L. F. N. D. Carramate

Information about the paper titled "MEDICAL IMAGING AND RADIOTHERAPY EDUCATION DURING PANDEMIC EMERGENCY: IMPACT OF EMERGENCY REMOTE TEACHING" at IATED Digital Library

The response of a sealed MicroPatterned Gaseous Detector (MPGD), with an enclosed gas purification system based on getters, was monitored for several weeks. An average of 2 discharges per day was registered during the monitoring period and the charge gain varied a maximum of 15% during the more stable period. The temperature of the getters was varied from 180^oC to 250^oC and no significant influence was registered in the detector response. A reactivation of the getters also did not affect the charge gain, which means that their gettering rate was at full efficiency before the reactivation. However, careful attention is paid to charge gain reduction for long times of operation which can denote a loss of getters efficiency along time and the need of getter reactivation. On the other hand, turning off the getters lead to a rapid decrease in the charge gain. This allows concluding that a purification system based on getters is really effective in removing gas impurities, being a crucial component of the detection system for a sealed gaseous detector.

The performance of a Thick-COBRA based detector operating in sealed mode for X-ray imaging applications, as well as the exploration of its spectral capabilities for X-ray imaging is described. The presented detector was specifically developed for energy resolved X-ray imaging.The detector operates in pure Kr at 1 bar in sealed mode with an enclosed purification system. Its performance for X-ray imaging was evaluated, achieving a contrast of about 30% for a spatial frequency of 1 lp/mm. The detector uniformity varies with the energy range considered for evaluation with the detector location.Spectral X-ray transmission images of a clothespin and a screw allowed exploring the detector spectral capability to enhance image quality.

The operation of a Micropattern Gaseous Detector (MPGD) comprising a cascade of two non-standard Gas Electron Multipliers (GEM) made from a 100 μm kapton foil was evaluated in pure krypton and in krypton-CO₂ mixtures. The final avalanche charge was collected in a 2D strip readout, providing an active area of 10×10 cm² for the entire detection system. For each mixture, the effective gain and energy resolution were measured as a function of the electric field in the drift, transfer and induction regions. Using X-rays from a ⁵⁵Fe radioactive source (5.9 keV), gains close to 10⁴ and energy resolution of 22% (FWHM) were achieved in pure krypton under stable conditions, showing the potential of the experimental setup for the following imaging studies.