Laser-based radiochromic film readout system: optoelectronic setup and feasibility trial for clinical applications

• Published in: Measurement : journal of the International Measurement Confederation 2024-05, Vol.231, p.114641, Article 114641
• Main Authors: Jiménez-Aviles, Gerardo, Camacho-López, Miguel Ángel, García-Garduño, Olivia Amanda
• Format: Article
• Language: English
• Subjects: Laser-based densitometer; Optical readout system; Radiochromic film dosimetry; Sensitometric response; Uncertainty
• ISSN: 0263-2241
• DOI: 10.1016/j.measurement.2024.114641

•End-to-end test of a densitometer based on laser-photodiode.•Laser-photodiode arrangement for film dosimetry.•Sensitometric data findings for three fitting models.•Sensitivity and dose uncertainty in radiochromic film dosimetry.•Dose distribution analysis with a novel densitometer and a flatbed scanner. The sensitometric response of radiochromic film for clinical dosimetry was measured using two transmission-mode digitizers: a flatbed scanner and a prototype densitometer based on a helium–neon laser, a mechatronic arrangement, and automated data acquisition. Twelve 3 × 3 cm2 film samples were exposed to doses of up to 25 Gy. After imaging, three 100-pixel regions were sampled from the green channel for calibration, including noise, sensitometric response, and uncertainty analysis. Under the same clinical dosimetry protocols, an end-to-end test was carried out to validate the laser-based densitometer using the gamma index from a dose distribution. 96 % of the data passed this criterion at 5 %/5mm. This novel film digitizer also exhibited up to a 1.24-fold increase in optical density compared to the scanner when testing three different fitting models, with 3.49-fold greater sensitivity. The scanner demonstrated the best noise rejection, with an average rejection rate of ≥98 % and the lowest uncertainty, being 3.49 %.