Xiong W
,
Li J
,
Ma CM
Effect of patient variation on standard and hypofractionated radiotherapy of prostate cancer
Physics in Medicine and Biology. 2005 ;50(7)
:14831492
Abstract
Recent publications suggested that the ?/? ratio in the wellknown linear quadratic (LQ) model could be as low as 1.5 Gy for prostate cancer, indicating that prostate cancer control might be very sensitive to changes in the dose fractionation scheme. This also suggests that the standardfractionation scheme based on large ?/? ratios may not be optimal for the radiotherapeutic management of prostate cancer. Hypofractionated radiotherapy for prostate cancer has received more attention recently as an alternative treatment strategy, which may lead to reduced treatment time and cost. However, hypofractionated radiotherapy may be more sensitive to patient variation in terms of disease control than standardfractionated radiotherapy. The variation of LQ parameters a and ? for a patient population may compromise the outcome of the treatment. This effect can be studied by the introduction of the ?? and ?? parameters, which are the standard deviations of Gaussian distributions around ?0 and ?0. The purpose of this study is to examine the effect of patient variation in a and ? on tumour control probability for standard and hypofractionated radiotherapy of prostate cancer. The tumour control probability based on the LQ model is calculated using parameters ?, ?, ?? and ??. Our results show that ?? is an important parameter for radiotherapy fractionation, independent of the ?/? ratio. A large ??will result in a significant increase in the radiation dose required to achieve the same 95% TCP. Compared with the standardfractionated scheme, ?? has a smaller effect on hypofractionated treatment at lower ?/? ratios. On the other hand, for lower ?/? ratios, the ? term also plays a more important role in cellkilling and therefore the patient variation parameter ?? must be considered when designing a new dose fractionation scheme. © 2005 IOP Publishing Ltd.
Notes
00319155 (ISSN)
Cited By: 0; Export Date: 25 May 2006; Source: Scopus
CODEN: PHMBA; DOI: 10.1088/00319155/50/7/011
Language of Original Document: English
Correspondence Address: Xiong, W.; Department of Radiation Oncology; Fox Chase Cancer Center Philadelphia, PA 19111, United States; email: w_xiong@fccc.edu
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