open access

Vol 22, No 1 (2017)
Original research articles
Published online: 2017-01-01
Submitted: 2016-05-08
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Simulation of positron emitters for monitoring of dose distribution in proton therapy

Mohsen Mashayekhi, Ali Asghar Mowlavi, Sayyed Bijan Jia
DOI: 10.1016/j.rpor.2016.10.004
·
Rep Pract Oncol Radiother 2017;22(1):52-57.

open access

Vol 22, No 1 (2017)
Original research articles
Published online: 2017-01-01
Submitted: 2016-05-08

Abstract

Aim

The purpose of this work was to estimate the dependency between the produced positron emitters and the proton dose distribution as well as the dependency between points of annihilation and the proton dose distribution.

Background

One important feature of proton therapy is that, through the non-elastic nuclear interaction of protons with the target nuclei such as 12C, 14N and 16O, it produces a small number of positron-emitting radioisotopes along the beam-path. These radioisotopes allow imaging the Bragg peak position which is related to the proton dose distribution by using positron emission tomography.

Methods

In this study, the GEANT4 toolkit was applied to simulate a soft and bone tissue phantom in proton therapy to evaluate the positron emitter productions and the actual annihilation points of β+. Simulation was done by delivering pencil and spread-out Bragg peak (SOBP) proton beams.

Results

The findings showed that (15O, 11C, 13N) and (11C, 15O, 38K, 30P, 39Ca, 13N) are the most suitable positron emitters in the soft and bone tissue respectively. By increasing the proton energy, the distance between the peak of annihilation profile and Bragg peak is almost constant, but the distance between the Bragg peak position and positron annihilation point peak in bone tissue is smaller than that in the soft tissue. The peak of β+ activity distribution becomes sharper at higher proton energies.

Conclusions

There is a good relationship between the positions of positron annihilation profile and positron emitters radioactive decay. Also, GEANT4 is a powerful and suitable tool for simulation of nuclear interactions and positron emitters in tissues.

Abstract

Aim

The purpose of this work was to estimate the dependency between the produced positron emitters and the proton dose distribution as well as the dependency between points of annihilation and the proton dose distribution.

Background

One important feature of proton therapy is that, through the non-elastic nuclear interaction of protons with the target nuclei such as 12C, 14N and 16O, it produces a small number of positron-emitting radioisotopes along the beam-path. These radioisotopes allow imaging the Bragg peak position which is related to the proton dose distribution by using positron emission tomography.

Methods

In this study, the GEANT4 toolkit was applied to simulate a soft and bone tissue phantom in proton therapy to evaluate the positron emitter productions and the actual annihilation points of β+. Simulation was done by delivering pencil and spread-out Bragg peak (SOBP) proton beams.

Results

The findings showed that (15O, 11C, 13N) and (11C, 15O, 38K, 30P, 39Ca, 13N) are the most suitable positron emitters in the soft and bone tissue respectively. By increasing the proton energy, the distance between the peak of annihilation profile and Bragg peak is almost constant, but the distance between the Bragg peak position and positron annihilation point peak in bone tissue is smaller than that in the soft tissue. The peak of β+ activity distribution becomes sharper at higher proton energies.

Conclusions

There is a good relationship between the positions of positron annihilation profile and positron emitters radioactive decay. Also, GEANT4 is a powerful and suitable tool for simulation of nuclear interactions and positron emitters in tissues.

Get Citation

Keywords

Proton therapy; β+ activity distribution; Positron emitters; GEANT4 toolkit

About this article
Title

Simulation of positron emitters for monitoring of dose distribution in proton therapy

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 22, No 1 (2017)

Pages

52-57

Published online

2017-01-01

DOI

10.1016/j.rpor.2016.10.004

Bibliographic record

Rep Pract Oncol Radiother 2017;22(1):52-57.

Keywords

Proton therapy
β+ activity distribution
Positron emitters
GEANT4 toolkit

Authors

Mohsen Mashayekhi
Ali Asghar Mowlavi
Sayyed Bijan Jia

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