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Related Concept Videos

Muscles of the Pelvic Floor and Perineum01:26

Muscles of the Pelvic Floor and Perineum

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Related Experiment Video

Updated: May 21, 2026

Quantification of Levator Ani Hiatus Enlargement by Magnetic Resonance Imaging in Males and Females with Pelvic Organ Prolapse
07:41

Quantification of Levator Ani Hiatus Enlargement by Magnetic Resonance Imaging in Males and Females with Pelvic Organ Prolapse

Published on: April 17, 2019

Large prostate motion produced by anal contraction.

Hiroshi Onishi1, Kengo Kuriyama, Takafumi Komiyama

  • 1University of Yamanashi, Japan. honishi@yamanashi.ac.jp

Radiotherapy and Oncology : Journal of the European Society for Therapeutic Radiology and Oncology
|June 8, 2012
PubMed
Summary

Voluntary anal contraction causes significant prostate and pelvic motion, primarily anterior and cranial. Further research is needed to understand the impact of these movements during prostate cancer radiotherapy.

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Related Experiment Videos

Last Updated: May 21, 2026

Quantification of Levator Ani Hiatus Enlargement by Magnetic Resonance Imaging in Males and Females with Pelvic Organ Prolapse
07:41

Quantification of Levator Ani Hiatus Enlargement by Magnetic Resonance Imaging in Males and Females with Pelvic Organ Prolapse

Published on: April 17, 2019

Ultrasonography of the Adult Male Urinary Tract for Urinary Functional Testing
05:25

Ultrasonography of the Adult Male Urinary Tract for Urinary Functional Testing

Published on: August 14, 2019

Spatiotemporal Mapping of Motility in Ex Vivo Preparations of the Intestines
12:00

Spatiotemporal Mapping of Motility in Ex Vivo Preparations of the Intestines

Published on: January 27, 2016

Area of Science:

  • Radiotherapy
  • Medical Imaging
  • Oncology

Background:

  • Prostate cancer treatment often involves radiotherapy.
  • Patient movement during treatment can affect radiation delivery accuracy.
  • Understanding factors influencing prostate motion is crucial for optimizing radiotherapy outcomes.

Purpose of the Study:

  • To quantify the effect of voluntary anal contraction on prostate and pelvic motion.
  • To assess the magnitude and direction of displacement induced by anal contraction.
  • To evaluate the clinical relevance of anal contraction in the context of prostate cancer radiotherapy.

Main Methods:

  • Thirty-eight prostate cancer patients were included.
  • Thin-slice computed tomography (CT) scans were performed before and after active anal contraction.
  • Three-dimensional displacement of the prostate and pelvis was measured.

Main Results:

  • Prostate motion averaged 9.3 mm anterior and 5 mm cranial.
  • Pelvic motion averaged 4.1 mm anterior and 1 mm cranial.
  • Relative prostate motion to the pelvis was 5.2 mm anterior and 4 mm cranial.

Conclusions:

  • Voluntary anal contraction induces substantial prostate and bone motion, predominantly in anterior and cranial directions.
  • The findings highlight the potential for significant intra-fraction motion during prostate cancer radiotherapy.
  • Further investigation into the frequency and extent of anal contractions during actual radiotherapy sessions is warranted.