Hidenori Otake

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BACKGROUND Computed tomography (CT) is the largest source of medical radiation exposure to the general population, and is considered a potential source of increased cancer risk. The aim of this study was to assess the current situation of CT use in Japan, and to investigate variations in radiation exposure in CT studies among institutions and scanners. (More)
Optimisation of computed tomography (CT) parameters is important in avoiding excess radiation exposure. The aim of this study is to establish the diagnostic reference levels (DRL) of CT in Japan by using dose-length product (DLP). Datasheets were sent to all hospitals/clinics which had CT scanner(s) in Gunma prefecture. Data were obtained for all patients(More)
The depth distribution of residual long-lived radioactivity in the inner concrete wall of a medical cyclotron room was measured by assaying concrete cores. Seven long-lived radioactive nuclides ((46)Sc, (60)Co, (65)Zn, (134)Cs, (152)Eu, (22)Na and (54)Mn) were identified by gamma-ray spectrometry of the concrete samples. It was confirmed that the(More)
OBJECTIVE The objective of this study was to assess differences in the semiquantitative values of 18F-fluorodeoxyglucose (18F-FDG) uptake among different positron emission tomographic (PET) systems. METHODS A phantom study was performed to compare standardized uptake value (SUV) in five PET scanners including a dedicated PET scanner and four PET/computed(More)
A 53-year-old man was found dead after a fire at his residence had been extinguished. Although a pistol was recovered beside the body, external examination was unable to indicate any gunshot wound because of severe charring of the body. Postmortem computed tomography (CT) scan performed prior to autopsy suggested an entrance gunshot wound in the posterior(More)
A 22-year-old woman was found dead in her bed, and subsequent postmortem examination was performed using ordinary methods such as external examination, Triage®, and computed tomography (CT) scan which demonstrated a high-density content of the duodenum. Autopsy and quantitative analysis of drugs present in the GI tract showed that high amounts of radiopaque(More)
PURPOSE The aim of this study is to investigate various intra-fractional errors and to determine the appropriate planning target volume (PTV) margins in intensity modulated radiation therapy (IMRT) for prostate cancer. METHODS Ten patients with prostate cancer treated with IMRT between July 2009 and March 2010 were analyzed. PTV was created by adding 4 mm(More)
According to the (18)O(p, n) (18)F reaction, fast neutrons produced in the target will cause residual radioactivity in a cyclotron itself and in the concrete walls mainly after thermalization of neutrons.As exploratory work prior to decommissioning of a medical cyclotron facility, surface and core samples of the facility's concrete walls were collected(More)
PURPOSE The purpose of our study is the establishment of normal database (NDB) from persons (aged 50-80 years) for 3D-SSP analysis of 123I-IMP brain perfusion SPECT image, and we analyzed whether the presence or absence of image correction methods, scatter correction (SC) and attenuation correction (AC), affects the created NDB and 3D-SSP analysis. (More)
PURPOSE There is no established method to determine a diagnostic reference level of panoramic radiology. As the basic principle of the panoramic radiology dose index (PRDI) and CT dose index (CTDI) is almost identical, we evaluated the usefulness of PRDI for this purpose. METHODS Using the imaging plate (IP) sandwiched between the 160-mm thick acrylic(More)