open access

Vol 21, No 3 (2016)
Original research articles
Published online: 2016-05-01
Submitted: 2015-07-29
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Should we customize PTV expansions for BMI? Daily cone beam computerized tomography to assess organ motion in postoperative endometrial and cervical cancer patients

Arya Amini, Peter E. DeWitt, Yevgeniy Vinogradskiy, Chad G. Rusthoven, Cem Altunbas, Tracey E. Schefter, Christine M. Fisher
DOI: 10.1016/j.rpor.2016.02.003
·
Rep Pract Oncol Radiother 2016;21(3):195-200.

open access

Vol 21, No 3 (2016)
Original research articles
Published online: 2016-05-01
Submitted: 2015-07-29

Abstract

Aim

A single-institution review assessing patient characteristics contributing to daily organ motion in postoperative endometrial and cervical cancer patients treated with intensity-modulated radiotherapy (IMRT).

Background

The Radiation Therapy Oncology Group has established consensus guidelines for postoperative pelvic IMRT, recommending a 7[[ce:hsp sp="0.25"/]]mm margin on all three axes of the target volume.

Materials and methods

Daily shifts on 457 radiation setups for 18 patients were recorded in the x axis (lateral), y axis (superior–inferior) and z axis (anterior–posterior); daily positions of the planning tumor volume were referenced with the initial planning scan to quantify variations.

Results

Of the 457 sessions, 85 (18.6%) had plan shifts of at least 7[[ce:hsp sp="0.25"/]]mm in one of the three dimensions. For obese patients (body mass index [BMI][[ce:hsp sp="0.25"/]]≥[[ce:hsp sp="0.25"/]]30), 75/306 (24.5%) sessions had plan shifts ≥7[[ce:hsp sp="0.25"/]]mm. Odds of having a shift ≥7[[ce:hsp sp="0.25"/]]mm in any direction was greater for obese patients under both univariate (OR 4.227, 95% CI 1.235–14.466, p[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]0.021) and multivariate (OR 5.000, 95% CI 1.341–18.646, p[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]0.016) analyses (MVA). Under MVA, having a BMI[[ce:hsp sp="0.25"/]]≥[[ce:hsp sp="0.25"/]]30 was associated with increased odds of shifts in the anterior–posterior (1.173[[ce:hsp sp="0.25"/]]mm, 95% CI 0.281–2.065, p[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]0.001) and lateral (2.074[[ce:hsp sp="0.25"/]]mm, 95% CI 1.284–2.864, p[[ce:hsp sp="0.25"/]]<[[ce:hsp sp="0.25"/]]0.000) directions but not in the superior–inferior axis (0.298[[ce:hsp sp="0.25"/]]mm, 95% CI −0.880 to 1.475, p[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]0.619) exceeding 7[[ce:hsp sp="0.25"/]]mm.

Conclusions

Based on these findings, the standard planned tumor volume expansion of 7[[ce:hsp sp="0.25"/]]mm is less likely to account for daily treatment changes in obese patients.

Abstract

Aim

A single-institution review assessing patient characteristics contributing to daily organ motion in postoperative endometrial and cervical cancer patients treated with intensity-modulated radiotherapy (IMRT).

Background

The Radiation Therapy Oncology Group has established consensus guidelines for postoperative pelvic IMRT, recommending a 7[[ce:hsp sp="0.25"/]]mm margin on all three axes of the target volume.

Materials and methods

Daily shifts on 457 radiation setups for 18 patients were recorded in the x axis (lateral), y axis (superior–inferior) and z axis (anterior–posterior); daily positions of the planning tumor volume were referenced with the initial planning scan to quantify variations.

Results

Of the 457 sessions, 85 (18.6%) had plan shifts of at least 7[[ce:hsp sp="0.25"/]]mm in one of the three dimensions. For obese patients (body mass index [BMI][[ce:hsp sp="0.25"/]]≥[[ce:hsp sp="0.25"/]]30), 75/306 (24.5%) sessions had plan shifts ≥7[[ce:hsp sp="0.25"/]]mm. Odds of having a shift ≥7[[ce:hsp sp="0.25"/]]mm in any direction was greater for obese patients under both univariate (OR 4.227, 95% CI 1.235–14.466, p[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]0.021) and multivariate (OR 5.000, 95% CI 1.341–18.646, p[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]0.016) analyses (MVA). Under MVA, having a BMI[[ce:hsp sp="0.25"/]]≥[[ce:hsp sp="0.25"/]]30 was associated with increased odds of shifts in the anterior–posterior (1.173[[ce:hsp sp="0.25"/]]mm, 95% CI 0.281–2.065, p[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]0.001) and lateral (2.074[[ce:hsp sp="0.25"/]]mm, 95% CI 1.284–2.864, p[[ce:hsp sp="0.25"/]]<[[ce:hsp sp="0.25"/]]0.000) directions but not in the superior–inferior axis (0.298[[ce:hsp sp="0.25"/]]mm, 95% CI −0.880 to 1.475, p[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]0.619) exceeding 7[[ce:hsp sp="0.25"/]]mm.

Conclusions

Based on these findings, the standard planned tumor volume expansion of 7[[ce:hsp sp="0.25"/]]mm is less likely to account for daily treatment changes in obese patients.

Get Citation

Keywords

BMI; Postoperative pelvic radiation; IMRT; IGRT; Organ motion

About this article
Title

Should we customize PTV expansions for BMI? Daily cone beam computerized tomography to assess organ motion in postoperative endometrial and cervical cancer patients

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 21, No 3 (2016)

Pages

195-200

Published online

2016-05-01

DOI

10.1016/j.rpor.2016.02.003

Bibliographic record

Rep Pract Oncol Radiother 2016;21(3):195-200.

Keywords

BMI
Postoperative pelvic radiation
IMRT
IGRT
Organ motion

Authors

Arya Amini
Peter E. DeWitt
Yevgeniy Vinogradskiy
Chad G. Rusthoven
Cem Altunbas
Tracey E. Schefter
Christine M. Fisher

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