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A geometric model for evaluating the effects of inter-fraction rectal motion during prostate radiotherapy

Domenii publicaţii > Fizica + Tipuri publicaţii > Articol în revistã ştiinţificã

Autori: Luciana M Pavel-Mititean, Carl G Rowbottom, Charlotte L Hector, Mike Partridge, Thomas Bortfeld and Wolfgang Schlegel

Editorial: Physics in Medicine and Biology (PMB), 49, p.2613–2629, 2004.


A geometric model is presented which allows calculation of the dosimetric
consequences of rectal motion in prostate radiotherapy. Variations in the
position of the rectum are measured by repeat CT scanning during the courses
of treatment of five patients. Dose distributions are calculated by applying
the same conformal treatment plan to each imaged fraction and rectal dosesurface
histograms produced. The 2D model allows isotropic expansion
and contraction in the plane of each CT slice. By summing the dose to
specific volume elements tracked by the model, composite dose distributions
are produced that explicitly include measured inter-fraction motion for each
patient. These are then used to estimate effective dose-surface histograms
(DSHs) for the entire treatment. Results are presented showing the magnitudes
of the measured target and rectal motion and showing the effects of this motion
on the integral dose to the rectum. The possibility of using such information
to calculate normal tissue complication probabilities (NTCP) is demonstrated
and discussed.

Cuvinte cheie: radioterapy, organ motion, rectal model, DSH, prostate

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