DOSIMETRY Lenka Goceliakov 6 27 July 2014, Dubna PROTON BEAM - - PowerPoint PPT Presentation

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DOSIMETRY Lenka Goceliakov 6 27 July 2014, Dubna PROTON BEAM - - PowerPoint PPT Presentation

Nov 18, 2023 160 likes •343 views

International Summer Student Practice at the Joint Institute for Nuclear Research PROTON BEAM DOSIMETRY Lenka Goceliakov 6 27 July 2014, Dubna PROTON BEAM DOSIMETRY Project participant : Lenka Goceliakov University of Pavol Jozef

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SLIDE 1

PROTON BEAM DOSIMETRY

Lenka Goceliaková

International Summer Student Practice at the Joint Institute for Nuclear Research

6 – 27 July 2014, Dubna

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SLIDE 2

PROTON BEAM DOSIMETRY

Project participant: Lenka Goceliaková University of Pavol Jozef Šafárik, Faculty of Science, Košice, Slovakia Supervisor:

  • Dr. S.V. Shvidky

Medico – Technical Complex, Dzhelepov Laboratory of Nuclear Problems, JINR, Dubna

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SLIDE 3

AIM OF THE PROJECT

  • To verify the correspondence of the dose

distribution in case of therapeutical proton beam, using film dosimetry and simulations in the 3D Treatment Planning System (TPS)

  • To compare the dose distribution obtained

using EBT films and the 3D TPS

  • To compare EBT2 & new EBT3 films
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SLIDE 4

Why do we need the dosimetry?

  • To verify the accuracy of a planning system

calculation algorithm and to determine the distal dose for the volume.

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SLIDE 5

Proton beam dosimetry

  • Measurements of the radiation dose

0,0001 Gy – 3 Gy

Properties of the Gafchromic films:

  • EBT2, EBT3
  • self developing dosimetry films

When the active component is exposed to ionizing radiation, it reacts and forms a green colored polymer.

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SLIDE 6

Materials and Methods

  • Irradiation EBT2 & EBT3 calibrate films(picture with the small pieces)
  • Irradiation EBT2 & EBT3 films
  • Scanning of films
  • Drawing of calibration curves
  • Calculation of the matrices for all films
  • Comparison of the dose distribution using EBT films dosimetry and the 3D

TPS

  • Gamma – index calculation
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SLIDE 7

Irradiation Method

  • The films were irradiated individually with protons in a

water tank;

  • The proton beams pass through colimator, water tank and

stops in radiochromic film;

  • Films were places in the water phantom and positioned

with a angle 5 degrees slope to the beam axis in the horizontal plane

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SLIDE 8

Films Scanning

  • Reflection Method:
  • light from the transmitter bounces off a reflector placed
  • utside of the housing and travels back to the receiver.

Positive Method:

  • a beam of light shines directly from the transmitter to the

receiver.

  • An object is detected when it passes between transmitter

and receiver and blocks the beam of light.

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SLIDE 9

Calibration curve

V

c b a Dose   

pixels V 0,98165 c

  • 34,25479

b

  • 0,84095

    a

EBT3 – Positive Method

110 120 130 140 150 160 170 180 190 200 210 0,0 0,5 1,0 1,5 2,0 2,5 3,0

Dose (Gy) Value of pixel

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SLIDE 10

Calibration curve

10 20 30 40 50 60 70 80 90 100 110 120 130 140 0,0 0,5 1,0 1,5 2,0 2,5 3,0

Dose (Gy) Value of Pixel

V

c b a Dose   

EBT3 – Reflective Method

pixels V 0,95327 c

  • 10,01656

b 0,12236     a

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SLIDE 11

Comparison between films and planning system

90 60 60 60 10 20 30 40 50 60 70 80 90

20 40 60 80 100 120 140 160 10 20 30 40 50 60 70 80 90

Width(mm) Depth(mm) Comparison between EBT2 (black) and Planning System (red) for Positive Method

dL=3mm; dD=3% G <= 1 (10%): 80.8% G <= 1 (20%): 72% G <= 1 (30%): 59% G <= 1 (40%): 11.5% G <= 1 (50%): 71% G <= 1 (60%): 98.6% G <= 1 (70%): 100% G <= 1 (80%): 99.4% G <= 1 (90%): 99.7% G <= 1 (100%): 100% G <= 1 (>90%): 99.7%

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SLIDE 12

10 20 30 40 50 60 60 60 60 60 70 80 90 60 60 60 60 60 60 60 60 60 70 70 70 70 60 60 60 60 60 60 60 60 10 20 30 40 50 60 70 80 90

20 40 60 80 100 120 140 10 20 30 40 50 60 70 80 Width(mm) Depth(mm) Comparison between EBT3 (black) and Planning System (red) for Positive Method

dL=3mm; dD=3% G <= 1 (10%): 90.4% G <= 1 (20%): 73.6% G <= 1 (30%): 58.8% G <= 1 (40%): 10.6% G <= 1 (50%): 59.5% G <= 1 (60%): 91.9% G <= 1 (70%): 99.6% G <= 1 (80%): 100% G <= 1 (90%): 100% G <= 1 (100%): 100% G <= 1 (>90%): 100%

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SLIDE 13

20 30 40 40 50 60 60 80 90 90 50 50 50 70 40 40 50 50 60

10 20 30 40 50 60 70 80 90

20 40 60 80 100 120 140 10 20 30 40 50 60 70 80 Width (mm) Depth(mm)

Comparison between EBT2 (black) and Planning System (red) for Reflective Method

dL=3mm; dD=3% G <= 1 (10%): 59.3% G <= 1 (20%): 80.3% G <= 1 (30%): 93.9% G <= 1 (40%): 58.4% G <= 1 (50%): 77.4% G <= 1 (60%): 99.6% G <= 1 (70%): 97.8% G <= 1 (80%): 90% G <= 1 (90%): 80.6% G <= 1 (100%): 100% G <= 1 (>90%): 80.7%

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SLIDE 14

40 50 50 50 50 60 60 80 50 50 50 50 50 70 60 10 20 30 40 50 60 70 80 90

20 40 60 80 100 120 140 20 40 60 80 Width(mm) Depth(mm)

Comparison between EBT3 (black) and Planning System (red) for Reflective Method

dL=3mm; dD=3% G <= 1 (10%): 67.5% G <= 1 (20%): 72.2% G <= 1 (30%): 87.1% G <= 1 (40%): 95.8% G <= 1 (50%): 99.5% G <= 1 (60%): 93.5% G <= 1 (70%): 96.1% G <= 1 (80%): 75.9% G <= 1 (90%): 71% G <= 1 (100%): 100% G <= 1 (>90%): 71.2%

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SLIDE 15

RESULTS

  • Positive Method: G – index more 90%
  • Reflective Method: G – index less 90%
  • Preferable is positive method of scanning
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SLIDE 16

Conclusions

  • Radiochromic films are accurate detectors for

proton beam dosimetry

  • Measured date are consistent with the date

from PS in the acceptable deviation (3%)

  • Results from G – index comply requierement

for the planning of proton therapy

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SLIDE 17

THANK YOU FOR YOUR ATTENTION !

Special thanks to:

My project consultant: Konstantin Shipulin – Medico-Technical Complex, Dzhelepov Laboratory of Nuclear Problems, JINR, Dubna