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Proton monoenergetic arc therapy (PMAT) to enhance LETd within the target
| Content Provider | Scilit |
|---|---|
| Author | Bertolet, Alejandro Carabe, Alejandro |
| Copyright Year | 2020 |
| Description | Journal: Physics in Medicine & Biology Purpose: To show the performance and feasibility of a proton arc technique so-called proton modulated arc therapy (PMAT). Monoenergetic partial arcs are selected to place spots at the middle of a target and its potential to enhance the dose-averaged LET (LETd) distribution within the target. Methods and material: Single-energy partial arcs in a single 360-degrees gantry rotation are selected to deposit Bragg's peaks at the central part of the target to increase LETd values. An in-house inverse planning optimizer seeks for homogeneous doses at the target while keeping dose to organs at risk (OARs) within constraints. The optimization consists of balancing weights of spots coming out of selected partial arcs. A simple case of a cylindrical target in a phantom is shown to illustrate the method. Three different brain cancer cases are then considered to produce actual clinical plans, compared to the clinically used with pencil beam scanning (PBS). RBE is calculated according to the microdosimetric kinetic model (MKM). Results: For the ideal case of a cylindrical target placed in a cylindrical phantom, mean LETd in the target increases from 2.8 keV/μm to 4.0 keV/μm when comparing a 3-field PBS plan with PMAT. This is replicated for clinical plans, increasing mean RBE-weighted doses to the CTV by 3.1%, 1.7% and 2.5%, respectively, assuming an α/β ratio equal to 10 Gy in the CTV. In parallel, LETd to OARs near the distal edge of the tumor decrease for all cases and metrics (mean LETd, LD,2% and LD,98%). Conclusion: PMAT technique increases LETd within the target, being feasible to produce clinical plans meeting physical dosimetric requirements for both target and OARs. Thus, PMAT increases RBE within the target, which may lead to a widening of the therapeutic index in proton radiotherapy that would be highlighted for low α/β ratios and hyperfractionated schedules. |
| Related Links | https://iopscience.iop.org/article/10.1088/1361-6560/ab9455/pdf |
| ISSN | 00319155 |
| e-ISSN | 13616560 |
| DOI | 10.1088/1361-6560/ab9455 |
| Journal | Physics in Medicine & Biology |
| Issue Number | 16 |
| Volume Number | 65 |
| Language | English |
| Publisher | IOP Publishing |
| Publisher Date | 2020-05-19 |
| Access Restriction | Open |
| Subject Keyword | Journal: Physics in Medicine & Biology Radiology, Nuclear Medicine and Imaging Letd Optimization Proton Arc Therapy Proton Therapy |
| Content Type | Text |
| Resource Type | Article |
| Subject | Radiology, Nuclear Medicine and Imaging Radiological and Ultrasound Technology |
