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Title: SU-F-J-63: Abdominal Diameter Changes in Children During Volumetric Modulated Arc Therapy (VMAT): Is Re-Planning Needed?

Abstract

Purpose: To investigate the dosimetric impact of daily changes in patient’s diameter, due to weight gain/loss and air in the bowel, based on CBCT information during radiotherapy treatment of pediatric abdominal tumors. Methods: 10 pediatric patients with neuroblastoma (n=6) and Wilms’ (n=4) tumors were included. Available CBCTs were affinely registered to the planning CT for daily set-up variations corrections. A density override approach assigning air-density to the random air pockets and water-density to the remaining anatomy was used to determine the CBCT and CT dose. Clinical VMAT plans, with a PTV prescribed dose ranging between (14.4- 36) Gy, were re-optimized on the density override CT and re-calculated on each CBCT. Dose-volume statistics of the PTV and kidneys, delineated on each CBCT, were used to compare the daily and cumulative CBCT dose with the reference CT dose. Results: The average patient diameter variation was (0.5 ± 0.7) cm (maximum daily difference of 2.3 cm). The average PTV mean dose difference (MDD) between the CT and the cumulative CBCT plans was (0.1 ± 1.1) % (maximum daily MDD of 2%). A reduction in target coverage up to 3% and 7% was observed for the cumulative and daily CBCT plans, respectively. The averagemore » kidneys’ cumulative MDD was (−2.7 ± 3.6) % (maximum daily MDD of −12%), corresponding to an overdosage. Conclusion: Due to patient’s diameter changes, a target underdosage was assessed. Given the high local tumor control of neuroblastoma and Wilms’ diseases, the need of re-planning might be discarded. However, the assessed kidneys overdosage could represent a problem when the normal tissue tolerance is reached. The necessity of re-planning should then be considered to reduce the risk of long-term renal complications. Due to the poor softtissue contrast on CBCT, MRI-guidance is required to obtain a better assessment of the accumulated dose on the remaining OARs.« less

Authors:
; ; ;  [1]
  1. University Medical Center Utrecht, Department of Radiotherapy and Imaging Division, Utrecht (Netherlands)
Publication Date:
OSTI Identifier:
22632193
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 43; Journal Issue: 6; Other Information: (c) 2016 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; 61 RADIATION PROTECTION AND DOSIMETRY; ANATOMY; ANIMAL TISSUES; CHILDREN; COMPUTERIZED TOMOGRAPHY; KIDNEYS; NEOPLASMS; NMR IMAGING; PATIENTS; PEDIATRICS; PLANNING; RADIATION DOSES; RADIOTHERAPY

Citation Formats

Guerreiro, F, Janssens, G, Seravalli, E, and Raaymakers, B. SU-F-J-63: Abdominal Diameter Changes in Children During Volumetric Modulated Arc Therapy (VMAT): Is Re-Planning Needed?. United States: N. p., 2016. Web. doi:10.1118/1.4955971.
Guerreiro, F, Janssens, G, Seravalli, E, & Raaymakers, B. SU-F-J-63: Abdominal Diameter Changes in Children During Volumetric Modulated Arc Therapy (VMAT): Is Re-Planning Needed?. United States. doi:10.1118/1.4955971.
Guerreiro, F, Janssens, G, Seravalli, E, and Raaymakers, B. Wed . "SU-F-J-63: Abdominal Diameter Changes in Children During Volumetric Modulated Arc Therapy (VMAT): Is Re-Planning Needed?". United States. doi:10.1118/1.4955971.
@article{osti_22632193,
title = {SU-F-J-63: Abdominal Diameter Changes in Children During Volumetric Modulated Arc Therapy (VMAT): Is Re-Planning Needed?},
author = {Guerreiro, F and Janssens, G and Seravalli, E and Raaymakers, B},
abstractNote = {Purpose: To investigate the dosimetric impact of daily changes in patient’s diameter, due to weight gain/loss and air in the bowel, based on CBCT information during radiotherapy treatment of pediatric abdominal tumors. Methods: 10 pediatric patients with neuroblastoma (n=6) and Wilms’ (n=4) tumors were included. Available CBCTs were affinely registered to the planning CT for daily set-up variations corrections. A density override approach assigning air-density to the random air pockets and water-density to the remaining anatomy was used to determine the CBCT and CT dose. Clinical VMAT plans, with a PTV prescribed dose ranging between (14.4- 36) Gy, were re-optimized on the density override CT and re-calculated on each CBCT. Dose-volume statistics of the PTV and kidneys, delineated on each CBCT, were used to compare the daily and cumulative CBCT dose with the reference CT dose. Results: The average patient diameter variation was (0.5 ± 0.7) cm (maximum daily difference of 2.3 cm). The average PTV mean dose difference (MDD) between the CT and the cumulative CBCT plans was (0.1 ± 1.1) % (maximum daily MDD of 2%). A reduction in target coverage up to 3% and 7% was observed for the cumulative and daily CBCT plans, respectively. The average kidneys’ cumulative MDD was (−2.7 ± 3.6) % (maximum daily MDD of −12%), corresponding to an overdosage. Conclusion: Due to patient’s diameter changes, a target underdosage was assessed. Given the high local tumor control of neuroblastoma and Wilms’ diseases, the need of re-planning might be discarded. However, the assessed kidneys overdosage could represent a problem when the normal tissue tolerance is reached. The necessity of re-planning should then be considered to reduce the risk of long-term renal complications. Due to the poor softtissue contrast on CBCT, MRI-guidance is required to obtain a better assessment of the accumulated dose on the remaining OARs.},
doi = {10.1118/1.4955971},
journal = {Medical Physics},
number = 6,
volume = 43,
place = {United States},
year = {Wed Jun 15 00:00:00 EDT 2016},
month = {Wed Jun 15 00:00:00 EDT 2016}
}