbers of 48 and 52, respectively, with large enough

bandgap energy (1.52 eV) to permit room temperature operation. The probability of

photoelectric absorption per unit pathlenght is approximately a factor of 4 to 5 times higher in

CdTe than in for example Ge for typical gamma-ray energies. Due to difficulties in charge

carrier transport, most CdTe detectors are generally small and are usually planar in design.

Energy resolution is best for low-energy gamma-ray and X-ray irradiation on the cathode

side. Although CdTe detectors can be generally efficient for low-energy gamma rays, suitable

detection efficiency for high-energy gamma rays requires larger volumes, which unfortunately

translates into poor spectroscopic performance [6].


8

2.2 Definitions

Deep dose equivalent (DDE) which applies to external whole body exposure means the

dose equivalent at a tissue depth of 1 centimeter (1000 mg/cm2

), also called personnel dose

equivalent at a depth of 1 cm. The unit for deep dose equivalent is J kg-1

or Sievert (Sv) [12].

Efficiency is fraction of emitted radiation detected by the probe (cps/ kBq). The efficiency of

the detector system, which depends in turn on many material and geometrical factors, will

determine how well the system uses the information in the available radiation. The counting

sensitivity of detectors varies, depending on size of the detector, energy of incident gamma

radiation, source-to-detector distance, source radial position and thickness of the

semiconductor. With increasing distance between source and detector, the efficiency will

decrease (Inverse square law, the rule that states that the intensity of radiation from a source

decreases as 1/d2 from the source in a nonabsorbent medium, where d is the distance from the

source). Efficiency has two separate components such as geometric efficiency and intrinsic

efficiency. Geometric efficiency is the fraction of emitted radiations that intersect the

detector, which is the fraction of the total solid angle subtended by the detector. It is directly

proportional to the radiation-sensitive detector area and, for a point source, inversely

proportional to the square of the source-detector distance. Intrinsic efficiency, or efficiency, is

the fraction of radiations intersecting the detector that is stopped within the detector [11].

Angular sensitivity, the probe should be sensitive to the photons in a limited solid angle.

This ensures good spatial resolution for the localization of the radionuclide.

Spatial resolution (FWHM, Full Width at Half Maximum) is the capacity of the detector

to determine correctly the location of a source. Spatial resolution is related to the material,

size and lateral shielding of the detector. FWHM illustrated in the fig 2 and is defined as the

width of the spreading at a level that is just half the maximum ordinate of the peak.


9

Fig 2. Schematic determination of FWHM [7]

3. Statistics

Radioactive decay is a random process and, therefore, random fluctuations will occur in the

measured counts or counts rates arising from decay of radioactivity. For this reason, if an intra

operative probe were used to repeatedly measure the counts or count rate from a given activity

of radionuclides, a dissimilar value would be obtained for each measurement. Such random

fluctuations complicate the true detection and measurement of radioactivity. If a measurement

is made on a radioactive sample and N counts is obtained, the standard deviation (s) of the

number of counts is the square root of the number of counts

s = N (1)

The standard deviation was calculated for tow centering of sources in the front of the detector,

also mean value calculated for tow centering.

Uncertainty in the mean value of two different sources was estimated according to

equation (2);


10

s = (s1

m1)2 + (

s2

m2)2 (2)

Were s1 and m1 are standard deviation and mean value for the first measuring series, s2 and m1

are standard deviation and mean value for the second measuring series. The ratio m1/ m2 are

the relation between mean values of two different sources.

m2

m1 ± s

Uncertainty in the Reproducibility

m1 ± s1

m2 ± s2

4. Materials and methods

4.1 MicroShield simulation

The simulation begun with choosing appropriate nuclides in this situation, 60

Co, 137

Cs, 192

Ir, 131

I and 241

Am were used, since they are industrial radionuclides and medical. Simulation was

carried out in MicroShield (Grove Software, Inc, Lynchburg-USA, version 6.20) program to

calculate Deep Dose Equivalents Rate (DDER).

To study the attenuation in the tissue, the simulation was performed in water between the

point sources and measuring point in MicroShield for different sources such as 60

Co, 137

Cs, 131

I and 192

Ir between 2 and 15 cm depth with 1 MBq activity, to obtain DDER.


11

To simulate an adult human, a three section cylindrical phantom was used that was similar to

an adult human phantom (in 1969 Snyder et al [8] developed the first heterogeneous model to

represent the adult male). The phantom’s head, torso, and leg sections had a cylindrical form

which is shown in fig. 3, furthermore was simulated a child phantom with the same parts as an

adult phantom, but the length of 140 cm, which was taken from PCXMC program [13], a 10-

year-old child was selected and the lengths of each element was scaled in proportion to the

adult phantom (fig 3).

Fig 3. An adult phantom which represents an adult human in order to calculate DDER in MicroShield

[8]

A unit surface concentration of 1MBq m-2

simulated for the whole phantom i.e. a uniform

distribution of activity was used to calculate DDER from each part. The total DDER was

estimated a sum of the three parts. This was simulated for 20 cm and 100 cm distance from

the body in the middle of the large phantom (at mid torso)

Fig 4. A child phantom which represents a child in order to calculate DDER in MicroShield.


12

4.2 Experimental

4.2.1 Efficiency

The efficiency was measured 1cm in front of the detector and the sources used were the

nuclides which have only one major gamma energy peak. Nuclides with different energies

were used in order to see how the efficiency changes at a constant depth with varying energy.

It is also important when gamma probe detection is performed with more than one

radionuclide having different energies. The detector, placed in the holder. Table 1 shows the

radionuclides which were utilized in the case of the efficiency.

Table 1. Physical properties of the radionuclides which were used to determine efficiency

Radionuclide Half-life Type of

emission

Energy (keV) Iγ (%)

60Co 5.27 y γ rays 1173, 1333 99.97, 99.99

137Cs 30.07 y γ rays 662 85.1

131I 8.00 d γ rays 364, 637 81.7, 7.17

99mTc 6.00 h γ rays 140, 142 89, 0.02

57Co 271.79 d γ rays 122, 136.5 85.60, 10.8

54Mn 312.3 d γ rays 835 99.9

65Zn 244.26 d γ rays 1115 50.6

109Cd 462.6 d γ rays 88 3.61

The CdTe detector (Eurorad SA, Eckbolsheim France, issued in Paris on April 24th, 2009)

which was used has been designed for low to mid energy radiation detection (125

I, 99m

Tc,

etc…). The detector and the preamplifier are mounted in a probe of 11mm (detection head)

and the collimator is a part of the probe.


13

The small probe (SOE311) was used which has a short angled probe (30º) to permit easier

contact to certain tissues (fig 5). It was connected to the read-out module through a 3.5 m

flexible cable [9].

Europrobe electronic system allows the visualization of the counting rates or counts on a

digital display (fig 6).

Fig 5. CdTe probe (SOE311) which was utilized in this case [10].

Table 2. Characteristics of the CdTe gamma probe

CdTe probe

Length 175 mm

Diameter 11 mm (detection head)

Tip angle 30°

Shielding High Energy Tungsten

Collimation Internal (optional: additional external collimation)

Energy range 20 keV to 364 keV

Weight 140 g


14

Fig 6. Europrobe electronic system which is a gamma detection device for radioguided surgery[10].

For each measurement, the activity of each source was decay corrected. The nuclides used

were 60

Co, 137

Cs, 54

Mn, 65

Zn, 99m

Tc, 131

I, 109

Cd and 57

Co (Table 1). The detector had two own

enengy windows for 99m

Tc and 125

I. The own energy window for measurement of 99m

Tc was

used and the total energy window was used for the rest. Then sources were placed in front of

the detector and 21 readings were recorded. Then the detector was moved and centered again

and 21 new readings were recorded. Because of technical limitations the sources could only

be measured for 50 seconds, therefore, it was measured 21 times, and the individual readings

were summed (see Appendix 1). The next step was to assess the efficiency of the sources

used. This efficiency is expressed as the count rate (cps) per kBq according to equation (3);

ε = C

A ×t (3)

Were A is the activity (kBq), Iγ is the gamma intensity, t is the measurement time (s) and C

is the number of counts.

ε = cps

kBq

The efficiency expressed in percent according to equation (4);


15

ε % = C

Iγ × A × t × 100 (4)

Were Iγ is the gamma intensity.

To examine if the measured efficiency of the detector is similar compared to the manual of

the detector, the intrinsic efficiency was calculated by using the measured efficiency of such

as 57

Co. It was appropriate to compare with the manual description due to this has a low

energy. The intrinsic efficiency (𝛆i) was calculated by the head area of the detector and the

distance between the detector and the source (see fig 7). The solid angle was calculated

according to equation (5).

Fig 7. The figure presents how the internal efficiency was calculated, r is the distance between the

source and the detector head and A is the detector head area.

Ω = A

r2 (4)


16

Ω

4π=

A

4πr2 (5)

Were distance (r) between the detector and the source was 1 cm and area (A) was 1cm

2. The

solid angle was divided with 4π since the radiation from the source is assumed to be emitted

isotropically.

4.2.2 Angular sensitivity

The angular sensitivity of the detector was measured in air, using a disc which could be

rotated at different angles and a plastic holder was used to maintain stable sources without

moving during measurements. The source placed 4 cm from detector on the plastic holder (see

fig 8). The radionuclides used in this operation were 60

Co, 57

Co, 137

Cs and 133

Ba. The sources

were positioned coaxial to the aperture of the probe sensitive area. The counts were acquired

for source-detector angles between 0° and 90° and also between 0° and -90° in the steps of

15°. Because of the low number of the counts, 30 measurements were carried out, each

measurement in 50 s, and then summed for each of the angles (see Appendix 2).

Fig 8. The plan for studying the angular sensitivity of the detector


17

4.2.3 Phantom

Measurements were performed at a doll which weighed 50 kg, and had cavities were it was

possible to place sources in order to detect them with the CdTe detector (fig 9). The purpose

of this was to see it the detector could be used to find hidden sources in the body. The source

was placed 3 cm deep in the cavity, and measurements were performed by moving the probe

in steps to 5 cm laterally from the source. The measurement time was 50 seconds and the

number of counts were recorded (see Appendix 4). To perform the measurements, different

sources such as 60

Co, 57

Co, 137

Cs and 133

Ba (gamma ray, 81, 276 and 356 keV) was used to

have a spread in energy. The measurements were carried out also with Plexiglas in cylinder

form (ρ ≈1.2 g/cm3) in front of the source to consider attenuation in tissue with similar

procedure as without the Plexiglas. Plexiglas is a good approximation for water, because the

body contains most water and these have a density and atomic composition (Zeff) nearly as the

water.

The audio signal was used to guide the localization of the sources. The measurements could

be performed without timing by just using audio signal and this was an advantage in this case

i.e. to locate sources in the body at accidents.

Fig 9. The phantom used to localize the sources


18

4.2.4 Line profile

To determine the line profile a capillary tube filled with a solution of water, bovine serum

albumin (BSA) and 0.02 sodium aside (NaN3, it is extremely toxic) was used and nuclide

which were 131

I and 99m

Tc. The tube was placed at different distances on a PMMA (Polymetyl

methacrylate phantom) slab. The detector, placed in a motorized holder, was moved

horizontally perpendicular to the line source (fig 10). The counts were determined every 1

mm for positions less than 10 mm distal to the line source and every 2 mm for positions more

than 10 mm distal to the line source, extending from -30 to 30 mm from the source. 131

I

solution had 2.83 MBq ml-1

for activity concentrations, BSA were used to reduce absorption

of nuclide to the capillary tube wall. Capillary tube was used as a line profile which it had 10

µl for volume (≈ 30 mm length) and then the solution was drawn up by the capillary tube. 137

Cs was also used to see the response at a higher energy. Unfortunately this had a low

activity concentration and therefore the measurement was performed at 1 mm distance. Due to

the low number of counts, 20 measurements were carried out in the each position from the

center of the line source. It was not possible to mix the 137

Cs with BSA due to the low activity

concentration (0.015 kBq µl-1

). The spatial resolution of the detector was determined as full

width at half maximum (FWHM) of the response profile for the radionuclides as utilized.

Fig 10. The method utilized for studying the line response of the detector


19

5. Results

5.1 Simulation

Table 3 presents DDER for an adult phantom which was simulated in MicroShield with

different radionuclides and different energies. It is seen that for 60

Co the DDER is highest but

it is the lowest for 241

Am. DDER is higher at 20 cm than 100 cm from the cylinder surface for

all nuclides.

Table 3. Deep Dose Equivalent rate (DDER) from an adult phantom with a uniform surface activity of 1MBq m

-2

Radionuclide Gamma energy

(keV) WMVE

†

(keV)

Iγ % DDER (µSv h-1

)

At 20 cm*

DDER (µSv h-1

)

At 100 cm*

60Co 1173, 1333 1253 99.99, 99.97 2,0 0,31

137Cs 662 − 85.1 0,52 0,08

131I 284, 364, 637 432.1 6.1, 81.7, 7.1 0,38 0,06

192Ir 317, 468 373.3 82.81, 47.83 0,80 0,13

241Am 14, 60 − 35.9 0,06 0,009

*Distance between the cylinder surface and dose point †Weighted Mean Value of Energies

Table 4 shows DDER for a child phantom which was simulated in MicroShield also with

similar radionuclide’s as the adult phantom. The same results present in table 3, that the

higher energy, except for 137

Cs and 192

Ir, increases also DDER. DDER is also higher for 20

cm than 100 cm from the surface. The child phantom compare to the adult phantom has lower

DDER at all nuclides due to the less surface activity.


20

Table 4. Deep Dose Equivalent rate (DDER) from a child phantom with a uniform surface activity of

1MBq m-2

Radionuclide Gamma energy

(keV) WMVE

†

(keV)

Iγ % DDER (µSv h-1

)

At 20 cm*

DDER (µSv h-1

)

At 100 cm*

60Co 1173, 1333 1253 99.99, 99.97 1,6 0,25

137Cs 662 − 85.1 0,48 0,045

131I 284, 364, 637 432.1 6.1, 81.7, 7.1 0,35 0,048

192Ir 317, 468 373.3 82.81, 47.83 0,74 0,10

241Am 14, 60 − 35.9 0,057 0,0073

*Distance between the cylinder surface and dose point †Weighted Mean Value of Energies

Simulation in water for different radionuclides shows the attenuation in water, DDER

decreases with increasing depth (Fig 11). Attenuation is lowest for 60

Co clearly due to the

higher energy and highest for 131

I which has the lowest energy in this situation.

Fig 11. Simulation in water which was performed between 2 and 15 cm depth to consider the

attenuation of the dose in tissue which has a density close to the water

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

0 2 4 6 8 10 12 14 16

DD

ER (

mSv

/h)

Depth[cm]

MicroShield simulation in water

Co-60

Cs-137

I-131

Ir-192


21

5.2 Experimental

5.2.1 Efficiency

Fig 12 presents the efficiency for different energies in the air and constant source to detector

distance, the efficiency decreases with increasing energy and for high energy the efficiency is

approximately constant (from 400 keV). Efficiency was highest for 57

Co (Eγ =122 keV) and

lowest for 65

Zn. The efficiency for 60

Co was acceptable at this point due to the detector

system, i.e. the detector is more effective for the lower energies. The detector makes it

possible to detect the sources with the higher energies.

Fig 12. The efficiency at varying energy at 1 cm in front of detector with different radionuclides in air

In order to see if the measured efficiency of the detector is similar compared to the manual of

the detector, the calculations was performed according below. It was approximately correct

compare to the manual;

Ω

4π≈ 0.08

0

1

2

3

4

5

6

7

0 200 400 600 800 1000 1200 1400

Effi

cien

cy %

Energy [keV]

Efficiency


22

𝛆i = ε

Ω 4π ≈

6,5

0,08 ≈ 81% for the efficiency measurements of

57Co.

5.2.2 Angular sensitivity

Fig 13 presents results regarding the relative angular sensitivity. The data are normalized for

each radionuclide on the sensitivity at an angle of 0°. At high energy such as 60

Co the angular

sensitivity is less than lower energy such as 133

Ba and 57

Co, which shows that the detector is

more sensitive at low energies and almost independent of angle for high energies i.e. the

detector has a good angular sensitivity for low energies and less angular sensitivity for high

energies.

Fig 13. Angular sensitivity at varying energies at 4 cm from the detector. The responses are

normalized to the highest response i.e. at 0°.

0

0,2

0,4

0,6

0,8

1

1,2

-100 -50 0 50 100

rela

tive

re

spo

nse

%

Angle (degrees)

Angular sensitivity

Co-60

Co-57

Cs-137

Ba-133


23

5.2.3 Phantom

Measurements of different radionuclides in the phantom (see fig. 9) at different lateral

distances are shown in fig 14 and 15. The response for high energy decreases more slowly

compared to the low energies. The localization without and with Plexiglas are also presented

in fig 14 and15.

Fig 14. The response of the sources which was placed in the phantom to localize them with

the detector. The responses are normalized to the highest response i.e. in front of sources.

Fig 15. The response of the sources which was placed in the phantom with Plexiglas. The

responses were normalized to the highest response i.e. in front of sources.

0

0,2

0,4

0,6

0,8

1

1,2

0 5 10 15 20 25

Re

lati

ve r

esp

on

ce %

Lateral distance(cm)

Localization without plexiglas

Co-57

Co-60

Cs-137

Ba-133

0

0,2

0,4

0,6

0,8

1

1,2

0 5 10 15 20 25

Rel

ativ

e r

esp

on

ce %

Lateral distance (cm)

Localization with plexiglas

Co-60

Co-57

Cs-137

Ba-133


24

5.2.4 Line profile

As shown in the figure 17 and 18 the resolution (FWHM) deteriorates dramatically with

increasing the source-detector distance, and also this is depended of the sources energies i.e.

the higher energy leads to worsens in FWHM which can be observed in the fig 17 and 18. The

comparison between the figures show that with increasing of the energy, in addition to 131

I

was measured in shorter distance (1 mm) than 99m

Tc (1 cm) decreases spatial resolution. It

applies also that for 137

Cs with high energy (662 keV), according to the fig 16, the resolution

is worsens more compare to the 99m

Tc and 131

I which have lower energies.

Fig 16. The line profile of

137Cs at 1 mm distance on a PMMMA slab to study line spread function,

measurement was performed every one millimeter inside 10 mm from center of the line source and

every 2 mm outside 10 mm, i.e. from -20 to 20 mm from the source. Normalization was to the highest

response.

00,10,20,30,40,50,60,70,80,9

11,1

-25 -20 -15 -10 -5 0 5 10 15 20 25

rela

tive

re

spo

nse

%

Position[mm]

Cs-137, 1mm distance on a PMMA slab


25

Fig 17. Line profile of

131I at 1 mm (blue) and 5 cm (red) distance on a PMMMA slab to study line

spread function, measurement was performed every one millimeter inside 10 mm from center of the

line source and every 2 mm outside 10 mm, i.e. from -30 to 30 mm from the line source.

Normalization was to the highest response.

Fig 18. Line profile of 99m

Tc at 1 cm (blue) and 5 cm (red) distance on a PMMMA slab to

study line spread function, measurement was performed every millimeter inside 10 mm from

center of the line source and every 2 mm outside 10 mm, i.e. from -30 to 30 mm from the line

source. Normalization was to the highest response.

0

0,2

0,4

0,6

0,8

1

1,2

-35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35

Re

lati

ve r

esp

on

ce %

Position [mm]

I-131, 1 mm distance on a PMMA SLAB I-131, 5 cm distance on a PMMA slab

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1

1,1

-35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35

Rel

ativ

e r

esp

on

se %

Position [mm]

Tc-99m, 1 cm distance on a PMMA slab Tc-99m, 5 cm distance on a PMMA slab


26

Fig 19. Line profile of 131

I at 5 cm distance on a PMMMA slab to study line spread function,

measurement was performed every millimeter inside 10 mm from center of the line source and every 2

mm outside 10 mm, i.e. from -30 to 30 mm from the line source. Normalization was to the highest

response

Figure 19 showes a separate figure of 131

I to present the better line spread function of 131

I at 5

cm.

Table 5. Spatial Resolution for different nuclides at different distances from the detector on a PMMA

slab

Radionuclide→ 137

Cs 131

I 99m

Tc

Distance (mm) FWHM (mm) FWHM (mm) FWHM (mm)

1 30 18 −

10 − − 21

50 − 50 44

FWHM = Full width at Half Maximum − No measuerements in this distance

FWHM is lower for 131

I at 1 mm (the smaller the FWHM, the better the spatial resolution),

highest for 131

I at 50 mm (worse spatial resolution), 99m

Tc has the best FWHM at 1 cm. The

other nuclides wasn’t measured at 1 cm. Althought 131

I had the lower FWHM but at 1 mm

compare to 99m

Tc. 137

Cs had a worse FWHM at 1mm. At 5 cm 99m

Tc has the better spatial

resolution than 131

I (table 5).

0

0,2

0,4

0,6

0,8

1

1,2

-40 -30 -20 -10 0 10 20 30 40

Re

lati

ve r

esp

on

se %

Position [mm]

I-131, 5 cm distance on a PMMA SLAB


27

6. Discussion

6.1 Simulation

DDER reduces by increase of the distance between the surface of source and the dose point

obviously due to the inverse square law, which the intensity of radiation from a source

decreases as 1/d2 from the source. The dose could be less for children than the adult human

with the activity which used in the MicroShield simulation program (1MBqcm-2

) due to the

smaller surface of the children. DDER decreases also with increasing depth in water due to

attenuation and this also dependent of energy i.e. the higher energy leads to less attenuation,

the radiation passes through the water. Fig 11 recognizes this phenomenon well then DDER

for 60

Co which has high gamma energy (1253 keV) decreases more slowly than other

radionuclides.

6.2 Efficiency

Photoelectric absorption for the photon energies of for example 57

Co is higher than for

example 60

Co in the detector such as CdTe which have a high atomic number (see fig 12). 60

Co and 131

I had almost similar efficiency and the results are promising in this case. The

thickness of the detector is which results in a decrease of efficiency when the energy of the

gamma rays increases. The efficiency affected by the dimensions and composition of the

radiation source, and by the absorption of the radiation in the source as well as in the

surrounding materials. The efficiency measurements were performed in air in this work i.e.

without attenuating and scattering medium, in reality there are attenuating medium such as

tissue which leads to lower efficiency of the detector when lowered efficiency leads to a low

number of counts and high statistical uncertainty.

6.3 Angular sensitivity

The detector may perhaps be able to detect the sources with the higher energies, but by the

lower efficiency. However, this can utilize at localization of the radioactive fragments with

the higher energies such as 60

Co or 137

Cs. Contamination couldn’t happen with the sources

which emit radiation with the higher energy than 60

Co. A higher angular sensitivity is required

in order to achieve good spatial resolution, but this work shows that the CdTe detector is poor

angular sensitive to the higher energies as 60

Co (due to the longer range of the photons by the


28

higher energy i.e. the photons can nevertheless reach the detector) and excellent angular

sensitivity at lower energies such as 57

Co and 133

Ba.

6.4 Phantom

The localization of sources in the phantom by different energies presents that at the higher

energy the lateral response decreases more slightly compare to the lower energies due to the

longer range of the photons and hence photons undergo more Compton scattering. The

localization with Plexiglas shows that due to the attenuation in the Plexiglas the response

decreases somewhat than the localization without Plexiglas.

6.5 Line profile

In the case of that estimate the line spread function, this work is shown the ability of the

detector (CdTe) which used to detect a line source which deep-seated can unfortunately be too

difficult according to the fig 17 and 18 for radionuclides as 99m

Tc and 131

I. This presents also

for the lower energy its capability is much better than the higher energy by reason of the

detector is more efficient for the lower energy. The spatial resolution of this detector

deteriorates dramatically with increasing distance of the source from the detector, mainly

because the probe’s field of view increases with increasing distance. The line profile for 137

Cs

was too poor at 1 mm, this can caused also by its low activity concentration (0.015 kBq µl-1

).

6.6 Statistics

What is often necessary is a measure of uncertainty that defines an interval about the

measurement result M within which the value of the measured Y can be confidently asserted

to lie. The measure of uncertainty proposed to meet this requirement is termed expanded

uncertainty (U), and is obtained by multiplying s by a coverage factor (k), thus

U = k s

and it is confidently believed that Y is greater than or equal to M - U, and is less than or equal

to M + U, which is commonly written as Y = M ± U.


29

Typically, k is in the range 2 to 3. When the normal distribution applies and s is a reliable

estimate of the standard deviation of M, U = 2 s (i.e. k = 2) defines an interval having a level

of confidence of approximately 95 %. In this work were performed many measurements

which the expanded uncertainty was tested and uncertainty was approximately 1% between

two measurement i.e. measurements were well done.

In determining the distance between the source and the detector a ruler has been used, this

contributes to an uncertainty of 1-2 mm because of the manual reading. The very short

distance such as 1mm between the detector and the source in the case of line profile can give

uncertainties due to the uncertainty in the where the detector sits in relation to the entry

window.

6.7 Detector

The purpose of shielding and collimation is to use attenuation to stop radiations from

unwanted locations from striking the detector and producing counts. To maximize attenuation,

collimator should be fabricated out of high- atomic number materials. Among such materials,

lead has been the most commonly used shielding and collimation material but other material

such as tungsten has even greater attenuation than lead. The gamma probe which used in this

work has tungsten as shielding and this provides an advantage.

It is essential that the instrument be equipment with an audible signal to enable the user to

perform the search without watching the meter, the detector which used in this work has this

benefit.

For search application light weight and comfortable carrying handle equipment should be

used, the gamma probe which utilized, was a light weight probe, hopefully.


30

7. Conclusions

This work recognizes that the detector was utilized in the aim to investigate its properties with

different radionuclides and different energies can be used at contamination but this presents

the better response for the radionuclides with lower energies such as 99m

Tc and 57

Co. The

contamination can include radionuclides which emit radiation with higher energy than 60

Co,

this can happen with different radioactive nuclides either medical or industry and the detector

is efficient also for higher energy but not so superior compare to the lower energy. The

detector isn’t good for localization of deep-seated sources for example at 5 cm as were

investigated in this work. For search application the detector is comfortable and has a good

audio signal. This detector can be used at the contamination of humans in the absence of any

other instruments in the hospital.

8. Acknowledgements

I would like especially to thank my supervisor Assoc. Prof Mats Isaksson who has helped me

accomplish this work and his great helpfulness and advices during my study.

I would like to thank all my classmates for their supporting and fine time during my study at

the Department of Radiation Physics and the Chalmers University and their help during my

work.

Furthermore I would like to thank the workshop, especially Mats Sak and Jan Samuelsson for

their fine help during my work.

Many thanks to the Department of Radiation Physics.

Finally I would like to thank my family, my dear husband and my beautiful sons for their

wonderful supporting and their great interest for my study.


31

Appendix 1

Efficiency

57

Co A= 15.66 kBq 60

Co A= 32.65 kBq

Measuring series 1 2 Measuring series 1 2

1 4705,0 4608,0 1 1596,0 1768,0

2 4617,0 4709,0 2 1635,0 1637,0

3 4633,0 4503,0 3 1612,0 1696,0

4 4603,0 4574,0 4 1674,0 1700,0

5 4651,0 4497,0 5 1614,0 1729,0

6 4669,0 4493,0 6 1605,0 1678,0

7 4624,0 4603,0 7 1645,0 1669,0

8 4699,0 4508,0 8 1584,0 1710,0

9 4665,0 4598,0 9 1581,0 1798,0

10 4646,0 4672,0 10 1489,0 1687,0

11 4572,0 4558,0 11 1616,0 1720,0

12 4578,0 4648,0 12 1638,0 1812,0

13 4703,0 4618,0 13 1594,0 1690,0

14 4625,0 4658,0 14 1637,0 1705,0

15 4611,0 4600,0 15 1548,0 1739,0

16 4561,0 4646,0 16 1636,0 1712,0

17 4524,0 4655,0 17 1625,0 1716,0

18 4621,0 4711,0 18 1611,0 1712,0

19 4665,0 4563,0 19 1590,0 1717,0

20 4535,0 4501,0 20 1628,0 1717,0

sum 92507,0 91923,0 21 1613,0 1673,0

std 304,1 303,2 sum 33771,0 35985,0

Cnt-Bg 92129,0 91545,0 std 183,8 189,7

cps 87,7 87,2 Cnt-Bg 33393,0 35607,0

eff 5,5 cps 31,8 33,9

Eff% 6.48 eff 1,0064

Eff% 1,01

Uncertainty in reproducibility Uncertainty in reproducibility

M1= 4625,4 S1= 52,5

M2= 4596,2 S2= 70,3

M1= 1608,1 S1= 38,4

M2= 1713,6 S2= 40,8

M1 ± S1=4625±52,5 M2 ± S2=4596,2±70,3 M1 ± S1=1608,1±38,4 M2 ± S2=1713,6±40,8 Uncertainty in the measurement of two

different sources

Uncertainty in the measurement of two different

sources m2

m1 ± s = 0,99 ± 0,005

m 2

m 1 ± s = 1,1 ± 0,008


32

65Zn A= 7.92 kBq

54Mn A=12.004 kBq


1 163,0 172,0 1 498,0 525,0

2 172,0 181,0 2 521,0 520,0

3 154,0 189,0 3 552,0 532,0

4 187,0 174,0 4 490,0 501,0

5 190,0 196,0 5 508,0 535,0

6 177,0 174,0 6 511,0 556,0

7 181,0 177,0 7 568,0 520,0

8 172,0 177,0 8 520,0 528,0

9 167,0 166,0 9 527,0 520,0

10 179,0 173,0 10 514,0 535,0

11 198,0 173,0 11 547,0 557,0

12 171,0 163,0 12 536,0 544,0

13 187,0 183,0 13 529,0 512,0

14 184,0 182,0 14 517,0 510,0

15 196,0 178,0 15 542,0 551,0

16 195,0 174,0 16 536,0 539,0

17 179,0 185,0 17 540,0 545,0

18 163,0 172,0 18 521,0 474,0

19 173,0 183,0 19 537,0 496,0

20 179,0 163,0 20 512,0 549,0

21 171,0 174,0 21 508,0 514,0

sum 3738,0 3709,0 sum 11034,0 11063,0

std 61,1 60,9 std 105,0 105,2

Cnt-Bg 3360,0 3331,0 Cnt-Bg 10656,0 10685,0

cps 3,2 3,2 cps 10,1 10,2

eff 0,4 eff 0,8

Eff% 0,8 Eff% 0,85


M1= 178,0 S1= 11,6

M2= 176,6 S2= 8,1

M1= 525,4 S1= 18,9

M2=526,8 S2= 21,2

M1 ± S1=178,0±11,6 M2 ± S2=176,6±8,1 M1 ± S1=525,4±18,9 M2 ± S2=526,8±21,2 Uncertainty in the measurement of two

different sources Uncertainty in the measurement of two

different sources m2

m1 ± s = 0,99 ± 0,02

m2

m1 ± s = 1,003 ± 0,01


33

109

Cd A= 16.62 kBq 131

I A= 42.43 kBq


1 445,0 409,0 1 2476,0 2535,0

2 388,0 420,0 2 2611,0 2511,0

3 403,0 416,0 3 2562,0 2494,0

4 415,0 430,0 4 2486,0 2537,0

5 407,0 408,0 5 2497,0 2480,0

6 387,0 441,0 6 2549,0 2453,0

7 412,0 412,0 7 2510,0 2481,0

8 405,0 416,0 8 2466,0 2472,0

9 409,0 440,0 9 2611,0 2510,0

10 437,0 449,0 10 2616,0 2540,0

11 393,0 411,0 11 2543,0 2537,0

12 398,0 414,0 12 2565,0 2474,0

13 404,0 420,0 13 2473,0 2543,0

14 434,0 419,0 14 2502,0 2557,0

15 414,0 420,0 15 2578,0 2479,0

16 476,0 454,0 16 2501,0 2461,0

17 396,0 424,0 17 2480,0 2402,0

18 389,0 390,0 18 2443,0 2512,0

19 430,0 413,0 19 2516,0 2413,0

20 431,0 440,0 20 2521,0 2483,0

21 452,0 376,0 21 2598,0 2474,0

sum 8725,0 8822,0 sum 53104,0 52348,0

std 93,4 93,9 std 230,4 228,8

Cnt-Bg 8347,0 8444,0 Cnt-Bg 52726,0 51970,0

cps 7,9 8,0 cps 50,2 49,5

eff 0,5 eff 1,2

Eff % 1,33 Eff % 1,44


M1= 415,5 S1= 23,6

M2= 420,1 S2= 18,3

M1= 2528,8 S1= 52,8

M2= 2492,8 S2= 41,5

M1 ± S1=415,5±23,6 M2 ± S2=420,1±18,3 M1 ± S1=2528,8±52,8 M2 ± S2=2492,8±41,5

Uncertainty in the measurement of two

different sources Uncertainty in the measurement of two

different sources m2

m1 ± s = 1,01 ± 0,02

m 2

m 1 ± s = 0,99 ± 0,006


34

99m

Tc A= 23 kBq / µl 137

Cs A= 4.61kBq

Measuring series 1 2 Measuring

series

1

counts

2

counts

1 2590,0 2627,0 1 279,0 259,0

2 2480,0 2729,0 2 276,0 268,0

3 2568,0 2598,0 3 272,0 259,0

4 2592,0 2783,0 4 265,0 264,0

5 2556,0 2578,0 5 271,0 268,0

6 2514,0 2627,0 6 247,0 292,0

7 2585,0 2689,0 7 239,0 286,0

8 2533,0 2725,0 8 267,0 297,0

9 2489,0 2658,0 9 263,0 292,0

10 2496,0 2693,0 10 249,0 260,0

11 2442,0 2725,0 11 259,0 257,0

12 2501,0 2643,0 12 254,0 283,0

13 2574,0 2663,0 13 266,0 280,0

14 2422,0 2571,0 14 297,0 285,0

15 2470,0 2577,0 15 276,0 287,0

16 2512,0 2597,0 16 272,0 272,0

17 2457,0 2635,0 17 235,0 252,0

18 2409,0 2586,0 18 245,0 256,0

19 2460,0 2613,0 19 298,0 295,0

20 2382,0 2571,0 20 241,0 273,0

21 2541,0 2514,0 21 257,0 264,0

sum 52573.0 55402,0 sum 5528,0 5749,0

std 229,3 235,4 std 74,4 75,8

Cnt-Bg 52195.0 51817.0 Cnt-Bg 5150,0 5371,0

cps 49,7 49,3 cps 4,9 5,1

eff 2,2 eff 1,1

Eff % 2,42 Eff % 1,27


M1= 2503,5 S1= 61,8

M2= 2638,2 S2= 67,0

M1= 1623,1 S1= 263,2

M2= 1769,4 S2= 273,8

M1 ± S1=2503,5±61,8 M2 ±S2=2638,2±67,0 M1± S1=1623,1±263,2 M2 ± S2=1769,4±273,8

Uncertainty in the measurement of two

different sources Uncertainty in the measurement of two different

sources m2

m1 ± s = 1,05 ± 0,006

m2

m1 ± s = 1,04 ± 0,02


35

Appendix 2

Angular sensitivity

57

Co A= 15 kBq

Angle→ 0° 15° 30° 45° 60° 75° 90°

1 293,0 192,0 149,0 41,0 37,0 44,0 44,0

2 282,0 208,0 143,0 48,0 42,0 47,0 38,0

3 275,0 213,0 135,0 42,0 30,0 47,0 38,0

4 271,0 200,0 148,0 34,0 31,0 27,0 44,0

5 287,0 208,0 160,0 38,0 29,0 32,0 40,0

6 258,0 209,0 132,0 37,0 26,0 39,0 44,0

7 259,0 220,0 155,0 43,0 27,0 33,0 41,0

8 246,0 185,0 142,0 32,0 44,0 51,0 31,0

9 255,0 199,0 151,0 53,0 32,0 32,0 42,0

10 293,0 193,0 172,0 44,0 29,0 35,0 47,0

11 250,0 174,0 150,0 40,0 44,0 36,0 31,0

12 243,0 202,0 131,0 45,0 30,0 34,0 41,0

13 292,0 209,0 128,0 37,0 33,0 33,0 40,0

14 257,0 215,0 159,0 34,0 37,0 43,0 39,0

15 289,0 204,0 149,0 49,0 39,0 44,0 49,0

16 251,0 201,0 133,0 34,0 33,0 26,0 30,0

17 289,0 212,0 132,0 31,0 36,0 29,0 27,0

18 250,0 210,0 142,0 39,0 42,0 35,0 39,0

19 250,0 211,0 139,0 49,0 40,0 31,0 42,0

20 258,0 194,0 133,0 41,0 23,0 43,0 39,0

21 249,0 237,0 134,0 42,0 43,0 43,0 43,0

22 260,0 193,0 155,0 37,0 39,0 37,0 34,0

23 256,0 214,0 143,0 47,0 35,0 26,0 47,0

24 266,0 210,0 149,0 46,0 39,0 30,0 40,0

25 239,0 191,0 164,0 32,0 38,0 31,0 43,0

26 238,0 194,0 135,0 40,0 27,0 38,0 39,0

27 270,0 195,0 160,0 43,0 29,0 34,0 48,0

28 260,0 222,0 126,0 37,0 41,0 31,0 37,0

29 249,0 205,0 148,0 50,0 36,0 44,0 34,0

30 244,0 194,0 122,0 40,0 44,0 33,0 40,0

sum 7879,0 6114,0 4319,0 1225,0 1055,0 1088,0 1191,0

std 88,8 78,2 65,7 35,0 32,5 33,0 34,5

mean 262,6 203,8 144,0 40,8 35,2 36,3 39,7

std 17,3 12,4 12,3 5,8 6,1 6,8 5,4


36

57

Co A= 15 kBq

Angle→ -15° -30° -45° -60° -75° -90°

1 249,0 213,0 112,0 70,0 38,0 30,0

2 269,0 217,0 93,0 51,0 40,0 31,0

3 247,0 228,0 87,0 57,0 26,0 33,0

4 261,0 211,0 93,0 55,0 25,0 31,0

5 256,0 208,0 100,0 61,0 34,0 27,0

6 236,0 214,0 100,0 44,0 31,0 24,0

7 254,0 178,0 85,0 45,0 31,0 32,0

8 256,0 151,0 101,0 79,0 27,0 27,0

9 256,0 177,0 97,0 58,0 30,0 26,0

10 259,0 166,0 89,0 48,0 41,0 27,0

11 257,0 175,0 92,0 53,0 37,0 24,0

12 265,0 167,0 95,0 55,0 28,0 40,0

13 261,0 172,0 90,0 64,0 27,0 19,0

14 270,0 175,0 87,0 72,0 29,0 21,0

15 249,0 175,0 101,0 59,0 33,0 15,0

16 301,0 166,0 92,0 53,0 38,0 28,0

17 279,0 151,0 108,0 65,0 43,0 30,0

18 268,0 165,0 105,0 64,0 37,0 27,0

19 275,0 192,0 109,0 57,0 36,0 24,0

20 248,0 155,0 94,0 64,0 33,0 29,0

21 282,0 175,0 88,0 53,0 30,0 27,0

22 272,0 173,0 97,0 46,0 33,0 28,0

23 254,0 166,0 86,0 63,0 31,0 20,0

24 249,0 144,0 71,0 52,0 41,0 18,0

25 230,0 187,0 97,0 48,0 33,0 40,0

26 261,0 149,0 99,0 77,0 33,0 20,0

27 216,0 168,0 104,0 55,0 36,0 28,0

28 231,0 171,0 102,0 51,0 29,0 29,0

29 265,0 183,0 95,0 59,0 30,0 26,0

30 283,0 156,0 99,0 66,0 35,0 21,0

sum 7759,0 5328,0 2868,0 1744,0 995,0 802,0

std 88,1 73,0 53,6 41,8 31,5 28,3

mean 258,6 177,6 95,6 58,1 33,2 26,7

std 17,3 22,2 8,4 9,0 4,8 5,7


37

60

Co A= 32,5 kBq

Angle→ 0° 15° 30° 45° 60° 75° 90°

1 212,0 216,0 219,0 198,0 175,0 177,0 182,0

2 223,0 221,0 202,0 222,0 196,0 180,0 163,0

3 227,0 219,0 198,0 209,0 196,0 153,0 189,0

4 211,0 203,0 212,0 211,0 189,0 191,0 219,0

5 259,0 222,0 209,0 183,0 184,0 172,0 166,0

6 242,0 204,0 197,0 191,0 192,0 155,0 181,0

7 218,0 220,0 209,0 149,0 185,0 183,0 171,0

8 225,0 213,0 224,0 177,0 198,0 168,0 182,0

9 211,0 202,0 221,0 187,0 192,0 167,0 176,0

10 213,0 239,0 193,0 193,0 176,0 167,0 189,0

11 244,0 232,0 222,0 188,0 202,0 177,0 183,0

12 211,0 244,0 222,0 204,0 197,0 174,0 197,0

13 185,0 241,0 203,0 214,0 198,0 187,0 176,0

14 208,0 229,0 214,0 179,0 205,0 176,0 186,0

15 205,0 219,0 202,0 169,0 178,0 157,0 168,0

16 206,0 215,0 219,0 177,0 156,0 181,0 167,0

17 217,0 220,0 210,0 192,0 180,0 173,0 199,0

18 240,0 219,0 200,0 196,0 212,0 160,0 187,0

19 243,0 221,0 198,0 208,0 211,0 187,0 178,0

20 236,0 215,0 217,0 205,0 199,0 163,0 173,0

21 235,0 215,0 235,0 189,0 193,0 160,0 158,0

22 235,0 238,0 226,0 186,0 174,0 191,0 166,0

23 189,0 232,0 228,0 192,0 191,0 178,0 165,0

24 245,0 207,0 222,0 185,0 199,0 184,0 179,0

25 197,0 221,0 231,0 180,0 192,0 188,0 168,0

26 220,0 212,0 191,0 196,0 194,0 171,0 169,0

27 226,0 257,0 184,0 174,0 202,0 197,0 184,0

28 254,0 215,0 192,0 185,0 194,0 178,0 165,0

29 244,0 223,0 215,0 202,0 184,0 162,0 177,0

30 240,0 221,0 201,0 179,0 195,0 179,0 166,0

sum 6721,0 6655,0 6316,0 5720,0 5739,0 5236,0 5329,0

std 82,0 81,6 79,5 75,6 75,8 72,4 73,0

mean 224,0 221,8 210,5 190,7 191,3 174,5 177,6

std 18,8 12,6 13,3 15,1 11,8 11,6 12,9


38

60

Co A= 32,5 kBq

Angle→ -15° -30° -45° -60° -75° -90°

1 220,0 173,0 177,0 191,0 170,0 163,0

2 193,0 209,0 178,0 165,0 163,0 171,0

3 197,0 198,0 183,0 170,0 161,0 149,0

4 223,0 194,0 197,0 156,0 141,0 141,0

5 193,0 190,0 169,0 177,0 171,0 177,0

6 223,0 215,0 173,0 167,0 184,0 148,0

7 238,0 225,0 188,0 154,0 140,0 158,0

8 224,0 196,0 181,0 160,0 166,0 203,0

9 219,0 196,0 152,0 176,0 161,0 156,0

10 211,0 199,0 185,0 149,0 173,0 179,0

11 209,0 209,0 160,0 138,0 156,0 164,0

12 205,0 220,0 182,0 159,0 175,0 134,0

13 211,0 209,0 169,0 164,0 163,0 163,0

14 224,0 186,0 157,0 163,0 173,0 172,0

15 174,0 202,0 173,0 181,0 189,0 174,0

16 184,0 187,0 174,0 160,0 170,0 150,0

17 205,0 230,0 203,0 156,0 149,0 164,0

18 224,0 218,0 182,0 181,0 161,0 183,0

19 225,0 173,0 195,0 161,0 151,0 147,0

20 186,0 190,0 166,0 158,0 161,0 168,0

21 184,0 199,0 178,0 189,0 138,0 201,0

22 197,0 188,0 200,0 184,0 186,0 165,0

23 203,0 198,0 169,0 167,0 156,0 168,0

24 191,0 179,0 178,0 172,0 169,0 160,0

25 229,0 203,0 199,0 153,0 148,0 178,0

26 220,0 185,0 168,0 160,0 168,0 166,0

27 185,0 202,0 180,0 177,0 174,0 184,0

28 210,0 190,0 186,0 176,0 176,0 169,0

29 199,0 181,0 169,0 170,0 175,0 149,0

30 196,0 204,0 171,0 138,0 156,0 159,0

sum 6202,0 5948,0 5342,0 4972,0 4924,0 4963,0

std 78,8 77,1 73,1 70,5 70,2 70,4

mean 206,7 198,3 178,1 165,7 164,1 165,4

std 16,4 14,4 12,6 13,2 13,1 15,8


39

137

Cs A= 169,4 kBq

Angle→ 0° 15° 30° 45° 60° 75° 90° -15° -30° -45° -60° -75° -90°

1 610 593 512 450 405 383 373 648 566 498 403 382 384

2 655 592 543 419 426 424 367 702 588 513 466 365 399

3 671 638 514 406 402 386 406 658 635 473 396 382 382

4 629 621 516 396 403 404 386 685 557 521 438 414 398

5 663 622 516 404 414 402 382 671 578 499 403 399 374

6 676 636 505 425 400 399 346 653 584 510 448 391 389

7 712 591 512 466 367 427 384 623 569 439 418 385 404

8 692 604 502 475 358 399 408 606 557 471 394 372 392

9 675 584 503 413 387 384 357 643 579 453 462 449 396

10 623 587 549 434 406 393 374 611 550 439 411 379 397

Sum 6606 6068 5172 4288 3968 4001 3783 6500 5763 4816 4239 3918 3915

Std 81 78 72 65 63 63 62 81 76 69 65 63 63

Mean 661 607 517 429 397 400 378 650 576 482 424 392 392

std 32 21 16 27 21 15 20 31 24 31 27 24 9

133

Ba A= 32,65 kBq

Angle→ 0° 15° 30° 45° 60° 75° 90° -15° -30° -45° -60° -75° -90°

1 779 677 455 230 142 129 109 749 614 284 186 123 107

2 855 702 456 212 119 120 102 785 570 304 202 117 110

3 890 721 445 204 120 107 117 719 573 305 169 129 124

4 843 741 468 242 119 126 117 740 541 307 192 120 103

5 789 713 448 204 125 106 91 750 595 292 182 107 116

6 915 683 483 247 123 111 120 731 585 316 207 130 121

7 842 734 414 231 114 124 113 715 531 320 211 124 140

8 926 705 457 226 111 121 118 774 560 308 186 133 106

9 833 710 468 214 115 120 112 765 574 328 196 131 118

10 886 711 481 197 137 120 106 779 556 330 213 102 127

Sum 8558 7097 4575 2207 1225 1184 1105 7507 5699 3094 1944 1216 1172

Std 93 84 68 47 35 34 33 87 75 56 44 35 34

Mean 856 710 458 221 123 118 111 751 570 309 194 122 117

std 49 20 20 17 10 8 9 25 25 15 14 10 11


40

Appendix 3

Microsheild simulation in the water

60

Co A= 1 MBq

Depth[cm] DDER[mSv/hr]

2 0,840

3 0,367

4 0,203

5 0,128

6 0,070

7 0,063

8 0,047

9 0,037

10 0,029

11 0,023

12 0,019

13 0,016

14 0,014

15 0,012

137

Cs A= 1 MBq

Depth [cm] DDER[mSv/hr]

2 0,223

3 0,098

4 0,054

5 0,034

6 0,023

7 0,017

8 0,013

9 0,010

10 0,008

11 0,006

12 0,005

13 0,004

14 0,004

15 0,003


41

192

Ir A= 1 MBq

Depth [cm] DDER[mSv/hr]

2 0,352

3 0,158

4 0,089

5 0,057

6 0,039

7 0,029

8 0,022

9 0,017

10 0,014

11 0,011

12 0,009

13 0,008

14 0,006

15 0,005

131

I A= 1MBq

Depth[cm] DDER[mSv/hr]

2 0,165

3 0,074

4 0,042

5 0,026

6 0,018

7 0,013

8 0,010

9 0,008

10 0,006

11 0,005

12 0,004

13 0,003

14 0,003

15 0,002


42

Appendix 4

Localization in the phantom

57Co With

Plexiglas

Depth→ 3 cm 3 cm

Lateral distance

(cm)↓

0 799 581

5 66 54

10 27 17

15 10 10

20 9 10

60

Co With

Plexiglas

Depth→ 3 cm 3 cm

Lateral distance

(cm)↓ 0 468 436

5 125 133

10 67 53

15 39 38

20 19 21

137

Cs With

Plexiglas

Depth→ 3 cm 3 cm

Lateral distance

(cm)↓

0 1923 1490

5 386 329

10 139 126

15 79 69

20 44 39

133

Ba With

Plexiglas

Depth→ 3 cm 3 cm

Lateral distance

(cm)↓ 0 3081 2085

5 290 190

10 56 53

15 21 29

20 11 17


43

Appendix 5

Line profile

131I A≈ 40 kBq, 1mm

D (mm)→ 0 1 2 3 4 5 6 7 9 10

Measuring

series↓

1 4276 4271 4226 4229 4348 4267 4210 4198 4054 4001

2 4293 4282 4250 4365 4289 4115 4271 4114 4085 3921

3 4282 4336 4277 4269 4270 4203 4207 4124 4141 3980

4 4327 4305 4246 4223 4272 4339 4207 4277 4207 4037

5 4300 4219 4177 4326 4333 4300 4190 4249 4160 3988

6 4309 4398 4307 4320 4186 4177 4185 4137 4224 3921

7 4432 4161 4286 4409 4258 4199 4289 4242 4070 3881

8 4286 4238 4435 4246 4340 4123 4314 4085 4206 3881

9 4270 4297 4302 4288 4216 4310 4141 4187 4189 4064

10 4303 4217 4305 4163 4350 4292 4245 4226 4107 3851

mean 4307,8 4272,4 4281,1 4283,8 4286,2 4232,5 4225,9 4183,9 4144,3 3952,5

std 46,8 67,6 67,9 73,3 57,0 79,9 53,0 65,6 62,3 71,8 131

I A≈ 40 kBq, 1mm

D (mm)→ 12 14 16 18 20 22 24 26 28 30

Measuring

series↓

1 2929 1877 1162 854 579 541 373 298 255 232

2 2813 1906 1172 834 614 488 404 283 259 213

3 2907 1899 1205 824 670 482 416 308 264 229

4 2791 1898 1230 799 667 519 430 296 299 252

5 2914 1897 1240 851 644 516 420 322 286 246

6 2910 1982 1173 842 612 517 400 306 279 236

7 2983 1825 1220 785 567 505 449 296 282 233

8 2917 1979 1234 822 607 517 412 300 272 207

9 2912 1842 1200 836 623 518 385 315 276 214

10 2892 1940 1188 797 630 500 431 300 272 277

mean 2896,8 1904,5 1202,4 824,4 621,3 510,3 412 302,4 274,4 233,9

std 55,7 51,6 28,1 23,7 33,6 17,1 22,6 10,9 13,1 20,9


44

131I A≈ 40 kBq, 1mm depth

D(mm)→ -1 -2 -3 -4 -5 -6 -7 -8 -10 -12

Measuring

series↓

1 4279 4332 3963 3399 2370 2023 1479 1057 907 681

2 4199 4112 4048 3485 2397 1950 1481 1110 957 687

3 4296 4249 4091 3550 2418 1981 1440 1153 987 663

4 4257 4249 4091 3490 2346 1889 1430 1168 923 758

5 4299 4178 4097 3457 2354 1958 1431 1088 899 665

6 4229 4081 4048 3417 2403 1929 1449 1125 915 676

7 4111 4287 4118 3417 2306 1945 1412 1111 935 627

8 4340 4253 4027 3430 2366 1910 1363 1107 909 669

9 4163 4160 3970 3501 2373 1997 1475 1111 895 678

10 4246 4128 4068 3381 2377 1939 1458 1115 908 631

mean 4242 4203 4052 3453 2371 1952 1442 1115 924 674

std 69 83 53 53 32 40 36 31 29 36 131

I A≈ 40 kBq, 1mm depth

D(mm)→ -14 -16 -18 -20 -22 -24 -26 -28 -30

Measuring

series↓

1 549 435 392 373 284 289 220 196 198

2 501 451 391 336 288 244 228 200 175 3 525 485 397 325 304 259 262 191 189

4 537 464 392 336 291 279 203 205 193

5 518 468 388 301 310 261 204 226 187

6 589 428 371 322 268 257 239 221 170 7 520 480 380 325 290 267 219 187 200

8 551 424 381 345 293 240 213 217 210

9 468 456 417 327 301 224 219 205 192

10 546 452 395 341 268 261 237 203 178

mean 530 454 390 333 290 258 224 205 189

std 33 21 12 19 14 19 18 13 12


45

137Cs A= 0,15 kBq, 1mm depth

D (mm)→ 0 1 2 3 4 5 6 7 8 9 10

Measuring

series ↓

1 45,0 48,0 58,0 57,0 48,0 57,0 51,0 40,0 46,0 56,0 50,0

2 48,0 65,0 52,0 44,0 48,0 50,0 45,0 51,0 43,0 50,0 47,0

3 56,0 39,0 51,0 63,0 62,0 54,0 55,0 44,0 61,0 52,0 50,0

4 56,0 45,0 52,0 62,0 37,0 47,0 49,0 57,0 59,0 48,0 56,0

5 59,0 46,0 44,0 55,0 49,0 53,0 50,0 49,0 45,0 58,0 47,0

6 57,0 51,0 41,0 48,0 49,0 47,0 48,0 49,0 46,0 51,0 56,0

7 61,0 53,0 62,0 51,0 59,0 51,0 51,0 55,0 56,0 51,0 54,0

8 55,0 62,0 48,0 50,0 62,0 45,0 52,0 54,0 56,0 60,0 47,0

9 52,0 50,0 56,0 52,0 45,0 53,0 60,0 49,0 49,0 60,0 57,0

10 41,0 41,0 43,0 46,0 46,0 57,0 49,0 56,0 44,0 59,0 50,0

11 46,0 33,0 50,0 50,0 43,0 55,0 51,0 47,0 57,0 46,0 50,0

12 46,0 59,0 51,0 39,0 62,0 53,0 47,0 46,0 59,0 52,0 41,0

13 47,0 56,0 61,0 49,0 56,0 51,0 61,0 56,0 51,0 60,0 51,0

14 53,0 64,0 60,0 37,0 47,0 45,0 56,0 49,0 50,0 48,0 59,0

15 50,0 57,0 52,0 49,0 50,0 61,0 60,0 49,0 52,0 56,0 48,0

16 43,0 49,0 44,0 53,0 59,0 44,0 33,0 47,0 53,0 53,0 46,0

17 41,0 53,0 60,0 60,0 62,0 44,0 45,0 59,0 50,0 40,0 56,0

18 50,0 46,0 50,0 63,0 46,0 46,0 58,0 42,0 53,0 58,0 49,0

19 60,0 53,0 54,0 57,0 50,0 56,0 55,0 39,0 50,0 50,0 49,0

20 59,0 56,0 44,0 50,0 47,0 41,0 63,0 48,0 55,0 54,0 50,0

sum 1025,0 1026,0 1033,0 1035,0 1027,0 1010,0 1039,0 986,0 1035,0 1062,0 1013,0

std 32,0 32,0 32,1 32,2 32,0 31,8 32,2 31,4 32,2 32,6 31,8

mean 51,3 51,3 51,7 51,8 51,4 50,5 52,0 49,3 51,8 53,1 50,7

std 6,5 8,3 6,4 7,3 7,4 5,4 7,0 5,6 5,3 5,4 4,5


46

137Cs A= 0,15 kBq, 1mm depth

D (mm)→ 12 14 16 18 20 -1 -2 -3 -4 -5 -6

Measuring

series↓

1 47,0 48,0 39,0 35,0 23,0 55,0 53,0 37,0 34,0 50,0 51,0

2 47,0 51,0 30,0 32,0 32,0 51,0 52,0 58,0 62,0 57,0 46,0

3 50,0 55,0 45,0 35,0 45,0 53,0 50,0 44,0 53,0 60,0 54,0

4 51,0 37,0 39,0 37,0 35,0 49,0 37,0 56,0 47,0 44,0 54,0

5 50,0 33,0 38,0 31,0 36,0 49,0 50,0 49,0 49,0 51,0 44,0

6 40,0 27,0 51,0 38,0 25,0 54,0 55,0 62,0 55,0 46,0 38,0

7 37,0 35,0 32,0 36,0 37,0 47,0 47,0 49,0 52,0 65,0 45,0

8 46,0 49,0 45,0 41,0 31,0 50,0 51,0 63,0 52,0 53,0 49,0

9 57,0 42,0 33,0 41,0 38,0 58,0 60,0 69,0 60,0 50,0 48,0

10 60,0 33,0 56,0 34,0 42,0 43,0 55,0 47,0 42,0 50,0 54,0

11 45,0 42,0 43,0 44,0 44,0 52,0 56,0 41,0 50,0 47,0 67,0

12 50,0 41,0 33,0 30,0 46,0 50,0 54,0 43,0 67,0 58,0 49,0

13 38,0 40,0 34,0 24,0 39,0 58,0 34,0 51,0 43,0 55,0 45,0

14 54,0 48,0 37,0 30,0 25,0 60,0 42,0 38,0 58,0 44,0 42,0

15 62,0 42,0 38,0 36,0 33,0 47,0 54,0 44,0 61,0 49,0 56,0

16 48,0 41,0 39,0 30,0 39,0 47,0 49,0 49,0 49,0 47,0 48,0

17 56,0 35,0 41,0 38,0 37,0 54,0 41,0 50,0 39,0 36,0 47,0

18 40,0 46,0 39,0 28,0 36,0 54,0 43,0 46,0 47,0 37,0 56,0

19 53,0 34,0 35,0 35,0 24,0 52,0 57,0 39,0 49,0 41,0 56,0

20 46,0 40,0 37,0 36,0 37,0 50,0 62,0 63,0 62,0 58,0 55,0

sum 977,0 819,0 784,0 691,0 704,0 1033,0 1002,0 998,0 1031,0 998,0 1004,0

std 31,3 28,6 28,0 26,3 26,5 32,1 31,7 31,6 32,1 31,6 31,7

mean 48,9 41,0 39,2 34,6 35,2 51,7 50,1 49,9 51,6 49,9 50,2

std 7,0 7,1 6,4 4,8 6,9 4,2 7,4 9,2 8,5 7,6 6,5


47

137Cs A= 0,15 kBq, 1 mm depth

D (mm)→ -7 -8 -9 -10 -12 -14 -16 -18 -20

Measuring

series↓

1 50,0 42,0 45,0 40,0 35,0 37,0 37,0 29,0 41,0

2 43,0 39,0 46,0 42,0 40,0 34,0 46,0 40,0 37,0

3 48,0 40,0 57,0 39,0 41,0 24,0 31,0 43,0 36,0

4 56,0 45,0 41,0 53,0 51,0 40,0 37,0 23,0 32,0

5 58,0 31,0 45,0 47,0 49,0 49,0 64,0 33,0 46,0

6 48,0 51,0 46,0 48,0 35,0 45,0 39,0 31,0 34,0

7 42,0 37,0 43,0 44,0 29,0 44,0 28,0 35,0 33,0

8 58,0 41,0 47,0 45,0 47,0 38,0 39,0 41,0 31,0

9 43,0 39,0 49,0 56,0 49,0 40,0 31,0 44,0 34,0

10 45,0 41,0 54,0 46,0 38,0 40,0 41,0 56,0 35,0

11 42,0 42,0 48,0 42,0 47,0 44,0 48,0 43,0 44,0

12 44,0 35,0 45,0 45,0 40,0 26,0 53,0 36,0 34,0

13 55,0 55,0 36,0 41,0 40,0 41,0 34,0 33,0 40,0

14 43,0 49,0 39,0 30,0 38,0 34,0 39,0 29,0 31,0

15 37,0 56,0 48,0 34,0 45,0 32,0 40,0 34,0 35,0

16 51,0 48,0 41,0 42,0 39,0 46,0 39,0 36,0 38,0

17 55,0 48,0 41,0 40,0 41,0 27,0 39,0 32,0 33,0

18 45,0 38,0 40,0 46,0 55,0 42,0 29,0 32,0 43,0

19 47,0 58,0 49,0 40,0 40,0 29,0 31,0 39,0 39,0

20 47,0 60,0 55,0 44,0 38,0 43,0 28,0 36,0 39,0

sum 957,0 895,0 915,0 864,0 837,0 755,0 773,0 725,0 735,0

std 1,9 29,9 30,2 29,4 28,9 27,5 27,8 26,9 27,1

mean 47,9 44,8 45,8 43,2 41,9 37,8 38,7 36,3 36,8

std 6,0 8,1 5,4 5,8 6,3 7,2 8,9 7,1 4,4


48

99mTc 46,2 kBq, at 1 cm depth

D(mm)→ 0 1 2 3 4 5 6 7 8 9 10 12 14 16 18 20

Measuring

series↓

1 905 819 788 769 766 775 683 649 534 433 370 394 254 163 109 59

2 909 816 809 769 764 676 669 618 480 493 399 352 270 178 101 91

3 888 813 878 796 727 699 683 583 469 471 402 399 250 190 112 71

4 888 884 796 822 735 706 687 691 476 471 373 356 254 173 109 88

5 882 905 783 790 752 733 658 646 547 440 409 377 245 187 103 98

6 876 877 788 808 759 717 672 638 512 455 395 370 253 168 110 81

7 858 870 794 799 737 696 679 611 506 433 410 366 260 209 99 57

8 827 866 768 731 782 717 684 612 489 408 369 348 287 194 111 78

9 854 812 760 771 752 691 681 579 506 482 367 384 280 172 113 68

10 895 860 799 764 771 686 635 606 512 463 364 374 251 178 91 93

Mean 878 852 796 782 755 710 673 623 503 455 386 372 260 181 106 78

std 25 34 32 26 17 28 16 34 25 26 19 17 14 14 7 14 99m

Tc A= 46,2 kBq, at 1 cm depth

D(mm)→ 22 24 26 28 30 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -12

Measuring

series↓

1 60 58 43 39 44 826 832 860 696 696 678 666 635 561 555 475

2 61 63 40 43 24 821 810 811 779 748 719 678 608 600 504 467

3 54 54 36 35 44 847 784 748 789 722 666 645 626 579 528 443

4 49 49 43 49 54 806 795 755 732 741 632 667 585 543 510 459

5 66 41 50 41 50 867 813 831 722 756 700 646 564 532 492 432

6 69 57 43 34 47 795 767 762 758 688 705 605 571 586 530 428

7 68 61 39 46 41 773 800 767 770 708 649 651 574 565 496 452

8 70 55 43 33 37 799 793 787 746 733 709 604 610 543 576 464

9 57 49 54 52 41 804 777 762 779 711 617 624 569 551 528 464

10 55 36 48 40 40 778 752 724 734 692 685 629 604 560 505 456

Mean 61 52 44 41 42 812 792 781 751 720 676 642 595 562 522 454

std 7 9 5 6 8 29 23 42 30 24 34 26 25 21 27 15


49

99mTc A= 56 kBq, at 5 cm depth

D(mm)→ 0 1 2 3 4 5 6 7 8 9 10 12 14 16 18 20

Measuring

series↓

1 207 209 194 201 204 223 181 203 173 196 213 166 158 139 124 146

2 228 232 218 221 216 208 203 192 209 209 191 181 177 148 140 154

3 206 220 213 200 214 192 202 191 196 183 173 199 168 170 154 142

4 216 190 212 200 205 198 178 219 204 177 193 188 166 159 141 150

5 204 207 195 232 215 207 203 166 199 212 176 178 173 158 153 164

Mean 212 212 206 211 211 206 193 194 196 195 189 182 168 155 142 151

std 10 16 11 15 6 12 13 19 14 15 16 12 7 12 12 8 99m

Tc A= 56 kBq, at 5 cm depth

D(mm)→ 22 24 26 28 30 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -12

Measuring

series↓

1 129 133 115 113 101 175 207 213 208 195 186 181 176 163 157 151

2 147 125 105 102 103 192 207 192 199 177 173 139 165 160 159 141

3 129 140 99 116 112 215 171 195 190 181 183 164 185 170 148 149

4 135 109 102 114 114 215 216 181 175 195 189 181 167 179 176 147

5 135 109 95 103 77 179 189 215 216 178 192 186 170 171 172 177

Mean 135 123 103 110 101 195 198 199 198 185 185 170 173 169 162 153

std 7 14 8 7 15 19 18 14 16 9 7 19 8 7 11 14


50

131I A= 20 kBq, at 5 cm depth

D(mm)→ 0 1 2 3 4 5 6 7 8 9 10 12 14 16 18 20

Measuring

series↓

1 102 107 108 111 112 110 104 111 112 96 97 102 92 79 79 86

2 116 108 102 95 109 106 105 97 113 96 93 85 89 99 100 80

3 90 102 93 112 107 99 114 96 97 99 96 81 106 111 100 86

4 120 119 104 104 103 98 101 109 96 111 112 109 103 96 104 96

5 113 98 90 112 113 122 97 82 102 101 109 100 108 87 91 94

Mean 108 107 99 107 109 107 104 99 104 101 101 95 100 94 95 88

std 12 8 8 7 4 10 6 12 8 6 9 12 9 12 10 7 131

I A= 20 kBq, at 5 cm depth

D(mm)→ 22 24 26 28 30 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -12

Measuring

series↓

1 102 76 76 76 75 96 105 101 103 109 124 87 112 106 110 91

2 92 80 81 77 80 109 128 95 105 90 106 112 131 98 110 90

3 100 85 68 80 75 90 112 115 126 109 116 95 118 107 106 108

4 79 97 81 84 85 106 95 109 111 109 106 121 109 111 103 133

5 95 104 87 80 77 107 120 95 115 110 98 95 94 105 99 106

Mean 94 88 79 79 78 102 112 103 112 105 110 102 113 105 106 106

std 9 12 7 3 4 8 13 9 9 9 10 14 13 5 5 17


51

131

I A= 20 kBq, at 5 cm depth

D(mm)→ -14 -16 -18 -20 -22 -24 -26 -28 -30

Measuring

series↓

1 109 122 106 99 95 101 83 103 88

2 105 84 101 105 89 102 100 85 80

3 115 121 95 90 88 98 93 71 73

4 107 95 96 108 86 87 82 98 80

5 116 102 88 96 113 93 71 79 66

Mean 110 105 97 100 94 96 86 87 77

std 5 17 7 7 11 6 11 13 8

99m

Tc A= 46,2 kBq, at 1cm depth

D(mm)→ -14 -16 -18 -20 -22 -24 -26 -28 -30

Measuring

series↓

1 413 320 233 169 153 83 74 43 33

2 407 309 220 181 137 97 77 56 34

3 369 302 240 188 119 96 71 59 44

4 340 318 231 173 123 86 70 47 47

5 387 282 217 163 102 93 75 45 38

6 388 275 230 163 127 97 68 59 46

7 385 305 241 152 131 106 78 55 49

8 404 310 231 164 119 82 58 42 36

9 359 249 226 206 144 97 68 50 47

10 358 308 206 172 127 95 64 64 45

Mean 381 298 228 173 128 93 70 52 42

std 24 22 11 15 14 7 6 8 6

99m

Tc A= 56 kBq, at 5 cm depth

D(mm)→ -14 -16 -18 -20 -22 -24 -26 -28 -30

Measuring

series↓

1 159 150 141 108 97 107 89 77 87

2 165 144 134 107 109 104 86 72 74

3 182 138 151 108 111 105 113 91 81

4 137 147 141 111 100 97 107 98 83

5 142 124 128 110 120 96 85 98 90

Mean 157 141 139 109 107 102 96 87 83

std 18 10 9 2 9 5 13 12 6


52

References

[1] Cabanas RM. An approach for the treatment of penile carcinoma, Cancer.1977;

39:456-466

[2] Morton DL, Wen DR, Wong JH, et al. Technical details of intraoperative

lymphatic mapping for early stage melanoma. Arch Surg. 1992; 127:392–399.

[3] Thurston MO, Kaehr JW, Martin EW ІІІ, et al. Rdionuclide Immunoconj

Radiopharm 1991; ХХVІІ: 55-67

[4] Microshield users’ manual version 6.20, Grove Software, Inc, Lynchburg-USA

[5] Semiconductor for room temperature nuclear detector applications, T. Ehud Schlesinger,

Ralph B. James. United Kingdom published by Academic press limited, 1995

[6] Radiation Detection and Measurement, Glenn F. Knoll, third edition 2000

[7] support.svi.nl/wikiimg/FWHM.png

[8] Snyder WS, Fisher HL, Ford MR, Warner GG. Estimates of absorbed dose fractions

for monoenergitic photon sources uniformly distributed in various organs of

a heterogeneous phantom. J Nucl Med Suppl 3:7-52; 1996

[9] Surgical probe europrobe 3 operation manual, Eurorad SA, Eckbolsheim France,

issued in Paris on April 24th, 2009

[10] http://www.eurorad.com/radio.php

[11] Pat Zanzonico and Sherman Heller, The intraoperative gamma probe:

Basic principles and choices available, Seminars in Nuclear medicine, January 2000, 33-48

[12] ICRU (International Commission on Radiation Units and Measurements), 1993,

Quantities and Units in Radiation Protection Dosimetry, Report 51, Bethesda, Maryland.

[13] PCXMC 2.0 user’s guide Topiovaara, M. & Siiskonen, T. STUK-TR

NOVEMBER 2008

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