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Oliver-Canamas, L., Vijande, J., Candela-Juan, C., Gimeno-Olmos, J., Pujades-Claumarchirant, M. C., Rovira-Escutia, J. J., et al. (2023). A User-Friendly System for Mailed Dosimetric Audits of Ir-192 or Co-60 HDR Brachytherapy Sources. Cancers, 15(9), 2484–14pp.
Abstract: Nowadays, the options available to perform external dosimetric audits of the high dose rate (HDR) brachytherapy treatment process are limited. In this work, we present a methodology that allows for performing dosimetric audits in this field. A phantom was designed and manufactured for this purpose. The criteria for its design, together with the in-house measurements for its characterization, are presented. The result is a user-friendly system that can be mailed to perform dosimetric audits in HDR brachytherapy on-site for systems using either Iridium-192 (Ir-192) or Cobalt-60 (Co-60) sources. Objectives: The main goal of this work is to design and characterize a user-friendly methodology to perform mailed dosimetric audits in high dose rate (HDR) brachytherapy for systems using either Iridium-192 (Ir-192) or Cobalt-60 (Co-60) sources. Methods: A solid phantom was designed and manufactured with four catheters and a central slot to place one dosimeter. Irradiations with an Elekta MicroSelectron V2 for Ir-192, and with a BEBIG Multisource for Co-60 were performed for its characterization. For the dose measurements, nanoDots, a type of optically stimulated luminescent dosimeters (OSLDs), were characterized. Monte Carlo (MC) simulations were performed to evaluate the scatter conditions of the irradiation set-up and to study differences in the photon spectra of different Ir-192 sources (Microselectron V2, Flexisource, BEBIG Ir2.A85-2 and Varisource VS2000) reaching the dosimeter in the irradiation set-up. Results: MC simulations indicate that the surface material on which the phantom is supported during the irradiations does not affect the absorbed dose in the nanoDot. Generally, differences below 5% were found in the photon spectra reaching the detector when comparing the Microselectron V2, the Flexisource and the BEBIG models. However, differences up to 20% are observed between the V2 and the Varisource VS2000 models. The calibration coefficients and the uncertainty in the dose measurement were evaluated. Conclusions: The system described here is able to perform dosimetric audits in HDR brachytherapy for systems using either Ir-192 or Co-60 sources. No significant differences are observed between the photon spectra reaching the detector for the MicroSelectron V2, the Flexisource and the BEBIG Ir-192 sources. For the Varisource VS2000, a higher uncertainty is considered in the dose measurement to allow for the nanoDot response.
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Perez-Curbelo, J., Carvalho, C. M., Schafasand, M., Rossomme, S., Llosa, G., & Grevillot, L. (2026). Assessing the delivery error detection sensitivity of a new 2D detector prototype for carbon ion PSQA measurements. J. Appl. Clin. Med. Phys, 27(5), e70580–6pp.
Abstract: Background Particle therapy requires stringent patient-specific quality assurance (PSQA) to validate dose distributions delivered by the system. Purpose This study presents preliminary results on the performance evaluation of the MatriXX AiR 2D ionization-chamber array for patient-specific QA (PSQA) in carbon-ion therapy, comparing measured and planned dose distributions. Methods A series of 10 test cases, including a treatment plan for a box-shaped target (6-cm side length), uniformly covered by the dose and nine patient-specific treatment plans, were assessed. Measurements were conducted at two water equivalent depths using RW3 phantoms: beam entrance and within the Spread-Out Bragg Peak (SOBP). The study examined the detector's ability to detect deviations by systematically modifying treatment plans, comparing the measured and planned dose utilizing gamma index analysis. Results Passing rate analysis revealed depth-dependent sensitivity to treatment plan delivery modifications. Measurements at the entrance depth showed better sensitivity to delivery changes than those taken within the SOBP Conclusions The MatriXX AiR detector demonstrated strong potential for PSQA in carbon ion therapy. These findings support its application in clinical workflows to enhance treatment verification and accuracy.
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