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Discrimination of inter-crystal scattering events by signal processing for the X'tal cube PET detector
In this study, we proposed a method to discriminate the ICS events and showed its feasibilit y by the following method. For each 96 MPPC, we measured the mean and standard deviation of the peak in the pulse height distribution obtained by the photoabsorption events in a scintillator pixel. Every time a newly detected event was identified as the segment, we monitored the reduced chi-square v alue that was calculated with the pulse height and the prepared mean and the standard deviation for each 96 MPPC. Since the pulse height caused by the photoabsorption event resulted in a small reduced chi-square value, we could eliminat...
Source: Radiological Physics and Technology - October 2, 2023 Category: Physics Source Type: research

Effect of shape of automatic dose rate control and wedge compensation filter on radiation dose in an angiography system with a flat-panel detector
AbstractThe purpose was to investigate air-kerma area product (PKA) and entrance surface air-kerma rate (\(\dot{K}\)a,e) on the effect of the shape of automatic dose rate control (ADRC) in the presence of a wedge compensation filter. We compared and evaluated the variability of the X-ray output using a combination of wedge compensation filters and the ADRC. Two ADRC shapes (round and square) and three poly-methyl-methacrylate thicknesses (15, 20, and 25  cm) were used. A wedge compensation filter was inserted 2 cm at a time, up to 6 cm. When the wedge compensation filter was inserted to 6 cm for 20 cm of poly-methyl-me...
Source: Radiological Physics and Technology - September 21, 2023 Category: Physics Source Type: research

Investigation of uncertainty in internal target volume definition for lung stereotactic body radiotherapy
This study evaluated the validity of internal target volumes (ITVs) defined by three- (3DCT) and four-dimensional computed tomography (4DCT), and subsequently compared them with actual movements during treatment. Five patients with upper lobe lung tumors were treated with stereotactic body radiotherapy (SBRT) at 48  Gy in four fractions. Planning 3DCT images were acquired with peak-exhale and peak-inhale breath-holds, and 4DCT images were acquired in the cine mode under free breathing. Cine images were acquired using an electronic portal imaging device during irradiation. Tumor coverage was evaluated based on the manner i...
Source: Radiological Physics and Technology - September 15, 2023 Category: Physics Source Type: research

Current status of the educational environment to acquire and maintain the professional skills of radiotherapy technology and medical physics specialists in Japan: a nationwide survey
This study aimed to investigate the educational environment of radiotherapy technology and medical physics specialists (RTMP) in Japan. We conducted a nationwide questionnaire survey in radiotherapy institutions between June and August 2022. Participants were asked questions regarding the educational system, perspectives on updating RTMP ’s skills and qualifications, and perspectives on higher education for RTMP at radiotherapy institutions. The results were then analyzed in detail according to three factors: whether the hospital was designed for cancer care, whether it was a Japanese Society for Radiation Oncology (JAST...
Source: Radiological Physics and Technology - September 5, 2023 Category: Physics Source Type: research

Novel method for calculating the effective dose using size-specific dose estimates conversion factors in abdomen –pelvis computed tomography
AbstractWe propose a novel method for calculating the effective dose that closely reflects the individual attenuation, utilizing two conversion coefficients. A total of 180 adult patients who underwent abdomen –pelvis computed tomography were categorized into six groups based on sex and body type. The effective dose was calculated by multiplying the dose-length product with the effective dose conversion coefficient and the size-specific dose estimate conversion factor. The effective dose calculated usin g a simulation-based dose calculator (WAZA-ARI) was employed as the reference value. The following values, obtained thr...
Source: Radiological Physics and Technology - August 30, 2023 Category: Physics Source Type: research

Development of a new coordinate calibration phantom for a light-section-based optical surface monitoring system
This study aimed to develop a new calibration phantom using different materials and to propose a procedure that minimizes setup errors. The new phantom, primarily made of PET100, which exhibits good reflectivity without scattering or attenuating the red-slit laser at the phantom surface, was shaped in a manner similar to that of previous designs. The detection accuracy and stability were evaluated using six different regions of interest (ROIs) and compared with previous phantom designs. The coordinate coincidence between the machine and VOXELAN was compared for both phantom designs. The detection accuracy and stability of ...
Source: Radiological Physics and Technology - August 23, 2023 Category: Physics Source Type: research

Number of computed tomography scanners and regional disparities based on population and medical resources in Japan
This study aimed to discover the associations between the number of computed tomography (CT) scanners and the population, as well as number of medical resources to identify regional disparities in Japan. The number of CT scanners was tabulated for each detector row of CT scanners for hospitals and clinics in each prefecture. The number of CT scanners, patients, medical doctors, radiological technologists, facilities, and beds per 100,000 population was compared. Additionally, the number of hospitals with  ≥ 200 beds and multidetector-row CT scanners with ≥ 64 rows were tabulated, and their ratios were calculate...
Source: Radiological Physics and Technology - August 23, 2023 Category: Physics Source Type: research

Development of a new coordinate calibration phantom for a light-section-based optical surface monitoring system
This study aimed to develop a new calibration phantom using different materials and to propose a procedure that minimizes setup errors. The new phantom, primarily made of PET100, which exhibits good reflectivity without scattering or attenuating the red-slit laser at the phantom surface, was shaped in a manner similar to that of previous designs. The detection accuracy and stability were evaluated using six different regions of interest (ROIs) and compared with previous phantom designs. The coordinate coincidence between the machine and VOXELAN was compared for both phantom designs. The detection accuracy and stability of ...
Source: Radiological Physics and Technology - August 18, 2023 Category: Physics Source Type: research

The influence of image reconstruction methods on the diagnosis of pulmonary emphysema with convolutional neural network
This study investigated the influence of iterative reconstruction (IR) methods on computed tomography (CT) images when training convolutional neural network (CNN) models to diagnose pulmonary emphysema. To evaluate the influence of the IR algorithm on CNN, the present study comprised two steps: the comparison of noise reduction by IR algorithms using phantom examinations and the change in performance of CNN with IR algorithms using patient data. We retrospectively analyzed 97 patients. Raw CT data were reconstructed using the filtered back-projection (FBP) and adaptive statistical iterative reconstruction V (ASIR-V) algori...
Source: Radiological Physics and Technology - August 15, 2023 Category: Physics Source Type: research