Bringing FLASH to the Clinic: Treatment Planning Considerations for Ultrahigh Dose-Rate Proton Beams.
Heart
Humans
Lung
Lung Neoplasms
/ radiotherapy
Organ Sparing Treatments
/ methods
Organs at Risk
Proof of Concept Study
Proton Therapy
/ adverse effects
Radiation Injuries
/ prevention & control
Radiosurgery
/ methods
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted
/ methods
Radiotherapy, Intensity-Modulated
/ methods
Spinal Cord
Thoracic Wall
Time Factors
Journal
International journal of radiation oncology, biology, physics
ISSN: 1879-355X
Titre abrégé: Int J Radiat Oncol Biol Phys
Pays: United States
ID NLM: 7603616
Informations de publication
Date de publication:
01 03 2020
01 03 2020
Historique:
received:
22
07
2019
revised:
14
10
2019
accepted:
13
11
2019
pubmed:
24
11
2019
medline:
15
2
2020
entrez:
24
11
2019
Statut:
ppublish
Résumé
Preclinical research into ultrahigh dose rate (eg, ≥40 Gy/s) "FLASH"-radiation therapy suggests a decrease in side effects compared with conventional irradiation while maintaining tumor control. When FLASH is delivered using a scanning proton beam, tissue becomes subject to a spatially dependent range of dose rates. This study systematically investigates dose rate distributions and delivery times for proton FLASH plans using stereotactic lung irradiation as the paradigm. Stereotactic lung radiation therapy FLASH-plans, using 244 MeV scanning proton transmission beams, with the Bragg peak behind the body, were made for 7 patients. Evaluated parameters were dose rate distribution within a beam, overall irradiation time, number of times tissue is irradiated, and quality of the FLASH-plans compared with the clinical volumetric-modulated arc therapy (VMAT) plans. Sparing of lungs, thoracic wall, and heart in the FLASH-plans was equal to or better than that in the VMAT-plans. For a spot peak dose rate (SPDR, the dose rate in the middle of the spot) of 100 Gy/s, ∼40% of dose is delivered at FLASH dose rates, and for SPDR = 360 Gy/s this increased to ∼75%. One-hundred percent FLASH dose rate cannot be achieved owing to small contributions from distant spots with lower dose rates. The total irradiation time varied between 300 to 730 ms, and around 85% of the dose-receiving body volume was irradiated by either 1 or 2 beams. Clinical implementation of FLASH using scanning proton beams requires multiple treatment planning considerations: dosimetric, temporal, and spatial parameters all seem important. The FLASH efficiency of a scanning proton beam increases with SPDR. The methodology proposed in this proof-of-principle study provides a framework for evaluating the FLASH characteristics of scanning proton beam plans and can be adapted as FLASH parameters are better defined. It currently seems logical to optimize plans for the shortest delivery time, maximum amount of high dose rate coverage, and maximum amount of single beam and continuous irradiation.
Identifiants
pubmed: 31759074
pii: S0360-3016(19)34038-6
doi: 10.1016/j.ijrobp.2019.11.011
pii:
doi:
Types de publication
Journal Article
Research Support, Non-U.S. Gov't
Langues
eng
Sous-ensembles de citation
IM
Pagination
621-629Commentaires et corrections
Type : CommentIn
Type : CommentIn
Informations de copyright
Copyright © 2019 Elsevier Inc. All rights reserved.