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We quantified the level of backscatter radiation generated from physicians' heads using a phantom. We also evaluated the shielding rate of the protective eyewear and optimal placement of the eye-dedicated dosimeter (skin surface or behind the Pb-eyewear). We performed diagnostic X-rays of two head phantoms: Styrofoam (negligible backscatter radiation) and anthropomorphic (included backscatter radiation). Radiophotoluminescence glass dosimeters were used to measure the eye-lens dose, with or without 0.07-mm Pb-equivalent protective eyewear. We used tube voltages of 50, 65 and 80 kV because the scattered radiation has a lower mean energy than the primary X-ray beam. The backscatter radiation accounted for 17.3-22.3% of the eye-lens dose, with the percentage increasing with increasing tube voltage. Furthermore, the shielding rate of the protective eyewear was overestimated, and the eye-lens dose was underestimated when the eye-dedicated dosimeter was placed behind the protective eyewear. We quantified the backscatter radiation generated from physicians' heads. To account for the effect of backscatter radiation, an anthropomorphic, rather than Styrofoam, phantom should be used. Close contact of the dosimeter with the skin surface is essential for accurate evaluation of backscatter radiation from physician's own heads. To assess the eye-lens dose accurately, the dosimeter should be placed near the eye. If the dosimeter is placed behind the lens of the protective eyewear, we recommend using a backscatter radiation calibration factor of 1.2-1.3., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Japanese Radiation Research Society and Japanese Society for Radiation Oncology.)

This study aimed to assess fetal radiation exposure in pregnant women undergoing computed tomography (CT) and rotational angiography (RA) examinations for the diagnosis of pelvic trauma. In addition, this study aimed to compare the dose distributions between the two examinations. Surface and average fetal doses were estimated during CT and RA examinations using a pregnant phantom model and real-time dosemeters. The pregnant model phantom was constructed using an anthropomorphic phantom, and a custom-made abdominal phantom was used to simulate pregnancy. The total average fetal dose received by pregnant women from both CT scans (plain, arterial and equilibrium phases) and a single RA examination was ~60 mGy. Because unnecessary repetition of radiographic examinations, such as CT or conventional 2D angiography can increase the radiation risk, the irradiation range should be limited, if necessary, to reduce overall radiation exposure., (© The Author(s) 2024. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The purpose of this study was to estimate the internal dose of radiation in Japanese macaques (aka Nihonzaru or snow monkey) due to the Fukushima nuclear power plant accident. Images of a male Japanese macaque weighing ~10 kg were acquired using a multi-slice computed tomography (CT) scan with a 64-row segment detector. The CT images were used to create voxel phantoms of the bones, bone marrow, brain, eyes, heart, lungs, stomach, liver, spleen, pancreas, kidneys, intestines, bladder, testes, thyroid and miscellaneous tissue. The Particle and Heavy Ion Transport System (PHITS) Monte Carlo code was used to calculate the internal exposure rate conversion factors for 134Cs, 137Cs and 131I isotopes for the created voxel phantoms with a statistical precision higher than 1%. The PHITS-calculated energy deposits were compared with those for rhesus monkeys. The results showed that the fractions of energy deposits for β-radiation in different organs were almost identical between the two species. For γ-radiation, there was excellent agreement in the self-absorption rate with the approximate curve of the Japanese macaque, with an average deviation of 2%. The maximum deviation of 12% was for the kidney, which has two organs, so the error with the approximate curve is slightly larger due to the energy loss created between organs., (© The Author(s) 2023. Published by Oxford University Press on behalf of The Japanese Radiation Research Society and Japanese Society for Radiation Oncology.)

This study aimed to compare the lens equivalent dose (LED) measured during endoscopic retrograde cholangiopancreatography (ERCP) using DOSIRIS™ as a dedicated dosemeter to that measured using glass badges to determine if glass badges can be alternative tools for LED measurement. LEDs for physicians during ERCP were measured using the DOSIRIS™ [3-mm dose equivalent] worn on the outer edge of the eyes and personal dosemeters (glass badges) [0.07-mm dose equivalent] worn on the right and left sides of the neck. The cumulated doses over 6 months for the left eye using DOSIRIS™ were 9.5 and 11.8 mSv for physicians A and B, whereas doses measured using glass badges were 7.5 and 11.6 mSv, respectively. The LEDs of the physicians at the left eye and left neck side showed almost similar values and were significantly correlated (r = 0.95; p < 0.01). For an accurate LED measurement during ERCP, using a dosemeter such as DOSIRIS™ is recommended, although similar LED estimation values were reported using glass badges on the left neck side., (© The Author(s) 2022. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

We determined the effect of a new scout image acquisition technique ('smart scout'), which also serves as a tube warm-up, on radiation dose and automatic exposure control (AEC) mA settings. The entrance surface dose (ESD) of a chest phantom with and without the smart scout was measured. A conical AEC phantom was scanned in the setting for abdominal CT, and AEC curves were generated. ESD when the smart scout was not used was 0.75 mGy at 120 kV, 50 mA. ESD when using the smart scout was 0.24 mGy for a body habitus setting of 'Less', 0.54 mGy for 'Moderate' and 0.95 mGy for 'More'. When the diameter of the subject was ≥32 cm, the mA setting became lower in 'Less'. The smart scout reduced exposure at the 'Less' and Moderate' settings compared to the conventional scout scan., (Published by Oxford University Press 2022.)

The new recommendation of the International Commission on Radiological Protection for occupational eye dose is an equivalent dose limit to the eye of 20 mSv year-1, averaged over a 5-year period. This recommendation is a drastic reduction from the previous limit of 150 mSv year-1. Hence, it is important to protect physicians' eyes from X-ray radiation. Particularly in interventional radiology (IVR) procedures, many physicians use protective lead (Pb) glasses to reduce their occupational exposure. This study assessed the shielding effects of novel 0.07 mm Pb glasses. The novel glasses (XR-700) have Pb-acrylic lens molded in three dimensions. We studied the novel type of 0.07 mm Pb glasses over a period of seven consecutive months. The eye dose occupational radiation exposure of seven IVR physicians was evaluated during various procedures. All IVR physicians wore eye dosimeters (DOSIRIS™) close to the left side of the left eye. To calculate the shielding effects of the glasses, this same type of eye dosimeter was worn both inside and outside of the Pb lenses. The average shielding effect of the novel glasses across the seven physicians was 61.4%. Our results suggest an improved shielding effect for IVR physicians that use these glasses. No physician complained that the new glasses were uncomfortable; therefore comfort is not a problem. The lightweight glasses were acceptable to IVR physicians, who often must perform long procedures. Thus, the novel glasses are comfortable and reasonably protective. Based on the results of this study, we recommend that IVR physicians use these novel 0.07 mm Pb glasses to reduce their exposure., (© The Author(s) 2021. Published by Oxford University Press on behalf of The Japanese Radiation Research Society and Japanese Society for Radiation Oncology.)

Although the clinical value of fluoroscopically guided respiratory endoscopy (bronchoscopy) is clear, there have been very few studies on the radiation dose received by staff during fluoroscopically guided bronchoscopy. The International Commission on Radiological Protection (ICRP) is suggesting reducing the occupational lens dose limit markedly from 150 to 20 mSv/year, averaged over defined periods of five years. The purpose of this study was to clarify the current occupational eye dose of bronchoscopy staff conducting fluoroscopically guided procedures. We measured the occupational eye doses (3-mm-dose equivalent, Hp(3)) of bronchoscopy staff (physicians and nurses) over a 6-month period. The eye doses of eight physicians and three nurses were recorded using a direct eye dosimeter, the DOSIRIS. We also estimated eye doses using personal dosimeters worn at the neck. The mean ± SD radiation eye doses (DOSIRIS) to physicians and nurses were 7.68 ± 5.27 and 2.41 ± 1.94 mSv/6 months, respectively. The new lens dose limit, 20 mSv/year, may be exceeded among bronchoscopy staff, especially physicians. The eye dose of bronchoscopy staff (both physicians and nurses) was underestimated when measured using a neck dosimeter. Hence, the occupational eye dose of bronchoscopy staff should be monitored. To reduce the occupational eye dose, we recommend that staff performing fluoroscopically guided bronchoscopy wear Pb glasses. correct evaluation of the lens dose [Hp(3)] using an eye dosimeter such as the DOSIRIS is necessary for bronchoscopy staff., (© The Author(s) 2020. Published by Oxford University Press on behalf of The Japanese Radiation Research Society and Japanese Society for Radiation Oncology.)

The purpose of this study was to measure the peak skin dose (PSD) and bilateral lens doses using radiophotoluminescence glass dosimeters and to determine the factors influencing the radiation dose in cases of cerebral aneurysm treated with pipeline embolization devices (PEDs). The cumulative dose, PSD and right and left lens doses were 3818.1 ± 1604.6, 1880.0 ± 723.0, 124.8 ± 49.2 and 180.7 ± 124.8 mGy, respectively. Using multivariate analysis, body mass index (p < 0.01; odds ratio (OR) = 1.806; 95% confidence interval (CI) = 1.007-3.238) and deployment time of PED (p < 0.05; OR = 1.107; 95% CI = 1.001-1.224) were found to be the independent predictors of PSD exceeding 2 Gy. Measures such as collimation of the radiation field and optimization of radiation dose should be taken to reduce the radiation to the patient., (© The Author(s) 2020. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The aim of this study was to investigate differences in volume computed tomography dose index (CTDIvol) and dose-length product (DLP) values according to facility size in Japan. A questionnaire survey was sent to 3000 facilities throughout Japan. Data from each facility were collected including bed number, computed tomography (CT) scan parameters employed and the CTDIvol and/or DLP values displayed on the CT scanner during each examination. The CTDIvol and DLP for 11 adult and 6 paediatric CT examinations were surveyed. Comparison of CTDIvol and DLP values of each examination according to facility size revealed key differences in CT dose between small and large facilities. This study highlights the importance of lowering the dose of coronary artery examination with contrast agent in smaller facilities and of lowering the dose of adult and paediatric head CT without contrast agent in larger facilities. The results of this study are valid in Japan., (© The Author(s) 2020. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Interventional radiology (IR) procedures tend to be complex, which delivers high radiation exposure to patient. In the present study, we measured the radiation exposure dose [Hp(3)] in the eye using a direct eye dosemeter placed next to the physician's eye during procedures. Physicians wore a direct eye dosemeter just lateral to eyes and an additional direct eye dosemeter outside the radiation protective eyeglasses close to their eyes. Additionally, a neck glass badge was worn at the neck. Although we found a positive correlation between the left neck glass badge dose [Hp(0.07)] and the left eye lens dose [Hp(3)], the value of R2 of the regression equation were 0.62 and 0.71 (outside and inside). We thought that the exact eye lens dose might not be estimated from the neck glass badge. In conclusion, a correct evaluation of the lens dose [Hp(3)] using the direct eye dosemeter is recommended for tachyarrhythmia physicians., (© The Author(s) 2019. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Neurovascular interventional radiology (neuro-IR) procedures tend to require an extended fluoroscopic exposure time and repeated digital subtraction angiography. To evaluate the actual measurement of eye lens dose using a direct eye dosemeter in neuro-IR physicians is important. Direct dosimetry using the DOSIRIS™ (IRSN, France) [3 mm dose equivalent, Hp(3)] was performed on 86 cases. Additionally, a neck personal dosemeter (glass badge) [0.07 mm dose equivalent, Hp(0.07)] was worn outside the protective apron to the left of the neck. The average doses per case of neuro-IR physicians were 0.04 mSv/case and 0.02 mSv/case, outside and inside the radiation protection glasses, respectively. The protective effect of radiation protection glasses was approximately 60%. The physician eye lens dose tended to be overestimated by the neck glass badge measurements. A correct evaluation of the lens dose [Hp(3)] using an eye dosemeter such as DOSIRIS™ is needed for neuro-IR physicians., (© The Author(s) 2019. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The purpose of this study was to investigate the dose distribution and lens doses associated with C-arm cone-beam computed tomography (CBCT), using a head phantom, and to estimate the contribution ratio of C-arm CBCT to each patient's lens dose during interventional neuroradiology ('lens dose ratio') in 109 clinical cases. In the phantom study, the peak skin doses and respective right and left lens doses of C-arm CBCT were as follows: 63.0 ± 1.9 mGy, 19.7 ± 1.4 mGy and 21.9 ± 0.8 mGy in whole brain C-arm CBCT and 39.2 ± 1.4 mGy, 4.7 ± 0.9 mGy and 3.6 ± 0.3 mGy in high-resolution C-arm CBCT. In the clinical study, the lens dose ratios were 25.4 ± 8.7% in the right lens and 19.1 ± 9.8% in the left lens. This study shows that, on average, ~25% of patients' total lens dose was contributed by C-arm CBCT., (© The Author(s) 2018. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

In a previous study, we reported on a novel (prototype) real-time patient dosimeter with non-toxic phosphor sensors. In this study, we developed new types of sensors that were smaller than in the previous prototype, and clarified the clinical feasibility of our newly proposed dosimeter. Patient dose measurements obtained with the newly proposed real-time dosimeter were compared with measurements obtained using a calibrated radiophotoluminescence glass reference dosimeter (RPLD). The reference dosimeters were set at almost the same positions as the new real-time dosimeter sensors. We found excellent correlations between the reference RPLD measurements and those obtained using our new real-time dosimeter (r2 = 0.967). However, the new type of dosimeter was found to underestimate radiation skin dose measurements when compared with an RPLD. The most probable reason for this was the size reduction in the phosphor sensor of the new type of dosimeter. We believe that, as a result of reducing the phosphor sensor size, the backscattered X-ray irradiation was underestimated. However, the new dosimeter can accurately determine the absorbed dose by correcting the measured value with calibration factors. The calibration factor for the new type dosimeter was determined (by linear regression) to be ~1.15. New real-time patient dosimeter design would be an effective tool for the real-time measurement of patient skin doses during interventional radiology treatments., (© The Author(s) 2019. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.)

Objective:: To propose a new set of Japanese diagnostic reference levels (DRLs) and achievable doses (ADs) for 2017 and to verify the usefulness of Japanese DRLs (DRLs 2015) for CT, by investigating changes in the volume CT dose index (CTDI vol ) from 2014 to 2017., Methods:: Detailed information on the CT scan parameters used throughout Japan were obtained by questionnaire survey. The CTDI vol and dose-length product for the 11 commonest adult and 6 commonest paediatric CT examinations were surveyed and compared with 2014 data and DRLs 2015., Results:: Evaluations of adult head (helical), and abdomen and pelvis without contrast agent, paediatric chest without contrast agent, and abdomen and pelvis without contrast agent showed a slightly lower mean CTDI vol in 2017 than in 2014 (t-test, p < 0.05). The interquartile range of CTDI vol for all 2017 examinations was lower than in 2014., Conclusions:: This study verified the lower mean, 75th percentile, and interquartile range by investigating changes in the CTDI vol from 2014 to 2017. The DRLs 2015 contributed to CT radiation dose reduction., Advances in Knowledge:: The widespread implementation of iterative reconstruction algorithms and low-tube voltage in CT scanners is likely to facilitate further reduction in the CT radiation dose used in Japan. Although radiological technologists may require further education on appropriate CTDI vol and DLP usage, the DRLs 2015 greatly contributed to the reduction of the CT radiation dose used in Japan.

Endoscopic retrograde cholangiopancreatography (ERCP) is often complex and involves long fluoroscopic times, with significant radiation exposure to medical staff. We investigated protective effects of an additional attached lead shielding device. The lead shielding device covered with the X-ray tube table (0.125 mm lead equivalent) during ERCP procedures. Fluoroscopy scatter radiation, with or without the lead shielding device, was measured using an acrylic phantom and a radiation survey meter. Measurements (25 points) were made at 50 cm intervals, at both 90 and 150 cm above the floor. We created radiation maps, with and without the additional lead shielding device. Moreover, we monitored annual staff exposure to radiation, before and after inclusion of the shielding device. Without additional shielding, exposure doses at the physician's position, 90 and 150 cm above the floor, were 1940 and 4040 (μSv/h) respectively. In contrast, with the shielding device, corresponding exposures were 270 and 450 (μSv/h) at 90 and 150 cm, respectively. Scattered radiation was decreased by 86.1% at 90 cm or 88.9% at 150 cm. However, with additional lead shielding in the middle, rather than hung over the operating table, scattered radiation was decreased by only ~10%. The staff's annual dose equivalents (DEs) were 12.2-29.8 mSv/year without and 3.8-8.4 mSv/year with lead shielding. With lead shielding, dose equivalent values for the staff were decreased by 41.0-76.5%. Thus, with additional lead shielding, properly used, scattered radiation would be decreased by ~90%, thus decreasing exposure doses to medical staff during ERCPs.

We investigated changes in the entrance skin dose (ESD) and the mean glandular dose (MGD) during plain radiography or mammography in Japan from 1974 to 2014. Surveys regarding the conditions used for plain radiography and mammography were performed throughout Japan in 1974, 1979, 1989, 1993, 1997, 2001, 2003, 2007, 2011 and 2014. The anatomical regions considered were categorised as follows: skull anteroposterior (AP), lumbar AP, lumbar lateral (LAT), pelvis (AP), ankle, chest posteroanterior (PA), Guthmann (lateral pelviography for pregnant women), infant hip joint and mammography. The doses for all anatomical regions decreased from 1974 to 1993. The MGD for mammography remained low from 1993 to 2014, and the ESDs for chest (PA) radiography trended upward. After the 2000s, the use of digital imaging increased in Japan. This is the first long-term study to examine changes in ESDs and MGDs in Japan., (© The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The purpose of this research was to measure accurate patient entrance skin dose and maximum skin absorbed dose (MSD) to prevent radiation skin injuries in percutaneous coronary interventions (PCIs). We directly measured the MSD on 50 PCIs by using multiple radiophotoluminescence glass dosimeters and a modified dosimetry gown. Also, we analysed the correlation between the MSD and indirect measurement parameters, such as fluoroscopic time (FT), dose-area product (DAP) and cumulative air kerma (C-AK). There were very strong correlations between MSD and FT, DAP and C-AK, with the correlation between MSD and C-AK being the strongest (r = 0.938). In conclusion, the regression lines using MSD as an outcome value (y) and C-AK as predictor variables (x) were y = 1.12x (R2 = 0.880). From the linear regression equation, MSD is estimated to be ~1.12 times that of C-AK in real time., (© The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The purpose of this study was to evaluate the maternal and foetal effective doses during foetal computed tomography (CT) and to compare the radiation dose, dose profile and image noise on 80-row CT in helical scanning mode and 320-row CT in wide-volume scanning mode. The radiation doses were measured using thermoluminescent dosemeters implanted at various organ sites of an anthropomorphic pregnant phantom. The foetal doses in the 320-row multi-detector CT (MDCT) and 80-row MDCT units were higher than the volume CT dose index (CTDIvol). The dose profile in the 320-row MDCT overlapped in two places but showed no overlap in the 80-row MDCT. There were no significant differences in image noise between the two scanning modes. The foetal dose evaluation by CTDIvol may underestimate the foetal radiation risk. When using the wide-volume mode, operators must take into account the number of scans and overlap between volumetric sections., (© The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Objective: The aims of this study were to estimate the effective radiation doses from CT examinations of both adults and children in Japan and to study the impact of various scan parameters on the effective doses., Methods: A questionnaire, which contained detailed questions on the CT scan parameters employed, was distributed to 3000 facilities throughout Japan. For each scanner protocol, the effective doses for head (non-helical and helical), chest and upper abdomen acquisitions were estimated using ImPACT CT Patient Dosimetry Calculator software v. 1.0.4 (St George's Hospital, London, UK)., Results: The mean effective doses for chest and abdominal examinations using 80-110 kV were significantly lower than those using 120 kV. However, there was no statistically significant difference in the mean effective doses for head scans between facilities employing 80-110 kV and 120 kV. In chest and abdominal examinations, the mean effective doses using CT scanners from Western manufacturers [Siemens (Forchheim, Germany), Philips (Eindhoven, Netherlands) and GE Medical Systems (Milwaukee, WI)] were significantly lower than those of examinations using Japanese scanners [Hitachi (Kashiwa, Japan) and Toshiba (Otawara, Tochigi, Japan)], except for in paediatric chest examinations., Conclusion: The mean effective doses for adult head, chest and abdominal CT examinations were 2.9, 7.7 and 10.0 mSv, respectively, whereas the corresponding mean effective doses for paediatric examinations were 2.6, 7.1 and 7.7 mSv, respectively., Advances in Knowledge: Facilities using CT scanners by Western manufacturers commonly adopt low-tube-voltage techniques, and low-tube-voltage CT may be useful for reducing the radiation doses to the patients, particularly for the body region.

The purpose of this study was to evaluate the effect of tube current modulation for dose estimation of a body computed tomography (CT) examination using a simulation tool. The authors also compared longitudinal variations in tube current values between iterative reconstruction (IR) and filtered back-projection (FBP) reconstruction algorithms. One hundred patients underwent body CT examinations. The tube current values around 10 organ regions were recorded longitudinally from tube current information. The organ and effective doses were simulated by average tube current values and longitudinal modulated tube current values. The organ doses for the bladder and breast estimated by longitudinal modulated tube current values were 20 % higher and 25 % lower than those estimated using the average tube current values, respectively. The differences in effective doses were small (mean, 0.7 mSv). The longitudinal variations in tube current values were almost the same for the IR and FBP algorithms., (© The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Cardiac interventional procedures have been increasing year by year. However, radiation skin injuries have been still reported. There is a necessity to measure the patient entrance skin dose (ESD), but an accurate dose measurement method has not been established. To measure the ESD, a lot of radiophotoluminescence dosemeters (RPLDs) provide an accurate measurement of the direct actual ESD at the points they are arrayed. The purpose of this study was to examine the characteristics of RPLD to measure the ESD. As a result, X-ray permeable RPLD (with no tin filter) did not interfere with the percutaneous coronary intervention procedure. The RPLD also had good fundamental performance characteristics. Although the RPLD had a little energy dependence, it showed excellent dose and dose-rate linearity, and good angular dependence. In conclusion, by calibrating the energy dependence, RPLDs are useful dosemeter to measure the ESD in cardiac intervention., (© The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Children with complex congenital heart diseases often require repeated cardiac catheterization; however, children are more radiosensitive than adults. Therefore, radiation-induced carcinogenesis is an important consideration for children who undergo those procedures. We measured entrance skin doses (ESDs) using radio-photoluminescence dosimeter (RPLD) chips during cardiac catheterization for 15 pediatric patients (median age, 1.92 years; males, n = 9; females, n = 6) with cardiac diseases. Four RPLD chips were placed on the patient's posterior and right side of the chest. Correlations between maximum ESD and dose-area products (DAP), total number of frames, total fluoroscopic time, number of cine runs, cumulative dose at the interventional reference point (IRP), body weight, chest thickness, and height were analyzed. The maximum ESD was 80 ± 59 (mean ± standard deviation) mGy. Maximum ESD closely correlated with both DAP (r = 0.78) and cumulative dose at the IRP (r = 0.82). Maximum ESD for coiling and ballooning tended to be higher than that for ablation, balloon atrial septostomy, and diagnostic procedures. In conclusion, we directly measured ESD using RPLD chips and found that maximum ESD could be estimated in real-time using angiographic parameters, such as DAP and cumulative dose at the IRP. Children requiring repeated catheterizations would be exposed to high radiation levels throughout their lives, although treatment influences radiation dose. Therefore, the radiation dose associated with individual cardiac catheterizations should be analyzed, and the effects of radiation throughout the lives of such patients should be followed., (© The Author 2014. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.)

Radiation protection for interventional radiology (IR) physicians is very important. Current IR X-ray systems tend to use flat-panel detectors (FPDs) rather than image intensifiers (IIs). The purpose of this study is to test the hypothesis that there is no difference in physician-received scatter radiation (PRSR) between FPD systems and II systems. This study examined 20 X-ray systems in 15 cardiac catheterisation laboratories (11 used a FPD and 9 used an II). The PRSR with digital cineangiography and fluoroscopy were compared among the 20 X-ray systems using a phantom and a solid-state-detector electronic pocket dosemeter. The maximum PRSR exceeded the minimum PRSR by ~12-fold for cineangiography and ~9-fold for fluoroscopy. For both fluoroscopy and digital cineangiography, the PRSR had a statistically significant positive correlation with the entrance surface dose (fluoroscopy, r = 0.87; cineangiography, r = 0.86). There was no statistically significant difference between the average PRSR of FPDs and IIs during either digital cineangiography or fluoroscopy. There is a wide range of PRSR among the radiography systems evaluated. The PRSR correlated well with the entrance surface dose of the phantom in 20 X-ray units used for IR. Hence, decreasing the dose to the patient will also decrease the dose to staff.

Many of the X-ray systems that are used for cardiac interventional radiology provide no way to evaluate the patient maximum skin dose (MSD). The authors report a new method for evaluating the MSD by using the cumulative patient entrance skin dose (ESD), which includes a back-scatter factor and the number of cineangiography frames during percutaneous coronary intervention (PCI). Four hundred consecutive PCI patients (315 men and 85 women) were studied. The correlation between the cumulative ESD and number of cineangiography frames was investigated. The irradiation and overlapping fields were verified using dose-mapping software. A good correlation was found between the cumulative ESD and the number of cineangiography frames. The MSD could be estimated using the proportion of cineangiography frames used for the main angle of view relative to the total number of cineangiography frames and multiplying this by the cumulative ESD. The average MSD (3.0 ± 1.9 Gy) was lower than the average cumulative ESD (4.6 ± 2.6 Gy). This method is an easy way to estimate the MSD during PCI.

In this study, the entrance surface dose rates received by a phantom during cineangiography and fluoroscopy were compared. The X-ray conditions used in the measurements were those normally used in facilities performing percutaneous coronary intervention. Although, today, the entrance surface doses (cineangiography and fluoroscopy) of X-ray equipment used for cardiac interventional radiology (IVR) tends to be lower than they were previously, some equipment produces a high radiation dose. Therefore, the X-ray equipment used for cardiac IVR procedures must be maintained in good repair and must be carefully calibrated. In addition, periodic measurement of the radiation dose from the X-ray equipment used for both cineangiography and fluoroscopy for cardiac IVR is necessary. If the radiation dose of the X-ray system in use is too high, the IVR staff should determine the reason and make an effort to reduce it. Hence, the IVR staff must be adequately trained in radiation protection.

Although the wide acceptance of interventional radiology (IVR) procedures has led to increasing numbers of interventions being performed, the radiation doses from IVR are higher. Increasing numbers of case reports of patient radiation injury resulting from IVR are being published. Therefore, radiation protection during IVR poses a very important problem. To protect against radiation injury, the evaluation of radiation dose is essential. The radiation dose must be evaluated for each IVR x-ray machine and each laboratory, because it varies greatly. To obtain this information easily, and to ensure practical use of the radiation information, good relationships between interventionists and medical physicists are essential.

At present, interventional radiology (IVR) tends to involve long procedures (long radiation duration), and physicians are near to the source of scattered radiation. Hence, shielding is critical in protecting physicians from radiation. Protective aprons and additional lead-shielding devices, such as tableside lead drapes, are important means of protecting the physician from scattered radiation. The purpose of this study was to evaluate whether non-lead aprons are effective in protecting physicians from radiation during IVR procedures. In this study, the radiation protection effects of commercially available protective lead and non-lead aprons, when exposed to diagnostic X rays, are compared. The performance of these non-lead and lead aprons was similar for scattered X rays at tube voltages of 60-120 kV. Properly designed non-lead aprons are thus more suitable for physicians because they weigh approximately 20% less than the lead aprons, and are non-toxic.

To describe the stability of radiation survey meters (RSMs) and electronic pocket dosemeters (EPDs), we examined 28 EPDs and 24 RSMs: 12 used NaI(Tl) scintillation RSMs and 12 used Geiger-Muller(GM) RSMs. We used simple methods for the relative calibration of the 24 RSMs and 28 EPDs. The RSM and EPD measurements were compared with a calibrated RSM and EPD (reference: traceable from the national standard of exposure) using a homemade measurement device to maintain the reproducibility of the measurements with reference radiation sources (i.e. 137Cs, 90Sr and 67Ga). The response of RSMs and EPDs, especially after prolonged use, should be checked periodically. In particular, GMRSMs that have been in use for many years have very low sensitivity and poor reproducibility. Our simple method for the relative calibration of RSMs and EPDs was shown to be effective for quality assurance purposes in checking RSMs and EPDs. We recommend regular checks and calibration for sustained performance of RSMs and EPDs.