0000000000275246
AUTHOR
Ignacio Pérez-calatayud
Phantom development for daily checks in electron intraoperative radiotherapy with a mobile linac.
Abstract Purpose IORT with mobile linear accelerators is a well-established modality where the dose rate and, therefore, the dose per pulse are very high. The constancy of the dosimetric parameters of the accelerator has to be checked daily. The aim of this work is to develop a phantom with embedded detectors to improve both accuracy and efficiency in the daily test of an IORT linac at the surgery room. Methods The developed phantom is manufactured with transparent polymethyl methacrylate (PMMA), allocating 6 parallel-plate chambers: a central one to evaluate the on-axis beam output, another on-axis one placed at a fixed depth under the previous one to evaluate the energy constancy and four…
Electronic Design for a Bleeding Detector to be Used in Intraoperative Radiotherapy Applications
An electronic design for a bleeding detector used with mobile linac during intraoperative radiotherapy (IORT) is presented. It consists on a readout circuit based on a De Sauty Bridge and a wireless power supply using a supercapacitor. The goal is the measurement of the height of fluid present in the applicator in order to avoid a misadministration dose during the irradiation process. A minimum measurement height of 5 mm is required by clinic to be confident with the selected radiation dose. The measurement circuit uses a capacitive sensor which detects variations lower than 0.1 pF. The readout circuit converts dynamic capacitance variation from the bleeding detector into an analog voltage …
Improving bleeding detector features for electron intraoperative radiotherapy
Abstract Purpose The aim of this work is to improve the potential bleeding detection during intraoperative radiotherapy with linac polymethyl methacrylate applicators (PMMA), based on one previously developed. The improvements carried out have been focused on: i) minimizing the impact of the detector on the visual through the plastic applicators and ii) avoiding the asymmetry in the detection capability when the applicator is tilted. Methods Simulations have been made to select the geometry that provides a reduced visual impact on the applicator as well as allowing an independent response with the tilting angle of the applicator. A low-noise circuit for signal conditioning has been develope…
Detector for monitoring potential bleeding during electron intraoperative radiotherapy
Purpose: The aim of this work is to develop a bleeding detector integrated into the acrylic circular applicators for specific mobile linacs. Thus, a bleeding detector has been developed based on a capacitive sensor to be used with plastic applicators, as in the case of LIAC HWL from Sordina IORT Technologies SpA. According to the clinical impact, we have selected 0.5 cm as the minimum depth of fluid that should be detected. Methods: An experiment was developed using water-simulating blood. Two setups were considered: non-beveled applicators with 7 cm and 10 cm diameter. Measurements were done for applicators 0 degrees and 45 degrees tilted, both with respect to the horizontal surface, in or…