magdalena mazur proton beam dosimetry -...

PROTON BEAM DOSIMETRY

International Summer Student Practice in JINR Fields of Research 7 - 28 July 2013, Dubna

Magdalena Mazur

PROTON BEAM DOSIMETRY Project participant: Magdalena Mazur Adam Mickiewicz University, Faculty of Physics, Poznań, Poland Supervisor: D.M. Borowicz, MSc Dzhelepov Laboratory of Nuclear Problems, JINR, Dubna The Greater Poland Cancer Centre, Poznań, Poland


Proton beam dosimetry

Aim of the project: dosimetrical verification of the dose distribution in case of beam modification.

Proton beam dosimetry - aim of the project Magdalena Mazur



Proton beam dosimetry – introduction Magdalena Mazur


DLNP JINR Phasotron (Russian terminology)

E ≈ 670 MeV

Emedical use ≈ 160 MeV

Proton beam dosimetry – introduction Magdalena Mazur


Why do we use proton beams?


Bragg peak


Proton beam’s path

P a s s i v e s y s t e m Beam modification is achieved by placing various elements in the beam path.


Proton beam dosimetry – introduction - materials and method Magdalena Mazur




RIDGE FILTERS



RIDGE FILTERS what do they do?

A flat spread-out Bragg peak (SOBP) is achieved by placing spots with increasing weights throughout the target to produce a uniform field.




bolus

ridge filters



BOLUS

Another element to modify the shape of the beam to match the shape of the target. 1 target/plan = 1 individual bolus.




GAFCHROMIC® EBT are self developing dosimetry films. When the active component is exposed to ionizing radiation, it reacts to form a blue colored polymer.


(measurement of radiation dose)

0.001 Gy – 8 Gy

Film irradiation

Two virtually created targets irradiated in 3 ways:

• No filter

• Ridge filter #11

• Ridge filter #13

Proton beam dosimetry – method description Magdalena Mazur




Several pieces of EBT film were irradiated individually in the water tank. To obtain a calibration curve, the films were exposed perpendicularly to the radiation beam at the dose levels of 0 – 3 Gy.

Proton beam dosimetry – step by step Magdalena Mazur



Calibration curve



Plan #1 Plan #2

RIDGE FILTER

Target #1 Target#2

-

#11

#13

Proton beam dosimetry - results - PLAN #1 Magdalena Mazur


Plan #1 – first target E = 160MeV D = 2,5 Gy

no filter ridge filter #11

ridge filter #13


Plan #2 – second target E = 160MeV D = 2,5 Gy


no filter ridge filter #11

ridge filter #13


Plan #2 – second target E = 160MeV D = 2,5 Gy


no filter ridge filter #11 ridge filter #13

Proton beam dosimetry – summary Magdalena Mazur


Conclusions:

Radiochromic films are accurate detectors for proton beam dosimetry Modification of the Bragg peak (SOBP) let’s us match the Bragg peak to the target’s size Ridge filter #13 spreads out the Bragg peak more than the ridge filter #11 Raw (not spread) Bragg peak is a good tool for small lesions and radiosurgery

Special thanks to:


My project’s supervisor:

D.M. Borowicz, JINR

Bogolubov – Infeld program supervisors and coordinators:

Roman Zawodny, Polish group supervisor, UAM, Poznań

Władysław Chmielowski, Polish group coordinator, JINR, Dubna

Stanislav Pakuliak, program supervisor, JINR, Dubna

+ my lab friend – Jozef Bokor

THANK YOU FOR YOUR ATTENTION!

Proton beam dosimetry – in case of questions Magdalena Mazur



RIDGE FILTERS

magdalena mazur proton beam dosimetry -...

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