A total of 1,156 patients were treated with 1,819 interventional pain management procedures by 3 physicians in an ambulatory surgery center over a period of 3 months under fluoroscopy. Our results showed that total exposure on average was 12.0 ± 0.49 seconds, 9.0 ± 0.37 seconds and 7.5 ± 0.27 seconds per procedure in Groups I, II, and III respectively. Radiation exposure ranged from a low of 3.7 ± 0.29 seconds for caudal/interlaminar epidurals to 61.0 ± 9.0 for discography. Scatter radiation exposure at chest level was 510 mREM, 535 mREM, and 690 mREM for Groups I, II, and III respectively, which translated to 1.5455 mREM, 0.8082 mREM, and 0.8343 mREM per procedure in each group respectively. This showed no significant differences among the groups.
Inside the apron, over the thyroid collar on the neck, the scatter radiation exposure was 68 mREM in Group I for 330 procedures with 0.2060 mREM per procedure, 25 mREM in Group II for 662 procedures with 0.0378 mREM per procedure, and 0 mREM for 827 procedures indicating differences in exposure patterns with increased levels of exposures in Groups II and III compared to Group I and Group I compared to Group II.
Inside the apron, groin exposure showed 0 mREM exposure in Groups I and II for 330 procedures and 662 procedures, whereas, it showed 15 mREM scatter radiation exposure in Group III for 827 procedures with exposure of 0.0181 mREM exposure per procedure, which was higher than in Groups I and II. This was also higher than the exposure in the neck compared to Group II. However, the groin exposure to scatter radiation inside the apron was less than the neck exposure inside the apron in Groups I and II.
The scatter radiation exposure for groin outside the apron in Group I was 1260 mREM and per procedure was 3.8182 mREM. In Group II the scatter radiation exposure for groin outside the apron was 400 mREM with 0.6042 mREM per procedure. In Group III the scatter radiation exposure for groin outside the apron was 1152 mREM with 1.3930 mREM per procedure exposure. There was no significant difference between the exposure rates in Group I and Group II. However, exposures were higher in Group I and III compared to Group II.
Utilization is explained by the physician experience. However, groin exposure rates are somewhat difficult to explain. These are in contradiction to the exposure rates of the upper part of the body. The physician performing the procedures in Group III was exposed to the least radiation in the upper body, however, was exposed to the highest radiation at the groin even under the lead apron with significantly higher radiation outside the apron compared to Group II at outside the apron and compared to Group I and II inside the groin. While we do not have reasons for this finding, this may explain the physician behavior patterns of standing close to or away from the scatter. This also explains the fact that the same measures or behaviors, which reduce scatter exposure in the upper part of the body, are not effective to reduce the exposure in the lower part of the body.
This evaluation illustrates the importance of measuring radiation exposure not only in the upper body but also the lower body, as well as using protective measures. Our results are similar to the results of Botwin et al [7
] and Schade [9
]. This study emphasizes, similar to the one by Schade [9
], that in spite of appropriate lead apron and shielding, there is a significant exposure to the groin area even with all the precautionary measures and employing the principles of ALARA (as low as reasonably achievable), with regard to time, distance, and shielding. Based on this evaluation with approximately 1.4 to 5.4 mREM exposure per procedure outside the apron and with approximately 0.02 to 0.21 mREM inside the apron per procedure, and extrapolated to 3,000 procedures, a physician will be exposed to a maximum of 4,200 to 16,100 mREM on the outside and 50 to 620 mREM exposure inside the apron in the lower part of the body. This is higher than the upper body exposure. It is explained by the fact that most scatter is generated in the lower part. Scatter is also higher with steep oblique and lateral positions. Physician exposure increases with live fluoroscopy due to the inability to move away from scatter radiation. Considering the annual limit for whole body exposure of 5 REM per year total effective dose equivalent, if no protection is used, an interventionalist performing 3000 procedures will still be at less than maximum level. General radiation exposure guides to extremities and skin are 50 REM per year [16
This study showed that radiation exposure is well within the established safety limits. However, multiple variables should be taken into account in extrapolating these results for other situations. Further, interventional physicians must seriously consider utilizing protective measures for the lower part of the body other than the lead apron including lead shielding applied from the patient to the floor to reduce scatter radiation, specifically at groin, knee and feet as shown by Schade [9
]. However, this shielding will not provide any protection in deep oblique or lateral exposures. Fluoroscopy times and exposure risk depends on the technique applied for each procedure, training of the individual, and the mode of the fluoroscopy utilized. It should also be taken into consideration that, an interventionalist must, at all times, have unhindered access to the patient. This will preclude bulky radiation shields and other types of protective measures, which may reduce access to the patient. Consequently, intermittent fluoroscopy or pulsed fluoroscopy will reduce the exposure, whereas, continuous fluoroscopy and visualization in a multitude of views will increase the exposure. Further factors include the patient volume, number of regions treated in each patient, number of procedures performed on each patient, and the experience of the interventionalist and the radiographic technologist. Thus, absolute exposure to the physician can only be calculated on an individual basis, taking into account various factors described above, along with consideration of cumulative exposure over a lifetime. However, leaded aprons, glasses, thyroid shields and other types of lead barriers seem most appropriate to minimize the physician's exposure. This has been shown repeatedly by multiple investigators [24
Even though, for the most part this research suggests that the level of fluoroscopy utilization is well below a level of elevated concern, interventionalists should be cognizant of the fact that long-term effects of low-dose radiation are uncertain. Botwin et al [7
] showed that exposure in their study was greatest to the hands and then eyes to the interventionalists. Thus, they have argued for not only leaded aprons, glasses, thyroid shields, but also leaded gloves. They also recommended extended tubing for administration of radiographic contrast. Manchikanti et al [10
] showed lack of significant exposure provided that all the principles of ALARA were followed in their practice setting. In contrast, Schade [9
] argued for protection for the lower part of the body. Our evaluation confirms the results of Schade [9
] with regard to risk. Thus, we recommend collection of accurate data of fluoroscopy times used at various facilities for various procedures.