When performing tomosynthesis, the section thickness needs to be set depending on a radiographic part and its diagnostic purpose. However, the section thickness in tomosynthesis has not been clearly defined and its measurement method has not been established yet. In this study, we devised the alternative measurement method to diagnose the section thickness using an edge of thin metal plate, and compared with the simulation results, the wire and bead method reported in the previous papers. The tomographic image of the thin metal plate positioned on the table top inclining 30 degrees, which showed the edge spread function (ESF) of each tomographic height, was taken, and then the line spread function (LSF) was obtained by differentiating the ESF image. For the next, a profile curve was plotted by maximum values of LSF of each tomographic height, and a section thickness was calculated using the full width at half maximum (FWHM) of the profile curve. The edge method derived the section thickness close to the simulation results than the other methods. Further, the section thickness depends on the thickness of the metal plate and not the material. The thickness of the metal plate suitable for the evaluation of section thickness is 0.3 mm that is equivalent to pixel size of the flat panel detector (FPD). We conducted quantitative verification to establish the measurement method of the section thickness. The edge method is a useful technique as well as the wire and bead method for grasping basic characteristics of an imaging system.

Purpose: This study aimed at developing the realistic striatal digital brain (SDB) phantom and to assess specific binding ratio (SBR) for ventricular effect in the ¹²³I-FP-CIT SPECT imaging. Methods: SDB phantom was constructed in to four segments (striatum, ventricle, brain parenchyma, and skull bone) using Percentile method and other image processing in the T2-weighted MR images. The reference image was converted into 128×128 matrixes to align MR images with SPECT images. The process image was reconstructed with projection data sets generated from reference images additive blurring, attenuation, scatter, and statically noise. The SDB phantom was evaluated to find the accuracy of calculated SBR and to find the effect of SBR with/without ventricular counts with the reference and process images. Results: We developed and investigated the utility of the SDB phantom in the ¹²³I-FP-CIT SPECT clinical study. The true value of SBR was just marched to calculate SBR from reference and process images. The SBR was underestimated 58.0% with ventricular counts in reference image, however, was underestimated 162% with ventricular counts in process images. Conclusion: The SDB phantom provides an extremely convenient tool for discovering basic properties of ¹²³I-FP-CIT SPECT clinical study image. It was suggested that the SBR was susceptible to ventricle.

Purpose: The N-Isopropyl-p-[123I] Iodoamphetamine (¹²³I-IMP) SPECT imaging reduces the image quality and quantitative accuracy due to scatter and septal penetration occurred by radioactive uptake from outside of the field of view such as the lungs. We evaluated the influence of scatter and septal penetration using phantom-simulated radioactivity from outside of the field of view, and subsequently compared the effect of scatter and septal penetration corrections between the simulation-based effective scatter source estimation (ESSE) method and the multi-window method (ellipse approximation method). Methods: We used the phantom filled with 10 and 25 kBq/mL for the brain and lung parts corresponding to radioactive concentration in the clinical study. The SPECT images were acquired with and without lung phantom using low-energy high-resolution (LEHR) and cardiac high-resolution (CHR) collimators. We quantitatively evaluated a brain phantom by count analysis and coefficient of variation as reference data without lung phantom simulated the radioactivity from outside of the field of view, and compared between two scatter corrections by each collimator. Results: The brain count in cerebral base with the ESSE method using LEHR collimator was higher than that of the ellipse approximation method. The whole brain count with the ellipse approximation method using CHR collimator shows 28.8% lower than the ESSE method, so that it suggests that the ellipse approximation method for LEHR collimator and the ESSE method for CHR collimator was close to reference counts. The coefficient of variation of the ESSE method was lower than that of the ellipse approximation method for both two collimators. Conclusions: It was possible to correct the scatter and penetration from outside the field of view with high accuracy, by using the ellipse approximation method with LEHR collimator and the ESSE method with CHR collimator.

Purpose: The frame-of-reference using computed-tomography (CT) coordinate system on single-photon emission computed tomography (SPECT) reconstruction is one of the advanced characteristics of the xSPECT reconstruction system. The aim of this study was to reveal the influence of the high-resolution frame-of-reference on the xSPECT reconstruction. Methods: ^99mTc line-source phantom and National Electrical Manufacturers Association (NEMA) image quality phantom were scanned using the SPECT/CT system. xSPECT reconstructions were performed with the reference CT images in different sizes of the display field-of-view (DFOV) and pixel. Results: The pixel sizes of the reconstructed xSPECT images were close to 2.4 mm, which is acquired as originally projection data, even if the reference CT resolution was varied. The full width at half maximum (FWHM) of the line-source, absolute recovery coefficient, and background variability of image quality phantom were independent on the sizes of DFOV in the reference CT images. Conclusion: The results of this study revealed that the image quality of the reconstructed xSPECT images is not influenced by the resolution of frame-of-reference on SPECT reconstruction.

The purpose of this study is to investigate a reduction method of radiation exposure for operator and medical staff in balloon pulmonary angioplasty (BPA) for chronic thromboembolic pulmonary hypertension (CTEPH). We devised a new radiation protection, which is U-shaped acrylic supporting table with 0.35 mmPb unleaded radiation protection sheet. A human phantom was put on the bed of cardiac angiography system [C-arm angulation: posteroanterior (PA), L-arm angulation: left anterior oblique (LAO) 60°]. The ambient equivalent dose rate was measured under fluoroscopy with and without three radiation protections: U-shaped acrylic supporting table with 0.35 mmPb unleaded radiation protection sheet, radiation protection for the lower body, and radiation protection for the upper body. With the three radiation protections, the ambient equivalent dose rate was decreased more than 99% at the height of 100 cm above the floor at the operator position (PA: from 186.2 μSv/h to 0.5 μSv/h, LAO 60°: from 350.4 μSv/h to 1.6 μSv/h). Ambient equivalent dose rate at the other points are also decreased effectively. The devised dose reduction method can reduce operator and medical staff radiation exposure effectively and be set up without interference for BPA procedure.

Purpose: The purpose of this study was to evaluate the accuracy for quantitative predictor of hepatic functional reserve using planar and single photon emission computed tomography (SPECT) images. Methods: We acquired planar and SPECT images of the myocardial torso phantom and calculated LHL (uptake ratio of the liver to the liver plus heart). Planar images were used with and without scatter correction. Myocardial torso phantom was simulated radioactivity distribution of normal liver function and poor liver function. This study compared the LHL_planar (calculated by planar images) and the LHL_SPECT (calculated by SPECT images) with the true value (calculated by radioactivity concentration in the phantom) and evaluated the error rate. Results: Error rate of LHL_SPECT was improved compared with the LHL_planar. The error rate of LHL_planar (with scatter correction) was increased in the poor liver function than in the normal liver function. Conclusions: The SPECT images have higher advantage to predict the liver function than the planar images.

Japanese society of radiological technology (JSRT) categorizes three international delegation projects; short-term studying abroad program (STSAP), international academic society visit program (overseas) (IASVP), and international internship visit program (Stanford University) (IIVP) for driving globalization of JSRT. In this survey, we conducted a questionnaire evaluating effectiveness of the international delegations. The survey covered 50 delegates of STSAP, 180 delegates of IASVP, and 100 delegates of IIVP. This survey includes detailed histories of career, current position, academic articles, and presentations as a first presenter before and on, and after each program. We categorized into six groups (change career, promoted in a position in hospital, kept a current position in hospital, promoted in a position in university, kept a current position in university, and others) in three programs. The response rate is approximately 58% (191/330 delegators). In all programs, almost all the delegates were radiological technologists in the hospital. They had reported a lot of academic articles and made a lot of presentations, and promoted in the hospital and/or university. STSAP, IASVP and IIVP were descending order of the average number of the articles as a first author and presentations as a first presenter. They published more the academic articles in Japanese than in English compared to JJRT and RPT. Therefore, research achievements and human resource conducted by this project provide great technologists and technique, and education. For further JRST globalization, it is desirable that we can continue these international delegations and verify the effectiveness.