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Article

J Vet Clin 2024; 41(3): 157-164

https://doi.org/10.17555/jvc.2024.41.3.157

Published online June 30, 2024

Evaluation of a Curtain-Type Radiation Protection Device for Veterinary Interventional Procedures

Minsik Choi1 , Jaepung Han1 , Changgyu Lim1 , Jiwoon Park1 , Sojin Kim1 , Uhjin Kim1 , Jinhwa Chang2 , Dongwoo Chang1 , Namsoon Lee1,*

1Section of Veterinary Medical Imaging, College of Veterinary Medicine, Chungbuk National University, Cheongju, 28644, Korea
2Korea animal medical center, Cheongju, 28651, Korea

Correspondence to:*ultravet@cbnu.ac.kr

Received: May 20, 2024; Revised: June 12, 2024; Accepted: June 12, 2024

Copyright © The Korean Society of Veterinary Clinics.

The standard radiation protection method in the angiography suite involves the use of a thyroid shield, a lead apron, and lead glasses. However, exposure to substantial amounts of ionizing radiation can cause cataracts, tumors, and skin erythema. A newly developed curtain-type radiation protection device consists of a curtain drape composed of a five-layer bismuth and lead acrylic head-shielding plate, with both bearing an equivalent 0.25 mm lead thickness. In this study, a quality assurance phantom was used as the patient to create radiation scatter from the radiographic source, and an anthropomorphic mannequin phantom was used as the interventionalist to measure the radiation dose at seven different anatomical locations. Thermoluminescent dosimeters were used to measure the radiation dose. The experimental groups consisted of all-sided or one-sided curtain set-ups, the presence or absence of a conventional shielding system, and the orientation of beam irradiation. Consequently, the curtain-type radiation protection device exhibited better radiation protection range and capabilities than conventional radiation protection systems, especially in safeguarding the forehead, eyes, arms, and feet, with minimal radiation exposure. Moreover, the mean shielding ratios of the conventional shielding system and curtain-type radiation protection device were measured at 51.94% and 93.86%, respectively. Additionally, no significant decrease in the radiation protection range or capability was observed, even with changes in the beam orientation or one-sided protection. Compared with a conventional shielding system, the curtain-type radiation protection device decreased radiation exposure doses and improved comfort. Therefore, it is a potential new radiation protection device for veterinary interventional procedures.

Keywords: curtain-type radiation protection, head-shielding plate, interventional radiology, radiation safety, weightless radiation shield

Exposure to radiation in interventionalists using ionizing radiation has long been an active area of concern (11). Although occupational dose limits have been established by the International Council on Radiation Protection, the “as low as reasonably achievable” principle recommends practitioners at high occupational risk for increased radiation exposure to judiciously use radiation (6,10,13).

Growth in the utilization and complexity of fluoroscopic procedures has increased the workload of interventionalists, resulting in cumulative radiation doses. Moreover, the weight from the lead apron commonly leads to musculoskeletal disorders (1,9,16). The International Commission on Radiological Protection stated that “particular attention should be paid to radiation effects in the lens of the eye and on the cardiovascular system, because of recent published observations of radiation effects occurring at much lower doses than reported previously” (7,8,15).

The standard radiation protection method in the angiography suite involves the use of a thyroid shield, lead apron, and lead glasses. However, despite the additional use of table skirts and ceiling-suspended shields, the operator is typically exposed to substantial ionizing radiation (5). In addition, traditional lead glasses may provide only meager protection to the lens, which is a radiation-sensitive structure in the human body (3). Moreover, conventional radiation protection does not provide radiation protection to the head of the operator; therefore, the brain may be exposed to higher radiation doses (4,11).

In this study, we aimed to evaluate the radiation protection capability and range of a prototype veterinary curtain-type radiation protection device and to compare the shielding capability and range among combinations of curtain-type radiation protection devices and conventional shielding systems.

We hypothesized that the curtain-type radiation protection device would have a better capability and wider range of radiation shielding to the head and extremities, which are difficult to protect with the conventional shielding system. We also anticipated that it would have better shielding capabilities than the conventional radiation shielding system for all anatomical locations, even amidst variations in beam orientation or minimal one-sided protection.

Materials

An experimental setup was designed using a cylindrical acrylic water phantom (22 cm in diameter, 14 cm in thickness, and 5.5 kg in weight; Helios QA phantom k52290, GE Healthcare, WI, USA) filled with distilled water to create radiation scatter from an X-ray source. The phantom was used for a patient phantom. A mannequin phantom was used to represent an interventionalist for measuring the radiation doses at different parts of the body. An image intensifier C-arm (Oscar classic, Genoray, Seongnam, Korea) was used as the fluoroscopy equipment to generate radiation sources.

We utilized a conventional shielding system consisting of a 0.25 mm lead-equivalent lead-free apron (Rad-Ban TH BF2, Drview, Seoul, Korea), a 0.25 mm lead-equivalent thyroid shield (Rad-Ban TH, Drview, Seoul, Korea), and 0.13 mm lead-equivalent lead glasses (RG-202, Younglim M&T, Seoul, Korea).

Thermoluminescent dosimeters (TLDs) (UD-802AS, Panasonic Co., Japan) were utilized to measure the radiation exposure across the eight different set-ups. Seven TLDs were used in each setup; the TLDs were positioned on the interventionalist phantom at specific locations: the forehead, left eye, thyroid, left breast, gonad, left arm, and left foot (Fig. 1).

Figure 1.Thermoluminescent dosimeters (TLD) attachment on the interventionalist phantom. (A) TLDs are attached to seven locations of the body: forehead, chin, thyroid gland, left breast, left arm, gonad, and left foot in all groups. (B) In groups using the conventional shielding system, TLDs for the left eye, thyroid, left breast, and gonad locations are attached under the lead glasses, thyroid shield, and apron.

The interventionalist and patient phantoms were positioned with respect to the interventional table, that is, the position corresponding to the patient’s right femoral access. The patient phantom was placed in a fixed position on the interventional table in the center of the field of view of the fluoroscope. The height of the table was set to 80 cm, the distance from the X-ray tube to the image intensifier tube was set to 100 cm, and the distance from the midsection of the patient phantom to the interventionalist phantom was set to 70 cm (Fig. 2). The tube voltage was set to 70 kVp, the tube current was maintained at 3 mA, the field of view measured 9 in, and the fluoroscopy time was 1,200 s. Exposure parameters and geometrical set-up were configured to replicate the actual amount of radiation exposure encountered during interventional procedures.

Figure 2.The experimental set-up of the patient phantom, interventionalist phantom, and C-arm. (A) The interventionalist and patient phantoms are positioned with respect to the interventional table, namely the position corresponding to the patient’s right femoral access. (A, B) The distance from the X-ray tube to the image intensifier tube is set to 100 cm and that from the midsection of the patient phantom to the interventionalist phantom is set to 70 cm. (C) The experimental setup is represented by a schematic diagram.

The curtain-type radiation protection device consisted of a steel frame, side shield curtain, under-table curtains, and head-shielding plate (Fig. 3). The steel frame measured 68 cm in length, with an adjustable width and height ranging from 60 to 80 cm and from 50 to 60 cm, respectively. The curtain drapes were prepared from a five-layered bismuth cloth with a 0.25 mm lead-equivalent and were affixed to the exterior of the frame. The head-shielding plate comprised a lead acrylic material with a 0.25 mm lead-equivalent, measured 20 cm in length and 40 cm in width, and was installed to the outside of the frame. The angle was adjusted according to the convenience of interventionalist.

Figure 3.The curtain-type radiation protection device set-up. (A-C) A steel structure and radiation shielding curtain. (A) Steel frames are installed on the table. (B, C) Side and under-table curtain drapes. (B) The side curtain is attached to the outside of the frame. (C) The under-table curtains are attached to the interventional table. (D-F) The head-shielding plate comprised a lead acrylic material with a 0.25 mm lead-equivalent. (E) The angle is adjusted according to the convenience of the interventionalist. (F) The head-shielding plates are set up for the intervention procedure.

Procedures

The curtain drapes were divided into one-sided and all-sided curtain setups. The one-sided curtain set-up consisted of one side curtain, two under-table curtains, and one head-shielding plate and all-sided curtain set-up consisted of four side curtains, two under-table curtains, and two head-shielding plates.

The experimental groups were divided based on whether they utilized a one-sided or all-sided curtain set-up, the presence or absence of the conventional shielding system, and the orientation of beam irradiation. Seven experimental groups and one control group were established (Fig. 4).

Figure 4.Different radiation shielding systems and the beam orientation of C-arm for each group. CSS, conventional shielding system.

The TLDs were evaluated by a company specializing in TLD analysis (Orbitech Co., Korea). This experimental set-up aimed to evaluate and compare the absorbed radiation doses across seven anatomical body parts depending on the different shielding system groups.

We estimated the shielding ratio of each group using the radiation exposure dose values measured at each anatomical site, using the following equation (14).

Shielding ratio (%)=Dose with control group - dose with experimental groupDose with control group×100

Statistical analysis

Statistical analyses were performed using Prism software (version 9.1, CA, USA). The mean radiation exposure dose values and mean shielding ratio per group are presented as mean ± standard deviation (SD). Statistical significance was determined using the Student’s t-test and Mann–Whitney U test. The normality test was conducted using the Shapiro–Wilk test. Statistical significance was set at p < 0.05.

The radiation exposure doses absorbed by the seven anatomical body parts, depending on the different shielding system groups, are reported in Table 1. The mean radiation exposure dose measured in all anterior-posterior beam orientation groups using the curtain-type radiation protection device, regardless of whether one- or all-sided set-up, was < 0.027 mSv. Even in the lateral beam orientation group using a one-sided curtain-type radiation protection device, the mean radiation exposure dose was < 0.054 mSv. The mean exposure dose in the control group without a radiation shielding system was 0.767 mSv, which was higher than that in all experimental groups. The mean exposure dose in Group 1, with the conventional shielding system was 0.396 mSv, which was higher than that in all experimental groups using the curtain-type radiation protection device.

Table 1 Radiation exposure doses at seven anatomical body parts depending on the different shielding system group (unit: mSv)

ControlGroup 1Group 2Group 3Group 4Group 5Group 6Group 7
Forehead0.500.420.010.010.030.030.030.03
Left eye0.280.140.010.010.020.030.020.02
Thyroid0.760.060.010.010.010.020.010.02
Left breast0.830.070.010.010.010.010.010.01
Gonad0.740.050.010.010.010.010.010.01
Left arm1.191.100.040.050.040.050.100.26
Left foot1.070.930.040.030.030.040.030.03
Mean ± SD0.767 ± 0.3120.396 ± 0.4450.019 ± 0.0150.019 ± 0.0160.021 ± 0.0120.027 ± 0.0150.03 ± 0.0320.054 ± 0.091


Significant differences were observed between the control group and Groups 2 to 7 and between Group 1 and Groups 2 to 7. No significant differences were observed between the groups using the curtain-type radiation protection device or between the control group and Group 1 (Fig. 5). In other words, all curtain-type radiation protection groups, regardless of the curtain set-up or beam orientation, had lower radiation exposure doses than the group using the conventional shielding system.

Figure 5.Column box chart of mean radiation exposure dose values for all anatomical locations using different radiation shielding systems. Boxes indicate the mean, and error bars represent the standard deviation. *p ≤ 0.05; **p ≤ 0.01.

Compared with the control group, the radiation shielding ratio in all groups using the curtain-type radiation protection device was higher than 94%, 89.29%, 97.37%, 98.70%, 98.65%, 78.15%, and 96.26% for the forehead, left eye, thyroid, left breast, gonad, left arm, and left foot, respectively (Table 2). Similar to groups using curtain-type radiation protection devices, groups using conventional shielding systems also achieved high shielding ratios, measuring 92.11%, 91.57%, and 93.24% in the thyroid, left breast, and gonad, respectively.

Table 2 Shielding ratio by groups using different shielding system (unit: %)

Group 1Group 2Group 3Group 4Group 5Group 6Group 7
Forehead16989894949494
Left eye2096.4396.4392.8689.2992.8692.86
Thyroid92.1198.6898.6898.6897.3798.6897.39
Left breast91.5798.8098.7098.8098.8098.8098.80
Gonad93.2498.6598.6598.6598.6598.6598.65
Left arm7.5696.6496.6496.6495.8091.6078.15
Left foot13.0896.2697.2097.2096.2697.2097.20
Mean ± SD51.94 ± 40.1397.64 ± 1.1597.65 ± 1.2096.69 ± 2.4095.74 ± 3.3095.97 ± 3.0893.86 ± 7.29


The mean shielding ratios of the conventional shielding system and curtain-type radiation protection devices were measured at 51.94% and a minimum value of 93.86%, respectively (Table 2).

Significant differences were observed between Group 1 and Groups 2 to 7, which employed a curtain-type radiation protection device. No significant differences were observed between the groups when the curtain-type radiation protection device was used (Fig. 6).

Figure 6.Column box chart of shielding ratio for each group. Boxes indicate the shielding ratio, and error bars represent the standard deviation. *p ≤ 0.05.

Curtain-type radiation protection devices are designed to maintain the range of motion while eliminating weight from the operator’s body and reducing radiation exposure. To the best of our knowledge, many human radiation protection devices exist; however, this is the first such device to be developed in the field of veterinary interventional procedures.

In human interventional procedures, the patient’s torso is large, making it difficult to shield the scattered radiation from the patient using only the shielding system installed on the table (13). However, owing to their smaller size, a shielding system installed on the table can more effectively shield animals against scattered radiation. Therefore, in this experiment, the patient phantom similar in size to the animal was used to generate scattered radiation identical to that encountered during an interventional procedure.

In this study, the mean radiation exposure dose was lower for the curtain-type radiation protection device than that for the conventional shielding system. In particular, curtain-type radiation protection devices have a wider range and better capability for radiation protection of the forehead, eyes, and extremities, which are difficult to protect using conventional shielding systems. Similar to a previous study, the shielding ratio of both the conventional shielding system and curtain-type radiation protection device was measured high for the thyroid, breast, and gonad (9). Although a high shielding ratio was observed in the thyroid, left breast, and gonad locations, the conventional shielding system showed only 51.94% shielding ratio due to the low shielding ratio in the forehead, left eye, left arm, and left foot compared with that of the curtain-type radiation protection device, which measured at least 93.86% in this study.

Several case-control studies have demonstrated the brain’s sensitivity to developing benign and malignant tumors after diagnostic radiographs (15). In addition, publications in recent years suggest that the left side of the brain is more exposed than the right side of the brain, increasing the risk of left side brain tumors in interventionalists. Furthermore, the formation of cataracts is one of the main concerns for physicians throughout their careers, and cataracts can be found in up to 50% of interventional cardiologists (4,11). Lead glasses, which can significantly reduce the radiation dose passing from the anterior location, do not substantially shield the head. In addition, the upward direction of scattering toward the head allows radiation to pass under or from the sides of the lead glasses (5,12). Furthermore, secondary scattered radiation from the operator’s head increases ocular exposure, rendering lead glasses only partially effective (2). The head-shielding plate was designed to shield the entire head at all working positions without obstructing vision in this study. The radiation exposure dose in the left eye was measured at 0.14 mSv when only lead glasses were worn and was measured lower than 0.03 mSv in the groups using the head-shielding plate. Similar to a previous study, this phenomenon is attributable to radiation exposure from the side of the lead glasses and secondary scattered radiation from the phantom’s head (2). Additionally, the radiation exposure dose of the forehead was measured as 0.42 mSv when using the conventional shielding system, and lower than 0.03 mSv in the groups using the head-shielding plate. Therefore, we demonstrated that the head-shielding plate had better radiation protection capability not only in the eyes but also in the head area without obstruction of vision compared with lead glasses.

In an actual intervention procedure, most procedures are performed by changing the beam orientation of the fluoroscope. Therefore, in this experimental set-up, a one-sided curtain shield group that could change the beam orientation and lateral beam orientation group were set up. In the groups that used the curtain-type radiation protection device, there was no significant difference in the mean radiation exposure dose between the groups that shielded one side or changed the beam orientation and those that shielded all sides. Therefore, the groups that shielded one side and changed the beam orientation had better radiation protection ranges and capabilities than conventional shielding systems.

This study has a few limitations. Because the patient phantom was not a real dog or cat undergoing an actual intervention procedure, the scatter to the interventionalist phantom was not expected to be the same as what might be encountered in actual clinical practice. Further, as the interventionalist phantom was fixed during radiation exposure, the experimental setup might not accurately reflect all the actual intervention procedures of the interventionalist. Because this experiment was conducted only once, measurements were not based on the mean value. Therefore, more accurate results can be obtained if the number of experiments is increased.

In conclusion, compared with a conventional shielding system, the curtain-type radiation protection device decreases radiation exposure doses for an interventionalist phantom, particularly to the forehead, eyes, arms, and feet. Additionally, there was no significant decrease in the radiation protection range or capability, even with changing beam orientation or one-sided protection. Furthermore, the curtain-type radiation protection device improves comfort by eliminating the weight burden imposed by a conventional shielding system on the operator. Therefore, it is expected to be a novel radiation protection device for veterinary interventional procedures. Although a high radiation shielding ratio was measured when using only a curtain-type radiation protection device without a conventional radiation shielding system in this study, it is safer to use all available shielding devices to minimize radiation exposure in actual interventional procedures.

MSC drafted the initial manuscript of the research; MSC, JPH, and CGL acquired the data; MSC, JWP, SJK, and UJK analysed and interpreted the data; JHC, DWC, and NSL revised the article; and NSL approved the final version of the article prior to submission. All authors have read and approved the manuscript.

This work was supported by the research grant of the Chungbuk National University in 2023.

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Article

Original Article

J Vet Clin 2024; 41(3): 157-164

Published online June 30, 2024 https://doi.org/10.17555/jvc.2024.41.3.157

Copyright © The Korean Society of Veterinary Clinics.

Evaluation of a Curtain-Type Radiation Protection Device for Veterinary Interventional Procedures

Minsik Choi1 , Jaepung Han1 , Changgyu Lim1 , Jiwoon Park1 , Sojin Kim1 , Uhjin Kim1 , Jinhwa Chang2 , Dongwoo Chang1 , Namsoon Lee1,*

1Section of Veterinary Medical Imaging, College of Veterinary Medicine, Chungbuk National University, Cheongju, 28644, Korea
2Korea animal medical center, Cheongju, 28651, Korea

Correspondence to:*ultravet@cbnu.ac.kr

Received: May 20, 2024; Revised: June 12, 2024; Accepted: June 12, 2024

This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The standard radiation protection method in the angiography suite involves the use of a thyroid shield, a lead apron, and lead glasses. However, exposure to substantial amounts of ionizing radiation can cause cataracts, tumors, and skin erythema. A newly developed curtain-type radiation protection device consists of a curtain drape composed of a five-layer bismuth and lead acrylic head-shielding plate, with both bearing an equivalent 0.25 mm lead thickness. In this study, a quality assurance phantom was used as the patient to create radiation scatter from the radiographic source, and an anthropomorphic mannequin phantom was used as the interventionalist to measure the radiation dose at seven different anatomical locations. Thermoluminescent dosimeters were used to measure the radiation dose. The experimental groups consisted of all-sided or one-sided curtain set-ups, the presence or absence of a conventional shielding system, and the orientation of beam irradiation. Consequently, the curtain-type radiation protection device exhibited better radiation protection range and capabilities than conventional radiation protection systems, especially in safeguarding the forehead, eyes, arms, and feet, with minimal radiation exposure. Moreover, the mean shielding ratios of the conventional shielding system and curtain-type radiation protection device were measured at 51.94% and 93.86%, respectively. Additionally, no significant decrease in the radiation protection range or capability was observed, even with changes in the beam orientation or one-sided protection. Compared with a conventional shielding system, the curtain-type radiation protection device decreased radiation exposure doses and improved comfort. Therefore, it is a potential new radiation protection device for veterinary interventional procedures.

Keywords: curtain-type radiation protection, head-shielding plate, interventional radiology, radiation safety, weightless radiation shield

Introduction

Exposure to radiation in interventionalists using ionizing radiation has long been an active area of concern (11). Although occupational dose limits have been established by the International Council on Radiation Protection, the “as low as reasonably achievable” principle recommends practitioners at high occupational risk for increased radiation exposure to judiciously use radiation (6,10,13).

Growth in the utilization and complexity of fluoroscopic procedures has increased the workload of interventionalists, resulting in cumulative radiation doses. Moreover, the weight from the lead apron commonly leads to musculoskeletal disorders (1,9,16). The International Commission on Radiological Protection stated that “particular attention should be paid to radiation effects in the lens of the eye and on the cardiovascular system, because of recent published observations of radiation effects occurring at much lower doses than reported previously” (7,8,15).

The standard radiation protection method in the angiography suite involves the use of a thyroid shield, lead apron, and lead glasses. However, despite the additional use of table skirts and ceiling-suspended shields, the operator is typically exposed to substantial ionizing radiation (5). In addition, traditional lead glasses may provide only meager protection to the lens, which is a radiation-sensitive structure in the human body (3). Moreover, conventional radiation protection does not provide radiation protection to the head of the operator; therefore, the brain may be exposed to higher radiation doses (4,11).

In this study, we aimed to evaluate the radiation protection capability and range of a prototype veterinary curtain-type radiation protection device and to compare the shielding capability and range among combinations of curtain-type radiation protection devices and conventional shielding systems.

We hypothesized that the curtain-type radiation protection device would have a better capability and wider range of radiation shielding to the head and extremities, which are difficult to protect with the conventional shielding system. We also anticipated that it would have better shielding capabilities than the conventional radiation shielding system for all anatomical locations, even amidst variations in beam orientation or minimal one-sided protection.

Materials|Methods

Materials

An experimental setup was designed using a cylindrical acrylic water phantom (22 cm in diameter, 14 cm in thickness, and 5.5 kg in weight; Helios QA phantom k52290, GE Healthcare, WI, USA) filled with distilled water to create radiation scatter from an X-ray source. The phantom was used for a patient phantom. A mannequin phantom was used to represent an interventionalist for measuring the radiation doses at different parts of the body. An image intensifier C-arm (Oscar classic, Genoray, Seongnam, Korea) was used as the fluoroscopy equipment to generate radiation sources.

We utilized a conventional shielding system consisting of a 0.25 mm lead-equivalent lead-free apron (Rad-Ban TH BF2, Drview, Seoul, Korea), a 0.25 mm lead-equivalent thyroid shield (Rad-Ban TH, Drview, Seoul, Korea), and 0.13 mm lead-equivalent lead glasses (RG-202, Younglim M&T, Seoul, Korea).

Thermoluminescent dosimeters (TLDs) (UD-802AS, Panasonic Co., Japan) were utilized to measure the radiation exposure across the eight different set-ups. Seven TLDs were used in each setup; the TLDs were positioned on the interventionalist phantom at specific locations: the forehead, left eye, thyroid, left breast, gonad, left arm, and left foot (Fig. 1).

Figure 1. Thermoluminescent dosimeters (TLD) attachment on the interventionalist phantom. (A) TLDs are attached to seven locations of the body: forehead, chin, thyroid gland, left breast, left arm, gonad, and left foot in all groups. (B) In groups using the conventional shielding system, TLDs for the left eye, thyroid, left breast, and gonad locations are attached under the lead glasses, thyroid shield, and apron.

The interventionalist and patient phantoms were positioned with respect to the interventional table, that is, the position corresponding to the patient’s right femoral access. The patient phantom was placed in a fixed position on the interventional table in the center of the field of view of the fluoroscope. The height of the table was set to 80 cm, the distance from the X-ray tube to the image intensifier tube was set to 100 cm, and the distance from the midsection of the patient phantom to the interventionalist phantom was set to 70 cm (Fig. 2). The tube voltage was set to 70 kVp, the tube current was maintained at 3 mA, the field of view measured 9 in, and the fluoroscopy time was 1,200 s. Exposure parameters and geometrical set-up were configured to replicate the actual amount of radiation exposure encountered during interventional procedures.

Figure 2. The experimental set-up of the patient phantom, interventionalist phantom, and C-arm. (A) The interventionalist and patient phantoms are positioned with respect to the interventional table, namely the position corresponding to the patient’s right femoral access. (A, B) The distance from the X-ray tube to the image intensifier tube is set to 100 cm and that from the midsection of the patient phantom to the interventionalist phantom is set to 70 cm. (C) The experimental setup is represented by a schematic diagram.

The curtain-type radiation protection device consisted of a steel frame, side shield curtain, under-table curtains, and head-shielding plate (Fig. 3). The steel frame measured 68 cm in length, with an adjustable width and height ranging from 60 to 80 cm and from 50 to 60 cm, respectively. The curtain drapes were prepared from a five-layered bismuth cloth with a 0.25 mm lead-equivalent and were affixed to the exterior of the frame. The head-shielding plate comprised a lead acrylic material with a 0.25 mm lead-equivalent, measured 20 cm in length and 40 cm in width, and was installed to the outside of the frame. The angle was adjusted according to the convenience of interventionalist.

Figure 3. The curtain-type radiation protection device set-up. (A-C) A steel structure and radiation shielding curtain. (A) Steel frames are installed on the table. (B, C) Side and under-table curtain drapes. (B) The side curtain is attached to the outside of the frame. (C) The under-table curtains are attached to the interventional table. (D-F) The head-shielding plate comprised a lead acrylic material with a 0.25 mm lead-equivalent. (E) The angle is adjusted according to the convenience of the interventionalist. (F) The head-shielding plates are set up for the intervention procedure.

Procedures

The curtain drapes were divided into one-sided and all-sided curtain setups. The one-sided curtain set-up consisted of one side curtain, two under-table curtains, and one head-shielding plate and all-sided curtain set-up consisted of four side curtains, two under-table curtains, and two head-shielding plates.

The experimental groups were divided based on whether they utilized a one-sided or all-sided curtain set-up, the presence or absence of the conventional shielding system, and the orientation of beam irradiation. Seven experimental groups and one control group were established (Fig. 4).

Figure 4. Different radiation shielding systems and the beam orientation of C-arm for each group. CSS, conventional shielding system.

The TLDs were evaluated by a company specializing in TLD analysis (Orbitech Co., Korea). This experimental set-up aimed to evaluate and compare the absorbed radiation doses across seven anatomical body parts depending on the different shielding system groups.

We estimated the shielding ratio of each group using the radiation exposure dose values measured at each anatomical site, using the following equation (14).

Shielding ratio (%)=Dose with control group - dose with experimental groupDose with control group×100

Statistical analysis

Statistical analyses were performed using Prism software (version 9.1, CA, USA). The mean radiation exposure dose values and mean shielding ratio per group are presented as mean ± standard deviation (SD). Statistical significance was determined using the Student’s t-test and Mann–Whitney U test. The normality test was conducted using the Shapiro–Wilk test. Statistical significance was set at p < 0.05.

Results

The radiation exposure doses absorbed by the seven anatomical body parts, depending on the different shielding system groups, are reported in Table 1. The mean radiation exposure dose measured in all anterior-posterior beam orientation groups using the curtain-type radiation protection device, regardless of whether one- or all-sided set-up, was < 0.027 mSv. Even in the lateral beam orientation group using a one-sided curtain-type radiation protection device, the mean radiation exposure dose was < 0.054 mSv. The mean exposure dose in the control group without a radiation shielding system was 0.767 mSv, which was higher than that in all experimental groups. The mean exposure dose in Group 1, with the conventional shielding system was 0.396 mSv, which was higher than that in all experimental groups using the curtain-type radiation protection device.

Table 1 . Radiation exposure doses at seven anatomical body parts depending on the different shielding system group (unit: mSv).

ControlGroup 1Group 2Group 3Group 4Group 5Group 6Group 7
Forehead0.500.420.010.010.030.030.030.03
Left eye0.280.140.010.010.020.030.020.02
Thyroid0.760.060.010.010.010.020.010.02
Left breast0.830.070.010.010.010.010.010.01
Gonad0.740.050.010.010.010.010.010.01
Left arm1.191.100.040.050.040.050.100.26
Left foot1.070.930.040.030.030.040.030.03
Mean ± SD0.767 ± 0.3120.396 ± 0.4450.019 ± 0.0150.019 ± 0.0160.021 ± 0.0120.027 ± 0.0150.03 ± 0.0320.054 ± 0.091


Significant differences were observed between the control group and Groups 2 to 7 and between Group 1 and Groups 2 to 7. No significant differences were observed between the groups using the curtain-type radiation protection device or between the control group and Group 1 (Fig. 5). In other words, all curtain-type radiation protection groups, regardless of the curtain set-up or beam orientation, had lower radiation exposure doses than the group using the conventional shielding system.

Figure 5. Column box chart of mean radiation exposure dose values for all anatomical locations using different radiation shielding systems. Boxes indicate the mean, and error bars represent the standard deviation. *p ≤ 0.05; **p ≤ 0.01.

Compared with the control group, the radiation shielding ratio in all groups using the curtain-type radiation protection device was higher than 94%, 89.29%, 97.37%, 98.70%, 98.65%, 78.15%, and 96.26% for the forehead, left eye, thyroid, left breast, gonad, left arm, and left foot, respectively (Table 2). Similar to groups using curtain-type radiation protection devices, groups using conventional shielding systems also achieved high shielding ratios, measuring 92.11%, 91.57%, and 93.24% in the thyroid, left breast, and gonad, respectively.

Table 2 . Shielding ratio by groups using different shielding system (unit: %).

Group 1Group 2Group 3Group 4Group 5Group 6Group 7
Forehead16989894949494
Left eye2096.4396.4392.8689.2992.8692.86
Thyroid92.1198.6898.6898.6897.3798.6897.39
Left breast91.5798.8098.7098.8098.8098.8098.80
Gonad93.2498.6598.6598.6598.6598.6598.65
Left arm7.5696.6496.6496.6495.8091.6078.15
Left foot13.0896.2697.2097.2096.2697.2097.20
Mean ± SD51.94 ± 40.1397.64 ± 1.1597.65 ± 1.2096.69 ± 2.4095.74 ± 3.3095.97 ± 3.0893.86 ± 7.29


The mean shielding ratios of the conventional shielding system and curtain-type radiation protection devices were measured at 51.94% and a minimum value of 93.86%, respectively (Table 2).

Significant differences were observed between Group 1 and Groups 2 to 7, which employed a curtain-type radiation protection device. No significant differences were observed between the groups when the curtain-type radiation protection device was used (Fig. 6).

Figure 6. Column box chart of shielding ratio for each group. Boxes indicate the shielding ratio, and error bars represent the standard deviation. *p ≤ 0.05.

Discussion

Curtain-type radiation protection devices are designed to maintain the range of motion while eliminating weight from the operator’s body and reducing radiation exposure. To the best of our knowledge, many human radiation protection devices exist; however, this is the first such device to be developed in the field of veterinary interventional procedures.

In human interventional procedures, the patient’s torso is large, making it difficult to shield the scattered radiation from the patient using only the shielding system installed on the table (13). However, owing to their smaller size, a shielding system installed on the table can more effectively shield animals against scattered radiation. Therefore, in this experiment, the patient phantom similar in size to the animal was used to generate scattered radiation identical to that encountered during an interventional procedure.

In this study, the mean radiation exposure dose was lower for the curtain-type radiation protection device than that for the conventional shielding system. In particular, curtain-type radiation protection devices have a wider range and better capability for radiation protection of the forehead, eyes, and extremities, which are difficult to protect using conventional shielding systems. Similar to a previous study, the shielding ratio of both the conventional shielding system and curtain-type radiation protection device was measured high for the thyroid, breast, and gonad (9). Although a high shielding ratio was observed in the thyroid, left breast, and gonad locations, the conventional shielding system showed only 51.94% shielding ratio due to the low shielding ratio in the forehead, left eye, left arm, and left foot compared with that of the curtain-type radiation protection device, which measured at least 93.86% in this study.

Several case-control studies have demonstrated the brain’s sensitivity to developing benign and malignant tumors after diagnostic radiographs (15). In addition, publications in recent years suggest that the left side of the brain is more exposed than the right side of the brain, increasing the risk of left side brain tumors in interventionalists. Furthermore, the formation of cataracts is one of the main concerns for physicians throughout their careers, and cataracts can be found in up to 50% of interventional cardiologists (4,11). Lead glasses, which can significantly reduce the radiation dose passing from the anterior location, do not substantially shield the head. In addition, the upward direction of scattering toward the head allows radiation to pass under or from the sides of the lead glasses (5,12). Furthermore, secondary scattered radiation from the operator’s head increases ocular exposure, rendering lead glasses only partially effective (2). The head-shielding plate was designed to shield the entire head at all working positions without obstructing vision in this study. The radiation exposure dose in the left eye was measured at 0.14 mSv when only lead glasses were worn and was measured lower than 0.03 mSv in the groups using the head-shielding plate. Similar to a previous study, this phenomenon is attributable to radiation exposure from the side of the lead glasses and secondary scattered radiation from the phantom’s head (2). Additionally, the radiation exposure dose of the forehead was measured as 0.42 mSv when using the conventional shielding system, and lower than 0.03 mSv in the groups using the head-shielding plate. Therefore, we demonstrated that the head-shielding plate had better radiation protection capability not only in the eyes but also in the head area without obstruction of vision compared with lead glasses.

In an actual intervention procedure, most procedures are performed by changing the beam orientation of the fluoroscope. Therefore, in this experimental set-up, a one-sided curtain shield group that could change the beam orientation and lateral beam orientation group were set up. In the groups that used the curtain-type radiation protection device, there was no significant difference in the mean radiation exposure dose between the groups that shielded one side or changed the beam orientation and those that shielded all sides. Therefore, the groups that shielded one side and changed the beam orientation had better radiation protection ranges and capabilities than conventional shielding systems.

This study has a few limitations. Because the patient phantom was not a real dog or cat undergoing an actual intervention procedure, the scatter to the interventionalist phantom was not expected to be the same as what might be encountered in actual clinical practice. Further, as the interventionalist phantom was fixed during radiation exposure, the experimental setup might not accurately reflect all the actual intervention procedures of the interventionalist. Because this experiment was conducted only once, measurements were not based on the mean value. Therefore, more accurate results can be obtained if the number of experiments is increased.

In conclusion, compared with a conventional shielding system, the curtain-type radiation protection device decreases radiation exposure doses for an interventionalist phantom, particularly to the forehead, eyes, arms, and feet. Additionally, there was no significant decrease in the radiation protection range or capability, even with changing beam orientation or one-sided protection. Furthermore, the curtain-type radiation protection device improves comfort by eliminating the weight burden imposed by a conventional shielding system on the operator. Therefore, it is expected to be a novel radiation protection device for veterinary interventional procedures. Although a high radiation shielding ratio was measured when using only a curtain-type radiation protection device without a conventional radiation shielding system in this study, it is safer to use all available shielding devices to minimize radiation exposure in actual interventional procedures.

Authors Contributions

MSC drafted the initial manuscript of the research; MSC, JPH, and CGL acquired the data; MSC, JWP, SJK, and UJK analysed and interpreted the data; JHC, DWC, and NSL revised the article; and NSL approved the final version of the article prior to submission. All authors have read and approved the manuscript.

Source of Funding

This work was supported by the research grant of the Chungbuk National University in 2023.

Conflicts of Interest

The authors have no conflicting interests.

Fig 1.

Figure 1.Thermoluminescent dosimeters (TLD) attachment on the interventionalist phantom. (A) TLDs are attached to seven locations of the body: forehead, chin, thyroid gland, left breast, left arm, gonad, and left foot in all groups. (B) In groups using the conventional shielding system, TLDs for the left eye, thyroid, left breast, and gonad locations are attached under the lead glasses, thyroid shield, and apron.
Journal of Veterinary Clinics 2024; 41: 157-164https://doi.org/10.17555/jvc.2024.41.3.157

Fig 2.

Figure 2.The experimental set-up of the patient phantom, interventionalist phantom, and C-arm. (A) The interventionalist and patient phantoms are positioned with respect to the interventional table, namely the position corresponding to the patient’s right femoral access. (A, B) The distance from the X-ray tube to the image intensifier tube is set to 100 cm and that from the midsection of the patient phantom to the interventionalist phantom is set to 70 cm. (C) The experimental setup is represented by a schematic diagram.
Journal of Veterinary Clinics 2024; 41: 157-164https://doi.org/10.17555/jvc.2024.41.3.157

Fig 3.

Figure 3.The curtain-type radiation protection device set-up. (A-C) A steel structure and radiation shielding curtain. (A) Steel frames are installed on the table. (B, C) Side and under-table curtain drapes. (B) The side curtain is attached to the outside of the frame. (C) The under-table curtains are attached to the interventional table. (D-F) The head-shielding plate comprised a lead acrylic material with a 0.25 mm lead-equivalent. (E) The angle is adjusted according to the convenience of the interventionalist. (F) The head-shielding plates are set up for the intervention procedure.
Journal of Veterinary Clinics 2024; 41: 157-164https://doi.org/10.17555/jvc.2024.41.3.157

Fig 4.

Figure 4.Different radiation shielding systems and the beam orientation of C-arm for each group. CSS, conventional shielding system.
Journal of Veterinary Clinics 2024; 41: 157-164https://doi.org/10.17555/jvc.2024.41.3.157

Fig 5.

Figure 5.Column box chart of mean radiation exposure dose values for all anatomical locations using different radiation shielding systems. Boxes indicate the mean, and error bars represent the standard deviation. *p ≤ 0.05; **p ≤ 0.01.
Journal of Veterinary Clinics 2024; 41: 157-164https://doi.org/10.17555/jvc.2024.41.3.157

Fig 6.

Figure 6.Column box chart of shielding ratio for each group. Boxes indicate the shielding ratio, and error bars represent the standard deviation. *p ≤ 0.05.
Journal of Veterinary Clinics 2024; 41: 157-164https://doi.org/10.17555/jvc.2024.41.3.157

Table 1 Radiation exposure doses at seven anatomical body parts depending on the different shielding system group (unit: mSv)

ControlGroup 1Group 2Group 3Group 4Group 5Group 6Group 7
Forehead0.500.420.010.010.030.030.030.03
Left eye0.280.140.010.010.020.030.020.02
Thyroid0.760.060.010.010.010.020.010.02
Left breast0.830.070.010.010.010.010.010.01
Gonad0.740.050.010.010.010.010.010.01
Left arm1.191.100.040.050.040.050.100.26
Left foot1.070.930.040.030.030.040.030.03
Mean ± SD0.767 ± 0.3120.396 ± 0.4450.019 ± 0.0150.019 ± 0.0160.021 ± 0.0120.027 ± 0.0150.03 ± 0.0320.054 ± 0.091

Table 2 Shielding ratio by groups using different shielding system (unit: %)

Group 1Group 2Group 3Group 4Group 5Group 6Group 7
Forehead16989894949494
Left eye2096.4396.4392.8689.2992.8692.86
Thyroid92.1198.6898.6898.6897.3798.6897.39
Left breast91.5798.8098.7098.8098.8098.8098.80
Gonad93.2498.6598.6598.6598.6598.6598.65
Left arm7.5696.6496.6496.6495.8091.6078.15
Left foot13.0896.2697.2097.2096.2697.2097.20
Mean ± SD51.94 ± 40.1397.64 ± 1.1597.65 ± 1.2096.69 ± 2.4095.74 ± 3.3095.97 ± 3.0893.86 ± 7.29

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Vol.41 No.3 June 2024

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