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Trends in Medical Research
  Year: 2006 | Volume: 1 | Issue: 1 | Page No.: 55-65
DOI: 10.3923/tmr.2006.55.65
Prostate Radiotherapy: Evaluating the Effect of Bladder and Rectal Changes on Prostate Movement-A CT Study
Stephen Mangar, Jerome Coffey , Helen McNair , Vibeke N. Hansen , Syed Sohaib , Robert Huddart , Christopher Parker , Alan Horwich and David Dearnaley

Abstract:
Prostate motion during radiotherapy is influenced mainly by both bladder and rectal filling. This study assesses the impact of bladder and rectal changes on prostate movement and determines whether there are any predictive factors for prostate motion from the initial radiotherapy planning scan. Twenty six patients undergoing conformal radiotherapy for prostate cancer had two CT scans approximately 35 min apart whilst remaining in the same radiotherapy planning position. Prostate, bladder and rectal contours were outlined on both CTs and prostate movement with respect to the bony pelvis was calculated after fusion of CT data sets. This method for determining prostate movement was validated by fiducial markers placed in 6 patients. Cross sectional and volumetric bladder and rectal data were analysed from each scan and correlated with prostate movement. Considerable intra-patient variations in bladder and rectal volumes occurred over a 35 min interval. There were no predictive bladder, or rectal parameters on initial CT to predict for prostate motion, with poor correlations observed between A-P prostate movement and the initial rectal volume (r = -0.19), cross sectional area (r = 0.17) and A-P diameter (r = -0.21), and only weak positive correlations between S-I prostate movement and both initial rectal volume (r = 0.43, p = 0.03) and A-P diameter (r = 0.44, p = 0.02). However the changes between the initial and final rectal cross sectional area (r = 0.82, p<0.001) and AP diameter (r = 0.81, p<0.001) were more closely related to A-P prostate movement. These findings confirm the principal that as the rectum expands it moves the prostate anteriorly, whilst changes in bladder volume seems to contribute less to inferior prostate motion. Strategies to manage these movements include adapting the posterior margin to the degree of rectal filling, or using methods to empty the rectum prior to treatment.
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How to cite this article:

Stephen Mangar, Jerome Coffey , Helen McNair , Vibeke N. Hansen , Syed Sohaib , Robert Huddart , Christopher Parker , Alan Horwich and David Dearnaley , 2006. Prostate Radiotherapy: Evaluating the Effect of Bladder and Rectal Changes on Prostate Movement-A CT Study. Trends in Medical Research, 1: 55-65.

DOI: 10.3923/tmr.2006.55.65

URL: https://scialert.net/abstract/?doi=tmr.2006.55.65

 
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