Effectiveness of a radiation management safety checklist for non-vascular imaging and interventional radiology at a medical facility

Abstract

Objective: To investigate whether implementing a radiation management safety checklist (RMSC) can improve personnel dosimetry among physicians’ dosimeter wearing rate for those performing fluoroscopy. Methods: Initially, we visually inspected whether the physicians were wearing personal dosimeters. Subsequently, during a “time-out” period recommended by the RMSC, the medical worker mutually confirmed whether the personal dosimeters were worn correctly. If errors in personnel dosimetry were noted, verbal recommendations to correct the error and follow double dosimetry were made. Lastly, the physicians’ dosimeter wearing rates before and during RMSC implementation were compared and analyzed. Results: Before the measurement period, the personal dosimeter wearing rate among all physicians who perform fluoroscopy at the study center (n=72) was 58.2%; during the measurement period, it reached 80.1% (χ²[2]=21.254, p<0.01, φ=−0.227), indicating that RMSC implementation improved the physician’s dosimeter wearing rate. However, 40.1% and 37.9% of the physicians were not registered radiation workers before and during the measurement period, respectively, and RMSC implementation did not significantly improve the registration rate during the study period (χ²[2]=0.349, p=0.554, φ=−0.023). Conclusions: The risk of radiation injury may have been overlooked among physicians involved in fluoroscopy and other routine clinical practices that cause radiation exposure. The investigated medical facilities registered physicians as radiation workers at the individual’s discretion. There is an urgent need to develop a radiation management system that mandates the use of personal dosimeters among all physicians at risk of radiation exposure.

Introduction

The International Commission on Radiological Protection (ICRP) has lowered the threshold dose for cataracts to 0.5 Gy¹⁾. In response to this recommendation, the relevant national policy of Japan, the Regulations for the Prevention of Ionizing Radiation Hazards, and the lens equivalent dose limit was revised from 150 mSv/year to 100 mSv over 5 years and 50 mSv/year (revised in April 2021).

Owing to the popularity of interventional radiology (IR), occupational exposure to radiation has become a growing cause of concern among medical workers in this field. In particular, the threshold lens radiation dose for cataracts has been significantly lowered^2,3,4,5,6). Therefore, radiation protection should be optimized for IR. The ICRP also reported the need for an organizational radiation management system for occupational exposure management^7,8). Through these reports, the International Atomic Energy Agency has been disseminating information on the possibility of reducing exposure through the use of lead glass and radiation shielding screens installed on ceilings and educating workers on the importance of eye lens protection⁹⁾. To practice physician dose management and radiation protection, it is important to implement the following forms of control: general management, work environment management, work management, health management, and occupational health training^6,7,10,11). The International Labour Office (ILO) issued guidelines for occupational health and safety management system in 2001¹²⁾. These guidelines were designed as a practical tool to help organizations achieve continual improvement in occupational safety and health (OSH) performance. The basic concept of radiation management in radiation workers is recommended in ICRP Publication 75⁷⁾, which recommends establishing a health and safety management system. A system has been developed in Japan to introduce an occupational safety and health management system (OHSMS)¹¹⁾ based on the International Organization for Standardization (ISO) 45001 (ISO 2018)¹³⁾. Although monitoring with personal dosimeters is necessary to assess occupational exposure in physicians, the dosimeter wearing rate among physicians is low, ranging from 17% to 54%^6,14,15,16), which indicates a major gap in exposure management.

Several studies have been conducted on radiation protection education for physicians¹⁶⁾, but there is little evidence that the personal dosimeter wearing rate has reached 100% so far. Currently, radiation protection education alone is insufficient; thus, direct measures are essential.

In 2009, the World Health Organization (WHO) recommended the WHO Guidelines for Safe Surgery 2009¹⁷⁾ and published the Surgical Safety Checklist (Surgical SC) to improve safety during surgery. The Surgical SC was customized for each clinical area and helped avoid adverse surgical events and reduce human error. Furthermore, to prevent simple human errors, a “time-out” is implemented wherein the entire team stops working for a short period just before surgery to check patient information and the surgical site^18,19,20,21). IR is similar to surgery in many aspects, such as complexity of the procedure, need for emergency response, need for a high degree of specialization, and potential risk of miscommunication among medical workers, which may result in procedural errors. Therefore, the number of facilities introducing the surgical SC in operations and IR is increasing, with Corso et al. publishing a new IR-specific SC based on the surgical SC^{22,23,24,25,26,27)}. We assume that it is possible to ensure patient safety and implement physicians’ radiation exposure management by further adapting the surgical SC for use in IR. However, to the best of our knowledge, no reports have assessed the effectiveness of “time-outs” and an SC adapted for IR. Consequently, we further modified the IR-specific surgical SC developed by Corso et al. to include an evaluation for personal dosimeter use among physicians and named the modified instrument the Radiation Management Safety Checklist (RMSC).

The purpose of this study was to evaluate the physicians’ personal dosimeter wearing rate using the RMSC. The physicians’ personal dosimeter wearing rate was visually surveyed initially. Thereafter, the RMSC was used during time-outs to cross-check with medical personnel that their personal dosimeters were worn correctly. If any wearing defects or errors were noted, the physicians were verbally encouraged to wear their dosimeters correctly and follow double dosimetry. Lastly, the effectiveness of RMSC was evaluated based on the rate of physicians wearing their personal dosimeters.

Methods

This study first clarified physicians’ use of personal dosimeters (before measurement). The physicians’ wearing status of the dosimeter was visually checked before the start of the inspection. Radiological technologists trained in dosimetry readings visually checked the physicians’ wearing status of the dosimeter before the start of the inspection. Subsequently, the physicians’ personal dosimeter wearing status was investigated using the RMSC (during measurement). RMSC was performed at the time of admission (ie., before the start of fluoroscopy). “Time-outs” were followed by all medical workers involved in IR procedures, including physicians, radiological technologists, and nurses. If personal dosimeter use was flawed, the medical worker verbally urged the participants to use the dosimeters correctly. Lastly, we analyzed the effects of RMSC implementation on the physicians’ personal dosimeter wearing status.

Measurement target

This study included all physicians engaged in radiological practice in fluoroscopy laboratories (in controlled areas) in accordance with the relevant Japanese laws and regulations, the Regulations for the Prevention of Ionizing Radiation Hazards. All physicians wore lead aprons (0.25- or 0.35-mm-Pb equivalent) and were asked to follow “double dosimetry”^28,29).

Social networking services (SNS) were used to survey facilities that introduced SC for IR during fluoroscopy (April 2021). The percentage of physicians wearing personal dosimeters was investigated during two periods; May–June 2021 (2 months) was considered the pre-measurement period, and July–August 2021 (2 months) was considered the measurement period. For physicians who did not wear personal dosimeters, an electronic personal dosimeter (EPD) (PDM-127B-SZ, Hitachi City, Tokyo, Japan) was fitted to measure the 1 cm dose equivalent (H_p (10)) (during the measurement period). An EPD that can perform H_p (10) in real time was used in this study to determine the occupational dose per examination for those not wearing a dosimeter. Individual occupational dose control can be implemented by using this dosimeter even if an unspecified number of physicians are not wearing dosimeters.

Investigation method

Figure 1A shows the correct mounting position of the dosimeter (double-dosimetry)^28,29) (Glass Badge, Chiyoda Technology, Tokyo, Japan, and Luminess Badge, NAGASE-LANDAUER, LTD., Ibaraki, Japan). The double-dosimetry approach used a main dosimeter under the lead apron and an additional dosimeter over the lead apron. The overseeing radiological technologist visually inspected whether the personal dosimeters were worn correctly. The results were recorded in the RMSC (Figure 2), which was created by adding the dosimeter wearing status to the existing data²²⁾.

Fig. 1.

(A) We urged physicians to follow double dosimetry to record radiation exposure while engaging in fluoroscopy. As per the recommendations, one dosimeter should be placed under the lead apron (A, white dotted line) and one over (B, Glass Badge). (B) For those who did not wear personal dosimeters, we placed two electronic personal dosimeters (EPD) (PDM-127B-SZ, Hitachi, Tokyo, Japan) under (A, orange dotted line) and over (B, EPD) the lead apron.

Fig. 2.

Radiation Management Safety Checklist (RMSC) has added a section on installing dosimeters to existing SC for IR. dose area product (DAP), air kerma (Ka, r), Intravenous access (IV access), Picture Archiving and Communication System (PACS).

The wearing status of the personal dosimeters was classified into three categories, namely “wearing,” “not wearing,” and “unregistered” (Table 1). The dosimeter wearing rate among the physicians was calculated using Equation (1). The dosimeter unregistered rate among physicians (radiation worker registration: no) was calculated using Equation (2).   

$${\text{Wearing rate=Wearing / N}}_{\text{registration}}\times \text{100},$$(1)

where,

Wearing rate: dosimeter wearing rate among registered physicians, wearing: the number of times the physicians wore the personal dosimeter in the proper position, and N_registration: number of visual surveys (Radiation worker registration: yes).   

$$\text{Unregistered rate=Unregistered /N}\times \text{100},$$(2)

where,

Unregistered rate: dosimeter unregistered rate in radiation workers engaged in fluoroscopy, unregistered: number of unregistered radiation workers engaged in fluoroscopy, and N: total number of visual surveys.

Table 1. Wearing status of personal dosimeters into three categories

Categories	Was the physician a registered radiation worker?	Were the personal dosimeters correctly worn? ¶
Wearing †	yes	yes
Not wearing ‡	yes	no
Unregistered §	no	no

^†  The number of times the physicians were wearing the personal dosimeter in the proper position.

^‡  The number of times the physicians were not wearing the personal dosimeter in the proper position.

^§  Number of physicians who were engaged in fluoroscopy but were not registered radiation workers.

^¶  Personal dosimeters are worn inside and outside the lead apron (double dosimetry).

Physician occupational dose

Figure 1B shows the mounting position of the EPD. The physician’s exposure during fluoroscopy was monitored by assessing the effective dose using the H_p (10) measured during the fluoroscopy procedure inside and outside the lead apron.

The minimum detectable EPD was 1 μSv. The inside and outside doses were used to estimate the effective whole-body dose. The tissue load coefficients on which the dose estimation equations are based are provided in the ICRP 1990 recommendations³⁰⁾. Physicians performing fluoroscopy wore lead aprons while performing their duties. Therefore, a single personal dosimeter attached to the chest or abdomen may not be representative of the total body dose of the wearer. This situation is generally referred to as “non-uniform exposure,” and personal exposure control, in which two or more personal dosimeters are used as necessary, is practiced currently. The effective dose is calculated from the weighted average of the indicated values of these personal dosimeters³¹⁾. The effective dose is a theoretical quantity defined by the ICRP to measure whole-body cancer risk from exposure to ionizing radiation. The effective dose was estimated from the EPD measurements inside and outside the lead apron using Equation (3).   

$$E=0.11Ha+0.89Hb,$$(3)

Where,

E; effective dose (μSv); Ha; H_p (10) outside the lead apron; Hb, H_p (10) inside the lead apron.

Statistical analysis

Differences in dosimeter wearing rates before and during the measurement period were confirmed using Pearson’s chi-square test. The differences were considered statistically significant at p<0.05. All analyses were performed using Statistical Package for the Social Sciences version 25.0 (IBM Corp., Armonk, NY, USA).

Ethical considerations

This study was approved by the Ethics Committee of the University of Occupational and Environmental Health, Kitakyushu, Japan (Protocol Number R1-054), and was conducted in compliance with the tenets of the Declaration of Helsinki.

Results

Responses were obtained from 25 facilities that used SNS. Among these, four facilities had implemented the SC for IR procedures, and only one facility (a general hospital with over 500 beds) had implemented both the RMSC and surgical SC for IR procedures. The study was conducted in these facilities. Table 2 shows the surveyed clinical departments and the number of physicians.

Table 2. Clinical departments and number of physicians that perform fluoroscopy

Department	Number of physicians	Number of surveys before (during) measurement period
Total	72	304 (372)
Urology	7	15 (22)
Rehabilitation	6	27 (21)
Radiology	4	21 (17)
Pediatrics	8	22 (25)
Orthopedic Surgery	11	69 (109)
Neurosurgery	4	12 (9)
Gastroenterology	14	44 (67)
Nephrology	7	52 (73)
Gastroenterological Surgery	11	42 (29)

Wearing rate of personal dosimeter

Table 3 shows the status of personal dosimeter use among physicians. The dosimeter wearing rate among registered physicians was 58.2% (106/182) before the measurement and 80.1% (185/231) during the measurment (χ²[2]=21.254, p<0.01, φ=−0.227, Table 3). Among the physicians who performed fluoroscopy, 40.1% (122/304, before measurment) and 37.9% (141/372, during measurement) were not registered radiation workers (χ²[2]=0.349, p=0.554, φ=−0.023, Table 3). The RMSC resulted in two physicians voluntarily registering as radiation workers.

Table 3. Physicians’ personal dosimeter wearing status

Was the physician a registered radiation worker?		Status before measures	Status during measures	p-value
Total number of visual surveys d		304	372
yes	Number of visual surveys a	182	231	<0.01
	Wearing b (not wearing)	106* (76)	185* (46)
	Wearing rate †[%]	58.2	80.1
no	Number of visual surveys c	122	141	0.554
	Unregistered rate ‡[%]	40.1	37.9

Differences in dosimeter wearing rates before and during the measures were confirmed using Pearson’s chi-square test. All analyses were performed using the Statistical Package for the Social Science (version 25.0; IBM Corporation, Armonk, NY, USA).

^†  Wearing rate of personal dosimeter: (b/a)×100 [%]

^‡  The inspection implementation rate of unregistered radiation workers: (c/d)×100 [%]

^*  p<0.05.

Physicians’ occupational dose (effective dose)

Table 4 shows the effective dose for physicians not wearing personal dosimeters. The median effective dose was 2 (range, 0–95) μSv/procedure.

Table 4. Effective dose for physicians not wearing personal dosimeters

	Occupational effective dose, μSv/procedure, median (range)
Ha	12 (0–439)
Hb	0 (0–92)
E	2 (0–95)

Note: E=0.11Ha+0.89Hb

E; overall effective dose, Ha; effective dose outside the lead apron, and Hb; effective dose inside the lead apron.

Discussion

The WHO Guidelines for Safe Surgery 2009 were introduced in recent years as a safety measure for surgical procedures^{17,18,19,20,21)}. The implementation of the SC during IR procedures has contributed to the elimination of adverse events through robust information-sharing and increased awareness of medical safety. Thus, SC use in IR has proven to be effective in improving patient medical safety^{22,23,24,25,26,27)}. However, there has been little research objectively evaluating the impact of SC use on radiation management of physicians engaged in IR. In this study, we first visually inspected whether the physicians were wearing personal dosimeters. Thereafter, we implemented the RMSC and objectively evaluated its effect on the wearing rate of personal dosimeters among physicians.

Radiation protection is essential for physicians exposed to radiation during clinical practice, and the ICRP calls for the provision of appropriate and sufficient information and training in radiation protection^7,8). The rate of personal dosimeter use before the measurement period in this study was 58.2%, and the rate of personal dosimeter use has been found to be low among physicians^6,14,15,16). The wearing rate during the measurement period, as assessed using the RMSC, was 80.1%; thus, the use of the RMSC improved the rate of personal dosimeter use (χ²[2]=21.254, p<0.01, φ=−0.227, Table 3). Two factors improved the dosimeter wearing rate among physicians: (1) medical workers mutually checked the dosimeters and verbally encouraged each other to wear them, if inappropriate; and (2) the RMSC results were posted in the electronic medical records for record keeping. As a result, physicians’ poor fitting of the dosimeters was documented, raising awareness of the problem. These results show that it is impossible to raise physicians’ awareness of radiation control using only annual radiation protection education, which is required by law. Furthermore, it must be considered that physicians may not voluntarily wear personal dosimeters.

Fluoroscopy was also performed by physicians who were not registered as radiation workers. The unregistered rate was 40.1% before measurement and 37.9% during the measurement period. In other words, RMSC implementation did not improve the rate of radiation worker registration and did not improve the rate of personal dosimeter use among unregistered physicians. The radiation management systems of the medical institutions surveyed in this study registered physicians as radiation workers at the discretion of the physician. Physicians were unaware of the need for personal dosimeters. In addition, management intervention is essential for worker health care; however, the surveyed facilities had radiation control systems that were not functioning properly. This could be the reason why the rate of physicians wearing personal dosimeters did not improve despite the checklist being used to highlight the problem during the time-outs. As described in the guidelines on occupational safety and health management systems^11,12) and ICRP⁷⁾, there is a need for strong leadership by the chief executive. The findings suggest that physicians involved in fluoroscopy may overlook the risk of radiation exposure by not wearing personal dosimeters.

One of the solutions identified is the need for a radiation control system “established by an organization, a program, and regular and independent audits,” as proposed by the ICRP⁷⁾. This radiation management system applies the OHSMS widely implemented in the industry for radiation management and is centered on the administrator (hospital director)¹³⁾. This system is characterized by its ability to establish a radiation management system as an administrative requirement rather than a guideline followed at the discretion of individual physicians. However, only a few medical facilities in Japan have implemented OHSMS radiation control. One reason for this may be that occupational radiation exposure among medical workers is not considered important^6,16). Although radiation practice is dangerous work, countermeasures tend to be neglected because cataracts and skin cancer appear more than 10 years later, and the priority in the medical field is to treat patients and save their lives. We were able to confirm the presence of unregistered physicians using RMSCs in this study. However, since the RMSCs did not have coercive power to force them to wear dosimeters, it was not possible to improve the dosimeter use rate among unregistered physicians. Therefore, an OHSMS must be implemented and actively managed to improve the registration rate of unregistered physicians; visible and proactive leadership by the highest level of management is essential to develop and sustain an OHSMS culture. The installation of personal radiation dosimeters should be prioritized to recognize the effects of chronic radiation exposure on physicians. The installation of personal radiation dosimeters must be prioritized for recognizing the effects of chronic radiation exposure among physicians.

Occupational effective doses were also measured for physicians who were not registered as radiation workers during the measurement period. The results showed that the median effective dose for physicians was 2 (range, 0–95) μSv/procedure (Table 4); the ICRP reports that occupational dosimetry is not required if the annual effective dose is less than 1 mSv⁷⁾. In our study, occupational dosimetry was required for physicians performing fluoroscopy if they performed more than 10 examinations per year (1,000 µSv/95 µSv [maximum], Table 4). Furthermore, the relevant law in Japan, the Ordinance on Prevention of Ionizing Radiation Hazards, requires that doses due to external exposure and internal exposure received by workers in the controlled area must be measured. In addition, the measurement of occupational effective doses is a means of exposure control, but monitoring is also useful for the optimization and substantiation of radiation protection. Therefore, we believe that radiation exposure monitoring with personal dosimeters is essential for physicians who regularly perform fluoroscopy.

A limitation of this study is that it was conducted at a few medical facilities. We believe that the SC for IR is more effective in facilities where radiation control is properly implemented, as there are no physicians who are unregistered radiation workers. To prove this hypothesis and verify the effectiveness of SC for IR, it is necessary to investigate the use of SC during fluoroscopy in multiple medical facilities.

Conclusion

We showed that the use of RMSC during fluoroscopy improves the compliance rate of physicians wearing personal dosimeters. However, even after the implementation of RMSC, the personal dosimeter wearing rate did not improve among physicians who were not registered for radiation work. The establishment and implementation of a radiation control system applying OHSMS under the leadership of the facility’s chief administrator will lead to the use of dosimeters by unregistered personnel. It is also urgent to mandate the use of personal dosimeters among physicians performing radiological treatment in controlled areas.

Approval of the research protocol

Not applicable.

Informed consent

Not applicable.

Registry and the registration no. of the study/trial

Not applicable.

Animal studies

Not applicable.

Conflict of interest

The authors have no conflicts of interest directly relevant to the content of this article.

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 Numbers JP22K10379).

Author contributions

Keisuke Nagamoto: Conceptualization, methodology, formal analysis, data curation, writing—original draft, writing—review & editing, visualization, investigation, project administration, funding acquisition.

Naoki Kunugita: Validation, writing—review & editing, supervision, funding acquisition.

Both authors reviewed and approved the final version of this manuscript.

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