Thin low-gain avalanche detectors for particle therapy applications

none18The University of Torino (UniTO) and the National Institute for Nuclear Physics (INFN-TO) are investigating the use of Ultra Fast Silicon Detectors (UFSD) for beam monitoring in radiobiological experiments with therapeutic proton beams. The single particle identification approach of solid state detectors aims at increasing the sensitivity and reducing the response time of the conventional monitoring devices, based on gas detectors. Two prototype systems are being developed to count the number of beam particles and to measure the beam energy with time-of-flight (ToF) techniques. The clinically driven precision (< 1%) in the number of particles delivered and the uncertainty < 1 mm in the depth of penetration (range) in radiobiological experiments (up to 108 protons/s fluxes) are the goals to be pursued. The future translation into clinics would allow the implementation of faster and more accurate treatment modalities, nowadays prevented by the limits of state-of-the-art beam monitors. The experimental results performed with clinical proton beams at CNAO (Centro Nazionale di Adroterapia Oncologica, Pavia) and CPT (Centro di Protonterapia, Trento) showed a counting inefficiency <2% up to 100 MHz/cm2, and a deviation of few hundreds of keV of measured beam energies with respect to nominal ones. The progresses of the project are reported.noneVignati, A.; Donetti, M.; Fausti, F.; Ferrero, M.; Giordanengo, S.; Hammad Ali, O.; Mart Villarreal, O.A.; Mas Milian, F.; Mazza, G.; Monaco, V.; Sacchi, R.; Shakarami, Z.; Sola, V.; Staiano, A.; Tommasino, F.; Verroi, E.; Wheadon, R.; Cirio, R.Vignati, A.; Donetti, M.; Fausti, F.; Ferrero, M.; Giordanengo, S.; Hammad Ali, O.; Mart Villarreal, O. A.; Mas Milian, F.; Mazza, G.; Monaco, V.; Sacchi, R.; Shakarami, Z.; Sola, V.; Staiano, A.; Tommasino, F.; Verroi, E.; Wheadon, R.; Cirio, R

Cause of Death and Predictors of All-Cause Mortality in Anticoagulated Patients With Nonvalvular Atrial Fibrillation : Data From ROCKET AF

M. Kaste on työryhmän ROCKET AF Steering Comm jäsen.Background-Atrial fibrillation is associated with higher mortality. Identification of causes of death and contemporary risk factors for all-cause mortality may guide interventions. Methods and Results-In the Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF) study, patients with nonvalvular atrial fibrillation were randomized to rivaroxaban or dose-adjusted warfarin. Cox proportional hazards regression with backward elimination identified factors at randomization that were independently associated with all-cause mortality in the 14 171 participants in the intention-to-treat population. The median age was 73 years, and the mean CHADS(2) score was 3.5. Over 1.9 years of median follow-up, 1214 (8.6%) patients died. Kaplan-Meier mortality rates were 4.2% at 1 year and 8.9% at 2 years. The majority of classified deaths (1081) were cardiovascular (72%), whereas only 6% were nonhemorrhagic stroke or systemic embolism. No significant difference in all-cause mortality was observed between the rivaroxaban and warfarin arms (P=0.15). Heart failure (hazard ratio 1.51, 95% CI 1.33-1.70, P= 75 years (hazard ratio 1.69, 95% CI 1.51-1.90, P Conclusions-In a large population of patients anticoagulated for nonvalvular atrial fibrillation, approximate to 7 in 10 deaths were cardiovascular, whereasPeer reviewe

Fluence profiling at JSI TRIGA reactor irradiation facility

We present an analysis of the fluence profile at the JSI TRIGA neutron reactor facility in Ljubljana. For the study, multi-pad Low-Gain Avalanche Diodes (LGADs) are used. The deactivation of acceptor doping in the gain layer implant due to the irradiation, typical of LGAD devices, is exploited to map the fluence profile inside the irradiation channels. The amount of active doping of the LGAD gain layer is extracted via capacitance–voltage measurements for each pad before and after irradiation to a fluence of 1.5 × 1015 neq/cm2, where stands for 1 MeV equivalent neutron count, providing a precise and prompt measurement of the fluence distribution over the LGAD sensor. Experimental results are compared to neutron fluence expectations calculated with Monte Carlo techniques

Energy measurement of clinical proton beams with a telescope of Ultra-Fast Silicon Detectors

Within the MoveIT-project of the National Institute for Nuclear Physics (INFN), the University of Torino (UNITO) and INFN-Torino are developing a detector made of a telescope of two Ultra-Fast Silicon Detectors (UFSD) aligned along the beam direction to determine the energy of clinical proton beams from the measurement of the time-of-flight of single protons. Following the promising results obtained at the Centro Nazionale di Adroterapia Oncologica (CNAO, Pavia, Italy) with single pads, a second beam test was conducted at the Trento Proton Therapy Center (Italy) with dedicated UFSD sensors segmented in strips. The results obtained at Trento facility show that for 97 cm distance between sensors and for all the energies tested (chosen in the 62–227 MeV clinical range), the root mean square deviation between the measured beam energies with respect to the nominal ones corresponds to a range uncertainty < 1 mm in water, as clinically require

Characterization of thin LGAD sensors designed for beam monitoring in proton therapy

A fast 144-channel proton counter prototype, designed for monitoring the fluence rate of clinical proton beams, is based on a thin Low Gain Avalanche Detector (LGAD), segmented into 146 strips (114 width, 26214 length, 180 pitch). The layout of the sensor was designed in the framework of the Modeling and Verification for Ion beam Treatment planning (MoVe-IT) project in collaboration with Fondazione Bruno Kessler (FBK, Trento, Italy) and fourteen wafers were produced and delivered by FBK in 2020. In this paper, we present the laboratory characterization of the sensors performed on the entire wafer at FBK, right after production, and at the University of Turin after cutting the sensors using a probe station connected with a power device analyzer for static electrical tests and an infrared picosecond laser to study the dynamic properties. In addition, one sensor was tested with the clinical proton beam at National Center for Oncological Hadrontherapy (CNAO, Pavia, Italy). The results obtained from the test at FBK and UNITO facilities demonstrated that the cut did not affect the yield production. The static electrical tests proved that the MoVe-IT-2020 sensors production was of very high quality. The width of the inter-strip dead region measured was 80.8 . 22% larger than the distance of the gain layers, and has a small dependence on laser intensities. A preliminary beam test at CNAO showed good separation between signal and noise in the LGAD strip, which allows counting properly the protons by selecting the optimal signal threshold