Validation of a Monte-Carlo model of the Varian as500 electronic portal imaging device for radiotherapy dosimetry

Overview

Topic status: In progress

Project background

The main goal of radiotherapy for the treatment of cancer is to deliver a lethal dose of ionising radiation to the perceived tumour volume while minimising the dose to surrounding healthy tissue.

This is the motivation for the recent development of 3D conformal radiotherapy techniques such as Intensity Modulated Radiotherapy (IMRT) that are able to deliver dose distributions that more closely match the shape of the tumour volume and spare neighbouring healthy tissue.

Crucial to the success of 3D conformal radiotherapy is the accurate and precise targeting of the dose distribution to the prescribed volume(s) on a daily basis over the course of a 6-8 week treatment regime. This is one of the biggest challenges faced in radiotherapy. There is therefore an increasing and timely requirement for an in-vivo technique for measuring and verifying the daily dose distribution delivered to the patient.

Hypothesis or aims

The project aims to develop and validate a Monte-Carlo model of the Varian as500 electronic portal imaging device (EPID) for dosimetric verification of patient IMRT treatments. The Monte-Carlo models simulate the physics of the interactions of the x-ray beams with the model detector so that they can be compared directly with the measured dose and serve as a verification of the treatment delivery.

Approaches

A previous project at QUT developed a Monte Carlo model of the Varian as500 EPID for predicting the dose delivered to the detector. This project will commission the model for verifying patient IMRT treatment fields. The commissioning process will involve performing Monte Carlo simulations of the predicted dose in the EPID for patient IMRT treatments. The predicted dose will be compared with the measured dose to investigate the accuracy of the models and their potential for clinical use. The project will involve experimental work at the Mater Hospital’s radiation oncology department and Monte-Carlo simulations of x-ray transport physics using High Performance Computing Resources at QUT.

Duration

Starting December 2011 and January 2012 for 8 weeks

References

  1. A.L Boyer, M. Goitein, A.J. Lomax and E.S. Pedroni: Radiation in the Treatment of Cancer, Physics Today, September 2002, p. 34-36
  2. W. van Elmpt et al: A literature review of electronic portal imaging for radiotherapy dosimetry, Radiotherapy and Oncology Vol 88, p. 289-309 (2008)
  3. F. Verhaegen and J. Seuntjens: Monte-Carlo Modelling of External Radiotherapy Photon Beams, Physics in Medicine and Biology, Vol 48, p. R107-R164 (2003)
Study level
Vacation research experience scholarship
Supervisors
QUT
Organisational unit

Science and Engineering Faculty

Research area

Physics

Keywords
Monte-Carlo, Varian as500, as500, Varian, electronic portal imaging device, imaging device, radiotherapy dosimetry, dosimetry, VRES
Contact

For more information please contact Dr Andrew Fielding.