Experimental verification the electron return effect around spherical air cavities for the MR-Linac using Monte Carlo calculation.
IGRT
Image-guided radiotherapy
MR-guided radiotherapy
MRgRT
Radiotherapy
cancer
dose
experimental dosimetry
Journal
Medical physics
ISSN: 2473-4209
Titre abrégé: Med Phys
Pays: United States
ID NLM: 0425746
Informations de publication
Date de publication:
Jun 2020
Jun 2020
Historique:
received:
22
11
2019
revised:
28
02
2020
accepted:
28
02
2020
pubmed:
8
3
2020
medline:
15
5
2021
entrez:
8
3
2020
Statut:
ppublish
Résumé
Dose deposition around unplanned air cavities during magnetic resonance-guided radiotherapy (MRgRT) is influenced by the electron return effect (ERE). This is clinically relevant for gas forming close to or inside organs at risk (OARs) that lie in the path of a single beam, for example, intestinal track during pelvic treatment. This work aims to verify Monte Carlo calculations that predict the dosimetric effects of ERE around air cavities. For this, we use GafChromic EBT3 film inside poly-methyl methacrylate (PMMA) -air phantoms. Four PMMA phantoms were produced. Three of the phantoms contained centrally located spherical air cavities (0.5, 3.5, 7.5 cm diameter), and one phantom contained no air. The phantoms were split to sandwich GafChromic EBT3 film in the center. The phantoms were irradiated on an Elekta Unity system using a single 10 × 10 cm The gamma analysis showed that >95% of the points agreed between the TPS-calculated and measured dose distributions, using 3%/3 mm criteria. The phantom containing the largest air cavity had the lowest agreement, with most of the disagreeing points lying inside the air cavity (dose to air region). The dose effects due to ERE around spherical air cavities are being calculated in the TPS with sufficient accuracy for clinical use.
Types de publication
Journal Article
Langues
eng
Sous-ensembles de citation
IM
Pagination
2506-2515Subventions
Organisme : European Association of National Metrology Institutes
Organisme : European Metrology Programme for Innovation and Research
ID : R120635
Informations de copyright
© 2020 American Association of Physicists in Medicine.
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