Radiation tests of Hamamatsu multi-pixel photon counters Blazey, G.; Colston, J.; Dyshkant, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2019, Letnik:
927, Številka:
C
Journal Article
Recenzirano
Odprti dostop
Results of radiation tests of Hamamatsu 2.0 × 2.0 mm2 through-silicon-via (S13360-2050VE) multi-pixel photon counters, or MPPCs, are presented (Hamamatsu, 0000). Distinct sets of eight MPPCs were ...exposed to four different 1 MeV neutron equivalent doses of 200 MeV protons. Measurements of the breakdown voltage, gain and noise rates at different bias overvoltages, photoelectron thresholds, and LED illumination levels were taken before and after irradiation. No significant deterioration in performance was observed for breakdown voltage, gain, and response. Noise rates increased significantly with irradiation. These studies were undertaken in the context of MPPC requirements for the Cosmic Ray Veto detector of the Mu2e experiment at the Fermi National Accelerator Laboratory.
Relevance. There are many causes of spontaneous hemorrhage into the vitreous cavity. Sometimes spontaneous nontraumatic vitreous hemorrhage can be rhegmatogenous in nature, occurring as a result of a ...ruptured retinal vessel running through the site of a retinal tear. Usually, a patient with spontaneous nontraumatic vitreous hemorrhage is managed with a conservative approach, but it is questionable whether conservative management of patients with this pathology is advisable. Purpose. To evaluate the results of surgical treatment of patients with idiopathic, presumably rhegmatogenous vitreous hemorrhage. Material and methods. Surgical treatment of 10 patients diagnosed with idiopathic vitreous hemorrhage, presumably of rhegmatogenous nature, was performed and the results of treatment were evaluated. The best corrected visual acuity (BCVA) before treatment was on average 0.03. Slit lamp examination revealed dispersed vitreous hemorrhage into the vitreous body with a total obscuration of the posterior pole. According to B-scan data there was no retinal detachment in all cases. All patients underwent surgical treatment. Results. By the third month of follow-up after surgical treatment, visual acuity was 0.9±0.04 on average. B-scan data showed no pathology in all cases. Light sensitivity was 28.7±0.15 dB on average. Conclusion. If other obvious causes of vitreous hemorrhage are excluded, urgent surgical treatment is, in our opinion, the most preferable approach and can be recommended as a first line of treatment instead of conservative therapy. Key words: vitreous hemorrhage, conservative treatment, vitreoretinal surgery, retinal tear, ultrasound diagnostics
Relevance. There are many causes of spontaneous hemorrhage into the vitreous cavity. Sometimes spontaneous nontraumatic vitreous hemorrhage can be rhegmatogenous in nature, occurring as a result of a ...ruptured retinal vessel running through the site of a retinal tear. Usually, a patient with spontaneous nontraumatic vitreous hemorrhage is managed with a conservative approach, but it is questionable whether conservative management of patients with this pathology is advisable. Purpose. To evaluate the results of surgical treatment of patients with idiopathic, presumably rhegmatogenous vitreous hemorrhage. Material and methods. Surgical treatment of 10 patients diagnosed with idiopathic vitreous hemorrhage, presumably of rhegmatogenous nature, was performed and the results of treatment were evaluated. The best corrected visual acuity (BCVA) before treatment was on average 0.03. Slit lamp examination revealed dispersed vitreous hemorrhage into the vitreous body with a total obscuration of the posterior pole. According to B-scan data there was no retinal detachment in all cases. All patients underwent surgical treatment. Results. By the third month of follow-up after surgical treatment, visual acuity was 0.9±0.04 on average. B-scan data showed no pathology in all cases. Light sensitivity was 28.7±0.15 dB on average. Conclusion. If other obvious causes of vitreous hemorrhage are excluded, urgent surgical treatment is, in our opinion, the most preferable approach and can be recommended as a first line of treatment instead of conservative therapy.
Superelastic alloys of titanium (titanium-niobium-zirconium and titanium-niobium-tantalum) are more favorable in comparison with titanium for dental implants due to their physico-mechanical ...properties closer to those of bone tissue. Animal morphological studies of the biocompatibility of these alloys in comparison with titanium have been carried out. The control of the titanium alloy samples’ interaction with bone tissue was performed at the time points of 30 and 90 days; scanning electron microscopy and microprobe element analysis of tissue along the boundary with titanium alloys were used as the methods of investigation. The proximity of the morphological pattern and elemental composition of bone tissue along the border with titanium and superelastic alloys of titanium is shown, both at the control period of 30 days (in contact with alloys, a poorly mineralized connective tissue is found) and at 90 days (the border with titanium alloys is covered with mineralized bone tissue, similar in its composition to the surrounding bone tissue).
Light yield and spatial uniformity for a large variety of configurations of scintillator tiles was studied. The light from each scintillator was collected by a Silicon Photomultiplier (SiPM) directly ...viewing the produced scintillation light (SiPM-on-tile technique). The varied parameters included tile transverse size, tile thickness, tile wrapping material, scintillator composition, and SiPM model. These studies were performed using 120 GeV protons at the Fermilab Test Beam Facility. External tracking allowed the position of each proton penetrating a tile to be measured. The results were compared to a GEANT4 simulation of each configuration of scinitillator, wrapping, and SiPM.
Results of radiation tests of Hamamatsu 2.0 x 2.0~mm2 through-silicon-via (S13360-2050VE) multi-pixel photon counters, or MPPCs 1, are presented. Distinct sets of eight MPPCs were exposed to four ...different 1~MeV neutron equivalent doses of 200 MeV protons. Measurements of the breakdown voltage, gain and noise rates at different bias overvoltages, photoelectron thresholds, and LED illumination levels were taken before and after irradiation. No significant deterioration in performance was observed for breakdown voltage, gain, and response. Noise rates increased significantly with irradiation. These studies were undertaken in the context of MPPC requirements for the Cosmic Ray Veto detector of the Mu2e experiment at the Fermi National Accelerator Laboratory.
Northern Illinois University in collaboration with Fermi National Accelerator Laboratory (FNAL) and Delhi University has been designing and building a proton CT scanner for applications in proton ...treatment planning. The Phase II proton CT scanner consists of eight planes of tracking detectors with two X and two Y coordinate measurements both before and after the patient. In addition, a range stack detector consisting of a stack of thin scintillator tiles, arranged in twelve eight-tile frames, is used to determine the water equivalent path length (WEPL) of each track through the patient. The X-Y coordinates and WEPL are required input for image reconstruction software to find the relative (proton) stopping powers (RSP) value of each voxel in the patient and generate a corresponding 3D image. In this Note we describe tests conducted in 2015 at the proton beam at the Central DuPage Hospital in Warrenville, IL, focusing on the range stack calibration procedure and comparisons with the GEANT~4 range stack simulation.
A New Proton CT Scanner Uzunyan, S A; Blazey, G; Boi, S ...
arXiv.org,
01/2016
Paper, Journal Article
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The design, construction, and preliminary testing of a second generation proton CT scanner is presented. All current treatment planning systems at proton therapy centers use X-ray CT as the primary ...imaging modality for treatment planning to calculate doses to tumor and healthy tissues. One of the limitations of X-ray CT is in the conversion of X-ray attenuation coefficients to relative (proton) stopping powers, or RSP. This results in more proton range uncertainty, larger target volumes and therefore, more dose to healthy tissues. To help improve this, we present a novel scanner capable of high dose rates, up to 2~MHz, and large area coverage, 20~x~24~cm\(^2\), for imaging an adult head phantom and reconstructing more accurate RSP values.
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