Purpose: Using a magnetic resonance (MR) image generation technique with deep learning, we elucidated whether changing the training data patterns affected image generation accuracy. Methods: The pix2pix training model generated T1-weighted images from T2-weighted images or FLAIR images. Head MR images obtained at our hospital were used in this study. We prepared 300 cases for each model and four training data patterns for each model (a: 150 cases for one MR system, b: 300 cases for one MR system, c: 150 cases and augmentation data for one MR system, and d: 300 cases for two MR systems). The extension data were images of 150 cases rotated in the XY plane. The similarity between the images generated by the training and evaluation data in each group was evaluated using the peak signal-to-noise ratio (PSNR) and structural similarity (SSIM). Results: For both MR systems, the PSNR and SSIM were higher for training dataset b than training dataset a. The PSNR and SSIM were lower for training dataset d. Conclusion: MR image generation accuracy varied among training data patterns.

Purpose: Root Cause Analysis (RCA) of reported incident reports can lead to measures to prevent the recurrence of accidents. The purpose of this study is to clarify the relationship between the occurrence of cases, causal factors, contributing factors, and the experience years of the reporters classified into three groups: less than 2 years, 3 to less than 5 years, and more than 5 years, for incident reports subject to RCA. Methods: From April 2018 to March 2023, a chi-square test was conducted between each item extracted from 239 cases subject to RCA and the experience years of the reporters, with a significance level of less than 5% considered significant. Results: Regarding the occurrence cases, radiological technologists with longer experience had more misidentified a patient and fewer errors in imaging conditions and range, while radiological technologists with 3 to less than 5 years of experience had more errors in imaging conditions (p<0.001). In terms of occurrence factors, radiological technologists with 3 to less than 5 years of experience had more cases of insufficient confirmation (p<0.05). For contributing factors, there was no significant difference between the experience year groups (p=0.19), with “Impatience” being the most common factor. Conclusion: This survey suggested that in incident reports of radiological technologists, “Impatience” is a contributing factor that can occur regardless of years of experience.

Purpose: Diagnostic reference levels (DRLs) are defined as fluoroscopic dose rate measurements that are used for patient dose management in angiography. It is recommended that DRLs be measured at least once a year. This study aimed to evaluate the long-term fluctuations of fluoroscopic dose rate in an angiography system. Methods: An unconnected X-ray output analyzer was used to measure the fluoroscopic dose rate (air kerma rate) at the patient’s entrance reference point for a specific angiography system. The target period was from 2015 to 2022, and four measurements per year were made. First, the fluoroscopic dose rate was measured, and the average value and standard deviation for the target period were calculated. Next, the uncertainty of the measured values and the coefficient of variation were calculated. Finally, we calculated the fluoroscopic dose rate measurement error. Results: The average±standard deviation of the fluoroscopic dose rate was 353.29±9.11 µGy/s. The maximum uncertainty and coefficient of variation for each year were 5.41 µGy/s and 0.03, respectively. The maximum measurement error was 4.67%, where the mean measured value was taken as the true value. Conclusion: The fluctuation in the measured value of the fluoroscopic dose rate by an angiography system for 8 years is within ±5%, indicating stable X-ray output.

Purpose: The purpose of this study was to evaluate the effect of patient transfer slide boards with automatic couch height positioning compensation (AHC) on image quality and radiation dose during computed tomography (CT) examinations. Methods: The chest phantom for Kyoto Kagaku (Kyoto) Type PBU-SS 2 was performed helical scan using a Canon Medical Systems (Tochigi) 80-row CT Aquilion Prime SP/i Edition. Scan parameters were tube voltage: 120 kV, tube current: min 50 mA max 500 mA with AHC for noise index: 15, slice thickness: 5.0 mm, rotation time: 0.35 s/rotation, pitch factor: 0.813, reconstruction kernel: FC03. Filtered back projection was used for image reconstruction. We compared the image noise and volume computed tomography dose index (CTDI_vol) displayed on the console with and without the patient transfer slide boards by using or not using the AHC. Results: When using the AHC, CTDI_vol was increased (p<0.05), and image noise was decreased (p<0.05). Without the AHC, there was no significant difference in CTDI_vol (p=0.11) and image noise (p=0.29). Conclusion: The slide board utilized in this experiment did not have a notable impact on either image quality or exposure dose. Nonetheless, the use of the slide board was found to result in excessive exposure during CT scans that employed AHC.

Purpose: To verify the usefulness of three evaluation methods of short-time neuromelanin MRI, correlations between each method and the specific binding ratio (SBR) of dopamine transporter scintigraphy were investigated. Methods: Short-time neuromelanin MRI was used to measure the contents of melanin-containing cells in the midbrain substantia nigra based on the following methods. Method 1 evaluates the volume of the high-signal area of the midbrain substantia nigra. Method 2 evaluates the signal intensity ratio of the three dense areas of the midbrain substantia nigra. Method 3 evaluates the scoring of the data of Method 2. The subjects were 54 patients aged 60 years or older who underwent head MRI and DAT scan at the Department of Radiology of our hospital. Results: Significant correlations were found between the data of SBR and each of the three evaluation methods. Conclusion: All of our three methods to evaluate short-time neuromelanin MRI were considered to be useful in estimating the content of melanin-containing cells in the midbrain substantia nigra, showing the most effectiveness in Method 1.

In 2020, recording and management of exposure doses for computed tomography (CT) became mandatory. In terms of dose management, information regarding the imaged body part is particularly important information for proper tabulation. However, the actual body part to be imaged and the body part information obtained from the device may differ. In this study, we investigated the difference between the imaged area information obtained from a CT device and the dose index when the area is divided into actual areas to be examined using a facility’s unique imaging protocol. We collected 734784 radiation dose structured reports (RDSR) examined from 2014 to 2021 on CT equipment at 8 facilities and analyzed each facility’s volume CT dose index (CTDI_vol) and dose length product (DLP). The median values were tabulated and compared. Pre- and post-classing the body part, for CTDI_vol, increasing tendency was observed only in the head and abdomen. A similar trend was observed for DLP. Regarding dose management using RDSR as an information source, there were no major differences in dose information depending on the classification of the body part to be imaged. We hope that the accuracy of dose management will be improved by accurately classifying the body parts to be imaged.