TY - JOUR
T1 - Pediatric radiotherapy for thoracic and abdominal targets
T2 - Organ motion, reported margin sizes, and delineation variations – A systematic review
AU - Meijer, Karin M.
AU - van Dijk, Irma W. E. M.
AU - Huijskens, Sophie C.
AU - Daams, Joost G.
AU - Balgobind, Brian V.
AU - Bel, Arjan
N1 - Funding Information: We would like to thank C.A.A. Windmeijer for his contribution to the initial design and implementation of the search strategy, and participation in the screening process. This work was supported by the Dutch Cancer Society (KWF Kankerbestrijding) project no. 10113. Publisher Copyright: © 2022 The Authors
PY - 2022/8/1
Y1 - 2022/8/1
N2 - For radiotherapy of thoracic and abdominal tumors safety margins are applied to address geometrical uncertainties caused by e.g. set-up errors, organ motion and delineation variability. For pediatric patients no standardized margins are defined. Moreover, studies on these geometrical uncertainties are relatively scarce. Therefore, this systematic review presents an overview of organ motion, applied margin sizes and delineation variability in patients <18 years. A search from January 2000 to March 2021 in Medline, Embase, Web of Science, ClinicalTrials.gov and the International Trials Registry Platform resulted in the inclusion of 117 studies reporting on organ motion, margin sizes and/or delineation variability. Studies were heterogeneous concerning age, tumor types, the use of general anesthesia, imaging modalities; image guidance techniques were reported in 39% of the studies. Inter- and intrafractional motion as reported for different organs was largest in cranio-caudal direction and ranged from −9.1 to 10.0 mm and −4.4 to 19.5 mm, respectively. Motion quantification methodologies differed between studies regarding measures of displacement and definitions of motion direction. Reported CTV–PTV margins varied from 3 to 20 mm for both thoracic and abdominal targets, and for spinal and pelvic from 3to 15 mm and 3 to 10 mm, respectively. Studies reported wide variation in interobserver variability of target volume delineation, which may affect dose distributions to both target volumes and organs at risk. Results of this review indicate possible reduction of margin sizes for children, however, wide variation in organ motion and delineation variability caused by differences in methodologies and outcomes hamper the use of standardized margins.
AB - For radiotherapy of thoracic and abdominal tumors safety margins are applied to address geometrical uncertainties caused by e.g. set-up errors, organ motion and delineation variability. For pediatric patients no standardized margins are defined. Moreover, studies on these geometrical uncertainties are relatively scarce. Therefore, this systematic review presents an overview of organ motion, applied margin sizes and delineation variability in patients <18 years. A search from January 2000 to March 2021 in Medline, Embase, Web of Science, ClinicalTrials.gov and the International Trials Registry Platform resulted in the inclusion of 117 studies reporting on organ motion, margin sizes and/or delineation variability. Studies were heterogeneous concerning age, tumor types, the use of general anesthesia, imaging modalities; image guidance techniques were reported in 39% of the studies. Inter- and intrafractional motion as reported for different organs was largest in cranio-caudal direction and ranged from −9.1 to 10.0 mm and −4.4 to 19.5 mm, respectively. Motion quantification methodologies differed between studies regarding measures of displacement and definitions of motion direction. Reported CTV–PTV margins varied from 3 to 20 mm for both thoracic and abdominal targets, and for spinal and pelvic from 3to 15 mm and 3 to 10 mm, respectively. Studies reported wide variation in interobserver variability of target volume delineation, which may affect dose distributions to both target volumes and organs at risk. Results of this review indicate possible reduction of margin sizes for children, however, wide variation in organ motion and delineation variability caused by differences in methodologies and outcomes hamper the use of standardized margins.
KW - Delineation variability
KW - Organ motion
KW - Pediatric IGRT
KW - Pediatric thoracic and abdominal cancer
KW - Safety margins
UR - http://www.scopus.com/inward/record.url?scp=85131930411&partnerID=8YFLogxK
U2 - https://doi.org/10.1016/j.radonc.2022.05.021
DO - https://doi.org/10.1016/j.radonc.2022.05.021
M3 - Review article
C2 - 35640771
SN - 0167-8140
VL - 173
SP - 134
EP - 145
JO - Radiotherapy and oncology
JF - Radiotherapy and oncology
ER -