Qualitative estimation of pelvic organ interactions and their consequences on prostate motion: Study on a deceased person

Authors

  • Keros Laurent,

    1. Département de physique médicale, Centre Alexis Vautrin, Vandoeuvre-lès-Nancy, France and Centre de Recherche en Automatique de Nancy, I. N. P. L., C. N. R. S., U. M. R. 7039, Vandoeuvre-lès-Nancy, France
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  • Bernier Valérie,

    1. Département de radiotherapie, Centre Alexis Vautrin, Vandoeuvre-lès-Nancy, France
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  • Aletti Pierre,

    1. Département de physique médicale, Centre Alexis Vautrin, Vandoeuvre-lès-Nancy, France and Centre de Recherche en Automatique de Nancy, I. N. P. L., C. N. R. S., U. M. R. 7039, Vandoeuvre-lès-Nancy, France
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  • Marchesi Vincent,

    1. Département de physique médicale, Centre Alexis Vautrin, Vandoeuvre-lès-Nancy, France
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  • Wolf Didier,

    1. Centre de Recherche en Automatique de Nancy, I. N. P. L., C. N. R. S., U. M. R. 7039, Vandoeuvre-lès-Nancy, France
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  • Noel Alain

    1. Département de physique médicale, Centre Alexis Vautrin, Vandoeuvre-lès-Nancy, France and Centre de Recherche en Automatique de Nancy, I. N. P. L., C. N. R. S., U. M. R. 7039, Vandoeuvre-lès-Nancy, France
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Abstract

In an attempt to have better targeting of the prostate during radiotherapy it is necessary to understand the mechanical interactions between bladder, rectum, and prostate and estimate their consequences on prostate motion. For this, the volumes of bladder, rectum, and lungs were modified concomitantly on a deceased person. A CT acquisition was performed for each of these different pelvic configurations (36 acquisitions). An increase in the volume of the bladder or lungs induces a compression of tissues of the pelvic area from its supero-anterior (S-A) to infero-posterior (I-P) side. Conversely, an increase of rectum volume induces a compression from the I-P to the S-A side of the pelvic region. These compressive actions can be added or subtracted from each other, depending on their amplitudes and directions. Prostate motion occurs when a movement of the rectum is observed (this movement depends, itself, on lungs and bladder volume). The maximum movement of prostate is 9mm considering maximal bladder or rectal action, and 11mm considering maximum lung action. In some other cases, opposition of compressive effects can lead to stasis of the prostate. Based on the volumes of bladder, rectum, and lungs, it is possible to qualitatively estimate the movement of organs of the pelvic area. The best way to reduce prostate movement is to recommend the patient to have an empty rectum, with either full bladder and/or full lungs.

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