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Practical collimator optimization in the management of prostate IMRT planning: A feasibility study

Published online by Cambridge University Press:  27 June 2011

M Ahamed Badusha  and
CK McGarry
M Ahamed Badusha*
Affiliation:
Radiotherapy Physics Department, Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Belfast, Northern Ireland, UK
CK McGarry
Affiliation:
Radiotherapy Physics Department, Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Belfast, Northern Ireland, UK Centre for Cancer Research and Cell Biology, Queen’s University Belfast, Belfast, Northern Ireland, UK
*
Correspondence to: M. Ahamed Badusha M.Sc MIPEM, Clinical Scientist, Radiotherapy Physics Service, Northern Ireland Cancer Centre, Belfast Health & Social Care Trust, Lisburn Road, Belfast BT9 7AB, Northern Ireland, UK. E-mail: ahamed.badusha@belfasttrust.hscni.net
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Abstract

The objective of this study was to evaluate the delivery efficiency of intensity modulated radiation therapy (IMRT) with a non-zero collimator rotation approach compared to conventional planning IMRT in the management of prostate carcinoma. Inverse plans, created using conventional collimator angle 0° (CA0) for eight prostate patients, were compared to plans using collimator angle 70° (CA70) for all fields and also with plans utilizing an automatic collimator angle optimization tool (CAopt) for each field. Results demonstrate that IMRT plans created with rotational collimator techniques can produce comparable dose distributions to standard CA0 plans. The rotational collimator approach significantly reduced the total number of monitor units (MU) by 6% (p value = 0.027) and 9% (p value = 0.003) for CA70 and CAopt, respectively. The mean monitor units for CA0, CA70 and CAopt were 635 ± 107 MU, 597 ± 96 MU and 587 ± 104 MU, respectively. The mean peripheral dose was significantly increased with CA70 against CA0 (p value < 0.001) despite reduced monitor units. Collimator optimization resulted in reduction in monitor units and peripheral dose. The number of monitor units are reduced with the rotational collimator approach, which results in reduced delivery time. However, we conclude that peripheral dose should be analyzed when assessing monitor unit differences in IMRT plans.

Keywords

Inverse planningIMRTcollimator rotationcollimator optimization
Type
Original Article
Information
Journal of Radiotherapy in Practice , Volume 11 , Issue 2 , June 2012 , pp. 107 - 115
Copyright
Copyright © Cambridge University Press 2012

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