Contouring and constraining bowel on a full-bladder computed tomography scan may not reflect treatment bowel position and dose certainty in gynecologic external beam radiation therapy

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Abstract

Purpose: To evaluate, in a gynecologic cancer setting, changes in bowel position, dose-volume parameters, and biological indices that arise between full-bladder (FB) and empty-bladder (EB) treatment situations; and to evaluate, using cone beam computed tomography (CT), the validity of FB treatment presumption.

Methods and Materials: Seventeen gynecologic cancer patients were retrospectively analyzed. Empty-bladder and FB CTs were obtained. Full-bladder CTs were used for planning and dose optimization. Patients were given FB instructions for treatment. For the study purpose, bowel was contoured on the EB CTs for all patients. Bowel position and volume changes between FB and EB states were determined. Full-bladder plans were applied on EB CTs for determining bowel dose-volume changes in EB state. Biological indices (generalized equivalent uniform dose and normal tissue complication probability) were calculated and compared between FB and EB. Weekly cone beam CT data were available in 6 patients to assess bladder volume at treatment.

Results: Average (±SD) planned bladder volume was 299.7 ± 68.5 cm<sup>3</sup>. Median bowel shift in the craniocaudal direction between FB and EB was 12.5 mm (range, 3-30 mm), and corresponding increase in exposed bowel volume was 151.3 cm<sup>3</sup>(range, 74.3-251.4 cm<sup>3</sup>). Absolute bowel volumes receiving 45 Gy were higher for EB compared with FB (mean 328.0 ± 174.8 vs 176.0 ± 87.5 cm<sup>3</sup>; P=.0038). Bowel normal tissue complication probability increased 1.5× to 23.5× when FB planned treatments were applied in the EB state. For the study, the mean percentage value of relative bladder volume at treatment was 32%.

Conclusions: Full-bladder planning does not necessarily translate into FB treatments, with a patient tendency toward EB. Given the uncertainty in daily control over bladder volume for treatment, we strongly recommend a "planning-at-risk volume bowel" (PRV-Bowel) concept to account for bowel motion between FB and EB that can be tailored for the individual patient.

Original languageEnglish (US)
Pages (from-to)802-808
Number of pages7
JournalInternational Journal of Radiation Oncology Biology Physics
Volume90
Issue number4
DOIs
StatePublished - Nov 15 2014

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bladder
radiation therapy
Urinary Bladder
Radiotherapy
tomography
Tomography
dosage
Therapeutics
planning
Cone-Beam Computed Tomography

ASJC Scopus subject areas

  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Radiation
  • Cancer Research
  • Medicine(all)

Cite this

@article{3662f6f202b84f3badd02f263347fbbc,
title = "Contouring and constraining bowel on a full-bladder computed tomography scan may not reflect treatment bowel position and dose certainty in gynecologic external beam radiation therapy",
abstract = "Purpose: To evaluate, in a gynecologic cancer setting, changes in bowel position, dose-volume parameters, and biological indices that arise between full-bladder (FB) and empty-bladder (EB) treatment situations; and to evaluate, using cone beam computed tomography (CT), the validity of FB treatment presumption.Methods and Materials: Seventeen gynecologic cancer patients were retrospectively analyzed. Empty-bladder and FB CTs were obtained. Full-bladder CTs were used for planning and dose optimization. Patients were given FB instructions for treatment. For the study purpose, bowel was contoured on the EB CTs for all patients. Bowel position and volume changes between FB and EB states were determined. Full-bladder plans were applied on EB CTs for determining bowel dose-volume changes in EB state. Biological indices (generalized equivalent uniform dose and normal tissue complication probability) were calculated and compared between FB and EB. Weekly cone beam CT data were available in 6 patients to assess bladder volume at treatment.Results: Average (±SD) planned bladder volume was 299.7 ± 68.5 cm3. Median bowel shift in the craniocaudal direction between FB and EB was 12.5 mm (range, 3-30 mm), and corresponding increase in exposed bowel volume was 151.3 cm3(range, 74.3-251.4 cm3). Absolute bowel volumes receiving 45 Gy were higher for EB compared with FB (mean 328.0 ± 174.8 vs 176.0 ± 87.5 cm3; P=.0038). Bowel normal tissue complication probability increased 1.5× to 23.5× when FB planned treatments were applied in the EB state. For the study, the mean percentage value of relative bladder volume at treatment was 32{\%}.Conclusions: Full-bladder planning does not necessarily translate into FB treatments, with a patient tendency toward EB. Given the uncertainty in daily control over bladder volume for treatment, we strongly recommend a {"}planning-at-risk volume bowel{"} (PRV-Bowel) concept to account for bowel motion between FB and EB that can be tailored for the individual patient.",
author = "Ravindra Yaparpalvi and Mehta, {Keyur J.} and Bernstein, {Michael B.} and Rafi Kabarriti and Hong, {Linda X.} and Garg, {Madhur K.} and Chandan Guha and Shalom Kalnicki and Tome, {Wolfgang A.}",
year = "2014",
month = "11",
day = "15",
doi = "10.1016/j.ijrobp.2014.07.016",
language = "English (US)",
volume = "90",
pages = "802--808",
journal = "International Journal of Radiation Oncology Biology Physics",
issn = "0360-3016",
publisher = "Elsevier Inc.",
number = "4",

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TY - JOUR

T1 - Contouring and constraining bowel on a full-bladder computed tomography scan may not reflect treatment bowel position and dose certainty in gynecologic external beam radiation therapy

AU - Yaparpalvi, Ravindra

AU - Mehta, Keyur J.

AU - Bernstein, Michael B.

AU - Kabarriti, Rafi

AU - Hong, Linda X.

AU - Garg, Madhur K.

AU - Guha, Chandan

AU - Kalnicki, Shalom

AU - Tome, Wolfgang A.

PY - 2014/11/15

Y1 - 2014/11/15

N2 - Purpose: To evaluate, in a gynecologic cancer setting, changes in bowel position, dose-volume parameters, and biological indices that arise between full-bladder (FB) and empty-bladder (EB) treatment situations; and to evaluate, using cone beam computed tomography (CT), the validity of FB treatment presumption.Methods and Materials: Seventeen gynecologic cancer patients were retrospectively analyzed. Empty-bladder and FB CTs were obtained. Full-bladder CTs were used for planning and dose optimization. Patients were given FB instructions for treatment. For the study purpose, bowel was contoured on the EB CTs for all patients. Bowel position and volume changes between FB and EB states were determined. Full-bladder plans were applied on EB CTs for determining bowel dose-volume changes in EB state. Biological indices (generalized equivalent uniform dose and normal tissue complication probability) were calculated and compared between FB and EB. Weekly cone beam CT data were available in 6 patients to assess bladder volume at treatment.Results: Average (±SD) planned bladder volume was 299.7 ± 68.5 cm3. Median bowel shift in the craniocaudal direction between FB and EB was 12.5 mm (range, 3-30 mm), and corresponding increase in exposed bowel volume was 151.3 cm3(range, 74.3-251.4 cm3). Absolute bowel volumes receiving 45 Gy were higher for EB compared with FB (mean 328.0 ± 174.8 vs 176.0 ± 87.5 cm3; P=.0038). Bowel normal tissue complication probability increased 1.5× to 23.5× when FB planned treatments were applied in the EB state. For the study, the mean percentage value of relative bladder volume at treatment was 32%.Conclusions: Full-bladder planning does not necessarily translate into FB treatments, with a patient tendency toward EB. Given the uncertainty in daily control over bladder volume for treatment, we strongly recommend a "planning-at-risk volume bowel" (PRV-Bowel) concept to account for bowel motion between FB and EB that can be tailored for the individual patient.

AB - Purpose: To evaluate, in a gynecologic cancer setting, changes in bowel position, dose-volume parameters, and biological indices that arise between full-bladder (FB) and empty-bladder (EB) treatment situations; and to evaluate, using cone beam computed tomography (CT), the validity of FB treatment presumption.Methods and Materials: Seventeen gynecologic cancer patients were retrospectively analyzed. Empty-bladder and FB CTs were obtained. Full-bladder CTs were used for planning and dose optimization. Patients were given FB instructions for treatment. For the study purpose, bowel was contoured on the EB CTs for all patients. Bowel position and volume changes between FB and EB states were determined. Full-bladder plans were applied on EB CTs for determining bowel dose-volume changes in EB state. Biological indices (generalized equivalent uniform dose and normal tissue complication probability) were calculated and compared between FB and EB. Weekly cone beam CT data were available in 6 patients to assess bladder volume at treatment.Results: Average (±SD) planned bladder volume was 299.7 ± 68.5 cm3. Median bowel shift in the craniocaudal direction between FB and EB was 12.5 mm (range, 3-30 mm), and corresponding increase in exposed bowel volume was 151.3 cm3(range, 74.3-251.4 cm3). Absolute bowel volumes receiving 45 Gy were higher for EB compared with FB (mean 328.0 ± 174.8 vs 176.0 ± 87.5 cm3; P=.0038). Bowel normal tissue complication probability increased 1.5× to 23.5× when FB planned treatments were applied in the EB state. For the study, the mean percentage value of relative bladder volume at treatment was 32%.Conclusions: Full-bladder planning does not necessarily translate into FB treatments, with a patient tendency toward EB. Given the uncertainty in daily control over bladder volume for treatment, we strongly recommend a "planning-at-risk volume bowel" (PRV-Bowel) concept to account for bowel motion between FB and EB that can be tailored for the individual patient.

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