« Back
Comparison of dosimetry from bowel bag and individual bowel loop contouring for patients receiving pelvic Stereotactic Ablative Radiotherapy (SABR)
Poster Title: Comparison of dosimetry from bowel bag and individual bowel loop contouring for patients receiving pelvic Stereotactic Ablative Radiotherapy (SABR)
Submitted on 25 Sep 2019
Author(s): Eleanor Clarke, Rhiannon Howells, Matthew Beasley, Louise Murray
Affiliations: University of Leeds, Leeds Cancer Centre
This poster was presented at NCRI 2019, BIR Annual Congress 2019
Poster Views: 75
View poster »

Poster Information
Abstract: Background
Current practice for patients receiving SABR for pelvic oligometastases is to delineate individual bowel loops (BL) on planning CT; a time-consuming process. A bowel bag (BB) structure outlines the peritoneal cavity, allowing estimation of bowel dose.

This study investigated whether contouring only restricted BL in close tumour proximity, with the BB contoured to cover the remaining volume, would provide a more efficient contouring method without sacrificing valuable information.

Planning CTs with contoured BL for twenty patients who received SABR for pelvic oligometastatic nodal recurrence were included. BB was delineated. Planning target volume (PTV) was expanded 3 cm laterally and 2 cm superio-inferiorly (PTV3+2), to include BL closest to the tumour. Maximum doses to BL (0.5 cm3 (Dmax0.5cm3) and 5 cm3 (Dmax5cm3)) inside and beyond the PTV3+2 were evaluated.

Dmax0.5cm3 and Dmax5cm3 for BL within PTV3+2 were consistently higher than doses to BL beyond PTV3+2 (both p<0.001).

The median difference in Dmax0.5cm3 of BL outside the PTV3+2 (BL_outside_PTV3+2) and BB outside the PTV3+2 (BB_outside_PTV3+2) was 0.4 Gy (range:-0.2 to +7.0). In 17/20, dose to BB_outside_PTV3+2 was higher.

Median difference in Dmax5cm3 of BL_outside_PTV3+2 and BB_outside_PTV3+2 was 1.0 Gy (range:-0.1 to +7.1), with dose to BB_outside_PTV3+2 higher in all.

Contouring individual BL in close proximity to the target provides the relevant structures to limit high dose to individual BL during planning using Dmax constraints. Contouring BB only beyond PTV3+2 does not result in any meaningful under-estimation of dose to BL within this region. This process offers time-saving implications.
Summary: This study aimed to compare dosimetry for bowel bag and individual bowel loop contouring for patients receiving Stereotactic Ablative Radiotherapy for pelvic oligometastatic recurrence. Report abuse »
Ask the author a question about this poster.
Ask a Question »

Creative Commons

Related Posters

astrophYsics Experiments wiTh partIcles - YETI at IAYC 2018
Elizabeth Mondragon

Etiological diagnostics of cardiomyopathies in the cardiology unit of the HUEH internal medicine department during the period from 8 January 2014 to 14 June 2014
*Axler JEAN PAUL; **Lesly Ed. ARCHER; *Raema Mimrod JEAN; *Gerald VERNELUS; *Rodolph MALEBRANCHE

Medical Student: Move over Stem Cells – Exosomes are Here! What are Exosomes & their role in Regenerative Medicine?
Amartej Singh Deol MD4 & Advisor: Shivinder S. Deol MD

Briand Bounkeu MD; Ravi Shekarappa MD; La Toya Jackson DO, FAAFP; Chinedu Ivonye MD, FACP; Cristal Kudiwu MD

Striving for Equity in Surgical, Anesthesia, and Obstetric Research in Haiti: A Multi-Partner, International Research Training Collaboration
Dr. Jean Alouidor*, Dr. Frédéric Barau Déjean*, Dr. Louis-Franck Télémaque, Dr. Ronald Eveillard, Dr. Laëlle Mangurat, Dr. Isaac Martineau, Dr. Chartelin Jean Isaac, Dr. Darlène Rochelin Paultre, Carine Réveil Jean-Baptiste, Dr. Lucile Louis Riché, Dr. Jordan Pyda, Rolvix Patterson III, Dr. Blake Alkire, Dr. Eunice Dérivois-Mérisier (*Co-First Authors)