Radiation dose and radiation protection for patients and physicians during interventional procedure

Feasibility of transthoracic echocardiographic guidance for multicatheter electrophysiological mapping studies in horses

BACKGROUND

Improved characterization of arrhythmias is based on minimally invasive catheterizations. However, these catheterizations have been poorly explored in horses because apart from 3-dimensional (3D) mapping systems, continuous guidance of the catheter's position with adequate detail is difficult using current imaging modalities.

HYPOTHESIS

Position multiple electrophysiology catheters simultaneously at predetermined strategical positions in the heart using transthoracic echocardiographic guidance.

ANIMALS

Eight adult healthy horses.

METHODS

Observational study. Two electrophysiological studies were performed: 1 procedure with catheters positioned in the right heart in the standing sedated horse and 1 procedure under general anesthesia with catheters positioned in the left heart. Except for the coronary sinus catheter, each catheter positioning was simultaneously guided by right-parasternal transthoracic echocardiography and 3D electro-anatomical mapping.

RESULTS

For each catheter position, a central imaging plane was taken as the starting point, after which the imaging probe was shifted, rotated, and angulated to visualize the catheter over its entire length, including its distal electrode. Catheter positionings in the right heart and left ventricle were successfully guided in the majority of the horses whereas catheter positionings in the left atrium, and especially the pulmonary veins, were challenging to guide echocardiographically.

CONCLUSIONS AND CLINICAL IMPORTANCE

Ultrasound guidance of catheters to specific positions useful for electrophysiological mapping was feasible in the right heart and left ventricle but challenging for the left atrium. This approach creates a perspective for minimally invasive arrhythmia diagnosis without the need for a 3D mapping system. Left parasternal views and intracardiac echocardiography might provide better guidance for left atrial positions.

Effect of backscatter radiation on the occupational eye-lens dose

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.

Comparison of shielding effects of over-glasses-type and regular eyewear in terms of occupational eye dose reduction

Given the new recommendations for occupational eye lens doses, various lead glasses have been used to reduce irradiation of interventional radiologists. However, the protection afforded by lead glasses over prescription glasses (thus over-glasses-type eyewear) has not been considered in detail. We used a phantom to compare the protective effects of such eyewear and regular eyewear of 0.07 mm lead-equivalent thickness. The shielding rates behind the eyewear and on the surface of the left eye of an anthropomorphic phantom were calculated. The left eye of the phantom was irradiated at various angles and the shielding effects were evaluated. We measured the radiation dose to the left side of the phantom using RPLDs attached to the left eye and to the surface/back of the left eyewear. Over-glasses-type eyewear afforded good protection against x-rays from the left and below; the average shielding rates on the surface of the left eye ranged from 0.70-0.72. In clinical settings, scattered radiation is incident on physicians' eyes from the left and below, and through any gap in lead glasses. Over-glasses-type eyewear afforded better protection than regular eyewear of the same lead-equivalent thickness at the irradiation angles of concern in clinical settings. Although clinical evaluation is needed, we suggest over-glasses-type Pb eyewear even for physicians who do not wear prescription glasses.

Assessment of fetal radiation exposure in pregnant women undergoing computed tomography and rotational angiography examinations for pelvic trauma

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.

[Radiation Dose Reduction through the Optimization of Mask Images in Cerebral Angiography]

PURPOSE

To verify the effectiveness of optimizing the number of mask images in DSA for radiation dose reduction during cerebral angiography.

METHODS

A total of 60 angiography sessions in 2 times for 30 patients performed by the same operator were included in this study. In order to compare the effects of optimization to change the injection delay time of DSA from 1 s to the shortest possible time, the number of mask images, the number of imaging frames, and radiation doses between sessions were compared and analyzed retrospectively.

RESULTS

In one DSA run, the number of mask images was decreased from 6 (5-7) to 3 (2-3) frames (p<0.01)/57.1% (median [IQR]/reduction rate), the number of imaging frames was decreased from 34 (32-36) to 32 (29-34) frames (p<0.01)/7.9%, and the radiation dose was decreased from 33 (23-47) to 30 (21-40) mGy (p<0.01)/8.3%. In magnification angiography, the reductions rate was significantly increased. In one angiography session, the number of mask images was decreased from 45 (35-72) to 19 (16-34) frames (p<0.01)/54.6%, the number of imaging frames was decreased from 242 (199-385) to 211 (181-346) frames (p<0.01)/8.3%, the radiation dose of DSA was decreased from 295 (190-341) to 242 (167-305) mGy (p<0.01)/11.6%, and the total radiation dose was decreased from 369 (259-418) to 328 (248-394) mGy (p<0.01)/7.5%.

CONCLUSION

Using the shortest possible injection delay time for the number of mask image optimization was an effective radiation dose reduction method.

Energy spectrum measurement of scattered X-rays during IVR procedure

With the increase of the number of interventional radiology (IVR) procedures, the occupational exposure of operators and medical staff has attracted keen attention. The energy of scattered radiation in medical clinical sites is important for estimating the biological effects of occupational exposure. Recent years have seen many reports on the dose of scattered radiation by IVR, but few on the energy spectrum. In this study, the energy spectrum of scattered X-rays was measured by using a cadmium telluride (CdTe) semiconductor detector during IVR on several neurosurgical and cardiovascular cases. The cumulated spectra in each case were compared. The spectra showed little changes among neurosurgical cases and relatively large changes among cardiovascular cases. This was assumed to be due to the change of X-ray tube voltage and tube angle was larger in cardiovascular cases. The resulting energy spectra will be essential for the assessment of detailed biological effects of occupational exposure.

Usefulness of the spectral shaping dual-source computed tomography imaging technique in posterior corrective fusion for adolescent idiopathic scoliosis

PURPOSE

Since childhood exposure to radiation has been demonstrated to increase cancer risk with increase in radiation dose, reduced radiation exposure during computed tomography (CT) evaluation is desired for adolescent idiopathic scoliosis (AIS). Therefore, this retrospective study aimed to investigate the radiation dose of dual-source CT using a spectral shaping technique and the accuracy of the thoracic pedicle screw (TPS) placement for posterior spinal fusion (PSF) in patients with AIS.

METHODS

Fifty-nine female patients with thoracic AIS who underwent PSF using CT-guided TPSs were included and divided into two groups comprised of 23 patients who underwent dual-source CT (DSCT) with a tin filter (DSCT group) and 36 who underwent conventional multislice CT (MSCT group). We assessed the CT radiation dose using the CT dose index (CTDIvol), effective dose (ED), and accuracy of TPS insertion according to the established Neo's classification.

RESULTS

The DSCT and MSCT groups differed significantly (p < 0.001) in the mean CTDIvol (0.76 vs. 3.31 mGy, respectively) and ED (0.77 vs. 3.47 mSv, respectively). Although the correction rate of the main thoracic curve in the DSCT group was lower (65.7% vs. 71.2%) (p = 0.0126), the TPS accuracy (Grades 0-1) was similar in both groups (381 screws [88.8%] vs. 600 screws [88.4%], respectively) (p = 0.8133). No patient required replacement of malpositioned screws.

CONCLUSION

Spectral shaping DSCT with a tube-based tin filter allowed a 75% radiation dose reduction while achieving TPS insertion accuracy similar to procedures based on conventional CT without spectral shaping.

Effect of shape of automatic dose rate control and wedge compensation filter on radiation dose in an angiography system with a flat-panel detector

The purpose was to investigate air-kerma area product (PKA) and entrance surface air-kerma rate ([Formula: see text]a,e) on the effect of the shape of automatic dose rate control (ADRC) in the presence of a wedge compensation filter. We compared and evaluated the variability of the X-ray output using a combination of wedge compensation filters and the ADRC. Two ADRC shapes (round and square) and three poly-methyl-methacrylate thicknesses (15, 20, and 25 cm) were used. A wedge compensation filter was inserted 2 cm at a time, up to 6 cm. When the wedge compensation filter was inserted to 6 cm for 20 cm of poly-methyl-methacrylate, the X-ray output fluctuated significantly. The PKA was reduced by 39% when the wedge compensation filter was inserted to 6 cm and by 59% when it was inserted to 4 cm under round-type for 20 cm poly-methyl-methacrylate. The shape of the ADRC affects [Formula: see text]a,e and PKA.

Fundamental study on diagnostic reference level quantities for endoscopic retrograde cholangiopancreatography using a C-arm fluoroscopy system

The diagnostic reference level (DRL) is an effective tool for optimising protection in medical exposures to patients. However regarding air kerma at the patient entrance reference point (Ka,r), one of the DRL quantities for endoscopic retrograde cholangiopancreatography (ERCP), manufacturers use a variety of the International Electrotechnical Commission and their own specific definitions of the reference point. The research question for this study was whetherKa,ris appropriate as a DRL quantity for ERCP. The purpose of this study was to evaluate the difference betweenKa,rand air kerma incident on the patient's skin surface (Ka,e) at the different height of the patient couch for a C-arm system. Fluoroscopy and radiography were performed using a C-arm system (Ultimax-i, Canon Medical Systems, Japan) and a over-couch tube system (CUREVISTA Open, Fujifilm Healthcare, Japan).Ka,ewas measured by an ion chamber placed on the entrance surface of the phantom. Kerma-area product (PKA) andKa,rwere measured by a built-inPKAmeter and displayed on the fluoroscopy system.Ka,edecreased whileKa,rincreased as the patient couch moved away from the focal spot. The uncertainty of theKa,e/Ka,rratio due to the different height of the patient couch was estimated to be 75%-94%.Ka,rmay not accurately representKa,e.PKAwas a robust DRL quantity that was independent of the patient couch height. We cautioned against optimising patient doses in ERCP with DRLs set in terms ofKa,rwithout considering the patient couch height of the C-arm system. Therefore, we recommend thatKa,ris an inappropriate DRL quantity in ERCP using the C-arm system.

Evaluation of radiation dose and image quality for dental cone-beam computed tomography in pediatric patients

Children are sensitive to radiation; therefore, it is necessary to reduce radiation dose as much as possible in pediatric patients. In addition, it is crucial to investigate the optimal imaging conditions as they considerably affect the radiation dose. In this study, we investigated the effect of different imaging conditions on image quality and optimized the imaging conditions for dental cone-beam computed tomography (CBCT) examinations to diagnose ectopic eruptions and impacted teeth in children. To achieve our aims, we evaluated radiation doses and subjective and objective image quality. The CBCT scans were performed using 3D Accuitomo F17. All combinations of a tube voltage (90 kV), tube currents (1, 2, 3 mA), fields of view (FOVs) (4 × 4, 6 × 6 cm), and rotation angles (360°, 180°) were used. Dose-area product values were measured. SedentexCT IQ cylindrical phantom was used to physically evaluate the image quality. We used the modulation transfer function as an index of resolution, the noise power spectrum as an index of noise characteristics, and the system performance function as an overall evaluation index of the image. Five dentists visually evaluated the images from the head-neck phantom. The results showed that the image quality tended to worsen, and scores for visual evaluation decreased as tube currents, FOVs and rotation angles decreased. In particular, image noise negatively affected the delineation of the periodontal ligament space. The optimal imaging conditions were 90 kV, 2 mA, 4 × 4 cm FOV and 180° rotation. These results suggest that CBCT radiation doses can be significantly reduced by optimizing the imaging conditions.

Eye Lens Radiation Dose to Nurses during Cardiac Interventional Radiology: An Initial Study

Although interventional radiology (IVR) is preferred over surgical procedures because it is less invasive, it results in increased radiation exposure due to long fluoroscopy times and the need for frequent imaging. Nurses engaged in cardiac IVR receive the highest lens radiation doses among medical workers, after physicians. Hence, it is important to measure the lens exposure of IVR nurses accurately. Very few studies have evaluated IVR nurse lens doses using direct dosimeters. This study was conducted using direct eye dosimeters to determine the occupational eye dose of nurses engaged in cardiac IVR, and to identify simple and accurate methods to evaluate the lens dose received by nurses. Over 6 months, in a catheterization laboratory, we measured the occupational dose to the eyes (3 mm dose equivalent) and neck (0.07 mm dose equivalent) of nurses on the right and left sides. We investigated the relationship between lens and neck doses, and found a significant correlation. Hence, it may be possible to estimate the lens dose from the neck badge dose. We also evaluated the appropriate position (left or right) of eye dosimeters for IVR nurses. Although there was little difference between the mean doses to the right and left eyes, that to the right eye was slightly higher. In addition, we investigated whether it is possible to estimate doses received by IVR nurses from patient dose parameters. There were significant correlations between the measured doses to the neck and lens, and the patient dose parameters (fluoroscopy time and air kerma), implying that these parameters could be used to estimate the lens dose. However, it may be difficult to determine the lens dose of IVR nurses accurately from neck badges or patient dose parameters because of variation in the behaviors of nurses and the procedure type. Therefore, neck doses and patient dose parameters do not correlate well with the radiation eye doses of individual IVR nurses measured by personal eye dosimeters. For IVR nurses with higher eye doses, more accurate measurement of the radiation doses is required. We recommend that a lens dosimeter be worn near the eyes to measure the lens dose to IVR nurses accurately, especially those exposed to relatively high doses.

[Efficacy of L-shaped Shielding in Interventional Radiology by Transradial Approach and Consideration of Methods for Appropriate Use]

The present study investigated how effective an L-shaped shield was, depending on its position, in reducing a doctor's exposure to radiation during catheterization to access the transradial approach (TRA). The shield's effectiveness was evaluated by measuring the air kerma where the doctor stood under four conditions: with and without the shield, and with and without the shield in conjunction with conventional protection. To enable the shield to be positioned correctly in clinical practice, an illustrated instruction decal affixable to the shield's doctor-facing surface was produced, and the effectiveness of the decal was verified by means of a crossover test in which, as subjects of the study, different nurses set up the shield with and without the decal affixed to it. In the test, in which a human body phantom was used, the C-arm set at the PA angle, and the shield positioned 10 cm from the axilla of the phantom, the shield's effectiveness at 100 cm, 130 cm, and 160 cm above the floor where the doctor stood was 55%, 77%, and 47%, respectively. The effectiveness increased when the shield was positioned closer to the axilla. A significant difference in the positioning of the shield by the subjects was observed depending on whether or not the decal was affixed ( p<0.05, Wilcoxon signed-rank test), indicating that the use of the decal improved the positioning. It was concluded that, positioned correctly, the shield could effectively reduce the doctor's exposure to radiation during TRA.

Spatial Scattering Radiation to the Radiological Technologist during Medical Mobile Radiography

Mobile radiography allows for the diagnostic imaging of patients who cannot move to the X-ray examination room. Therefore, mobile X-ray equipment is useful for patients who have difficulty with movement. However, staff are exposed to scattered radiation from the patient, and they can receive potentially harmful radiation doses during radiography. We estimated occupational exposure during mobile radiography using phantom measurements. Scattered radiation distribution during mobile radiography was investigated using a radiation survey meter. The efficacy of radiation-reducing methods for mobile radiography was also evaluated. The dose decreased as the distance from the X-ray center increased. When the distance was more than 150 cm, the dose decreased to less than 1 μSv. It is extremely important for radiological technologists (RTs) to maintain a sufficient distance from the patient to reduce radiation exposure. The spatial dose at eye-lens height increases when the bed height is high, and when the RT is short in stature and abdominal imaging is performed. Maintaining sufficient distance from the patient is also particularly effective in limiting radiation exposure of the eye lens. Our results suggest that the doses of radiation received by staff during mobile radiography are not significant when appropriate radiation protection is used. To reduce exposure, it is important to maintain a sufficient distance from the patient. Therefore, RTs should bear this is mind during mobile radiography.

Evaluation of a New Real-Time Dosimeter Sensor for Interventional Radiology Staff

In 2011, the International Commission on Radiological Protection (ICRP) recommended a significant reduction in the lens-equivalent radiation dose limit, thus from an average of 150 to 20 mSv/year over 5 years. In recent years, the occupational dose has been rising with the increased sophistication of interventional radiology (IVR); management of IVR staff radiation doses has become more important, making real-time radiation monitoring of such staff desirable. Recently, the i3 real-time occupational exposure monitoring system (based on RaySafeTM) has replaced the conventional i2 system. Here, we compared the i2 and i3 systems in terms of sensitivity (batch uniformity), tube-voltage dependency, dose linearity, dose-rate dependency, and angle dependency. The sensitivity difference (batch uniformity) was approximately 5%, and the tube-voltage dependency was <±20% between 50 and 110 kV. Dose linearity was good (R2 = 1.00); a slight dose-rate dependency (~20%) was evident at very high dose rates (250 mGy/h). The i3 dosimeter showed better performance for the lower radiation detection limit compared with the i2 system. The horizontal and vertical angle dependencies of i3 were superior to those of i2. Thus, i3 sensitivity was higher over a wider angle range compared with i2, aiding the measurement of scattered radiation. Unlike the i2 sensor, the influence of backscattered radiation (i.e., radiation from an angle of 180°) was negligible. Therefore, the i3 system may be more appropriate in areas affected by backscatter. In the future, i3 will facilitate real-time dosimetry and dose management during IVR and other applications.

Awareness of Medical Radiologic Technologists of Ionizing Radiation and Radiation Protection

Japanese people experienced the Hiroshima and Nagasaki atomic bombings, the Japan Nuclear Fuel Conversion Co. criticality accident, it was found that many human resources are needed to respond to residents' concerns about disaster exposure in the event of a radiation disaster. Medical radiologic technologists learn about radiation from the time of their training, and are engaged in routine radiographic work, examination explanations, medical exposure counseling, and radiation protection of staff. By learning about nuclear disasters and counseling, we believe they can address residents' concerns. In order to identify items needed for training, we examined the perceptions of medical radiologic technologists in the case of different specialties, modalities and radiation doses. In 2016, 5 years after the Fukushima Daiichi nuclear power plant accident, we conducted a survey of 57 medical radiologic technologists at two medical facilities with different specialties and work contents to investigate their attitudes toward radiation. 42 participants answered questions regarding sex, age group, presence of children, health effects of radiation exposure, radiation control, generation of X rays by diagnostic X ray equipment, and radiation related units. In a comparison of 38 items other than demographic data, 14 showed no significant differences and 24 showed significant differences. This study found that perceptions of radiation were different among radiology technologists at facilities with different specialties. The survey suggested the possibility of identifying needed training items and providing effective training.

Evaluation of radiation dose for inferior vena cava filter placement during pregnancy: A comparison of dosimetry and dose calculation software

Numerous medical conditions are associated with pregnancy in women, including pulmonary thromboembolism, which can be fatal. An effective treatment of this condition is the positioning of an inferior vena cava filter (IVC-F) under the guidance of X-ray imaging. However, this procedure involves the risk of high radiation exposure to pregnant women and fetuses. Moreover, there are no published reports comparing the values of fetal dose, received during IVC-F placement in pregnant women, determined using dose calculation software and actual measurements. To address this issue, we compared the fetal radiation dose and entrance surface dose (ESD) for pregnant women for gestation periods of 6 and 9 months based on software calculations and actual measurements. The ESD and fetal doses were estimated for a pregnant woman for gestation periods of 6 and 9 months during IVC-F placement. For actual measurements, one pregnant model phantom was constructed using an anthropomorphic phantom, and two custom-made different-sized abdomen phantoms were used to simulate pregnancy. The custom-made abdomen phantoms were constructed using polyurethane. For software calculations, the software utilized a set of anatomically realistic pregnant patient phantoms. The ESD estimated using the software was consistent with the measured ESD, but the fetal dose estimations were more complicated due to fetal positioning. During fetal dose evaluation using software calculations, the user must carefully consider how much of the fetal length is in the irradiation field to prevent underestimation or overestimation. Despite the errors, the software can assist the user in identifying the magnitude of the dose approaching critical limits.

LENS EQUIVALENT DOSE OF STAFF DURING ENDOSCOPIC RETROGRADE CHOLANGIOPANCREATOGRAPHY: DOSE COMPARISON USING TWO TYPES OF DOSEMETERS

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.

Development of a New Radiation Shield for the Face and Neck of IVR Physicians

Interventional radiology (IVR) procedures are associated with increased radiation exposure and injury risk. Furthermore, radiation eye injury (i.e., cataract) in IVR staff have also been reported. It is crucial to protect the eyes of IVR physicians from X-ray radiation exposure. Many IVR physicians use protective Pb eyeglasses to reduce occupational eye exposure. However, the shielding effects of Pb eyeglasses are inadequate. We developed a novel shield for the face (including eyes) of IVR physicians. The novel shield consists of a neck and face guard (0.25 mm Pb-equivalent rubber sheet, nonlead protective sheet). The face shield is positioned on the left side of the IVR physician. We assessed the shielding effects of the novel shield using a phantom in the IVR X-ray system; a radiophotoluminescence dosimeter was used to measure the radiation exposure. In this phantom study, the effectiveness of the novel device for protecting against radiation was greater than 80% in almost all measurement situations, including in terms of eye lens exposure. A large amount of scattered radiation reaches the left side of IVR physicians. The novel radiation shield effectively protects the left side of the physician from this scattered radiation. Thus, the device can be used to protect the face and eyes of IVR physicians from occupational radiation exposure. The novel device will be useful for protecting the face (including eyes) of IVR physicians from radiation, and thus could reduce the rate of radiation injury. Based on the positive results of this phantom study, we plan to perform a clinical experiment to further test the utility of this novel radiation shield for IVR physicians.

What are useful methods to reduce occupational radiation exposure among radiological medical workers, especially for interventional radiology personnel?

Protection against occupational radiation exposure in clinical settings is important. This paper clarifies the present status of medical occupational exposure protection and possible additional safety measures. Radiation injuries, such as cataracts, have been reported in physicians and staff who perform interventional radiology (IVR), thus, it is important that they use shielding devices (e.g., lead glasses and ceiling-suspended shields). Currently, there is no single perfect radiation shield; combinations of radiation shields are required. Radiological medical workers must be appropriately educated in terms of reducing radiation exposure among both patients and staff. They also need to be aware of the various methods available for estimating/reducing patient dose and occupational exposure. When the optimizing the dose to the patient, such as eliminating a patient dose that is higher than necessary, is applied, exposure of radiological medical workers also decreases without any loss of diagnostic benefit. Thus, decreasing the patient dose also reduces occupational exposure. We propose a novel four-point policy for protecting medical staff from radiation: patient dose Optimization, Distance, Shielding, and Time (pdO-DST). Patient dose optimization means that the patient never receives a higher dose than is necessary, which also reduces the dose received by the staff. The patient dose must be optimized: shielding is critical, but it is only one component of protection from radiation used in medical procedures. Here, we review the radiation protection/reduction basics for radiological medical workers, especially for IVR staff.

Radiation Eye Dose for Physicians in CT Fluoroscopy-Guided Biopsy

It is important to evaluate the radiation eye dose (3 mm dose equivalent, Hp (3)) received by physicians during computed tomography fluoroscopy (CTF)-guided biopsy, as physicians are close to the source of scattered radiation. In this study, we measured the radiation eye dose in Hp (3) received by one physician during CTF in a timeframe of 18 months using a direct eye dosimeter, the DOSIRIS^TM. The physician placed eye dosimeters above and under their lead (Pb) eyeglasses. We recorded the occupational radiation dose received using a neck dosimeter, gathered CT dose-related parameters (e.g., CT-fluoroscopic acquisition number, CT-fluoroscopic time, and CT-fluoroscopic mAs), and performed a total of 95 procedures during CTF-guided biopsies. We also estimated the eye dose (Hp (3)) received using neck personal dosimeters and CT dose-related parameters. The physician eye doses (right and left side) received in terms of Hp (3) without the use of Pb eyeglasses for 18 months were 2.25 and 2.06 mSv, respectively. The protective effect of the Pb eyeglasses (0.5 mm Pb) on the right and left sides during CTF procedures was 27.8 and 37.5%, respectively. This study proved the existence of significant correlations between the eye and neck dose measurement (right and left sides, R² = 0.82 and R² = 0.55, respectively) in physicians. In addition, we found significant correlations between CT-related parameters, such as CT-fluoroscopy mAs, and radiation eye doses (right and left sides, R² = 0.50 and R² = 0.52, respectively). The eye dose of Hp (3) received in CTF was underestimated when evaluated using neck dosimeters. Therefore, we suggest that the physician involved in CTF use a direct eye dosimeter such as the DOSIRIS for the accurate evaluation of their eye lens dose.

Analysis of whole-blood antioxidant capacity after chronic and localized irradiation using the i-STrap method

Ionizing radiation exposure affects the redox state in vivo. Recently, whole-blood antioxidant capacity (WBAC) has been reported to decrease in a dose-dependent manner after acute total body irradiation (TBI). However, changes in WBAC after localized and chronic irradiations have not been reported. This study analyzed changes to WBAC in mice after either localized irradiation (irradiation of the left hind leg only) or chronic TBI using the i-STrap method. Leg-localized irradiation exerted limited effects on WBAC, while WBAC decreased in a dose rate-dependent manner after TBI. Further, the WBAC reached the minimum value in a shorter period at a smaller dose rate. Our results suggest that changes in WBAC do not directly reflect absorbed dose, but may reflect radiation-induced biological damage at the systemic level. This study will contribute to the understanding of radiation-induced injuries and diseases, and will facilitate the establishment of biomarkers for radiation exposure.

Non-Lead Protective Aprons for the Protection of Interventional Radiology Physicians from Radiation Exposure in Clinical Settings: An Initial Study

Radiation protection/evaluation during interventional radiology (IVR) poses a very important problem. Although IVR physicians should wear protective aprons, the IVR physician may not tolerate wearing one for long procedures because protective aprons are generally heavy. In fact, orthopedic problems are increasingly reported in IVR physicians due to the strain of wearing heavy protective aprons during IVR. In recent years, non-Pb protective aprons (lighter weight, composite materials) have been developed. Although non-Pb protective aprons are more expensive than Pb protective aprons, the former aprons weigh less. However, whether the protective performance of non-Pb aprons is sufficient in the IVR clinical setting is unclear. This study compared the ability of non-Pb and Pb protective aprons (0.25- and 0.35-mm Pb-equivalents) to protect physicians from scatter radiation in a clinical setting (IVR, cardiac catheterizations, including percutaneous coronary intervention) using an electric personal dosimeter (EPD). For radiation measurements, physicians wore EPDs: One inside a personal protective apron at the chest, and one outside a personal protective apron at the chest. Physician comfort levels in each apron during procedures were also evaluated. As a result, performance (both the shielding effect (98.5%) and comfort (good)) of the non-Pb 0.35-mm-Pb-equivalent protective apron was good in the clinical setting. The radiation-shielding effects of the non-Pb 0.35-mm and Pb 0.35-mm-Pb-equivalent protective aprons were very similar. Therefore, non-Pb 0.35-mm Pb-equivalent protective aprons may be more suitable for providing radiation protection for IVR physicians because the shielding effect and comfort are both good in the clinical IVR setting. As non-Pb protective aprons are nontoxic and weigh less than Pb protective aprons, non-Pb protective aprons will be the preferred type for radiation protection of IVR staff, especially physicians.

Evaluation of Radiation Protection Methods for Assistant Staff during CT Imaging in High-energy Trauma: Lens Dosimetry with a Phantom Study

Staff are exposed to radiation in the scanning room when assisting with CT scans of patients requiring ventilatory support during procedures. We measured lens doses using a phantom during a high-energy trauma protocol. Dosimetry showed that the unprotected lens received 2.02 mGy on the right and 1.91 mGy on the left, which are not negligible doses. Respective exposures to the right and left lens were 53.6% and 55.1% when wearing 0.07 mm Pb protective glasses with side covers; 53.7% and 64.2% when wearing 0.7 mm Pb glasses without side covers when facing away from the patient couch; and 92.1% and 91.2% using protective shielding in the gantry. Since the face direction may change during assistance with CT imaging, it is desirable that the protective glasses have a shape with a side cover. The protective shielding had a major radiation reduction effect, although it is expensive to acquire, install, and maintain.

Evaluation of novel X-ray protective eyewear in reducing the eye dose to interventional radiology physicians

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.

Occupational Radiation Dose to Eye Lenses in CT-Guided Interventions Using MDCT-Fluoroscopy

In computed tomography (CT)-guided interventions (CTIs), physicians are close to a source of scattered radiation. The physician and staff are at high risk of radiation-induced injury (cataracts). Thus, dose-reducing measures for physicians are important. However, few previous reports have examined radiation doses to physicians in CTIs. This study evaluated the radiation dose to the physician and medical staff using multi detector (MD)CT-fluoroscopy, and attempted to understand radiation-protection and -reduction methods. The procedures were performed using an interventional radiology (IVR)-CT system. We measured the occupational radiation dose (physician and nurse) using a personal dosimeter in real-time, gathered CT-related parameters (fluoroscopy time, mAs, CT dose index (CTDI), and dose length product (DLP)), and performed consecutive 232 procedures in CT-guided biopsy. Physician doses (eye lens, neck, and hand; μSv, average ± SD) in our CTIs were 39.1 ± 36.3, 23.1 ± 23.7, and 28.6 ± 31.0, respectively. Nurse doses (neck and chest) were lower (2.3 ± 5.0 and 2.4 ± 4.4, respectively) than the physician doses. There were significant correlations between the physician doses (eye and neck) and related factors, such as CT-fluoroscopy mAs (eye dose: r = 0.90 and neck dose: r = 0.83). We need to understand the importance of reducing/optimizing the dose to the physician and medical staff in CTIs. Our study suggests that physician and staff doses were not significant when the procedures were performed with the appropriate radiation protection and low-dose techniques.

Fetal radiation dose of four tube voltages in abdominal CT examinations during pregnancy: A phantom study

This study aimed to compare the dose and noise level of four tube voltages in abdominal computerized tomography (CT) examinations in different abdominal circumference sizes of pregnant women. Fetal radiation doses were measured with two anthropomorphic pregnant phantoms and real-time dosimeters of photoluminescence sensors using four tube voltages for abdominal CT. The noise level was measured at the abdomen of two anthropomorphic pregnant phantoms. In the large pregnant phantom, the mean fetal doses performed using 120 and 135 kV were statistically significantly lower than the lower tube voltages (P < 0.05). In the small pregnant phantom, the mean fetal dose performed by 100, 120, and 135 kV was significantly lower than the lowest tube voltage tested (P < 0.05). The ratios of the peripheral mean dose to the centric mean dose showed that the ratios of 80 kV were the highest and those for 135 kV were the lowest in both pregnant phantoms. The ratios of the peripheral mean dose to the centric mean dose decreased as the tube voltage increased. Compared with low tube voltages, high tube voltages such as 120 and 135 kV could reduce radiation doses to the fetus without compromising the image uniformity in abdominal CT examinations during pregnancy. On low tube voltage protocols, the dose near the maternal skin surface may be increased in large pregnant women because of reduced penetration of the x rays.

Evaluation of peak skin dose during percutaneous coronary intervention procedures: relationship with fluoroscopic pulse rate and target vessel

This study aimed to evaluate the relationship between the peak skin dose (PSD) associated with radiation skin injury and the fluoroscopic pulse rate or target vessel during percutaneous coronary intervention (PCI) procedures. We consecutively included 213 patients who underwent PCI procedures. The fluoroscopic time (FT), total number of cine frames, reference air kerma (RAK), and PSD were compared between the two types of fluoroscopic pulse rates (10 and 7.5 pulses/s) and among target vessels. The total number of X-ray tube angulations for each target vessel was also investigated. The median FT was 21.5 min in the 10 pulses/s group and 19.4 min in the 7.5 pulses/s group (p = 0.068, Wilcoxon rank sum test). The median PSD in the 10 pulses/s group was 749 mGy, which was significantly higher than that in the 7.5 pulses/s group (549 mGy) (p < 0.001). The median RAK in the right coronary artery (RCA) was equivalent to that in the left anterior descending artery. However, among the target vessels, the median PSD tended to be the highest in the RCA. There was a difference in the X-ray tube angulation used depending on the target vessel. PCI in the RCA used the left anterior oblique angle more frequently than PCI in the other vessels and tended to use only one angulation. The calculated PSD was related to the target vessel of the PCI procedure, and it was also closely related to the X-ray tube angulation.

Feasibility of dosimetric measurements using Al2O3:C OSL dosimeter during fluoroscopy-guided procedures

This study investigated the feasibility of dosimetric measurements using Al2O3:C optically stimulated luminescence (OSL) dosimeters during fluoroscopy-guided procedures. The linearity and energy dependence of Al2O3:C OSL dosimeters were evaluated, and the air kerma rate at the operator's position was measured. The response of Al2O3:C OSL dosimeters to short, repetitive irradiations was compared to that of long uninterrupted irradiation. The change in response of the Al2O3:C OSL dosimeter under automatic exposure rate control (AERC) was evaluated with the use of various thicknesses of polymethyl-methacrylate (PMMA) plates (15-30 cm). The Al2O3:C OSL dosimeters could detect 5µGy and showed good linearity in doses of ≥10µGy (R²: 0.997-0.999,p< 0.001). The relative response of the Al2O3:C OSL dosimeter normalised to that of 36.8 keV was 0.828-1.101 at the energies investigated (30.6-46.0 keV). The air kerma rate at the operator's position was estimated to be 2.61-7.17µGy min^-1depending on the heights representing different body parts. Repetitive short irradiations had no significant impact on the relative response of the Al2O3:C OSL dosimeters (p> 0.05). Despite a high energy dependence on the low energy beam used in fluoroscopy, the change in relative response of the Al2O3:C OSL dosimeter under AERC was within 5.7% depending on the thickness of the PMMA plates. Dosimetric measurement using Al2O3:C OSL dosimeters for patients and operators is feasible. However, one should be cautious about high standard deviations when measuring small doses of ≤20µGy using Al2O3:C OSL dosimeters. It is essential to perform intensive bleaching before measuring very small doses to minimise pre-irradiation counts.

Hybrid Operating Room System for the Treatment of Thoracic and Abdominal Aortic Aneurysms: Evaluation of the Radiation Dose Received by Patients

In recent years, endovascular treatment of aortic aneurysms has attracted considerable attention as a promising alternative to traditional surgery. Hybrid operating room systems (HORSs) are increasingly being used to perform endovascular procedures. The clinical benefits of endovascular treatments using HORSs are very clear, and these procedures are increasing in number. In procedures such as thoracic endovascular aortic repair (TEVAR) and endovascular aortic repair (EVAR), wires and catheters are used to deliver and deploy the stent graft in the thoracic/abdominal aorta under fluoroscopic control, including DSA. Thus, the radiation dose to the patient is an important issue. We determined radiation dose indicators (the dose–area product (DAP) and air karma (AK) parameters) associated with endovascular treatments (EVAR and TEVAR) using a HORS. As a result, the mean ± standard deviation (SD) DAPs of TEVAR and EVAR were 323.7 ± 161.0 and 371.3 ± 186.0 Gy × cm², respectively. The mean ± SD AKs of TEVAR and EVAR were 0.92 ± 0.44 and 1.11 ± 0.54 Gy, respectively. The mean ± SD fluoroscopy times of TEVAR and EVAR were 13.4 ± 7.1 and 23.2 ± 11.7 min, respectively. Patient radiation dose results in this study of endovascular treatments using HORSs showed no deterministic radiation effects, such as skin injuries. However, radiation exposure during TEVAR and EVAR cannot be ignored. The radiation dose should be evaluated in HORSs during endovascular treatments. Reducing/optimizing the radiation dose to the patient in HORSs is important.

Reducing the Breast Cancer Risk and Radiation Dose of Radiography for Scoliosis in Children: A Phantom Study

Full-spinal radiographs (FRs) are often the first choice of imaging modality in the investigation of scoliosis. However, FRs are strongly related to breast cancer occurrence due to multiple large-field radiographic examinations taken during childhood and adolescence, which may increase the risk for breast cancer in adulthood among women with scoliosis. The purpose of this study was to consider various technical parameters to reduce the patient radiation dose of FRs for scoliosis. To evaluate breast surface doses (BSDs) in FRs, radio photoluminescence dosimeters were placed in contact with a child phantom. Using the PC-based Monte Carlo (PMC) program for calculating patient doses in medical X-ray examinations, the breast organ dose (BOD) and the effective dose were calculated by performing Monte Carlo simulations using mathematical phantom models. The BSDs in the posteroanterior (PA) view were 0.15-0.34-fold those in the anteroposterior (AP) view. The effective dose in the PA view was 0.4-0.61-fold that in the AP view. BSD measurements were almost equivalent to the BODs obtained using PMC at all exposure settings. During FRs, the PA view without an anti-scatter grid significantly reduced the breast dose compared to the AP view with an anti-scatter grid.

Radiation eye dose to medical staff during respiratory endoscopy under X-ray fluoroscopy

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.

An initial investigation of a wireless patient radiation dosimeter for use in interventional radiology

Radiation exposure during interventional radiology (IR) procedures is a critical issue. We have developed a wireless real-time dosimeter for IR patients that use nontoxic phosphor (four sensors). We evaluated the basic performance parameters (such as dose linearity, batch uniformity, reproducibility, and wireless-communication conditions) of the developed system using an IR X-ray system. Further, we investigated the influence of noise from other medical equipment on our wireless real-time dosimeter in the IR X-ray room. Overall, our wireless system exhibited excellent performance in terms of uniformity, reproducibility, and linearity; moreover, the wireless communication performance was better. The developed system enabled real-time visualization of patient radiation dose, without noise contamination from other medical equipment. In addition, the wireless system can be easily installed in a location where the PC screen (display) can be readily viewed by the IR physician. Hence, we developed a wireless system that can display the patient radiation dose data in real time; the system performed satisfactorily upon application in radiation dosimetry. Therefore, our wireless system will facilitate the real-time monitoring/management of patient radiation dose during IR.

OCCUPATIONAL RADIATION EXPOSURE DOSE OF THE EYE IN DEPARTMENT OF CARDIAC ARRHYTHMIA PHYSICIAN

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.

Incidence of Chronic Radiodermatitis after Fluoroscopically Guided Interventions: A Retrospective Study

PURPOSE

To assess the incidence and risk factors for chronic radiodermatitis after fluoroscopically guided interventions (FGIs) in high-risk patients.

MATERIALS AND METHODS

Between 2010 and 2016, of 55,782 patients who underwent FGIs, 359 had a risk procedure for skin injury (maximal skin dose > 3 Gy, air kerma > 5 Gy, dose area product [DAP] > 500 Gy.cm², or fluoroscopy time > 60 minutes). Ninety-one of these patients were examined by a dermatologist for radiodermatitis (median time after procedure, 31.2 months [95% confidence interval, 14.2-50.7]). In each case, the clinical features and topography of the skin lesions were recorded and their incidence calculated. The characteristics of the patients and of the FGIs were tested as risk factors.

RESULTS

Eight patients (8.8%) had chronic radiodermatitis; 19 (20.9%) had acute radiodermatitis. Body mass index, DAP value, and air kerma were the only risk factors identified.

CONCLUSIONS

This study shows that chronic radiodermatitis may be considered a frequent side effect in an at-risk population. The lesions are commonly benign, but extensive sclerosis can occur. Patients should be better informed about the side effects and offered a skin exam periodically.

Pilot clinical study of ascorbic acid treatment in cardiac catheterization

Clinical radiodiagnosis and radiotherapy sometimes induce tissue damage and/or increase the risk of cancer in patients. However, in radiodiagnosis, a reduction in the exposure dose causes a blockier image that is not acceptable for diagnosis. Approximately 70% of DNA damage is induced via reactive oxygen species and/or radicals created during X-ray irradiation. Therefore, treatment with anti-oxidants and/or radical scavengers is considered to be effective in achieving a good balance between image quality and damage. However, few studies have examined the effect of using radical scavengers to reduce radiation damage in the clinical setting. In this study, we administrated 20 mg/kg ascorbic acid (AA) to patients before cardiac catheterization (CC) for diagnostic purposes. We analyzed changes in the number of phosphorylated H2AX (γH2AX) foci (a marker of DNA double-strand breaks) in lymphocytes, red blood cell glutathione levels, blood cell counts, and biochemical parameters. Unfortunately, we did not find satisfactory evidence to show that AA treatment reduces γH2AX foci formation immediately after CC. AA treatment did, however, cause a higher reduced/oxidized glutathione ratio than in the control arm immediately after CC. This is a preliminary study, but this result suggests that reducing radiation damage in clinical practice can be achieved using a biological approach.

Personal Protective Equipment Availability and Utilization Among Interventionalists

OBJECTIVE

This study explored personal protective equipment (PPE) availability and PPE utilization among interventionalists in the catheterization laboratory, which is a highly contextualized workplace.

METHODS

This is a cross-sectional study using mixed methods. Participants (108) completed a survey. A hyperlink was sent to the participants, or they were asked to complete a paper-based survey. Purposively selected participants (54) were selected for individual (30) or group (six) interviews. The interviews were conducted at conferences, or appointments were made to see the participants. Logistic regression analysis was performed. The qualitative data were analyzed thematically.

RESULTS

Lead glasses were consistently used 10.2% and never used 61.1% of the time. All forms of PPE were inconsistently used by 92.6% of participants. Women were 4.3 times more likely to report that PPE was not available. PPE compliance was related to fit and availability.

CONCLUSIONS

PPE use was inconsistent and not always available. Improving the culture of radiation protection in catheterization laboratories is essential to improve PPE compliance with the aim of protecting patients and operators. This culture of radiation protection must include all those involved including the users of PPE and the administrators and managers who are responsible for supplying sufficient, appropriate, fitting PPE for all workers requiring such protection.

New real-time patient radiation dosimeter for use in radiofrequency catheter ablation

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 effectiveness of additional lead-shielding drape and low pulse rate fluoroscopy in protecting staff from scatter radiation during cardiac resynchronization therapy (CRT)

PURPOSE

Cardiac resynchronization therapy (CRT) often requires a long fluoroscopic time and protection from scatter radiation. This study reports on scatter radiation levels during CRT, with and without additional shielding, and using standard or low pulse rate fluoroscopy.

MATERIALS AND METHODS

Additional lead-shielding drape (0.35-mm lead equivalent) was used on the left side of the table and pulsed fluoroscopy was performed at rates of 10 pulses/s (usual rate) and 7.5 pulses/s (low pulse rate). Fluoroscopy scatter radiation was measured for both pulse rates using an acrylic phantom with a radiation survey meter, both with and without the additional lead-shielding drape.

RESULTS

With the additional lead-shielding drape, the fluoroscopy scatter radiation was reduced by 74.3% at 10 pulses/s and 78.6% at 7.5 pulses/s. If the fluoroscopy was changed from 10 pulses/s to 7.5 pulses/s, the scattered radiation at the primary physician's position was reduced by 24.0%. The combined use of additional shielding drape and low pulse rate fluoroscopy reduced scatter radiation by over 80%.

CONCLUSION

Additional lead-shielding drape and low pulse rate fluoroscopy are effective in reducing the scattered radiation dose to physicians and nurses during CRT.

Effectiveness of additional lead shielding to protect staff from scattering radiation during endoscopic retrograde cholangiopancreatography procedures

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.

Effectiveness of a New Lead-Shielding Device and Additional Filter for Reducing Staff and Patient Radiation Exposure During Videofluoroscopic Swallowing Study Using a Human Phantom

Interventional radiology procedures often involve lengthy exposure to fluoroscopy-derived radiation. We therefore devised a videofluoroscopic swallowing study (VFSS) procedure using a human phantom that proved to protect the patient and physician by reducing the radiation dose. We evaluated a new lead-shielding device and separately attached additional filters (1.0-, 2.0-, and 3.0-mm Al filters and a 0.5-mm Cu filter) during VFSS to reduce the patient's entrance skin dose (ESD). A monitor attached to the human phantom's neck measured the ESD. We also developed another lead shield (VFSS Shielding Box, 1.0-mm Pb equivalent) and tested its efficacy using the human phantom and an ionization chamber radiation survey meter with and without protection from scattered radiation at the physician's position on the phantom. We then measured the scattered radiation (at 90 and 150 cm above the floor) after combining the filters with the VFSS Shielding Box. With the additional filters, the ESD was reduced by 15.4-55.1%. With the VFSS Shielding Box alone, the scattered radiation was reduced by about 10% compared with the dose without additional shielding. With the VFSS Shielding Box and filters combined, the scattered radiation dose was reduced by a maximum of about 44% at the physician's position. Thus, the additional lead-shielding device effectively provided protection from scattered radiation during fluoroscopy. These results indicate that the combined VFSS Shielding Box and filters can effectively reduce the physician's and patient's radiation doses.

Occupational eye dose in interventional cardiology procedures

It is important to measure the radiation dose [3-mm dose equivalent, Hp(3)] in the eye. This study was to determine the current occupational radiation eye dose of staff conducting interventional cardiology procedures, using a novel direct eye dosimeter. We measured the occupational eye dose [Hp(3)] in physicians and nurses in a catheterization laboratory for 6-months. The eye doses [Hp(3)] of 12 physicians (9 with Pb glasses, 3 without), and 11 nurses were recorded using a novel direct eye dosimeter, the DOSIRISTM. We placed dosimeters above and under the glasses. We also estimated the eye dose [0.07-mm dose equivalent] using a neck personal dosimeter. The eye doses among interventional staff ranked in the following order: physicians without Pb glasses > physicians with Pb glasses > nurses. The shielding effect of the glasses (0.07-mm Pb) in a clinical setting was approximately 60%. In physicians who do not wear Pb glasses, the eye dose may exceed the new regulatory limit for IR staff. We found good correlations between the neck dosimeter dose and eye dosimeter dose (inside or outside glasses, R2 = 0.93 and R2 = 0.86, respectively) in physicians. We recommend that interventional physicians use an eye dosimeter for correct evaluation of the lens dose.

Management of fluoroscopy-induced radiation ulcer: One-stage radical excision and immediate reconstruction

With increasing use of cardiac fluoroscopic intervention, the incidence of fluoroscopy-induced radiation ulcer is increasing. Radiation ulcer is difficult to manage and currently there are no treatment guidelines. To identify the optimal treatment approaches for managing cardiac fluoroscopy-induced radiation ulcers, we retrospectively reviewed medical records of 13 patients with fluoroscopy-induced radiation ulcers receiving surgical interventions and following up in our hospital from 2012 to 2015. Conventional wound care and hyperbaric oxygen therapy were of little therapeutic benefit. Twelve patients received reconstruction with advancement flap or split thick skin graft. One-stage radical excision of radiation damaged area in eight cases with immediate reconstruction led to better outcomes than conservative excisions in four cases. Radical surgical excision to remove all the radiation damaged tissues in combination with immediate reconstruction appears to offer the optimal treatment results for cardiac fluoroscopy-induced radiation ulcers. Adequate excision of the damaged areas in both vertical (to the muscular fascia) and horizontal (beyond the sclerotic areas) dimension is pivotal to achieve good treatment outcomes.

Direct measurement of a patient's entrance skin dose during pediatric cardiac catheterization

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.