open access

Vol 14, No 6 (2009)
Technical Notes
Published online: 2009-11-01
Submitted:
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Accuracy checks of physical beam modifier factors algorithm used in computerized treatment planning system for a 15MV photon beam

Muhammad Maqbool, Wazir Muhammad, Muhammad Shahid, Misbah Ahmad, Matiullah Matiullah
DOI: 10.1016/j.rpor.2009.12.002
·
Rep Pract Oncol Radiother 2009;14(6):214-220.

open access

Vol 14, No 6 (2009)
Technical Notes
Published online: 2009-11-01
Submitted:

Abstract

In order to optimize the tumour dose by using wedge filters, systematic studies were carried out to investigate the accuracy of the beam modifier algorithm in a computerized treatment planning system (Theraplan plus, version 3.8). The effect of different parameters such as beam hardening and softening coefficients on the wedge factor was also studied. A 15[[ce:hsp sp="0.25"/]]MV photon beam obtained from a linear accelerator was used throughout the experiments. Normalized wedge factors were determined experimentally as well as with the Theraplan plus system as a function of field size and depth in a water phantom for 15°, 30°, 45°, and 60° wedge filters. The attenuation coefficients, beam hardening coefficient, and beam softening coefficients were also determined experimentally using the 15[[ce:hsp sp="0.25"/]]MV photon beam for each wedge angle. The measured normalized wedge factor was found to increase with increasing depth and field size for the 15[[ce:hsp sp="0.25"/]]MV beam. The Theraplan plus calculated normalized wedge factor was found to be in good agreement with the experimental values. This study indicated that ignoring the dependence of the wedge factor on depth and field size will result in underexposure of the tumour.

Abstract

In order to optimize the tumour dose by using wedge filters, systematic studies were carried out to investigate the accuracy of the beam modifier algorithm in a computerized treatment planning system (Theraplan plus, version 3.8). The effect of different parameters such as beam hardening and softening coefficients on the wedge factor was also studied. A 15[[ce:hsp sp="0.25"/]]MV photon beam obtained from a linear accelerator was used throughout the experiments. Normalized wedge factors were determined experimentally as well as with the Theraplan plus system as a function of field size and depth in a water phantom for 15°, 30°, 45°, and 60° wedge filters. The attenuation coefficients, beam hardening coefficient, and beam softening coefficients were also determined experimentally using the 15[[ce:hsp sp="0.25"/]]MV photon beam for each wedge angle. The measured normalized wedge factor was found to increase with increasing depth and field size for the 15[[ce:hsp sp="0.25"/]]MV beam. The Theraplan plus calculated normalized wedge factor was found to be in good agreement with the experimental values. This study indicated that ignoring the dependence of the wedge factor on depth and field size will result in underexposure of the tumour.

Get Citation

Keywords

Computerized treatment planning system; Wedge; Beam hardening and softening

About this article
Title

Accuracy checks of physical beam modifier factors algorithm used in computerized treatment planning system for a 15MV photon beam

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 14, No 6 (2009)

Pages

214-220

Published online

2009-11-01

DOI

10.1016/j.rpor.2009.12.002

Bibliographic record

Rep Pract Oncol Radiother 2009;14(6):214-220.

Keywords

Computerized treatment planning system
Wedge
Beam hardening and softening

Authors

Muhammad Maqbool
Wazir Muhammad
Muhammad Shahid
Misbah Ahmad
Matiullah Matiullah

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