Measurement of ionization loss of 50 GeV protons in silicon with smoothly tunable up to 1 cm thickness using a single flat detector

Research of the ionization loss of 50 GeV protons, the path of which in the depleted layer of the silicon detector was smoothly regulated in the range from 0.3 to 10 mm, is presented. In the experiment, we used a flat silicon detector with a fixed thickness of the depleted layer of 300 μm. The smooth regulation of the path was realized due to the variation of the angle between the surface of the detector and the incident proton beam. The comparison of experimental data and theoretical calculations of the ionization loss demonstrates agreement in all range of thicknesses. Results of the research can be used in order to control the angle between the surface of the detector and the incident beam of relativistic particles. Besides, the results can be used in the analysis of data from astrophysical silicon detectors of charged particles if high-energy particles crossed flat detectors at arbitrary angle.

Percutaneous Angiographically Assisted Cryoablation of Renal Cell Carcinoma under the Control of Flat-Detector Computed Tomography: Capabilities and Potential Advantages of the Technique

Purpose: Percutaneous cryoablation (PCA) of renal cell carcinoma (RCC) stage T1a (≤4 cm) generally performed using MDCT with intravenous contrast material administration. Most interventional radiology departments are not equipped MDCT scanners and this is holding back widespread adoption of this technique into practical medicine. Flat-detector computed tomography (FDCT) is included in the standard equipment of modern angiographic systems, which makes it possible to combine the technologies of computed tomography with various technologies of intra-arterial contrasting and endovascular treatment. The purpose of the study was to assess the possibilities and potential advantages of using intraarterial contrasting during FDCT-controlled PCA of RCC T1a.Material and methods: Since 2017 angiographically assisted PCA under the FDCT control performed in 14 patients with RCC T1a. The procedure was performed in the X-ray operating room on an Artis Zee Floor angiographic unit with FDCT function and iGuide Needle Guidance and 3D/3D Fusion technologies (Siemens, Germany) using the SeedNet Gold system and IceEDGE 13 G, IceRod 17 G or IceSphere 17 G cryoprobes (Galil Medical, USA). At all stages of the procedure, FDCT-arteriography of the kidney (FDCT-A) performed according to the original technique: injection into the renal artery 12 ml of non-ionic contrast materials at a rate of 1 ml/s and performing scanning 5 s after the start of contrast materials injection.Results: The primary technical efficiency of FDCT-controlled PCA of RCC T1a was 92.9 %, the secondary — 100 %. Complications of grade 3 according to the CIRSE classification were identified in three patients (21.4 %), complications of grade 4, 5 and 6 not observed. The use of arterial access and the FDCT-A execution at different stages of PCA had the following advantages: 1) high-quality visualization of the tumor with minimal consumption of contrast materials; 2) simple and accurate positioning of cryoprobes using the iGuide Needle Guidance program; 3) estimation of the future ablative margin by fusion FDCT data about tumor with FDCT data about ice ball; 4) reliable diagnosis of bleeding after removal of cryoprobes with the possibility of immediate performing of endovascular hemostasis.Conclusion: Percutaneous angiographically assisted cryoablation under the FDCT control is an affordable, safe and effective technology for the treatment of RCC T1a, which has a number of potential advantages compared to performing procedures using MDCT control. Further research is advisable to study of this PCA technique with its subsequent possible introduction into the routine practice in Interventional Radiology departments of multidisciplinary oncological hospitals.

Reduction of radiation exposure in scoliosis monitoring using flat detector and pulsed fluoroscopy technology

A new flat detector and pulsed fluoroscopy technology is available to further reduce radiation exposure in radiological monitoring during scoliosis treatment in children and adolescents. The aim of this study is to compare different settings of the system (opening area(OA) and image quality settings (IQS)) in order to find the optimal parameters with high image quality and the lowest possible radiation exposure. Therefore, we examined four cadaver spines (T1 to sacrum) with the flat detector technique using digital pulsed fluoroscopy and simulated the abdominal soft tissues. The images were merged and evaluated by three different investigators using an established scoring system. For comparison, we used digital radiography images of the cadaver spines. The values for the DAP increased from the small OA (33% ; 0.56 µGy·m²) to the maximum OA (100% ; 0.82 µGy·m²) by 45% (p = .003) and from the low image quality setting (0.57 µGy·m²) to the high setting (0.84 µGy·m²) by 48% (p = .028). Despite the low DAP, the setting 33% OA achieved the best point values for image quality, therefore this setting is clearly preferred. Using a digital fluoroscopy system allows a significant reduction of radiation exposure by a factor of 7.5 (3.88µGy·m² to 0.5µGy·m²) compared to slot- scanning x-ray (EOS). Due to this success, the flat detector and pulsed fluoroscopy technology can be an alternative to established methods such as X-ray and EOS in clinical use.

Application of High-Resolution Flat Detector Computed Tomography in Stent Implantation for Intracranial Atherosclerotic Stenosis

ObjectiveTo evaluate the utility of high-resolution flat-detector computed tomography (HR-FDCT) compared with conventional flat-detector computed tomography (FDCT) for stent placement in symptomatic intracranial atherosclerotic stenosis (ICAS).MethodsWe retrospectively reviewed the clinical data of 116 patients with symptomatic ICAS who underwent stent implantation. Images were acquired using conventional FDCT [voxel size = 0.43 mm (isotropic)] and HR-FDCT [voxel size = 0.15 mm (isotropic)]. Immediately after stent deployment, dual-volume three-dimensional (3D) fusion images were obtained from 3D digital subtraction angiography (DSA) and HR-FDCT. The image quality for stent visualization was graded from 0 to 2 (0: not able to assess; 1: limited, but able to assess; 2: clear visualization), and the stent-expansion status (“full,” “under-expanded” or “poor apposition”) was recorded.ResultsA total of 116 patients with symptomatic ICAS were treated successfully using 116 stents (58 NeuroformTM EZ, 42 EnterpriseTM, and 16 ApolloTM). The mean pre-stent stenosis was 80.5 ± 6.4%, which improved to 20.8 ± 6.9% after stenting. Compared with FDCT, HR-FDCT improved visualization of the fine structures of the stent to improve the image quality that significantly (mean score: 1.63 ± 0.60 vs. 0.41 ± 0.59, P < 0.001). In 19 patients, stent under-expansion (n = 11) or poor apposition (n = 8) was identified by HR-FDCT but not by conventional FDCT. After balloon dilatation, stent malapposition was shown to have improved on HR-FDCT. None of the 19 patients with stent malapposition experienced short-term complications during hospitalization or had in-stent stenosis at 6-month follow-up.ConclusionHigh-resolution flat-detector computed tomography (HR-FDCT) improves visualization of the fine structures of intracranial stents deployed for symptomatic ICAS compared with that visualized using conventional FDCT. High-resolution flat-detector computed tomography improves assessment of stent deployment and could reduce the risk of complications.

Clinical Application of Medical Imaging in Neurointerventional Treatment of Brain Diseases

The incidence rate of cerebral infarction is high, and the risk of death is also grown significantly with age. Atherosclerotic stenosis is a part of the main causes of cerebral infarction. The effect of drug conservative therapy is not ideal. Interventional therapy is tantamount to send the guidewire, catheter and so on to the lesion site using imaging means, and operates the local area to achieve the purpose of a precise treatment. Therefore, it is important to explore the characteristics and high-risk factors of complications for clinical prevention and guidance of treatment righteousness. This study was to investigate the clinical effect of digital subtraction angiography (DSA) in the treatment of ischemic cerebrovascular disease. Also, this paper discusses the clinical effect of digital subtraction angiography (DSA) in the treatment of cerebral infarction. It has been proved that the application of flat detector CT in the interventional room can not only obtain high-quality 3D angiography (3D rotational angiography), but also display the vessels and high-density structures (skeleton, vascular clamp, coil, stent, and ingenious plaque). Fd-ct has also been proved to be able to perform 3D reconstruction on the stent placed in the patient’s heart and the stent of the external carotid artery. Compared with multi-slice spiral CT, the stent is much clearer and can be used to evaluate the soil and stent placement in the treatment of aneurysms.

Is a further reduction of radiation exposure in scoliosis monitoring achievable using flat detector and pulsed fluoroscopy technology? - A feasibility study on human specimen

Background: In the case of scoliosis therapy, frequent radiological monitoring of the spine is necessary. However, x-ray requires high radiation doses; therefore digital pulsed fluoroscopy with flat detector technique can be used alternatively. The latest developments in this technology lead to further dose reduction with an improved image quality. To evaluate the new system, we asked if there is a difference in dose area product (DAP) concerning the opening area (OA) and image quality settings (IQS). Further we wanted to investigate the inter-observer reliability using an established scoring system and correlate the DAP with the point value. Methods Therefore, we examined 4 cadaver spines (T1 to sacrum) with the flat detector technique using digital pulsed fluoroscopy and simulated the abdominal soft tissues with water bags. The images were merged calculating whole spine images from several digital single images and evaluated by 3 different investigators (spine surgeon, experienced pediatric radiologist, assistant physician) using an established scoring system. For comparison and validation of our model, we used digital radiography images of the cadaver spines. Results The values for the DAP increased from the small OA (33%; 0.56 µGy·m²) to the maximum OA (100%; 0.82 µGy·m²) by 45% (p = .003) and from low IQS (0.57 µGy·m²) to high IQS (0.84 µGy·m²) by 48% (p = .028). The inter-observer reliability was strong (3 vs. 1: ρ = .818; 3 vs. 2: ρ = .742; 2 vs. 1: ρ = .586; p <.001), but there was no correlation between DAP and point value (ρ = -.053, p = .588). Despite the low DAP, the setting 33% OA achieved the best point values, therefore this setting is preferred. Conclusions Using a digital fluoroscopy system allows a significant reduction of radiation exposure for whole spine images by a factor of 7.5 (3.88 µGy·m² to 0.5 µGy·m²) compared to slot-scanning x-ray (EOS).