[en] In interventional radiology, it is necessary to know the scattered radiation at the physician's position. Conventionally, survey meters have been used that can measure of 1 cm dose equivalent [Hp (10)] . This time, We had the opportunity to use a survey meter (OD-01) that can measure of 70μm [Hp (0.07)] , which can evaluate the equivalent dose (ED) of the crystalline lens. In this study, we report the basic performance evaluation of OD-01. As a result, it was found that the OD-01 had good basic performance in terms of tube voltage dependence and angle. We consider OD-01 is useful for evaluation of ED. (author)

[en] Monitoring and protecting of occupational eye doses in interventional radiology (IR) are very important matters. DOSIRIS™ is the useful solution to estimate the 3 mm dose-equivalent (Hp(3)), and it can be worn behind lead glasses. And DOSIRIS™, adjustable according to 3 axes, it is ideally placed as close to the eye and in contact with the skin. So, DOSIRIS™ will be suitable eye lens dosimeter. However, the fundamental characteristics of the DOSIRIS™ in the diagnostic x-ray energy domain (including that of IR x-ray systems) remain unclear. Here, we evaluated the performance of the dosimeter in that energy range. As a result, the DOSIRIS™ has good fundamental characteristics (batch uniformity, dose linearity, energy dependence, and angular dependence) in the diagnostic x-ray energy domain. We conclude that the DOSIRIS™ has satisfactory basic performance for occupational eye dosimetry in diagnostic x-ray energy settings (including IR x-ray systems). (note)

[en] In accordance with the 2011 ICRP recommendation, a reduction in the lens equivalent dose limit is also expected in Japan. Cardiac IVR staff are particularly exposed annually, so lens protection becomes even more important. We measured the shielding effect of 0.75 mmPb equivalent protective glasses in clinical practice. As a result, the shielding effect of the 0.75 mmPb equivalent protective glasses was about 80%, which was much higher than that of the lightweight type protective glasses. (author)

[en] There are no feasible real-time and direct skin dosimeters for interventional radiology. One would be available if there were x-ray phosphors that had no brightness change caused by x-ray irradiation, but the emission of the Y₂O₃:Eu, (Y, Gd, Eu)BO₃, and YVO₄:Eu phosphors investigated in our previous study was reduced by x-ray irradiation. We found that the brightness of those phosphors recovered, and the purpose of this study is to investigate their recovery phenomena. It is expected that more kinds of phosphors could be used in x-ray dosimeters if the brightness changes caused by x-rays are elucidated and prevented. Three kinds of phosphors—Y₂O₃:Eu, (Y, Gd, Eu)BO₃, and YVO₄:Eu—were irradiated by x-rays (2 Gy) to reduce their brightness. After the irradiation, brightness changes occurring at room temperature and at 80 °C were investigated. The irradiation reduced the brightness of all the phosphors by 5%–10%, but the brightness of each recovered immediately both at room temperature and at 80 °C. The recovery at 80 °C was faster than that at room temperature, and at both temperatures the recovered brightness remained at 95%–98% of the brightness before the x-ray irradiation. The brightness recovery phenomena of Y₂O₃:Eu, (Y, Gd, Eu)BO₃, and YVO₄:Eu phosphors occurring after brightness deterioration due to x-ray irradiation were found to be more significant at 80 °C than at room temperature. More kinds of phosphors could be used in x-ray scintillation dosimeters if the reasons for the brightness changes caused by x-rays were elucidated. (note)

[en] The Regulations for the Prevention of Ionising Radiation Hazards have been revised in 2021. In line with this, lens equivalent dose management's importance is increasing in Japan. Therefore, we assessed and analyzed the lens dose of six percutaneous coronary intervention (PCI) surgeons in real-time using a new type of personal dosimeter. We found that the dose rates varied according to the different X-ray irradiation directions, the surgeon's face position, and the ceiling protective plate. In addition, the percentage of incorrect use of the ceiling protective plate could be calculated. This study showed the value of real-time analysis and the need to pay attention to the conscious use of the ceiling protective plate. (author)

[en] The exposure of workers in general medicine is mainly X-ray exposure due to scattered rays from the subject. Therefore, the measurement of such scattered radiation is necessary for confirmation of exposure situation and radiation protection. Recently, the new hybrid survey meter RaySafe 452 was released by Unfors RaySafe. However, there are no detailed reports regarding the performance, which includes reproducibility and angular dependence, of RaySafe 452 survey meter. The purpose of this study was to evaluate the performance of RaySafe 452 survey meter. Experiments were conducted to compare the performance of RaySafe 452 survey meter with that of an ionization chamber survey meter. The results showed that the basic performance of the RaySafe 452 survey meter was good compared with the calibrated ionization chamber survey meter. (author)

[en] Real-time monitoring of the radiation doses received by interventional radiology (IR) staff has become highly desirable. However, occupational doses are rarely measured in real time, due to the lack of a feasible method for use in IR. Recently, the i2 system by RaySafe™ has been introduced to measure occupational exposure in IR in real time. The i2 system consists of several personal dosimeters (PDs) and a base station with a display and computer interfacing. We evaluated the fundamental performance (dose linearity, dose-rate dependence, angular dependence, batch uniformity and reproducibility) of the i2 system. The dose linearity of the i2 was excellent (R"2 = 1.00) The i2 exhibited slight dose-rate dependence (∼20%) at very high dose rates (250 mGy h"−"1). Little angular dependence (within 20%) was observed between 0° and ±45°, in either the vertical or horizontal direction. We also found that the PD was highly sensitive (about 200%) at angles behind it, e.g. 180°. However, this backscattered radiation is not a problem, in general, due to the placement of the i2 sensor (PD) on the lead apron. We conclude that the i2 system facilitates accurate real-time monitoring and management of occupational doses during IR. (note)

[en] The objective of this study was to compare the temperature dependence of a scintillation survey meter with and without the temperature compensation function. Investigation of temperature dependence is important to make precise measurements in various environments. The experiment was conducted using the NaI (Tl) scintillation survey meter with the temperature compensation function (TCS-1172) and the NaI (Tl) and CsI (Tl) scintillation survey meters without the temperature compensation function (TCS-171, PDR-111). In all, 1 cm dose equivalent rate (μSv/h) was measured by changing the room temperature from 10 to 40 degree Celsius. The results showed that the scintillation survey meter with the temperature compensation function had almost no change in the measured values with changes in room temperature, whereas the 1 cm dose equivalent rate of the scintillation survey meter without the temperature compensation function changed by a maximum of -7.2 (%/10 ℃) as temperature increased. This study confirms that the scintillation survey meter with the temperature compensation function was less dependent on temperature, and stable measurement was possible. However, it was suggested that the scintillation survey meter without the temperature compensation function might cause a drop in the measured value as the temperature rises. (author)

[en] We often measure both the dose and dose rate of scattered radiation when evaluating occupational exposure. However, no studies have emphasized the need to consider the energy of the scattered radiation. The conventional apparatus for taking energy measurements, X-ray spectrometers, are not easy to handle. Recently, the X2 survey meter that can measure both the dose and mean energy of scattered radiation was offered by Unfors RaySafe. However, no detailed the fundamental performance on mean energy of the X2 survey meter. Therefore, this study evaluated the fundamental performance of X2 survey meter in comparison to CdTe spectrometer. As a result, the X2 survey meter had a similar response to the CdTe spectrometer. Furthermore, the X2 survey meter has advantages that the sensor is small, the measured value is obtained immediately. We concluded that the X2 survey meter facilitates accurate monitoring of the scattered radiation. (author)

[en] Skin injury in patients due to radiation exposure has been a complication in percutaneous coronary intervention (PCI) for a long time. To the best of our knowledge, there have been no reports comparing radiation dose by treatment area with diagnostic reference levels (DRLs) 2020, although the radiation dose varies by treatment area in PCI. In this study, the treatment areas were classified into four segments (i.e., AHA no. 1-3, AHA no. 4, AHA no. 5-10, and AHA no. 11-15), and each segment was compared with DRLs 2020. This retrospective study included 984 consecutive patients with single-vessel disease and non-chronic total occlusion. PCI was performed on a single device. The median radiation dose was 1640.8 mGy, and the radiation dose for AHA no. 4 was 2732.0 mGy, which was significantly higher than the other treatment areas (p<0.001). In AHA no. 4, the radiation dose increased due to the heavy use of the left cranial view, and the patient background contributed to the increased lesion complexity. Therefore, it was challenging to evaluate AHA no. 4 and the other treatment areas with a uniform DRL value. Establishing a subdivided index for each treatment area is crucial if DRLs are used as a reference during procedures and as a guide for dose optimization. (author)