Abstract
To determine the eye lens dose (3 mm dose equivalent [Hp(3)]) received by spine surgeons during myelography and evaluate the effectiveness of radiation-protective glasses and x-ray tube system positioning in reducing radiation exposure. This study included spine surgeons who performed myelography using over- or under-table x-ray tube systems. Hp(3) was measured for each examination using a radio-photoluminescence glass dosimeter (GD-352M) mounted on radiation-protective glass. This study identified significantly high Hp(3) levels, especially in the right eye lens in spinal surgeons. The median Hp(3) values in the right eye were 524 (391–719) and 58 (42–83) μSv/examination for over- and under-table x-ray tube systems, respectively. Further, Hp(3)AK, which was obtained by dividing the cumulative air kerma from Hp(3), was 8.09 (6.69–10.21) and 5.11 (4.06–6.31) μSv mGy−1 for the over- and under-table x-ray tube systems, respectively. Implementing radiation-protective glasses resulted in dose reduction rates of 54% (50%–57%) and 54% (51%–60%) for the over- and under-table x-ray tube systems, respectively. The use of radiation protection glasses significantly reduced the radiation dose in the eye lens during myelography, with the most effective measures being the combination of using radiation protection glasses and an under-table x-ray tube system.
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1. Introduction
The International Commission on Radiological Protection (ICRP) recommends an equivalent dose limit of 20 mSv yr−1 for the eye lens averaged over a defined 5 year period with a limit of 50 mSv within a single year [1]. Accordingly, the relevant Japanese national policy, the Ordinance on Prevention of Ionizing Radiation Hazards, was revised in April 2021, and the lens equivalent dose limit was lowered from 150 mSv yr−1 to 100 mSv yr−1 over 5 years, with a limit of 50 mSv in a single year. This policy change reflects the importance of protecting the eye lens from radiation exposure and the need to minimise the risk of cataract formation.
Interventional radiology (IR) procedures are being increasingly performed by clinicians without adequate training in radiation safety or radiobiology, who are often unaware of the procedure-related injury risk or simple protective measures [2]. There is a significant occupational radiation dose to the eye lens in physicians extensively involved in clinical radiation procedures, including neurovascular IR [3–5], cardiovascular IR [3, 4, 6], tumour IR [3, 4], and endoscopic retrograde cholangiopancreatography [3, 4, 7]. Notably, the incidence of radiation exposure in spine surgeons has recently increased due to the introduction of various minimally invasive fluoroscopy-assisted surgical procedures, including percutaneous pedicle screw insertion [8, 9], oblique lateral interbody fusion, and extreme lateral interbody fusion [10–15]. Traditional radiographic examinations, such as myelography and computed tomography with myelography (CTM), are commonly used for preoperative assessment of the spinal condition [16–19]. Although magnetic resonance imaging (MRI) has become a popular alternative [18–20], these invasive radiographic examinations remain useful for evaluating patients with implanted medical devices, such as pacemakers or spinal instrumentation, and for surgical planning. Accordingly, myelography and CTM remain invaluable tools for spine surgeons since they allow detailed assessment of the spinal cord and facilitate surgical planning [17, 19, 20].
The increasing frequency of myelography procedures poses a potential risk of significant radiation exposure in spine surgeons. Occupational radiation protection in orthopaedics has traditionally focused on shielding the thyroid, thorax, and pelvis using leaded aprons [15], However, the importance of protecting the eye from radiation exposure is being increasingly recognized in other medical specialities, such as cardiology and IR [3, 21, 22]. Previous studies have demonstrated the sensitivity of the eye lens to ionising radiation and the possibility of cataract development with repeated radiology exposure [22–25]. Accordingly, the use of leaded glasses and other protective gear has become common practice in fields involving substantial exposure to ionising radiation. Therefore, it is crucial to also consider radiation exposure in the eye lens during myelography procedures. However, the radiation doses to the eye lens, especially in spinal surgeons during myelography, remain unclear.
Therefore, this study aimed to investigate the eye lens radiation exposure in spine surgeons during myelography examinations and to evaluate the impact of using different fluoroscopic equipment and radiation protective glasses on reducing this exposure.
2. Methods and materials
2.1. Participants
In this study, we first measured the actual eye lens dose (3 mm dose equivalent, i.e. Hp(3)) in spine surgeons during myelography. Moreover, we analysed the effectiveness of protective glasses based on changes in Hp(3). Additionally, we evaluated changes in Hp(3) values by classifying the characteristics of radiation exposure based on fluoroscopy methods and examination sites. Measurements were performed between November 2021 and April 2022 for 11 spine surgeons by radiation workers registered at the hospital who had attended educational and training sessions on radiation.
2.2. Myelography procedure
The myelography procedure began with the patient being positioned in a side-lying position on the bed and being instructed to create a 'cat's arched back'. The mid-lumbar spine skin was sterilised. Using the lumbar approach, the interlaminar or interspinous space between L2 and L3 or between L3 and L4 was localised under fluoroscopy. A subcutaneous and intramuscular local anaesthetic was administered, and a stilted spinal needle was inserted towards the midline through the anaesthetised region. During routine procedures, 5–10 ml of cerebrospinal fluid was collected for laboratory examination. Subsequently, the contrast agent Omnipaque® (lumbar: 300, 10 ml; thoracic: 300, 10 ml; cervical: 300, 10 ml), which was purchased from GE HealthCare Pharma (Tokyo, Japan), was injected under fluoroscopic control. Thoracic and lumbar myelography produced 16 images, including the lumbar spine lateral view (flexed, neutral, and extended); lumbar spine oblique, prone, and lumbar standing position (front, right lateral flexion, and left lateral flexion); lumbar spine standing position lateral view (flexed, neutral, and extended); lumbar spine standing position oblique; and thoracic spine in front and lateral views. Cervical myelography produced 12 images, including the lumbar spine lateral view (flexed, neutral, and extended); oblique, prone, thoracic spine front and lateral view; cervical spine (front); and cervical spine lateral view (flexed, neutral, and extended). When performing myelography, the spine surgeons either stood facing the patient or facing the imaging monitor with the fluoroscopic equipment placed at their right. Fluoroscopic time and the cumulative air kerma (C-AK) were recorded for each examination.
2.3. X-ray equipment and radioprotective methods
Myelography was performed using an over-table x-ray tube system (SONIALVISION G4; Shimazu, Kyoto, Japan) or an under-table x-ray tube system (Ultimax-I; Canon, Tochigi, Japan). The median dose index at our hospital was lower than the 2020 diagnostic reference level in Japan [26].
Figure 1 shows the position of the spinal surgeon. The spinal surgeon stands on the right side of the patient, with the monitor placed to the left of the spinal surgeon. All physicians were required to wear lead glasses (HF-380, 0.07 mm-Pb; Toray Medical Inc., Tokyo, Japan) and lead aprons (MSA-25 l, 0.25 mm-Pb; Maeda Co., Tokyo, Japan) for further protection from radiation exposure.
Figure 1. Standing position during myelography. (a) With over-table x-ray tube device. (b) With under-table x-ray device. A: spinal surgeon, B: x-ray tube, C: monitor.
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Standard image High-resolution image2.4. Method for measuring the occupational dose to the eye lens
The Hp(3) or lens equivalent dose was obtained using air kerma (AK) measurements determined through radio-photoluminescence glass dosimeters (GD-352M; Chiyoda Technol, Tokyo) [27], which were attached to the inner and outer sides of lead glasses worn by the spinal surgeons during the procedure. These radio-photoluminescence glass dosimeters met the requirements of the International Electrotechnical Commission (62 387) for dosimetry systems with passive detectors and had stable dose linearity in the low-dose range (<±5.0% in the range of 0.01–50 mGy) [27, 28]. The dimensions of the glass element detector are φ1.5 mm × 12.0 mm and it contains an Sn filter (0.75 mm) for absorbing low-energy photons to compensate for the excessive energy response resulting from the high effective atomic number of the detector material [27, 28]. Before the start of the examination, the coefficient of variation was confirmed to be <3.0%. Using previously described eye lens dosimeter clips [3], the GD-352M was mounted on each side of the lead glass and fixed inside and outside the lens (a total of four pieces were placed) (figures 2(a) and (b)). The eye lens dosimeter clips have shown similar measurement accuracy as commercially available dosimeters [29].
Figure 2. Eye lens dosimeter clip position on the lead glasses used: (a) top view and (b) side view. Location of radio-photoluminescence glass dosimeters on the lead glasses.
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After the measurements were completed, the dosimeters were stored in a low-background location outside the radiation-controlled area to avoid contamination. Subsequently, the data were read and analysed using a specialised reading device (FGD-1000; Chiyoda Technol, Tokyo, Japan). The 'conversion factor K from AK to Hp(3)' was implemented as previously described. The coefficient K was determined to be 1.21 [29]. Prior to use, the GD352M was annealed (400 °C, 20 min), followed by measurement of the initial (baseline) values. The per-dose and background readings were subtracted from the GD-352M readings and multiplied by the coefficient K to obtain Hp(3).
2.5. Analysis of the method for calculating Hp(3)AK
C-AK, which is a measure of the irradiation dose displayed by the fluoroscopy system, was used to determine the eye lens radiation dose per unit. Hp(3) values obtained in the previous step were divided by C-AK to obtain the eye lens dose rate per unit of C-AK (Hp(3)AK) according to equation (1) as follows:
where
Hp(3)AK: Hp(3) per unit AK (μSv mGy−1)
Hp(3): eye lens radiation dose of the physicians' eye per procedure (μSv)
C-AK: Cumulative—air kerma
2.6. Analysis of the eye lens dose reduction rate (DRR) with radiation protection glasses
The DRR was calculated by comparing the Hp(3)AK values outside and inside the glasses to determine the effectiveness of radiation protection glasses in reducing the radiation dose to the eye lens. The DRR was calculated using equation (2) as follows:
where
DRR: the dose-reduction rate
Hp(3)AK outside: outside radiation protection glasses Hp(3)AK (μSv)
Hp(3)AK inside: inside radiation protection glasses Hp(3)AK (Sv)
2.7. Analysis of myelography factors using a multiple regression analysis
Multiple regression analysis was performed to investigate myelography-related factors related to Hp(3), with Hp(3) as the dependent variable and C-AK, patient body weight, fluoroscopy time, and fluoroscopy system as independent variables. These independent variables were selected based on their potential impact on Hp(3) and relevance to the study objectives. Regression analysis was used to determine the relationship between the dependent and independent variables as well as to identify any significant predictors of the Hp(3) levels. All statistical analyses were conducted using SPSS software (version 25.0; IBM Corporation, Armonk, NY, USA). The significance of the independent variables was assessed using regression coefficients, t-values, and p-values. Before conducting the analysis, we performed assessments to ensure that the assumptions for multiple regression, including linearity, independence, and normality, were met.
2.8. Statistical analysis
Mann–Whitney U test was used to determine whether there was a statistically significant difference in Hp(3)AK values before and after the use of radiation protective glasses. This non-parametric test was used to compare the medians of the two independent groups. Statistical significance was set at p < 0.05. All analyses were performed using SPSS software (version 25.0; IBM Corporation, Armonk, NY, USA).
2.9. Ethical considerations
This study was approved by the Ethics Committee of our hospital (Protocol Number R1-054), which waived the requirement for informed consent.
3. Results
The over-table x-ray tube system was used in 40 myelography procedures, which were all performed on the lumbar spine. The under-table x-ray tube system was used in 30, 6, and 22 myelography procedures on the cervical, thoracic, and lumbar spine, respectively. This indicates that the over-table x-ray tube system was primarily utilised for lumbar examinations, while the under-table x-ray tube system was used for procedures on various spinal regions, including the cervical, thoracic, and lumbar spine (table 1).
Table 1. Patient information according to the myelography site (n = 98 procedures, November 2021–April 2022).
| Tube position | Myelography | n | Patient information | pps | C-AK (mGy) | Fluoroscopy time (s) | |
|---|---|---|---|---|---|---|---|
| Age (year) | Body weight (kg) | ||||||
| Median (IQR) | Median (IQR) | Median (IQR) | Median (IQR) | Median (IQR) | |||
| Over | Total (L-spine) | 40 | 76 (69–80) | 59 (39–102) | 7.5 (7.5–15) | 75.9 (46.6–88.3) | 265 (194–306) |
| Under | C-spine | 30 | 71 (59–82) | 59 (53–73) | 7.5 (7.5–7.5) | 9.9 (8.4–13.9) | 166 (150–200) |
| Th-spine | 6 | 64 (46–72) | 55 (49–63) | 13.6 (5.5–15.4) | 223 (157–277) | ||
| L-spine | 22 | 67 (60–73) | 63 (58–70) | 17.6 (13.9–21.1) | 223 (187–246) | ||
| Total | 58 | 69 (58–80) | 62 (52–71) | 7.5 (7.5–7.5) | 13.7 (8.6–17.8) | 198 (156–236) | |
Note: over, over-table x-ray tube system; under, under-table x-ray tube system; pps, pulses per second; C-Spine, cervical spine; Th-spine, thoracic spine; L-spine, lumbar spine; IQR, interquartile range; C-AK, cumulative air kerma.
3.1. Eye lens dose in physicians involved in myelography (Hp(3))
The eye lens dose with different fluoroscopic systems is shown in table 2. For the over-table x-ray tube system, the eye lens dose (right eye) with and without the use of radiation protection glasses was 236 (150–345) μSv/examination and 524 (391–719) μSv/examination, respectively (table 2, Mann–Whitney U test, p < 0.01). For the under-table x-ray tube system, the eye lens dose (right eye) with and without the use of radiation protection glasses was 27 (21–38) μSv/examination and 58 (42–83) μSv/examination, respectively (table 2, Mann–Whitney U test, p < 0.01).
Table 2. Hp(3) of spine surgeons during myelography.
| Tube position | Myelography | n | Hp(3), Right (μSv/examination) | p-value | Hp(3), Left (μSv/examination) | p-value | ||
|---|---|---|---|---|---|---|---|---|
| Outside | Inside | Outside | Inside | |||||
| Median (IQR) | Median (IQR) | Median (IQR) | Median (IQR) | |||||
| Over | Total (L-spine) | 40 | 524 (391–719) | 236 (150–345) | <0.01 | 53 (39–83) | 40 (25–61) | 0.014 |
| Under | C-spine | 30 | 47 (39–73) | 22 (15–28) | <0.01 | 13 (8–21) | 8 (5–14) | 0.017 |
| Th-spine | 6 | 68 (50–95) | 29 (21–45) | 0.026 | 12 (8–22) | 9 (7–12) | 0.310 | |
| L-spine | 22 | 72 (51–90) | 30 (24–46) | <0.01 | 18 (8–34) | 11 (7–21) | 0.225 | |
| Total | 58 | 58 (42–83) | 27 (21–38) | <0.01 | 14 (7–23) | 10 (6–15) | 0.001 | |
Note: The significant difference (p < 0.05) is set in boldface.Hp(3), 3 mm dose equivalent; IQR, interquartile range; over, over-table x-ray tube system; under, under-table x-ray tube systems; C-Spine, cervical spine; Th-spine, thoracic spine; L-spine, lumbar spine. To determine if there was a statistically significant difference in the median Hp(3)rate with and without the use of radiation protection glasses, the Mann–Whitney U test was used. Statistical significance was set at p < 0.05. All analyses were performed using Statistical Package for the Social Sciences (version 25.0, IBM Corporation, Armonk, NY, USA).
3.2. Eye lens dose in physicians involved in myelography (Hp(3)AK)
Table 3 shows the Hp(3)AK values according to the fluoroscopy system and site. For the over-table x-ray tube system, the Hp(3)AK values (right eye) with and without the use of radiation protection glasses were 4.01 (3.01–4.57) and 8.09 (6.69–10.21) μSv mGy−1, respectively (Mann–Whitney U test, p < 0.01).
Table 3. Hp(3)AK of the spine surgeons during myelography.
| Tube position | Myelography | Hp(3)AK, Right (μSv mGy−1) | p-value | Hp(3)AK, Left (μSv mGy−1) | p-value | ||
|---|---|---|---|---|---|---|---|
| Outside | Inside | Outside | Inside | ||||
| Median (IQR) | Median (IQR) | Median (IQR) | Median (IQR) | ||||
| Over | Total (L-spine) | 8.09 (6.69–10.21) | 4.01 (3.01–4.57) | <0.01 | 0.88 (0.51–1.25) | 0.66 (0.39–0.89) | 0.028 |
| Under | C-spine | 5.11 (3.48–6.03) | 2.20 (1.54–2.75) | <0.01 | 1.23 (0.78–1.95) | 0.73 (0.56–0.68) | 0.005 |
| Th-spine | 6.51 (5.73–7.92) | 3.14 (2.62–4.03) | 0.038 | 1.02 (0.91–1.45) | 0.68 (0.63–1.09) | 0.114 | |
| L-spine | 4.77 (3.96–6.47) | 2.24 (1.87–3.04) | <0.01 | 0.98 (0.82–1.83) | 0.66 (0.60–1.13) | 0.064 | |
| Total | 5.11 (4.06–6.31) | 2.27 (1.65–2.94) | <0.01 | 1.07 (0.81–1.94) | 0.71 (0.57–1.13) | 0.001 | |
Note: Significant differences (p < 0.05) are set in boldface.Hp(3), 3 mm dose equivalent; IQR, interquartile range; over, over-table x-ray tube system; under, under-table x-ray tube system; C-AK, Cumulative air kerma; C-Spine, Cervical spine; Th-spine, Thoracic spine; lumbar spine.Hp(3)AK = Hp(3)/C-AK.
For the under-table x-ray tube system, the Hp(3)AK values (right eye) with and without the use of radiation protection glasses were 2.27 (1.65–2.94) and 5.11 (4.06–6.31) μSv mGy−1, respectively (Mann–Whitney U test, p < 0.01).
3.3. Analysis of the physician eye lens DRR with radiation protection glasses
The results of the DRR analysis are presented in table 4. For the over-table x-ray tube system, the DRR was 54% (50%–57%) and 25% (11%–36%) in the right and left eyes, respectively, when radiation protection glasses were used. In the under-table x-ray tube system, the DRR was 54% (51%–60%) and 34% (16%–47%) in the right and left eyes, respectively, when radiation protection glasses were used.
Table 4. DRR of the spine surgeons during myelography.
| Tube position | Myelography | DRR (%) | |
|---|---|---|---|
| Right | Left | ||
| Median (IQR) | Median (IQR) | ||
| Over | Total (L-spine) | 54 (50–57) | 25 (11–36) |
| Under | C-spine | 56 (52–62) | 44 (25–50) |
| Th-spine | 53 (52–54) | 25 (25–43) | |
| L-spine | 53 (50–57) | 25 (12–37) | |
| Total | 54 (51–60) | 34 (16–47) | |
Note: IQR, Interquartile range; DRR, dose reduction rate; C-Spine, cervical spine; Th-spine, thoracic spine; L-spine, lumbar spine; over, over-table x-ray tube system; under under-table x-ray tube system.DRR = (1 − Hp(3)AK inside/Hp(3)AK outside) × 100.
3.4. Results of the multiple regression analysis
Multiple regression analysis revealed that C-AK (β = 0.774, p < 0.01) and the patient's body weight (β = 0.123, p= 0.047) had a significant positive effect on Hp(3), indicating that they are significant predictors of the Hp(3) value (table 5). Moreover, fluoroscopy time (β = 0.004, p= 0.941) and fluoroscopy systems (β = −0.102, p= 0.378) demonstrated no significant effect on Hp(3).
Table 5. Analysis of the myelography factors using multiple regression analysis.
| Hp(3), Right | Hp(3), Left | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Outside | Inside | Outside | Inside | |||||||||
| RG | β | t | p | β | t | p | β | t | p | β | t | p |
| C-AK (mGy) | 0.774 | 6.656 | <0.01 | 0.742 | 6.212 | <0.01 | 0.607 | 3.812 | <0.01 | 0.582 | 3.596 | 0.001 |
| Body weight (kg) | 0.123 | 2.021 | 0.047 | 0.159 | 2.548 | 0.013 | 0.248 | 2.978 | 0.004 | 0.271 | 3.209 | 0.002 |
| Fluoroscopy time (s) | 0.004 | 0.074 | 0.941 | 0.022 | 0.387 | 0.7 | 0.043 | 0.554 | 0.581 | 0.046 | 0.586 | 0.559 |
| Systems (0 = over, 1 = under) | −0.102 | −0.887 | 0.378 | −0.11 | −0.936 | 0.352 | −0.045 | −0.289 | 0.773 | −0.048 | −0.3 | 0.765 |
| R2 | 0.767 | 0.753 | 0.562 | 0.549 | ||||||||
Note: Significant differences (p < 0.05) are set in boldface.RG, radiation protection glasses; C-AK, cumulative air kerma; over, over-table x-ray tube system; under under-table x-ray tube systems.
4. Discussion
This study investigated the eye lens radiation dose in spine surgeons during myelography. The results indicated that practitioners involved in myelography should be aware of the following key factors for reducing eye lens dose: controlling the irradiation dose to minimise C-AK and optimising imaging sessions, positioning the x-ray tube under the patient table, and using radiation protection glasses.
Radiation safety has been recently promoted through proactive interventions using radiation visualisation [30–32]. Targeted radiation safety and protection education and training tailored to each procedure is warranted to reduce radiation doses to medical personnel [33].
In this study, the Hp(3) measured outside the protective eyewear was 524 and 58 μSv/examination for the over- and under-table x-ray system, respectively (table 2). Nagamoto et al reported that the lens-equivalent dose in orthopaedic surgeons during fluoroscopy-assisted surgery was 8.8 μSv/examination [3], which corresponds to 1/60 and 1/7 of the aforementioned values, respectively. Similarly, the lens-equivalent dose in cardiologists and neurosurgeons during IR has been reported to be 207.7 [3] and 40.0 μSv/examination [5], respectively. This demonstrates the significant eye lens radiation exposure during myelography using over-table x-ray tube equipment.
Furthermore, regarding the Hp(3) per unit C-AK, we found that the over-table x-ray system resulted in a Hp(3) per unit C-AK that was 1.69 times higher (median) than that for the under-table x-ray system. This indicates that using an under-table x-ray system can effectively reduce radiation exposure to the eye lens.
Previous studies have found that the radiation doses in surgeons during fluoroscopically assisted surgical procedures were within the level of safe occupational exposure risk [3, 12, 13, 15]. In our study, the annual dose with the utilisation of over-table and under-table x-ray tube devices was 4.28 mSv yr−1 (90 examinations × 524 μSv/examination ÷ 11 surgeons) and 0.66 mSv yr−1 (126 examinations × 58 μSv/examination ÷ 11 surgeons), which did not exceed the aforementioned annual dose limit. Therefore, the surgeon's radiation dose during myelography is also within safe occupational exposure risk levels. We recommend using under-table x-ray tube systems as a simple approach for reducing Hp(3). However, in Japan, various fluoroscopic examinations, including gastrofluoroscopy and enteroscopy, are often performed bedside, and thus require the wide beds often found in over-table x-ray tube systems. Therefore, understanding of the characteristics of the test and practical education and training in radiation safety and protection is required for all involved practitioners to ensure effective and safe use of equipment [3, 33, 34].
The use of radiation-protective glasses significantly reduced the radiation dose to the eye lens in both types of x-ray devices. Specifically, the DRR was 54% (50%–57%) and 54% (51%–60%) for the over- and under-table x-ray tube systems, respectively, which is consistent with values reported by other fluoroscopy studies [3, 6, 21, 22]. Additionally, we found that the use of radiation-protective glasses significantly reduced the Hp(3) during myelography procedures for the various spinal, cervical, thoracic, and lumbar regions. Therefore, using radiation-protective glasses during myelography can effectively protect against radiation exposure.
Multiple regression analysis revealed that C-AK and body weight, but not fluoroscopy duration, significantly influenced the Hp(3). The following methods can be used to reduce C-AK during examination: adjusting the pulse rate to a lower frequency that does not interfere with the examination, limiting the irradiation field to the necessary extent and avoiding unnecessary extensions, and optimising imaging sessions. In cases where a high image quality is not required, fluoroscopic images can be obtained using these measures to reduce the radiation dose.
In myelography, the eye lens radiation dose in spine surgeons may be reduced through a combination of several measures, including use of under-table x-ray tubes, reviewing imaging techniques and conditions, irradiation field reduction, adoption of fluoroscopic image storage devices, and use of radiation protective eyewear. Furthermore, spine surgeons may be trained on radiation visualisation [30–32] and systems that can simultaneously collect the radiation dose in patients and workers may be introduced [35]. Additionally, exploring alternative radiation protection strategies such as protective screens, ceiling-mounted protective plates, and x-ray shields could prove beneficial. Comprehensive training and education on radiation exposure and protection are important for ensuring effective, safe, and efficient use of imaging equipment.
5. Conclusion
This study emphasises the importance of implementing radiation protection measures to minimise eye lens radiation exposure in spine surgeons during myelography procedures. However, the findings suggest that there are no immediate concerns regarding radiation protection in spine surgeons since the estimated occupational doses were below the threshold for severe deterministic effects. Our findings highlight key factors that can contribute to reducing the eye lens radiation dose, such as controlling the irradiation dose, optimising imaging sessions, positioning the x-ray tube under the patient table, and using radiation protection glasses. These results emphasise the need to raise awareness about radiation protection among practitioners involved in myelography, especially spine surgeons.
Acknowledgments
The authors thank Tomomi Konari, Fumiko Kawagoe, and Kimi Kihara for technical support. The authors would also like to thank the medical staff who participated in this study. We express our profound respect and gratitude to the late Professor Kunugita, a co-author whose immeasurable contributions to radiation protection in Japan have left a lasting legacy. His spirit will endure through our continued research and the many lives he has profoundly touched.
Data availability statement
The data that support the findings of this study are available upon request from the authors.
The data cannot be made publicly available upon publication because they contain sensitive personal information. The data that support the findings of this study are available upon reasonable request from the authors.
Advances in knowledge
The study emphasises the importance of radiation protection for minimising eye lens exposure in spine surgeons during myelography; further, it highlights key protective factors, including controlling irradiation dose, optimising imaging sessions, under-table x-ray tube positioning, and using protective glasses.
Conflict of interest
The authors declare that they have no conflict of interest.
Funding
This work was supported in part by grants from the Japanese Ministry of Health, Labour, and Welfare (Grant Numbers 210501-01) and JSPS KAKENHI (Grant Number JP22K10379).