The 10 most-cited articles in Japanese Journal of Radiological Technology, 2023

BACKGROUND: If we try to perform the inspection for an electrometer, two types of electronic signals energized to the electrometer can be used. One is the signal that occurs in the ionization chamber irradiated by radiation. The other is the signal that is derived from a current source. The former signal is changed by radiation output, so we need to use two or more sets of the chambers and the electrometers in the inspection. In addition, the high-performance current source is relatively expensive. Therefore, it is difficult for users to inspect the electrometer simply. To deal with these, we have developed a new current source that allows users to perform highly accurate electrometer inspections at their own facilities. AIM: The purpose of this study was to verify that users can perform electrometer inspections with high accuracy in their own facilities by using a new current source. MATERIALS AND METHODS: A newly current source equips a dry cell battery as a charge generator. Current, polarity, and energized time can be changed by the source setting. We conducted an inspection by…

PURPOSE: Recently, the targeted radionuclide therapy (TRT) was urgently required to adapt the practice and environment because of the implementation of novel therapeutic radiopharmaceuticals such as alpha- and beta- radionuclides therapy. The present study aimed to clarify the questionnaire survey with the current situation (safety controls for workers and patients) at Japanese TRT facilities. METHODS: The massive questionnaire survey, 2 months from October to November 2021, was conducted among nationwide 251 facilities that have performed TRT in the past two years. The alpha- and beta- therapeutic radiopharmaceuticals were categorized and answered by one representative of the facility under anonymity. We analyzed the actual situation of each facility related to occupational exposure, radiation protection, contamination inspection, patient release criteria, and dosimetry for TRT. RESULTS: The survey response rate was 69.1% (174 facilities). About 75% of these facilities reported that they either follow the guidelines or take their own measures to reduce occupational exposure. The…

for each procedure have been set for IVR along with the reference fluoroscopic dose rate. The total dose of IVR includes fluoroscopic and digital acquisition (DA) doses, but in actual clinical practice, the ratio varies greatly depending on the procedure (diagnosis/treatment purpose and procedure content), and there are not many detailed data on the ratio. Therefore, we evaluated previous efforts that optimized radiation protection through examining dose for each procedure and the ratio of fluoroscopic and DA doses to total dose, and reviewing protocols. Since the ratio of fluoroscopy and DA dose differs depending on the procedure, it was suggested that the radiation dose exposed to patients can be optimized by sharing the dose information with physicians and constructing a protocol while considering the image quality for each procedure.

PURPOSE: In this study, we propose a system that combines a depth camera with a deep learning model for estimating the human skeleton and a depth camera to estimate the shooting part to be radiographed and to acquire the thickness of the subject, thereby providing optimized X-ray imaging conditions. METHODS: We propose a system that provides optimized X-ray imaging conditions by estimating the shooting part and measuring the thickness of the subject using an RGB camera and a depth camera. The system uses OpenPose, a posture estimation library, to estimate the shooting part. RESULTS: The recognition rate of the shooting part was 15.38% for the depth camera and 84.62% for the RGB camera at a distance of 100 cm, and 42.31% for the depth camera and 100% for the RGB camera at a distance of 120 cm. The measurement accuracy of the subject thickness was within ±10 mm except for a few cases, indicating that the X-ray imaging conditions were optimized for the subject thickness. CONCLUSION: The implementation of this system in an X-ray system is expected to enable automatic setting of X-ray…

Size-specific dose estimates（SSDE）は，computed tomography（CT）検査における体型の違いを考慮した線量指標であり，これまでvolume CT dose index（CTDIvol）では得られなかった任意の断面のおおよその吸収線量が評価できるようになった．Automatic exposure control（AEC）を使用した場合，CTDIvolは体軸方向に変調された値をとるが，検査終了後に表示される値はスキャン全体の平均値mean CTDIvolであり，局所のSSDE計算にどちらの値を使用するかにより値が変わることが予想できる．本研究では，SSDE算出にmean CTDIvolを用いるか，スライスごとの変調値を用いるかの違いが，局所の臓器線量評価へ与える影響について人体ファントムを用いて検証した．American Association of Physicists in Medicine （AAPM） Report No.220の手順に従いwater equivalent diameterを計算するプログラムを作成し比較検討した結果，mean CTDIvolを用いて計算されたSSDE（local-SSDEmean）は，肺野領域においてCT撮影による被ばく線量を評価するWebシステム（WAZA-ARIv2）で算出される臓器線量より18%–56%の過大評価となった．これに対しCTDIvolの変調値を用いて計算されるlocal-SSDEmodulatedは，臓器線量を10%–13%の相対誤差で評価できた．また体軸方向全域のlocal-SSDEを平均した値SSDEは，CTDIvolにいずれの方式を採用された場合でも両者の間に有意差を認めなかった．CT画像のdigital imaging and communications in medicine（DICOM）ヘッダータグ（0018, 9345）にmean CTDIvolが格納され，スライスごとに変調されたCTDIvolの値が得られない場合は，計算される局所のSSDEは誤差を多く含有し撮影部位の臓器線量を正しく反映しない．その場合には，スキャン全体のSSDEの平均値SSDEに臓器ごとの係数を乗じて局所の臓器線量を評価する手法は使用可能である．