Pancreatic cancer treated with SBRT: Effect of anatomical interfraction variations on dose to organs at risk.
Dosimetry
Interfraction variation
Organ motion
Pancreatic cancer
SBRT
Journal
Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology
ISSN: 1879-0887
Titre abrégé: Radiother Oncol
Pays: Ireland
ID NLM: 8407192
Informations de publication
Date de publication:
05 2019
05 2019
Historique:
received:
24
08
2018
revised:
14
01
2019
accepted:
17
01
2019
entrez:
22
4
2019
pubmed:
22
4
2019
medline:
28
3
2020
Statut:
ppublish
Résumé
Interfraction shape and position variations of organs at risk (OARs) may increase uncertainty in dose delivery during stereotactic body radiotherapy (SBRT), potentially leading to overirradiation or concessions in planned tumor dose and/or coverage to prevent clinical constraints violation. The aim of our study was to quantitatively analyze the impact of anatomical interfraction variations on dose to OARs in pancreatic cancer (PC) treated by SBRT using a CyberKnife with integrated CT-on-rails. Thirty-five PC patients treated with SBRT (40 Gy/5 fractions) underwent a CT-scan in treatment position before each of the first three fractions using the CT-on-rails system. OARs (stomach, duodenum, bowel) were manually delineated and concatenated to one structure (Gastro-Intestinal Organ, GIO). To overlay the planned dose distribution, fiducial-based alignment of the fraction CT with the planning CT was performed. Planned DVH parameters of the OAR were compared to the parameters calculated in the fractions CTs. Compared to the treatment plan, the median V35, D2, D5, D10 and Dmax of the fraction CTs in the GIO was increased by 1.0 (IQR: 0.2-2.6), 4.4% (0.4-10.8), 2.3% (0.2-7.5), 3.3% (-0.4 to 7.1), and 12.0% (5.0-18.9) respectively. Median increase was statistically significant for all parameters in GIO and for V35 in all critical structures at Wilcoxon test. Anatomical interfraction variations increase OAR dose during SBRT for pancreatic cancer daily imaging using integrated CT/CyberKnife may allow to implement strategies to reduce the risk of OAR overirradiation during pancreatic SBRT.
Sections du résumé
BACKGROUND AND PURPOSE
Interfraction shape and position variations of organs at risk (OARs) may increase uncertainty in dose delivery during stereotactic body radiotherapy (SBRT), potentially leading to overirradiation or concessions in planned tumor dose and/or coverage to prevent clinical constraints violation. The aim of our study was to quantitatively analyze the impact of anatomical interfraction variations on dose to OARs in pancreatic cancer (PC) treated by SBRT using a CyberKnife with integrated CT-on-rails.
MATERIALS AND METHODS
Thirty-five PC patients treated with SBRT (40 Gy/5 fractions) underwent a CT-scan in treatment position before each of the first three fractions using the CT-on-rails system. OARs (stomach, duodenum, bowel) were manually delineated and concatenated to one structure (Gastro-Intestinal Organ, GIO). To overlay the planned dose distribution, fiducial-based alignment of the fraction CT with the planning CT was performed. Planned DVH parameters of the OAR were compared to the parameters calculated in the fractions CTs.
RESULTS
Compared to the treatment plan, the median V35, D2, D5, D10 and Dmax of the fraction CTs in the GIO was increased by 1.0 (IQR: 0.2-2.6), 4.4% (0.4-10.8), 2.3% (0.2-7.5), 3.3% (-0.4 to 7.1), and 12.0% (5.0-18.9) respectively. Median increase was statistically significant for all parameters in GIO and for V35 in all critical structures at Wilcoxon test.
CONCLUSIONS
Anatomical interfraction variations increase OAR dose during SBRT for pancreatic cancer daily imaging using integrated CT/CyberKnife may allow to implement strategies to reduce the risk of OAR overirradiation during pancreatic SBRT.
Identifiants
pubmed: 31005226
pii: S0167-8140(19)30025-8
doi: 10.1016/j.radonc.2019.01.020
pii:
doi:
Types de publication
Journal Article
Langues
eng
Sous-ensembles de citation
IM
Pagination
67-73Informations de copyright
Copyright © 2019 Elsevier B.V. All rights reserved.