Abstract
OBJECTIVE To describe self-reported use of x-ray personal protective equipment (PPE) by veterinary workers in Saskatchewan, Canada, and to examine factors that affected their use of x-ray PPE.
DESIGN Cross-sectional survey.
SAMPLE 331 veterinary workers.
PROCEDURES A questionnaire was distributed to Saskatchewan veterinary workers electronically and by conventional mail. Recipients were encouraged to share the questionnaire with colleagues. The questionnaire consisted of questions regarding radiation safety practices used during small animal radiographic procedures, including frequency of use of dosimeters and lead aprons, thyroid shields, eyeglasses, and gloves. Respondents were also requested to provide suggestions for increasing use of PPE.
RESULTS 460 questionnaires were completed, of which 331 were returned by workers involved with performing radiographic procedures. Two hundred eighty-five of 331 (86%) respondents reported that at least 1 worker was always in the room during x-ray exposure, and 325 (98%), 291 (88%), and 9 (3%) respondents reported always wearing a lead apron, thyroid shield, and protective eyeglasses, respectively, during radiographic imaging. Two hundred seventeen of 327 (66%) respondents used lead gloves correctly less than half the time. Mean percentage of time that gloves were worn correctly was higher for workers who were required to do so by their employers than for those who were not.
CONCLUSIONS AND CLINICAL RELEVANCE Results suggested use of PPE during radiographic procedures can be increased by employers making PPE use mandatory. Other respondent-identified factors that would increase PPE use included the availability of properly fitting and functional PPE and education of workers about health risks associated with ionizing radiation exposure.
Veterinary workers regularly restrain animals during radiographic procedures to ensure that the patients are maintained in a standardized position to facilitate accurate diagnostic interpretation of the radiographs.1–7 Results of a 1957 survey1 of 54 veterinary clinics in New Jersey indicated that almost all workers manually restrain animals for the acquisition of radiographs. Results of another survey2 conducted 30 years later indicated that practice was relatively unchanged, with 253 of 304 (83%) female small animal veterinarians who graduated from a California veterinary school reporting that they restrained animals for radiographs at least 1 to 4 times/mo. All 47 veterinarians from Ontario, Canada, surveyed in 2002 reported that animals were sometimes or always manually restrained for radiographs by staff.3 In a 2012 survey,4 300 of 320 (94%) veterinarians in small animal practice in western Canada reported that staff manually restrained animals for radiographs. Manual restraint of animals in the radiology room is also common outside of North America. In Australia, 439 of 720 (61%) small animal veterinarians reported restraining animals for radiographs at least once a week in 2007,5 and 2,014 of 2,562 (79%) veterinarians from all practice types reported manually restraining animals for radiographic imaging in 2008.6 In the United Kingdom, 62 of 93 (67%) small animal practices surveyed in 2009 reported that patients were manually restrained for radiographs at times.7
When an animal is radiographed, x-rays scatter from the patient and table and travel toward restrainers.8 Therefore, workers must wear leaded PPE for protection against scattered radiation even if they are some distance from the primary beam. However, results of multiple surveys1–7 indicate that veterinary workers do not consistently wear PPE when restraining animals for radiographs, and that practice has not changed in the last 60 years. In 1957, about a quarter of New Jersey veterinarians surveyed reported that lead aprons or gloves were seldom if ever worn by personnel restraining patients during radiographic procedures.1 The respondents of that survey1 reported that the reason lead gloves were not worn was because their bulkiness made positioning of small animals difficult. In a 2012 survey4 of small animal veterinarians in western Canada, 114 of 308 (37%) respondents reported that they had been present in a room without PPE while a radiograph was being obtained. In a 2002 survey3 of 73 veterinary workers in Ontario, all 73 (100%) reported that they always wore a lead apron, 67 (92%) reported that they always wore a thyroid collar, and 62 (85%) reported that they always used lead gloves when restraining animals for radiographs. However, all the respondents of that survey3 were pregnant, which might have been an incentive for them to increase their use of PPE. In a 2007 survey5 of 1,197 female small animal veterinarians in Australia, 1,029 (86%) reported that they always or frequently wore lead aprons, 634 (53%) reported that they always or frequently wore a thyroid protector, and 515 (43%) reported that they always or frequently used lead gloves when restraining animals for radiographs. Only a survey9 conducted in 1989 inquired about the use of lead eyeglasses, and none of the 29 veterinary practices surveyed had that form of PPE available.
Personal protective equipment is recommended for all medical personnel present in a room during radiograph acquisition because exposure to any dose of ionizing radiation carries some risk for cancer induction.10 In women of child-bearing age, low-level radiation exposure is also associated with a very low risk of mutations that can result in congenital disease and adverse effects on an embryo or fetus.10 Cataract development is also a risk of radiation exposure once a threshold dose is exceeded.10
In Canada, recommendations on radiation protection in veterinary medicine are available from Health and Welfare Canada; however, private veterinary facilities in Saskatchewan and other provinces are under provincial Occupational Health and Safety jurisdiction.11 At the federal level, it is recommended that animals undergoing radiographic procedures be sedated or restrained with holding devices to avoid the need for manual restraint by veterinary personnel.11 If a worker must restrain an animal, protective aprons and gloves must be worn, and individual workers should avoid performing this duty regularly. Provincial regulations are less explicit. Employers are required to ensure that the effective radiation dose is ALARA and that no worker is unnecessarily exposed to radiation, and workers who are provided PPE by an employer are required to use it.12–14 Employers are required to ensure that their employees follow provincial regulations and can be subject to penalties if regulations are not followed in the workplace.13 Employers can take corrective action if employees do not follow provincial regulations.
Similar recommendations regarding radiation safety have been made for veterinary workers in the United States. The National Council on Radiation Protection and Measurements recommends that animals be restrained by mechanical supporting or restraining devices or sedated during radiographic procedures and that no person should routinely restrain patients during radiographic examinations.15 When manual restraint of an animal is necessary, workers should wear lead aprons and gloves that wholly enclose the hands. Regulations vary among states. For example, New York state law requires that animals be manually restrained for radiographs “only under extreme conditions when clinically necessary.”16 Additionally, the American College of Veterinary Radiology has created a position statement on radiation safety for veterinary workers.17
On the basis of the results of the previously cited studies,1–7,9 we hypothesized that federal recommendations on radiation protection were not consistently followed by veterinary workers tasked with performing small animal radiographic procedures. The objectives of the study reported here were to describe self-reported use of x-ray PPE (lead aprons, thyroid shields, gloves, and eyeglasses) by veterinary workers in Saskatchewan, Canada, and to examine factors that affect worker use of PPE.
Materials and Methods
Study recruitment
The study protocol was submitted to the University of Saskatchewan Behavioral Research Ethics Board and was determined to be exempt from review (BEH 16–127). An invitation to complete the online questionnaire was sent electronically to all members of the Saskatchewan Veterinary Medical Association with an email address (n = 727 veterinarians) and to all members of the Saskatchewan Association of Veterinary Technologists (421 veterinary technologists, 89 veterinary clinics, and 38 provisional and student members). Membership in those professional associations is mandatory for all veterinarians and technologists practicing in the province. The initial invitation and 2 reminders were sent over a 4-week period. At the start of the 4-week period, an invitation with 3 hard copies of the questionnaire was mailed to all members of the Saskatchewan Veterinary Medical Association whose practice codes identified them as working with birds, companion animals, exotic animals, or wildlife (n = 388 veterinarians). The questionnaire instructions indicated that an individual should complete the survey only once. Recipients were asked to forward the electronic survey link and to share hard copies of the survey with any workers involved in the acquisition of radiographs at their clinic who were not veterinarians or veterinary technologists.
Questionnaire
A copy of the questionnaire is available elsewhere (Supplementary Appendix S1, available at avmajournals.avma.org/doi/suppl/10.2460/javma.254.3.409). The questionnaire initially asked workers if they had been involved with the acquisition of radiographs of small animal patients (including companion animals, exotics, and wildlife) within the last year, and only workers who answered yes were asked to complete the remainder of the questionnaire. Workers were asked how often they were involved in the acquisition of radiographs, what type of x-ray PPE (lead apron, gloves, thyroid collar, or eyeglasses) they had been told their employer required them to wear, how often at least 1 worker was in the room when radiographs were taken (always, > 75% of the time, between 50% and 75% of the time, < 50% of the time, or never), and how often the clinic's lead aprons and gloves were checked for damage (don't know, twice a year, once a year, once every 2 years, other, or never). Workers were also asked how often they wore a personal dose–monitoring device (dosimeter), apron, thyroid shield securely closed around their neck, and eyeglasses (always, > 75% of the time, between 50% and 75% of the time, < 50% of the time, or never) when in a room where small animal radiographic procedures were being performed. Workers were then asked how often they used gloves in the following ways: both hands with hands inside the gloves, on one hand with the hand inside the glove and other hand and arm behind the back, no gloves, laid glove or gloves over one or both hands, or other. Workers were also asked how often they wore different types of gloves (eg, gloves that fully enclosed fingers and hands, gloves with an open portion for fingers or fingers and palms, or gloves of another type). The format for the questions exploring glove use was different from the format for the questions exploring apron, thyroid shield, and eyeglass use because we wanted to capture the multiple different ways by which workers could be expected to wear gloves, whereas aprons, securely closed thyroid shields, and eyeglasses either were or were not worn. Finally, workers were asked how often they held a radiographic cassette in position by hand or remained in the room during radiation exposure when not holding the animal or cassette (always, > 75% of the time, between 50% and 75% of the time, < 50% of the time, or never). Open-text questions were used to ask workers for suggestions of ways to increase use of thyroid shields, gloves, and eyeglasses.
Data analysis
Potential factors associated with the correct use of a lead apron, thyroid shield, gloves, and eyeglasses by veterinary workers during the acquisition of radiographs for small animal patients included employer requirement that the PPE be worn, how often the worker was involved in radiograph acquisition, worker role (veterinarian, veterinary student, technician or technologist, technician or technologist student, volunteer, or other), worker gender identification, worker age (> 65, 45 to 65, 25 to 44, 18 to 24, or < 18 years old), and method used to complete the questionnaire (electronic or hard copy). Correct glove use was defined as wearing gloves on both hands or wearing a glove on one hand with the other hand and arm held completely behind the back during radiation exposure. The effect of worker role, gender identification, age, and method used to complete the questionnaire on how often the worker was involved in performing radiographic procedures was also assessed. Risk factors were not examined for specific PPE that was worn by < 5% or > 95% of respondents.
The bivariate or unconditional associations between potential risk factors of interest and the percentage of time that gloves were used correctly were evaluated by means of linear regression because that percentage was calculated as a continuous outcome for survey respondents. For each respondent, the percentage of time that gloves were used correctly was calculated as the sum of the percentage of time that gloves were worn on both hands and the percentage of time that a glove was worn on one hand with the other hand and arm held completely behind the back during radiation exposure. Model residuals were graphed and visually checked for homogeneity of variance and normality. The respective associations between risk factors of interest and other outcomes (ie, proportion of time that lead aprons, thyroid shields, and eyeglasses were used) were assessed by means of appropriate nonparametric tests because each of those outcomes was reported on a 6-point ordinal scale. For categorical risk factors (employer requirement that the PPE be worn, worker role, worker gender identification, and method used to complete the questionnaire), the Kruskal-Wallis test was used with post hoc protected Wilcoxon rank sum tests to identify significant pairwise comparisons. For ordinal risk factors (frequency of taking radiographs and worker age), the Spearman correlation coefficient (ρ) was used to evaluate the association with use of each specific type of PPE. All analyses were performed with a commercial software program,a and values of P < 0.05 were considered significant.
Results
Respondents
Four hundred sixty questionnaires were completed and returned. Two hundred fifty-two (55%) were returned by mail (hard copy), whereas the remaining 208 (45%) were completed electronically. One hundred fifty of all 727 (21%) invited veterinarians and 150 of 388 (39%) invited veterinarians whose practice codes identified them as working with small animals completed the questionnaire. One hundred thirty-five of 421 (32%) veterinary technologists contacted completed the questionnaire.
Of the 460 respondents, 129 (28%) indicated that they had not been involved in performing radiographic procedures within the last year. Their questionnaires were considered complete after the first question and were excluded from all analyses regarding the use of PPE. Thus, only the questionnaires for the 331 (72%) respondents who indicated that they had been tasked with performing small animal radiographic procedures during the previous year were included in analyses of PPE use. Of those 331 respondents, 142 (43%) were veterinarians, 126 (38%) were veterinary technologists, 6 (2%) were veterinary students, 8 (2%) were veterinary technologist students, and 49 (15%) identified themselves as volunteers or some other type of veterinary personnel. Only 330 respondents reported their age; 3 (1%) were > 65 years old, 64 (19%) were between 45 and 65 years old, 193 (58%) were between 25 and 44 years old, and 70 (21%) were between 18 and 24 years old. None of the respondents were < 18 years old. With regard to gender identification, 293 of 331 (89%) respondents selected female, 37 (11%) selected male, and 1 (0.3%) selected other.
Frequency of radiograph acquisition and PPE use
Some respondents did not respond to all questions; therefore, the number of responses varied among questions. Among the 330 respondents who answered the question regarding how frequently they were involved with performing radiographic procedures, 40 (12%) reported more than once a day, 45 (14%) reported once/d, 114 (35%) reported 2 to 3 times/wk, 53 (16%) reported once/wk, 44 (13%) reported 2 to 3 times/mo, and 34 (10%) reported < 1 time/mo. Among the 331 respondents, 329 (99%), 320 (97%), 212 (64%), and 18 (5%) reported that their employer required them to wear a lead apron, thyroid shield, gloves, and eyeglasses, respectively, when obtaining radiographs of a patient. One hundred seventeen of 330 (35%) respondents indicated that they did not know how often lead aprons were radiographed to check for damage, and 127 of 329 (39%) respondents did not know how often lead gloves were checked for damage. One hundred fifty of 213 (70%) and 142 of 202 (70%) respondents reported that aprons and gloves, respectively, were checked for damage at least once annually.
The frequency of PPE use and other behaviors when respondents were in a room where radiographs of small animals were being obtained was summarized (Table 1). The frequency of how lead gloves were used and the types of gloves used was likewise summarized (Table 2). Two hundred seventeen of 327 (66%) respondents indicated that they used lead gloves correctly < 50% of the time. Moreover, 150 of 272 (55%) respondents indicated that they used gloves that had openings for finger or fingers and palms (ie, open gloves) ≥ 50% of the time, and 85 of those 150 (57%) respondents reported that they always used open gloves.
Frequency of PPE use and other behaviors reported by Saskatchewan veterinary workers involved with performing small animal radiographic procedures who responded to a questionnaire regarding their use of x-ray PPE.
| Frequency | |||||||
|---|---|---|---|---|---|---|---|
| PPE or behavior | No. of respondents* | Always | > 75% | 50%–75% | < 50% | Never | Not available |
| Lead apron | 330 | 325 (98) | 3 (1) | 2 (1) | 0 (0) | 0 (0) | 0 (0) |
| Lead thyroid shield | 331 | 291 (88) | 18 (5) | 6 (2) | 7 (2) | 8 (2) | 1 (0.3) |
| Lead eyeglasses | 330 | 9 (3) | 0 (0) | 3 (1) | 4 (1) | 113 (34) | 201 (61) |
| Dosimeter | 330 | 136 (41) | 61 (18) | 35 (11) | 55 (17) | 18 (5) | 25 (8) |
| At least 1 worker in room during exposure | 331 | 285 (86) | 36 (11) | 9 (3) | 0 (0) | 1 (0.3) | — |
| Respondent held a radiographic cassette in position by hand during exposure | 317 | 50 (16) | 13 (4) | 9 (3) | 27 (9) | 218 (69) | — |
| Spectator in room during exposure† | 331 | 28 (8) | 10 (3) | 2 (1) | 40 (12) | 251 (76) | — |
Values represent the number (percentage) of respondents unless otherwise indicated.
The number of respondents varied among PPEs and behaviors because some respondents did not answer all questions.
Respondent remained in the room while radiographs were being taken despite not being involved with animal or radiographic cassette positioning.
— = Not applicable.
Frequency of how lead gloves are used and the type of lead gloves used reported by respondents of the questionnaire described in Table 1.
| Frequency | ||||||
|---|---|---|---|---|---|---|
| Variable | No. of respondents* | Always | > 75% | 50%–75% | < 50% | Never |
| How gloves are used | ||||||
| Gloves on both hands | 327 | 19 (6) | 29 (9) | 25 (8) | 139 (43) | 115 (35) |
| Glove on 1 hand | 327 | 1 (0.3) | 2 (0.6) | 12 (4) | 132 (40) | 180 (55) |
| No gloves | 327 | 35 (11) | 88 (27) | 72 (22) | 57 (17) | 75 (23) |
| Gloves placed on top of hands | 327 | 4 (1) | 8 (2) | 23 (7) | 179 (55) | 113 (35) |
| Gloves used correctly† | 327 | 25 (8) | 39 (12) | 46 (14) | 130 (40) | 87 (27) |
| Type of gloves used | ||||||
| Gloves that fully enclose hands | 272 | 96 (35) | 16 (6) | 41 (15) | 26 (10) | 93 (34) |
| Gloves with an open portion | 272 | 85 (31) | 14 (5) | 51 (19) | 23 (8) | 99 (36) |
Gloves worn on both hands, or a glove worn on one hand with the other hand and arm held completely behind the back during radiation exposure.
See Table 1 for remainder of key.
Factors associated with PPE use
Factors associated with the use of lead aprons and eyeglasses were not assessed owing to the high and low frequency of use of those particular PPEs, respectively. The proportion of respondents who reported wearing a thyroid shield was significantly (P = 0.009) greater among those who had been told that their employer required them to wear a thyroid shield (median, 100%) than those who had not been told that their employer required them to wear a thyroid shield (median, > 75%). The frequency with which respondents were involved with acquiring radiographs was significantly (P = 0.008) associated with how frequently they wore a thyroid shield. Respondents who were tasked with obtaining radiographs more than once a day wore a thyroid shield significantly (P < 0.03) more frequently than respondents who were tasked with obtaining radiographs 1 to 3 times/wk. Role within the practice was also significantly (P = 0.01) associated with frequency of thyroid shield use; however, given that the number of veterinary students (n = 6), veterinary technologist students (8), and volunteers (1) was small, those roles were excluded from further analysis. Some veterinarians wore thyroid shields significantly (P = 0.01) less frequently than technologists. The frequency with which veterinarians and veterinary technologists wore thyroid shields did not differ significantly from the frequency with which respondents who reported their role as other (n = 48) wore thyroid shields. Two hundred twenty of 293 (75%) respondents who identified as female reported that they always wore a thyroid shield when taking radiographs, whereas 28 of 37 (76%) respondents who identified as male reported that they wore a thyroid shield at least 75% of the time when taking radiographs. Only 15 of 293 (5%) respondents who identified as female reported wearing a thyroid shield < 75% of the time when taking radiographs, and 2 of 37 (5%) respondents who identified as male reported that they never wore a thyroid shield when taking radiographs. Respondent age (P = 0.22) and method (hard copy or electronic) used to complete the questionnaire (P = 0.48) were not significantly associated with the frequency of thyroid shield use during radiograph acquisition.
Risk factors associated with correct use of gloves during the radiograph acquisition were summarized (Table 3). The proportion of respondents who wore gloves correctly was significantly (P < 0.001) greater among those whose employers required glove use than those whose employers did not require glove use. The proportion of respondents who wore gloves correctly was significantly (P = 0.005) greater for those who were ≥ 45 years old, compared with those who were < 45 years old, but did not differ significantly (P = 0.91) between respondents who were 25 to 44 years old and those who were 18 to 24 years old. The proportion of respondents who wore gloves correctly was significantly greater among those who took radiographs multiple times per day (P = 0.027), 2 to 3 times/mo (P = 0.015), and < 1 time/mo (P = 0.016), compared with those who took radiographs once weekly. The mean (SE) percentage of time that respondents wore gloves correctly did not differ significantly (P = 0.72) among veterinarians (35% [3%]), veterinary students (45% [14.7%]), veterinary technologists (30% [3.2%]), veterinary technologist students (33% [13%]), and volunteers and other veterinary personnel (34% [5.3%]). The mean (SE) percentage of time that respondents wore gloves correctly also did not differ significantly (P = 0.58) between those who identified as female (33% [2.1%]) and those who identified as male (36% [6.0%]). The method used to complete the questionnaire was not significantly (P = 0.60) associated with the frequency of correct glove use during radiograph acquisition.
Proportion of respondents of the survey described in Table 1 who reported that they correctly used lead gloves during small animal radiographic procedures when categorized on the basis of various potential risk factors.
| Risk factor | Category | Mean (95% confidence interval) proportion of respondents | P value* |
|---|---|---|---|
| Employer requires employees to use lead gloves when taking radiographs | Yes | 0.44 (0.39–0.49) | < 0.001 |
| No | 0.14 (0.93–0.19) | Referent | |
| Respondent age (y) | > 65 | 0.80 (0.40–1.20) | Referent |
| 45–65 | 0.43 (0.34–0.51) | 0.075 | |
| 25–44 | 0.31 (0.26–0.36) | 0.018 | |
| 18–24 | 0.30 (0.22–0.39) | 0.018 | |
| Frequency with which respondent was involved with taking radiographs | Multiple times per day | 0.40 (0.28–0.51) | 0.027 |
| Once daily | 0.29 (0.19–0.40) | 0.39 | |
| 2–3 times/wk | 0.31 (0.25–0.38) | 0.17 | |
| Once weekly | 0.23 (0.13–0.33) | Referent | |
| 2–3 times/mo | 0.41 (0.30–0.51) | 0.015 | |
| < 1 time/mo | 0.45 (0.33–0.57) | 0.016 |
Linear regression analysis.
See Table 1 for remainder of key.
Role was significantly (P = 0.012) associated with frequency of taking radiographs. Radiographs were most frequently obtained by veterinary technologists, and 32 of 126 (25%) veterinary technologist respondents reported that they obtained radiographs of patients at least once daily. There was a significant (P = 0.024) negative correlation between respondent age and frequency of taking radiographs (ρ, −0.13); however, respondent gender identification (P = 0.31) and method used to complete the questionnaire (P = 0.21) were not significantly correlated with frequency of taking radiographs.
Respondent suggestions for increasing use of PPE during acquisition of radiographs
Of the 331 survey respondents, 105, 221, and 237 provided suggestions for increasing the use of lead thyroid shields, eyeglasses, and gloves, respectively. The most common suggestions provided for increasing use of thyroid shields included the use of aprons with attached thyroid shields (n = 30), education of workers on the risks associated with exposure to ionizing radiation (28), stronger fasteners to securely fasten the thyroid shield in place (21), implementation of a rule requiring that all personnel in the room during radiation exposure use a thyroid shield (11), and availability of thyroid shields that fit better (10). The most common suggestions for increasing use of leaded eyeglasses included making such eyeglasses available (n = 111), education of workers on the risks associated with exposure to ionizing radiation (85), implementation of a rule requiring that all personnel in the room during radiation exposure use eyeglasses (19), making lead eyeglasses less expensive (6), and making lead eyeglasses that can be worn over prescription eyeglasses (5). The most common suggestions provided for increasing use of lead gloves included making the gloves more flexible so that it is easier to restrain animals (n = 188), improving the fit of gloves for small hands (25), education of workers on the risks associated with exposure to ionizing radiation (22), and implementation of a rule requiring that all personnel in the room during radiation exposure use gloves (13).
Discussion
Federal guidelines in both Canada and the United States recommend that individual workers should not routinely restrain animals for radiographic procedures and that lead aprons and gloves must be worn.11,15 However, those recommendations are not always followed in small animal veterinary practices in Saskatchewan, as evidenced by the fact that 285 of the 331 (86%) respondents of the present survey reported that there was always at least 1 worker in the room while small animal radiographic procedures were being performed and that 217 of 327 (66%) respondents reportedly used leaded gloves correctly < 50% of the time. Mechanical restraint of animals by means of positioning aids such as sandbags, foam wedges, and troughs may allow workers to leave the room during radiation exposure and should be used whenever possible.18,19 Chemical restraint is recommended when mechanical restraint is not sufficient to allow workers to leave the room during radiation exposure, but sedation and anesthesia are not routinely used for diagnostic imaging by most veterinarians.3,18 Results of an observational study20 on the use of x-ray PPE by workers at a veterinary teaching hospital indicate that 67% of animals were radiographed without sedation or anesthesia. Barriers to the sedation or anesthesia of animals for radiographic procedures include an increase in the risk for complications (including death) and the need for monitoring of patient cardiac and respiratory variables, which increases clinic workload.21,22 The use of sedation or anesthesia also increases the cost of radiographic procedures for owners.
Given that manual restraint of animals during radiographic procedures is common in many veterinary practices and that a small number of workers are usually responsible for radiograph acquisition, methods to increase use of x-ray PPE by veterinary personnel should be considered by employers. Almost all respondents (325/330 [98%]) of the present survey reported that they always wore a lead apron when restraining an animal for a radiographic procedure. Although the majority (291/331 [88%]) of respondents also reported that they always wore a thyroid shield while taking radiographs, 39 (12%) respondents indicated that they did not consistently wear a thyroid shield, and 1 respondent indicated that a thyroid shield was not available at his or her practice. Respondents suggested that the provision of aprons with attached thyroid shields or thyroid shields with fully functional fasteners would help increase use of that PPE. Making thyroid shields mandatory was another common suggestion for increasing their use, and results of the present survey indicated that respondents were more likely to wear thyroid shields if their employers required that they do so. Respondents also suggested that education of veterinary workers about risks associated with exposure to ionizing radiation would help to increase use of thyroid shields as well as eyeglasses and gloves during radiographic procedures. Only 9 of 330 (3%) respondents indicated that they always wore lead eyeglasses when assisting with radiographic procedures, and the majority (201/330 [61%]) of respondents indicated that lead eyeglasses were not available at their clinics. For workers exposed to ionizing radiation in the province of Saskatchewan, the current annual permissible dose equivalent limit is 150 mSv for eye lenses.12 However, in 2012, the International Commission on Radiation Protection recommended decreasing the annual equivalent dose limit for the lens of an eye to 20 mSv, averaged over 5 years, with no single year exceeding an equivalent dose of 50 mSv; that recommendation was made on the basis of evaluation of new data for cataractogenesis.23 Results of a study24 in which the scatter radiation dose was measured for 3 workers who routinely restrained small animals for radiographic procedures indicate that the unshielded eye of 1 worker was exposed to an equivalent dose of 3 mSv over a 2-month period, which would equate to an annual dose close to the annual limit recommended by the International Commission on Radiation Protection. When individual workers are regularly exposed to radiation doses > 20% of the annual permissible dose limit, Canadian guidelines recommend that protective measures must be improved.11 Annual occupational dose limits are based on an estimation of an acceptable health risk to workers and must not be exceeded; however, employers are also required to keep the radiation dose of all workers ALARA.12 If the recommendations of the International Commission on Radiation Protection are incorporated into federal legislation and results of worker radiation dose monitoring and other studies support the findings of the study24 involving 3 workers in a small animal radiology department, it may become mandatory for veterinary personnel to wear lead eyeglasses while assisting with radiographic procedures in the near future. The most common suggestions to increase eyeglass use provided by the respondents of the present survey were to make them available and educate veterinary workers and employers on the risks associated with exposure of the eyes to ionizing radiation.
The results of the present survey were less clear about ways to increase the use of lead gloves during radiograph acquisition. The most common suggestion for increasing glove use provided by respondents was to make the gloves more flexible. Many respondents indicated that they were unable to position and restrain animals for imaging when wearing the bulky gloves. Unfortunately, the recommended attenuation equivalent for gloves is 0.5 mm of lead, and that cannot be currently achieved with less bulky materials. The attenuation equivalent of a glove is directly related to the reduction in radiation dose it provides to a hand. Although decreasing the attenuation equivalent of a glove would increase its flexibility, the glove would not provide the same level of protection against scattered radiation that travels from the animal toward the person restraining it. Ensuring that veterinary workers have access to lead gloves that fit hands of all sizes, particularly small hands, was another common recommendation for increasing correct use of gloves. Respondents also suggested that sedation of animals might increase the use of gloves because sedated animals would be less resistant to positioning. In a recent observational study20 of 35 workers at a veterinary teaching hospital, sedation of animals significantly decreased the number of people in the room while radiographs were being taken, but it had no significant effect on glove use, likely because sedation was primarily used to facilitate positioning of patients not to influence glove use. When patients are sedated or anesthetized for radiographic procedures, a conscious effort should be made to use nonmanual methods of restraint whenever possible, minimize the number of people who remain in the room while radiographs are being obtained, and ensure that the people who must remain in the room are correctly wearing all forms of PPE. In the present survey, respondents who were required to wear gloves by their employers were significantly more likely to do so than workers who were not required to wear gloves by their employers. In fact, the mean percentage of time that respondents reported wearing gloves correctly was 30% greater for those who were required to wear gloves by their employers than those who were not required to wear gloves by their employers. This led us to conclude that veterinary workers were more likely to wear lead gloves during radiograph acquisition if they were required to do so by their employer. However, that finding may have been subject to a form of recall bias whereby behavior that is perceived to be self-threatening is underreported. For example, veterinary workers who are required to wear gloves by their employers may be more aware of the risks associated with not wearing gloves than workers who are not required to wear gloves by their employers.25 Another form of recall bias that might have affected the results of the present survey is that respondents who took radiographs frequently may have recalled their PPE use, or lack thereof, more accurately than respondents who took radiographs only occasionally.
From a radiation protection viewpoint, a common and troubling practice during the acquisition of radiographs for small animal patients is the laying of lead gloves over the top of the restrainer's hands or the use of gloves with open palms during radiation exposure. That practice may give restrainers a false sense of protection. The primary source of exposure is scatter radiation from the animal, and unless the lead is placed between the restrainer's hand and the animal, attenuation of scattered radiation will not occur.8 Gloves with a slit or opening for fingers and gloves that have a fully open palm have been designed for veterinary use. When gloves with a slit in the palm are used, the fingers should be fully retracted back into the lead glove during radiation exposure, which is difficult to achieve when the fingers are gripping a portion of the animal.
Federal guidelines recommend that personal dosimeters be worn by radiology personnel who are likely to receive a dose in excess of 1/20 of the permissible dose equivalent limit, and that additional dosimeters be worn on extremities if it is likely that the extremities will be exposed to higher radiant doses.11 In the study24 involving 3 small animal radiology department workers, an equivalent dose of 2.8 mSv over a 2-month period was measured on the unshielded arm of 1 worker. That worker restrained animals for a total of 778 exposures,24 which would be equivalent to approximately 4 to 5 single anatomic site studies/working day, assuming 4 exposures/study and 20 working days/mo. Given that a restrainer's hands are likely to be closer to the source (animal) of the scatter radiation than the arms, it is possible that the equivalent dose to unshielded hands of a person restraining animals for radiographs in a veterinary practice that obtains a high volume of radiographs will be > 25 mSv, which is 1/20 of 500 mSv, the annual permissible dose equivalent limit to hands for radiology personnel in Saskatchewan.12 Consequently, finger dosimeters should be considered for veterinary workers who consistently restrain animals for radiographs without wearing gloves, particularly in practices that take a high volume of radiographs. That recommendation is not meant to support the practice of not wearing gloves while radiographs are obtained. In fact, we would like to emphasize that veterinary workers who manually restrain animals for radiographs without wearing lead gloves and other PPE will be exposed to unnecessary radiation and at risk for associated adverse effects; such a practice is also contrary to federal recommendations and the principle of keeping radiation doses ALARA.
A limitation of the present survey was that we were unable to calculate the overall survey response rate because veterinarians and veterinary technologists were encouraged to share the questionnaire with their colleagues who were involved with radiograph acquisition, and there was no way for us to determine how many people actually received or had access to the questionnaire. Nevertheless, results of the present survey suggested that use of x-ray PPE was quite variable among veterinary workers in Saskatchewan and that further investigation of methods to decrease unnecessary radiation exposure and improve radiation safety practices is warranted. Additionally, although 2 methods (hard copy and electronic) were used to administer the questionnaire, the method of administration was not identified as a confounder in our analyses.
Results of the present survey of veterinary workers in Saskatchewan, Canada, indicated that federal recommendations regarding radiation protection in veterinary clinics were not consistently followed. The findings also suggested that use of x-ray PPE by veterinary workers might be improved if its use was mandated by employers. Suggestions by respondents to increase x-ray PPE use included ensuring that properly fitting and functional PPE was available to all workers tasked with performing radiographic procedures and educating workers about the health risks associated with exposure to ionizing radiation. Personal dosimeters were not consistently worn by the respondents of this survey; therefore, occupational exposure reporting that relies on dosimeter readings likely underestimates the radiation dose for most veterinary workers.
Acknowledgments
Student workers who helped conduct this survey were supported by stipends funded by the University of Saskatchewan College of Medicine Dean's Summer Research Projects.
The authors declare that there were no conflicts of interest.
ABBREVIATIONS
| ALARA | As low as reasonably achievable |
| PPE | Personal protective equipment |
Footnotes
Stata SE, version 14.1, Stata Corp LP, College Station, Tex.
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