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Robustness and dosimetric verification of hippocampal-sparing craniospinal pencil beam scanning proton plans for pediatric medulloblastoma

Edvardsson, Anneli LU ; Gorgisyan, Jenny LU ; Andersson, Karin M. ; Vallhagen Dahlgren, Christina ; Dasu, Alexandru ; Gram, Daniel ; Björk-Eriksson, Thomas and Munck af Rosenschöld, Per LU orcid (2024) In Physics and imaging in radiation oncology 29.
Abstract

Background and Purpose: Hippocampal-sparing (HS) is a method that can potentially reduce late cognitive complications for pediatric medulloblastoma (MB) patients treated with craniospinal proton therapy (PT). The aim of this study was to investigate robustness and dosimetric plan verification of pencil beam scanning HS PT. Materials and Methods: HS and non-HS PT plans for the whole brain part of craniospinal treatment were created for 15 pediatric MB patients. A robust evaluation of the plans was performed. Plans were recalculated in a water phantom and measured field-by-field using an ion chamber detector at depths corresponding to the central part of hippocampi. All HS and non-HS fields were measured with the standard resolution of... (More)

Background and Purpose: Hippocampal-sparing (HS) is a method that can potentially reduce late cognitive complications for pediatric medulloblastoma (MB) patients treated with craniospinal proton therapy (PT). The aim of this study was to investigate robustness and dosimetric plan verification of pencil beam scanning HS PT. Materials and Methods: HS and non-HS PT plans for the whole brain part of craniospinal treatment were created for 15 pediatric MB patients. A robust evaluation of the plans was performed. Plans were recalculated in a water phantom and measured field-by-field using an ion chamber detector at depths corresponding to the central part of hippocampi. All HS and non-HS fields were measured with the standard resolution of the detector and in addition 16 HS fields were measured with high resolution. Measured and planned dose distributions were compared using gamma evaluation. Results: The median mean hippocampus dose was reduced from 22.9 Gy (RBE) to 8.9 Gy (RBE), while keeping CTV V95% above 95 % for all nominal HS plans. HS plans were relatively robust regarding hippocampus mean dose, however, less robust regarding target coverage and maximum dose compared to non-HS plans. For standard resolution measurements, median pass rates were 99.7 % for HS and 99.5 % for non-HS plans (p < 0.001). For high-resolution measurements, median pass rates were 100 % in the hippocampus region and 98.2 % in the surrounding region. Conclusions: A substantial reduction of dose in the hippocampus region appeared feasible. Dosimetric accuracy of HS plans was comparable to non-HS plans and agreed well with planned dose distribution in the hippocampus region.

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author
; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Craniospinal irradiation, Hippocampal-sparing, Medulloblastoma, Pediatrics, Proton therapy, Quality assurance
in
Physics and imaging in radiation oncology
volume
29
article number
100555
publisher
Elsevier
external identifiers
  • pmid:38405431
  • scopus:85185801319
ISSN
2405-6316
DOI
10.1016/j.phro.2024.100555
language
English
LU publication?
yes
id
d6dcbd6c-d375-4874-b746-a5262e1638f1
date added to LUP
2024-03-19 15:19:32
date last changed
2024-04-16 13:56:26
@article{d6dcbd6c-d375-4874-b746-a5262e1638f1,
  abstract     = {{<p>Background and Purpose: Hippocampal-sparing (HS) is a method that can potentially reduce late cognitive complications for pediatric medulloblastoma (MB) patients treated with craniospinal proton therapy (PT). The aim of this study was to investigate robustness and dosimetric plan verification of pencil beam scanning HS PT. Materials and Methods: HS and non-HS PT plans for the whole brain part of craniospinal treatment were created for 15 pediatric MB patients. A robust evaluation of the plans was performed. Plans were recalculated in a water phantom and measured field-by-field using an ion chamber detector at depths corresponding to the central part of hippocampi. All HS and non-HS fields were measured with the standard resolution of the detector and in addition 16 HS fields were measured with high resolution. Measured and planned dose distributions were compared using gamma evaluation. Results: The median mean hippocampus dose was reduced from 22.9 Gy (RBE) to 8.9 Gy (RBE), while keeping CTV V<sub>95%</sub> above 95 % for all nominal HS plans. HS plans were relatively robust regarding hippocampus mean dose, however, less robust regarding target coverage and maximum dose compared to non-HS plans. For standard resolution measurements, median pass rates were 99.7 % for HS and 99.5 % for non-HS plans (p &lt; 0.001). For high-resolution measurements, median pass rates were 100 % in the hippocampus region and 98.2 % in the surrounding region. Conclusions: A substantial reduction of dose in the hippocampus region appeared feasible. Dosimetric accuracy of HS plans was comparable to non-HS plans and agreed well with planned dose distribution in the hippocampus region.</p>}},
  author       = {{Edvardsson, Anneli and Gorgisyan, Jenny and Andersson, Karin M. and Vallhagen Dahlgren, Christina and Dasu, Alexandru and Gram, Daniel and Björk-Eriksson, Thomas and Munck af Rosenschöld, Per}},
  issn         = {{2405-6316}},
  keywords     = {{Craniospinal irradiation; Hippocampal-sparing; Medulloblastoma; Pediatrics; Proton therapy; Quality assurance}},
  language     = {{eng}},
  publisher    = {{Elsevier}},
  series       = {{Physics and imaging in radiation oncology}},
  title        = {{Robustness and dosimetric verification of hippocampal-sparing craniospinal pencil beam scanning proton plans for pediatric medulloblastoma}},
  url          = {{http://dx.doi.org/10.1016/j.phro.2024.100555}},
  doi          = {{10.1016/j.phro.2024.100555}},
  volume       = {{29}},
  year         = {{2024}},
}