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Radiother Oncol. 2013 May;107(2):147-52. doi: 10.1016/j.radonc.2013.03.029. Epub 2013 May 14.

Prediction of rectum and bladder morbidity following radiotherapy of prostate cancer based on motion-inclusive dose distributions.

Author information

1
Department of Medical Physics, Aarhus University Hospital, Aarhus, Denmark. mariator@rm.dk

Abstract

BACKGROUND AND PURPOSE:

In radiotherapy (RT) of prostate cancer the key organs at risk (ORs) - the rectum and the bladder - display considerable motion, which may influence the dose/volume parameters predicting for morbidity. In this study we compare motion-inclusive doses to planned doses for the rectum and bladder and explore their associations with prospectively recorded morbidity.

MATERIALS AND METHODS:

The study included 38 prostate cancer patients treated with hypo-fractionated image-guided intensity-modulated RT that had an average of nine repeat CT scans acquired during treatment. These scans were registered to the respective treatment planning CT (pCT) followed by a new dose calculation from which motion-inclusive dose distributions were derived. The pCT volumes, the treatment course averaged volumes as well as the planned and motion-inclusive doses were associated with acute and late morbidity (morbidity cut-off: ≥ Grade 2).

RESULTS:

Acute rectal morbidity (observed in 29% of cases) was significantly associated with both smaller treatment course averaged rectal volumes (population median: 75 vs. 94 cm(3)) and the motion-inclusive volume receiving doses close to the prescription dose (2 Gy-equivalent dose of 76 Gy).

CONCLUSION:

Variation in rectum and bladder volumes leads to deviations between planned and delivered dose/volume parameters that should be accounted for to improve the ability to predict morbidity following RT.

PMID:
23684586
DOI:
10.1016/j.radonc.2013.03.029
[Indexed for MEDLINE]

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