Implementation of planar proton minibeam radiation therapy using a pencil beam scanning system: A proof of concept study.
Med Phys
; 45(11): 5305-5316, 2018 Nov.
Article
in En
| MEDLINE
| ID: mdl-30311639
ABSTRACT
PURPOSE:
Proton minibeam radiation therapy (pMBRT) is an innovative approach that combines the advantages of minibeam radiation therapy with the more precise ballistics of protons to further reduce the side effects of radiation. One of the main challenges of this approach is the generation of very narrow proton pencil beams with an adequate dose-rate to treat patients within a reasonable treatment time (several minutes) in existing clinical facilities. The aim of this study was to demonstrate the feasibility of implementing pMBRT by combining the pencil beam scanning (PBS) technique with the use of multislit collimators. This proof of concept study of pMBRT with a clinical system is intended to guide upcoming biological experiments.METHODS:
Monte Carlo simulations (TOPAS v3.1.p2) were used to design a suitable multislit collimator to implement planar pMBRT for conventional pencil beam scanning settings. Dose distributions (depth-dose curves, lateral profiles, Peak-to-Valley Dose Ratio (PVDR) and dose-rates) for different proton beam energies were assessed by means of Monte Carlo simulations and experimental measurements in a water tank using commercial ionization chambers and a new p-type silicon diode, the IBA RAZOR. An analytical intensity-modulated dose calculation algorithm designed to optimize the weight of individual Bragg peaks composing the field was also developed and validated.RESULTS:
Proton minibeams were then obtained using a brass multislit collimator with five slits measuring 2 cm × 400 µm in width with a center-to-center distance of 4 mm. The measured and calculated dose distributions (depth-dose curves and lateral profiles) showed a good agreement. Spread-out Bragg peaks (SOBP) and homogeneous dose distributions around the target were obtained by means of intensity modulation of Bragg peaks, while maintaining spatial fractionation at shallow depths. Mean dose-rates of 0.12 and 0.09 Gy/s were obtained for one iso-energy layer and a SOBP conditions in the presence of multislit collimator.CONCLUSIONS:
This study demonstrates the feasibility of implementing pMBRT on a PBS system. It also confirms the reliability of RAZOR detector for pMBRT dosimetry. This newly developed experimental methodology will support the design of future preclinical research with pMBRT.Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Proton Therapy
/
Proof of Concept Study
Type of study:
Health_economic_evaluation
/
Sysrev_observational_studies
Aspects:
Implementation_research
Language:
En
Journal:
Med Phys
Year:
2018
Document type:
Article
Affiliation country:
France