A new approach to radiochromic film dosimetry based on non-local means

Abstract

Radiochromic film in conjunction with flatbed scanners are frequently employed as dosimeters for advanced techniques in radiotherapy. Their strengths are as follows: light element composition, low energy dependence, near biological tissue equivalence and high spatial resolution. However, they have some weaknesses as well: non-uniformities, read out noise, and scanning artifacts. Several processing protocols have been proposed intending to correct the perturbations these weaknesses produce. The aim of this paper is to present a new processing protocol for radiochromic film dosimetry based on a non-local means denoising algorithm. Three dose distributions of open square fields and a spatial combination of these fields using different angles of incidence and monitor units have been employed to validate the protocol. The dose distributions are traceable to ionization chamber measurements. Additionally, a real dose distribution of a treatment was used to simulate scanning data with noise and scanning lateral artifact, and to study how the protocol behaves under these perturbations. The same measured raw data have been processed by means of an implementation of the multichannel protocol (multigaussian method). It has been found that the proposed protocol reduces dose uncertainty even though it uses fewer scans than the multichannel protocol.

Challenges in modeling the Agility multileaf collimator in treatment planning systems and current needs for improvement

“…Gafchromic EBT3 films (ISP, Wayne, NJ) were calibrated in Solid Water ® against a Farmer‐type ion chamber following each center's film dosimetry protocol. Centers used the commercial software Radiochromic.com 32 (centers A and B) and home‐made software (centers C and D) using triple‐channel dosimetry protocols 33–35 . RGB mode with 16 bits per channel with a resolution of 72 and 150 dpi was used.…”

“…Centers used the commercial software Radiochromic.com 32 (centers A and B) and home‐made software (centers C and D) using triple‐channel dosimetry protocols. 33 , 34 , 35 RGB mode with 16 bits per channel with a resolution of 72 and 150 dpi was used. Dose profiles across the tongue‐and‐groove junctions were extracted at a position 4 cm off‐axis.…”

PyMedPhys: A community effort to develop an open, Python-based standard library for medical physics applications

“…Many of these tools are in use clinically at affiliated sites, and additionally, aspects of PyMedPhys are implemented around the world for some applications. Many parties have embraced the gamma analysis module (Castle et al, 2022;Cronholm et al, 2020;Gajewski et al, 2021;Galić et al, 2020;Lysakovski et al, 2021;Milan et al, 2019;Pastor-Serrano & Perkó, 2021;Rodrıǵuez et al, 2020;Spezialetti et al, 2021;Tsuneda et al, 2021;Yang et al, 2022), while implementations of the electron cutout factor module and others (Baltz & Kirsner, 2021;Douglass & Keal, 2021;Rembish, 2021) have also been reported. Additionally, the work has been recognized by the European Society for Radiotherapy and Oncology (ESTRO) and referenced as recommended literature in their 3rd Edition of Core Curriculum for Medical Physics Experts in Radiotherapy (Bert et al, 2021).…”

Quantitative and Comparative Analysis of Effectivity and Robustness for Enhanced and Optimized Non-Local Mean Filter Combining Pixel and Patch Information on MR Images of Musculoskeletal System

“…These methods typically overcome some limitations, which are connected with the local filters, such as halo effect and gradient reversals. On the other hand, we should mention that these filters are usually more time consuming when compared with the local based filters [ 37 , 38 , 39 , 40 , 41 ].…”