Survey of self-reported radiation safety practices among North American veterinary technicians involved in equine radiography using portable x-ray equipment

Alexandra F. Belotta From the Department of Small Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada.

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Monique N. Mayer From the Department of Small Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada.

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Niels K. Koehncke Department of Medicine, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada.

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James Carmalt From the Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada.

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Fernando P. Freitas From the Department of Small Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada.

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Cheryl L. Waldner From the Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada.

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Abstract

OBJECTIVES

To describe self-reported radiation safety practices by equine veterinary technicians in North America and identify factors associated with these practices.

SAMPLE

154 equine technicians.

PROCEDURES

An electronic questionnaire regarding radiation safety practices during the use of portable x-ray equipment was sent to 884 members of the American Association of Equine Veterinary Technicians and Assistants. Data were summarized, and various factors were evaluated for associations with reported safety practices.

RESULTS

221 of 884 (25.0%) questionnaires were completed, including 154 by equine technicians who had been involved in equine radiography as x-ray tube operators, cassette holders, or both in the previous year. Lead apron use was suboptimal, reported as “always” for 80.0% (104/130) of tube operators and 83.1% (123/148) of cassette holders. Approximately 20% of participants never wore thyroid shields, and approximately 90% never wore lead eyeglasses. Almost 50% of participants did not have lead eyeglasses available. Although > 55% of participants always held the x-ray equipment by hand, 58.4% (73/125) of tube operators and 25.0% (35/140) of cassette holders never wore gloves. Cassette holders wore lead gloves and personal radiation dose–monitoring devices significantly more frequently than did tube operators.

CONCLUSIONS AND CLINICAL RELEVANCE

Compliance of North American equine technicians with radiation safety recommendations by the National Council on Radiation Protection and Measurements was suboptimal. Improvements in radiation safety training and education, strengthening the connection between academic institutions and private practices, and greater availability and requirement of personal protective equipment use by senior clinicians and employers might aid in improving safety practices.

Abstract

OBJECTIVES

To describe self-reported radiation safety practices by equine veterinary technicians in North America and identify factors associated with these practices.

SAMPLE

154 equine technicians.

PROCEDURES

An electronic questionnaire regarding radiation safety practices during the use of portable x-ray equipment was sent to 884 members of the American Association of Equine Veterinary Technicians and Assistants. Data were summarized, and various factors were evaluated for associations with reported safety practices.

RESULTS

221 of 884 (25.0%) questionnaires were completed, including 154 by equine technicians who had been involved in equine radiography as x-ray tube operators, cassette holders, or both in the previous year. Lead apron use was suboptimal, reported as “always” for 80.0% (104/130) of tube operators and 83.1% (123/148) of cassette holders. Approximately 20% of participants never wore thyroid shields, and approximately 90% never wore lead eyeglasses. Almost 50% of participants did not have lead eyeglasses available. Although > 55% of participants always held the x-ray equipment by hand, 58.4% (73/125) of tube operators and 25.0% (35/140) of cassette holders never wore gloves. Cassette holders wore lead gloves and personal radiation dose–monitoring devices significantly more frequently than did tube operators.

CONCLUSIONS AND CLINICAL RELEVANCE

Compliance of North American equine technicians with radiation safety recommendations by the National Council on Radiation Protection and Measurements was suboptimal. Improvements in radiation safety training and education, strengthening the connection between academic institutions and private practices, and greater availability and requirement of personal protective equipment use by senior clinicians and employers might aid in improving safety practices.

Introduction

The NCRP provides specific recommendations1 for the use of portable x-ray equipment during veterinary diagnostic radiographic procedures. The x-ray tube and the cassette should be supported by mechanical devices rather than being held by hand. Personal protective equipment such as aprons and gloves or portable shielding should be used. Furthermore, operators should stand at least 6 feet away from the patient, x-ray tube, and useful beam, when practicable.1

With the advent of digital radiography and the introduction of portable digital detectors to equine practice approximately 20 years ago, the overall number of radiographic evaluations has increased and use of portable x-ray equipment has increased.2 In contrast to small animal practice, where workers are not always required to be in the radiology room during diagnostic radiographic procedures,3 equine workers must always be present to operate the portable equipment. Factors inherent to the nature of horses might increase workers’ exposure to ionizing radiation during radiographic procedures. Such factors include proximity to the source of scattered radiation, use of high technical settings to examine thick body parts, and a high number of exposures obtained by a few workers, in particular during prepurchase examinations. In addition, use of digital radiography may be linked with a greater number of exposures than traditional radiography because of the capability to generate multiple radiographs over a brief period to ensure adequate positioning.

Because of the higher risk of exposure to ionizing radiation associated with equine radiography versus small animal radiography, workers’ safety practices should be compliant with radiation safety regulations to keep radiation doses ALARA. Use of some types of PPE by equine workers was suboptimal in an Australian survey,4 wherein radiographic procedures workers reported wearing thyroid shields in 83% of the 77 participating equine clinics and lead gloves in only 8%. In that study,4 the frequency of lead eyeglasses use and of other safety practices was not reported. In another survey of radiation protection compliance during mobile equine radiography in Norway, thyroid shields were reportedly never or rarely used by the person holding the x-ray generator or image detector plate in 11 of 37 (30%) practices, and lead glasses were used in only 1 (3%) practice.5 Lead gloves were used never or rarely by the person holding the generator in 20 of 37 (54%) practices and by the plate holder in 6 (16%) practices.

Although there seems to be a general lack of adherence to recommendations proposed by the NCRP, radiation safety practices among individual workers in equine practice have not been reported to the authors’ knowledge. Equine technicians potentially experience a high number of ionizing radiation exposures given their duties. The objective of the cross-sectional survey reported here was to describe self-reported radiation safety practices of equine technicians during radiography of horses using portable x-ray equipment and to identify factors associated with these practices. We hypothesized that safety practices would not be compliant with NRCP recommendations.

Materials and Methods

Study population

The target population for this survey study included equine veterinary technicians who were registered as members of the AAEVT. An email invitation to participate in the study was sent to all members of the AAEVT (n = 884) by a representative of the association. The email contained information about the study and a link to a web-based questionnaire. Respondents were asked to complete the questionnaire only once. Respondents who completed the questionnaire had the option to enter a draw for a $100 gift card. Reminders to complete the questionnaire were sent by email to all members of the AAEVT 1 and 2 weeks after the initial email invitation.

The research protocol was reviewed by the University of Saskatchewan Behavioral Research Ethics Board and was determined to be exempt from review according to article 2.5 of the Tri-Council Policy Statement for Ethical Conduct for Research Involving Humans, December 2014.

Questionnaire

The questionnaire consisted of 32 closed-ended questions addressing radiation safety practices and was developed by use of a web-based program.a The authors reviewed each question as a group and tested the questionnaire multiple times individually. The questionnaire was comprised of 4 sections, and only participants who had been involved in radiographic examination of a horse during the previous year were able to complete all sections. Given that technicians may participate in equine radiography as x-ray tube operators and as cassette holders and that their behaviors may differ between these 2 tasks, they were asked to describe their behavior for each task separately.

Questions for both tasks (x-ray tube operation and cassette holding) included the mean number of radiographic exposures acquired in a week (< 1, 1 to 15, 16 to 30, 31 to 45, or > 45) and frequency of use or performance of the following: lead apron, thyroid protector securely attached around the neck, lead eyeglasses, holding the x-ray equipment (x-ray tube or cassette) by hand, wearing a lead glove on the hand or hands holding the x-ray equipment, and wearing a PRDMD while operating the portable x-ray unit or handling the cassette (always, > 75% of the time, between 50% and 75% of the time, < 50% of the time, never, or except for holding equipment by hand, not available/I have not been assigned). Categories were used because participants could not be expected to accurately recall the precise frequency of use and were based on those used in 3 previous questionnaires regarding radiation safety behaviors during small animal radiography and fluoroscopy.6,7,89

Participants were also asked to select the 3 most important reasons they held the x-ray equipment (x-ray tube or cassette) by hand (“It takes too much time to use a stand/cassette holder,” “I cannot achieve the desirable quality of images when I use a stand/cassette holder,” “The risk of worker injury by the horse is higher when using a stand/cassette holder,” “I am not concerned about the adverse health effects of ionizing radiation,” “A stand/cassette holder is not available,” and “My employer does not require me to use a stand/cassette holder”). They were also asked to select the 3 most important reasons for not wearing lead gloves while holding the x-ray equipment by hand (“Gloves interfere with performing my task,” “Gloves are uncomfortable,” “Gloves are not required by my employer,” “Not enough gloves for all workers,” “I am not concerned about the adverse health effects of ionizing radiation,” “My coworkers do not wear gloves,” “Gloves are unhygienic,” and “Gloves do not fit properly”), with the first selected reason being the most important. These reasons were developed by the authors, and the reasons for not wearing gloves were based on reasons previously provided by small animal radiography workers.6 Participants were not required to select 3 reasons.

The next section of the questionnaire asked participants to rate their knowledge of the risks of ionizing radiation (excellent, good, fair, or poor); the frequency with which they stood 6 feet away from the horse, x-ray tube, and primary beam during the exposure; how they usually stored the lead aprons when traveling to other locations for radiographic examinations (hung by the shoulders on a clothes hanger, laid over a flat surface, folded/rolled, or other), and whether they regularly inspected and checked PPE for defects, cracks, creases, and perforations (no, I don’t know, or yes – please specify how often). The method of inspecting and checking the PPE for damage was not stated in the question, and participants were not asked whether they personally inspected and checked the PPE.

The fourth section of the questionnaire contained questions regarding personal information about the participants, including membership in the Academy of Equine Veterinary Nursing Technicians, percentage of their veterinary work that was with horses (< 50%, 50% to 75%, 75% to 100%, or 100% [per question phrasing]), country of the veterinary clinic where they primarily worked (United States, Canada, or other), type of practice (private, academic, or other – please specify), age group (< 18, 18 to 24, 25 to 44, 45 to 64, or > 65 years of age), and gender (female, male, transgender, prefer not to say, or other – please specify).

Statistical analysis

Knowledge of radiation risk, percentage of time working with horses, country, practice type, age, and gender (ie, factors of interest) were evaluated for associations with radiation safety practices (ie, outcomes of interest: percentage of time that lead aprons, thyroid shields, gloves, glasses, and PRDMDs were used, that equipment was held by hand, and that workers stood 6 feet away from the horse, x-ray tube, and primary beam during the exposure). These factors were chosen because worker knowledge of radiation risk, practice type, country, and gender were found to be significantly associated with radiation safety behaviors during small animal radiography or fluoroscopy.7,8,9

Associations between the factors of interest and percentage of time workers stood 6 feet away from the horse, x-ray tube, and primary beam during the exposure were assessed for all respondents. Radiation safety practices that pertained to both x-ray tube operators and cassette holders (percentage of time that lead aprons, thyroid shields, gloves, glasses and PRDMDs were used and equipment was held by hand) were compared between these 2 task groups with the Wilcoxon signed rank test. Within the cassette holder group, associations between factors of interest and each outcome of interest were assessed because of the higher radiation exposure expected for cassette holders versus x-ray tube operators.10 Within the tube operator group, only outcomes found to differ significantly between cassette holders and x-ray tube operators (ie, percentage of time that gloves and PRDMDs were worn) were analyzed for associations with the factors of interest.

Because each outcome was reported on an ordinal scale, nonparametric tests were used for analyses of associations. The Kruskal-Wallis test was used with the post hoc protected Wilcoxon rank sum test to identify significant pairwise comparisons. When only 2 factor categories were compared, the Wilcoxon rank sum test was used. The median categories for percentage of time are reported when a significant difference in medians was identified.

All analyses were performed by an analytic epidemiologist (CLW) who used a statistical software program.b Values of P < 0.05 were considered significant.

Results

Respondents

A total of 221 respondents completed the self-reported survey between May 12, 2019, and June 1, 2019, for a response rate of 25.0% (221/884). Of the 221 respondents, 8.6% (19/221) did not identify as equine veterinary technicians and were excluded from further analysis. Of the remaining 202 respondents who were equine technicians, 8 (4.0%) reported that they were not involved in obtaining radiographs in the previous year and 2 (1.0%) did not report whether they were involved in radiographic procedures and were thus prevented from completing the questionnaire. The remaining 192 (95.0%) equine technicians reported that they were involved in a radiographic examination with a portable x-ray unit in the previous year and were thus able to complete the 4 sections of the questionnaire.

Of the 192 equine technicians able to complete the questionnaire, 38 (19.8%) were excluded because they did not complete any questions in 1 or both of the questionnaire sections that included questions about factors of interest or did not complete at least half of the questions about radiation safety practices. Our study sample therefore was comprised of 154 participants, and their characteristics are summarized (Table 1). For the purposes of statistical analysis only, owing to very small numbers, respondents reporting a practice type other than academia or private practice (n = 2), age > 65 years (2), and country other than the United States or Canada (1) were excluded, representing 4 technicians in total (1 person was included in 2 of these categories).

Table 1

Selected characteristics of equine technicians (n = 154) who completed a questionnaire regarding radiation safety practices during equine radiography.

Characteristic Category* No. (%) of respondents
Gender Male 6 (3.9)
Female 148 (96.1)
Age (y) 18–24 9 (5.8)
25–44 104 (67.5)
45–65 41 (26.6)
Type of practice Academic 24 (15.6)
Private 130 (84.4)
Percentage of veterinary < 50 8 (5.2)
work spent with horses* 50–75 10 (6.5)
75–100 25 (16.2)
100 111 (72.1)
Country Canada 9 (5.8)
US 145 (94.2)

Categories are reported as phrased in the questionnaire.

Frequency of radiograph acquisition and safety practices

Overall, 130 of 150 (84.4%) respondents reported their typical behavior when operating the x-ray, tube and 148 (96.1%) described their typical behavior when holding the cassette. These statistics included several (125/154 [81.2%]) respondents who reported performing both tasks. Among the 130 respondents who had served as x-ray tube operators in the previous year, 17 (13.1%) reported acquiring > 45 exposures/wk on average, 12 (9.2%) reported between 31 and 45 exposures/wk, 21 (16.2%) between 16 and 30 exposures/wk, 61 (46.9%) reported between 1 and 15 exposures/wk, and 19 (14.6%) reported < 1/wk. Among the 148 respondents who had served as cassette holders, 12 (8.1%) reported acquiring > 45 exposures/wk on average, 18 (12.2%) reported between 31 and 45 exposures/wk, 32 (21.6%) reported between 16 and 30 exposures/wk, 69 (46.6%) reported between 1 and 15 exposures/wk, and 17 (11.5%) reported < 1/wk. Frequencies of use of PPE and PRDMDs and of holding the x-ray equipment by hand were summarized by task group (Table 2).

Table 2

Number (%) of respondents who reported various frequencies of PPE use and other radiation safety practices during x-ray tube operation or cassette holding.

Practice, by task Always > 75% 50%–75% < 50% Never Not available or not assigned
X-ray tube operation
Wearing lead apron (n = 130) 104 (80.0) 16 (12.3) 3 (2.3) 3 (2.3) 4 (3.1) 0 (0)
Wearing thyroid shield (n = 130) 49 (37.7) 22 (16.9) 11 (8.5) 18 (13.8) 25 (19.2) 5 (3.8)
Wearing lead eyeglasses (n = 129) 1 (0.8) 1 (0.8) 2 (1.6) 9 (7.0) 57 (44.2) 59 (45.7)
Holding tube by hand (n = 130) 73 (56.2) 26 (20.0) 7 (5.4) 19 (14.6) 5 (3.8)
Wearing gloves* (n = 125) 14 (11.2) 10 (8.0) 8 (6.4) 13 (10.4) 73 (58.4) 7 (5.6)
Wearing PRDMD (n = 129) 62 (48.1) 23 (17.8) 16 (12.4) 13 (10.1) 8 (6.2) 7 (5.4)
Cassette holding
Wearing lead apron (n = 148) 123 (83.1) 17 (11.5) 1 (0.7) 4 (2.7) 3 (2.0) 0 (0)
Wearing thyroid shield (n = 148) 54 (36.5) 25 (16.9) 17 (11.5) 13 (8.8) 29 (19.6) 10 (6.8)
Wearing lead eyeglasses (n = 146) 2 (1.4) 0 (0) 3 (2.1) 7 (4.8) 67 (45.9) 67 (45.9
Holding cassette by hand (n = 148) 90 (60.8) 25 (16.9) 15 (10.1) 9 (6.1) 9 (6.1)
Wearing gloves* (n = 140) 48 (34.3) 19 (13.6) 15 (10.7) 17 (12.1) 35 (25.0) 6 (4.3)
Wearing PRDMD (n = 146) 75 (51.4) 24 (16.4) 19 (13.0) 11 (7.5) 8 (5.5) 9 (6.2)

Wearing gloves pertains to the time while holding the x-ray tube or cassette.

— = Not applicable.

Reported reasons for suboptimal safety practices

The 3 most important reasons provided by respondents were summarized for holding the x-ray tube or cassette by hand during tube operation or cassette holding and for not wearing lead gloves when holding the x-ray equipment by hand (Table 3).

Table 3

The 3 most important reasons selected by respondents for holding portable x-ray equipment by hand and for not wearing lead gloves while holding the equipment by hand during radiographic procedures.

Practice, by task Reason No. (%) of respondents
X-ray tube operation
Equipment held by hand (n = 122)
  1. A stand is not available

  2. Cannot achieve desirable quality of image

  3. Risk of injury by horse

  • 51 (41.8)

  • 28 (23.0)

  • 19 (15.6)

Not wearing gloves (n = 106)
  1. Gloves interfere with performing task

  2. Gloves are not required by employer

  3. There are not enough gloves for all workers

  • 76 (71.7)

  • 14 (13.2)

  • 6 (5.7)

Cassette holding
Equipment held by hand (n = 130)
  1. Cannot achieve desirable quality of image

  2. A stand is not available

  3. Risk of injury by horse

  • 46 (35.4)

  • 44 (33.8)

  • 28 (21.5)

Not wearing gloves (n = 87)
  1. Gloves interfere with performing task

  2. Gloves are not required by employer

  3. There are not enough gloves for all workers

  • 70 (80.5)

  • 9 (10.3)

  • 4 (4.6)

Level of knowledge of effects of ionizing radiation and general safety practices

Level of knowledge of the effects of ionizing radiation and general safety practices reported by respondents were summarized (Table 4). Half (77/154 [50.0%]) of respondents reported that PPE was regularly inspected and checked for defects, cracks, creases, and perforations. Of those 77 respondents, 70 (90.9%) specified the frequency with which PPE was inspected as every other year (n = 3 [4.3%]), yearly (34 [48.6%]), twice a year (12 [17.1%]), every 2 to 5 months (5 [7.1%]), monthly (6 [8.6%]), and daily to every 2 weeks (10 [14.3%]).

Table 4

Knowledge of the risks of ionizing radiation and general safety practices as self-reported by respondents.

Knowledge or practice Category No. (%) of respondents
Level of knowledge of risks of ionizing radiation Excellent 28 (18.2)
Good 87 (56.5)
Fair 35 (22.7)
Poor 4 (2.6)
6 feet away from the horse, x-ray tube, and primary beam* Always 9 (5.8)
> 75% of time 21 (13.6)
50%–75% of time 19 (12.3)
< 50% of time 43 (27.9)
Never 62 (40.3)
Storage of lead apron Hung by shoulders on hanger 37 (24.0)
Folded or rolled 58 (37.7)
Laid on a flat surface 52 (33.8)
Regular inspection of PPE Yes 77 (50.0)
No 41 (26.6)
Do not know 36 (23.4)

Considered during the radiographic exposure.

Factors associated with safety practices

The percentage of time participants reported standing 6 feet away during the radiographic exposure was lower for those who rated their knowledge of radiation risk as fair (median category, never), compared with those who rated their knowledge as good (median category, < 50% of the time; P = 0.003) or excellent (median category, 50% to 75% of the time; P = 0.002). In addition, the percentage of time standing 6 feet away was lower for those who worked 100% of the time with horses (median category, < 50% of the time) than for those who worked 75% to 100% of the time with horses (median category, 50% to 75% of the time; P = 0.004) or 50% to 75% of the time with horses (median category, > 75% of the time; P = 0.01). The percentage of time was also lower for those who worked in private practice (median category, < 50% of the time) than for those who worked in academia (median category, 50% to 75% of the time; P = 0.03). Country (P = 0.76), age (P = 0.95), and gender (P = 0.40) were not associated with the percentage of time standing 6 feet away.

Comparisons of safety practices between the 2 radiographic task groups revealed that when serving as cassette holders, technicians wore lead gloves (median category, > 75% of the time; P < 0.001) and PRDMDs (median category, always; P = 0.02) more frequently than when serving as x-ray tube operators (median category, never and 50 to 75% of the time, respectively). There were no differences between the 2 task groups in frequencies of using lead aprons (P = 0.16), thyroid shields (P = 0.11), and lead eyeglasses (P = 0.99) and of holding x-ray equipment by hand (P = 0.16).

The percentage of time cassette holders reported wearing a lead apron was higher for those who worked in academia than for those who worked in private practice (P = 0.02). The percentage of time cassette holders reported wearing lead eyeglasses was higher for those who worked in private practice than for those who worked in academia (P = 0.02).

The percentage of time cassette holders reported holding the cassette by hand was higher for those who worked in private practice (median category, always) than for those who worked in academia (median category, 50% to 75% of the time; P < 0.001). Among cassette holders who held the cassette by hand, frequency of use of lead gloves was higher for those who worked in the United States (median category, > 75% of the time) than for those who worked in Canada (median category, never; P < 0.03), for those who worked in academia (median category, always) than for those who worked in private practice (median, 50% to 75% of the time; P < 0.02), and for workers who were 25 to 44 years old (median category, 50% to 75% of the time) and 45 to 64 years old (median category, always) than for those who were 18 to 24 years old (median category, never; P = 0.046 and 0.01, respectively).

The percentage of time cassette holders reported wearing a PRDMD was higher for those who were 45 to 64 years old (median category, always) than for those who were 25 to 44 years old (median category, > 75% of the time; P = 0.03). No significant (P ≥ 0.10) associations were identified between the factors of interest and the frequency of cassette holders wearing thyroid shields. No significant (P ≥ 0.06) associations were identified between the factors of interest and frequencies of x-ray tube operators wearing lead gloves and PRDMDs.

Discussion

Self-reported use of PPE in the present study was inconsistent among the surveyed population of equine technicians. Most participants reported always holding the x-ray equipment by hand, and approximately 40% reported never staying 6 feet away from the horse, x-ray tube, and primary beam during the exposure. Therefore, the findings supported our hypothesis and demonstrated suboptimal radiation safety practices and lack of compliance with NCRP recommendations during diagnostic radiographic procedures with portable x-ray equipment. These findings are of concern given that chronic exposure to low doses of ionizing radiation increases the risk of stochastic effects, which are effects occurring without a threshold level of dose and with a probability of happening proportional to the radiation dose. Within stochastic effects, cancer development is the major concern; however, heritable effects are also possible.11

Wearing of lead aprons and thyroid shields is essential to protect reproductive organs, thyroid gland, and other organs and tissues from scattered radiation during radiographic procedures. Previous studies4,6,7 have shown optimal use of lead aprons (frequency ≥ 98%) by equine veterinarians and small animal veterinarians and technologists. In contrast, the frequency of always wearing lead aprons among the equine technicians in our study was < 85%, and the frequency of never wearing a thyroid shield or not having it available for use was > 23%, regardless of the radiographic task (x-ray tube operation or cassette holding). These findings are of concern, particularly the suboptimal use of lead aprons, given that participants were primarily females of childbearing age, including professionals at the beginning of their career and working predominantly with horses. A high priority must be placed on the protection of equine technicians and on the correct use of PPE because these people might be involved in radiographic procedures for their entire professional life.

An increased risk of childhood cancer has been associated with in utero exposure to ionizing radiation.12 A previous study13 showed an increased risk of cancer development not only in the uterus, ovary, and breast but also in bone marrow, lymphoid system, thyroid, and larynx among women occupationally exposed to ionizing radiation versus women in the general public.13 These findings highlight the importance of wearing lead aprons and thyroid shields at all times during radiographic procedures.

Despite NCRP recommendations, > 55% of respondents in each task group of the present study reported that they held the x-ray tube or cassette by hand at all times. A survey5 of veterinarians performing mobile equine radiography in Norway revealed that workers used a stand for the x-ray tube often or always at 43% (16/37) of practices and a cassette holder often or always at 59% (22/37) of practices, which seems to reflect slightly better radiation safety practices than those of equine technicians in the United States and Canada. It is understandable that factors inherent to horses and the nature of this type of work, including horse temperament and the risk of injury to the worker, could restrict the use of mechanical devices to support the x-ray equipment for some patients. However, in such cases, protective lead gloves should be worn because the hands are the closest part of the body to the source of scattered radiation (the horse).

The lower frequency of lead glove wearing by x-ray tube operators in the present study could have been due to the perception that people involved as cassette holders are closer to the source of scattered radiation than are x-ray tube operators and, consequently, are exposed to higher doses of ionizing radiation. Indeed, a previous study10 showed that, without lead shielding, cassette holders were exposed to higher doses of ionizing radiation for all anatomic projections investigated. However, comparison of radiation doses between x-ray tube operators and cassette holders, particularly for body regions composed of thicker bone and soft tissue structures (and therefore associated with high levels of scattered radiation14), was not performed in that study.10 Therefore, insufficient scientific data are available to conclude that cassette holders are exposed to higher levels of scattered radiation for all types of radiographic examinations. In addition, regardless of which task exposes workers to the higher radiation dose, according to the ALARA principle, workers performing both tasks should wear lead gloves at all times to substantially reduce the risk of hand exposure to ionizing radiation.

In 2012, the International Commission on Radiological Protection recommended reducing the annual equivalent dose limit for the lens of the eyes in occupational workers exposed to ionizing radiation from 150 mSv/y to 20 mSv/y, the same equivalent dose limit as for the whole body.13 This reduction was based on epidemiological findings that suggested cataract formation could occur at significantly lower doses of ionizing radiation than previously established.15 In 2016, the NCRP also decreased the recommended annual occupational dose limit for the lens of the eyes to 50 mGy.16 The frequency of lead eyeglasses use by the equine technicians in the present study was very low, with approximately 90% of those involved in both tasks reporting that they never wore, or did not have available for use, lead eyeglasses. Given the high radiosensitivity of the lens of the eyes and the potential risk of cataract development as an adverse effect of low doses of ionizing radiation,17 it is crucial that equine technicians involved in radiographic procedures protect their eyes with lead eyeglasses.

According to the NCRP recommendations for veterinary medicine, PRDMDs should be used by occupational workers involved in radiographic procedures and by individuals who are likely to receive a radiation dose 10% above recommended limits.1 Recommendations for use of PRDMDs may vary by regulatory body. A low percentage of equine technicians in both task groups of the present study reported that they were not assigned a PRDMD. Only approximately half of respondents reported wearing their assigned PRDMD at all times, meaning that PRDMD readings of the remaining respondents underestimated their radiation exposure.

Workplace was an important factor in the frequencies of equine technicians using lead aprons, gloves, and eyeglasses; holding the cassette by hand; and maintaining proper distance from the source of scattered radiation. Frequencies of these radiation safety practices were higher among technicians in academia versus private practice, except for lead eyeglasses use, the frequency of which was higher among technicians in private practice versus academia. Better safety practices in academia may have been attributable to a different workplace culture, whereby workers were engaged in a teaching environment in which research and new information were routinely exchanged. Additionally, oversight at multiple levels by workplace safety committees and workers dedicated to workplace safety may be more common in academic institutions than in private practices. Although age category was associated with some radiation safety practices, including frequencies of glove and PRDMD use and holding of cassettes by hand, no conclusions could be drawn because superior safety compliance was not consistently found for a particular age group.

Together with shielding and time, distance from the source of radiation is an important means of keeping radiation doses ALARA. Equine technicians who reported excellent and good levels of knowledge of the risks of ionizing radiation were more likely to keep the NCRP-recommended distance from the horse, x-ray tube, and primary beam, suggesting that training and education may improve safety practices. It is also possible that technicians who reported excellent and good levels of knowledge were more aware of recommended practices, increasing the possibility of recall bias (overestimating the frequencies of desirable practices). Unfortunately, approximately one-quarter of equine technicians reported having poor knowledge of risks of ionizing radiation. The conditions in which lead PPE are stored and maintained are important because use of shielding with cracks, creases, or perforations might not provide effective protection against scattered radiation.18 However, only approximately one-quarter of equine technicians in the present study reported properly hanging lead aprons by the shoulders, and only half reported that PPE was inspected for defects on a regular basis.

Limitations of the study reported here included the possibility that respondents were not aware whether the PPE was regularly inspected and checked if another worker was responsible for this task. The questionnaire was anonymous to help avoid reporting bias, and no information was collected on the identity of respondents or their workplaces. Consequently, the effect of workplace on radiation safety practices could not be evaluated. More than 1 respondent from the same clinic may have completed the questionnaire, allowing the possibility that the practices at a particular clinic (eg, checking of PPE for damage) might influence the overall findings for individual equine technicians. Additionally, because the number of equine technicians in private practice versus academia was unknown, we were unable to determine whether the study sample was representative of the population of interest.

Another limitation was the use of subjective terms rather than objective measures to describe the knowledge of risks of ionizing radiation, given that interpretations of the questions likely varied among individual respondents. The questionnaire was limited to equine technicians who were registered members of the AAEVT, and their responses may not have represented other equine technicians. Both voluntary response bias and nonresponse bias likely affected the results. Furthermore, other reasons may have existed for suboptimal radiation safety practices that were not included among the questionnaire response options. The questionnaire was not pretested for validity and reliability.

Finally, the present study was designed as a hypothesis-generating exploratory study, and as such, no potential interactions or confounding among the factors of interest were examined during statistical analyses. Only a limited set of such factors was assessed. Although the number of statistical comparisons was intentionally kept to a minimum, the potential remained for type II error owing to the number of questions asked.

Because of the aforementioned limitations, the results of this study should be interpreted with caution. Nevertheless, some valuable information was obtained regarding current radiation safety practices of equine technicians that warrants remedial action. Protection of equine technicians from scattered radiation during diagnostic radiographic procedures was suboptimal. Our findings suggested that radiation safety practices could be improved through improvements in training and education, strengthened connection between academic institutions and private practices, increased availability of PPE, and required use of PPE by senior clinicians and employers.

Acknowledgments

The authors declare that there were no conflicts of interest.

Presented in abstract form (oral presentation) at the American College of Veterinary Radiology Scientific Meeting, Baltimore, October 2019.

The authors thank the Saskatchewan Health Research Foundation for the postdoctoral fellowship (Belotta) and Deborah B. Reeder, executive director of the American Association of Equine Veterinary Technicians.

Footnotes

a.

SurveyMonkey Enterprise, Ottawa, ON, Canada.

b.

Stata SE, version 15.0, Stata Corp LLC, College Station, Tex.

Abbreviations

AAEVT

American Association of Equine Veterinary Technicians and Assistants

ALARA

As low as reasonably achievable

NCRP

National Council on Radiation Protection and Measurements

PPE

Personal protective equipment

PRDMD

Personal radiation dose–monitoring device

References

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    Mayer MN, Koehncke NK, Belotta AF, et al. Use of personal protective equipment in a radiology room at a veterinary teaching hospital. Vet Radiol Ultrasound 2018;59:137146.

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    Mikkelsen MA, Ottesen N, Knutsen BH, et al. Lack of radioprotection knowledge and compliance in Norwegian equine ambulatory practice. Vet Radiol Ultrasound 2019;60:265272.

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    Mayer MN, Koehncke NK, Taherian AC, et al. Self-reported use of x-ray personal protective equipment by Saskatchewan veterinary workers. J Am Vet Med Assoc 2019;254:409417.

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    Mayer MN, Koehncke NK, Sidhu N, et al. Use of protective hand shielding by veterinary workers during small animal radiography. Can Vet J 2019;60:249254.

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    Freitas FP, Koehncke NK, Waldner CL, et al. Self-reported radiation safety behaviors among veterinary specialists performing fluoroscopic procedures. J Am Vet Med Assoc 2021;in press.

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    Ellis KL, Morton AJ, Hernandez JA, et al. Radiation exposure to personnel obtaining equine appendicular radiographs using a handheld generator. J Equine Vet Sci 2019;73:7074.

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    Widmer WR, Shaw SM, Thrall DE. Effects of low-level exposure to ionizing radiation: current concepts and concerns for veterinary workers. Vet Radiol Ultrasound 1996;37:227239.

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  • 12.

    Doll R, Wakeford R. Risk of childhood cancer from fetal irradiation. Br J Radiol 1997;70:130139.

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    Milacic S. The incidence of malignant neoplasms in individuals working in areas of ionizing radiation in hospitals. J BUON 2008;13:377384.

    • Search Google Scholar
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    Hupe O, Ankerhold U. Dose to persons assisting voluntarily during X-ray examinations of large animals. Radiat Prot Dosimetry 2008;128:274278.

  • 15.

    Stewart FA, Akleyev AV, Hauer-Jensen M, et al. ICRP publication 118: ICRP statement on tissue reactions and early and late effects of radiation in normal tissues and organs—threshold doses for tissue reactions in a radiation protection context. Ann ICRP 2012;41:1322.

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  • 16.

    Dauer LT, Ainsbury EA, Dynlacht J, et al. Guidance on radiation dose limits for the lens of the eye: overview of the recommendations in NCRP Commentary No. 26. Int J Radiat Biol 2017;93:10151023.

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  • 17.

    Ainsbury EA, Bouffler S, Dorr W, et al. Radiation cataractogenesis: a review of recent studies. Radiat Res 2009;172:19.

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Contributor Notes

Address correspondence to Dr. Belotta (alexandra.belotta.vet@gmail.com).
  • 1.

    NCRP. Radiation protection in veterinary medicine. Bethesda, Md: NCRP, 2004;148.

  • 2.

    McKnight AL. Digital radiography in equine practice. Clin Tech Equine Pract 2004;3:352360.

  • 3.

    D’Souza E, Barraclough R, Fishwick D, et al. Management of occupational health risks in small-animal veterinary practices. Occup Med (Lond) 2009;59:316322.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 4.

    Surjan Y, Ostwald P, Milross C, et al. Radiation safety considerations and compliance within equine veterinary clinics: results of an Australian survey. Radiography 2015;21:224230.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 5.

    Mayer MN, Koehncke NK, Belotta AF, et al. Use of personal protective equipment in a radiology room at a veterinary teaching hospital. Vet Radiol Ultrasound 2018;59:137146.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 6.

    Mikkelsen MA, Ottesen N, Knutsen BH, et al. Lack of radioprotection knowledge and compliance in Norwegian equine ambulatory practice. Vet Radiol Ultrasound 2019;60:265272.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 7.

    Mayer MN, Koehncke NK, Taherian AC, et al. Self-reported use of x-ray personal protective equipment by Saskatchewan veterinary workers. J Am Vet Med Assoc 2019;254:409417.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 8.

    Mayer MN, Koehncke NK, Sidhu N, et al. Use of protective hand shielding by veterinary workers during small animal radiography. Can Vet J 2019;60:249254.

    • Search Google Scholar
    • Export Citation
  • 9.

    Freitas FP, Koehncke NK, Waldner CL, et al. Self-reported radiation safety behaviors among veterinary specialists performing fluoroscopic procedures. J Am Vet Med Assoc 2021;in press.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 10.

    Ellis KL, Morton AJ, Hernandez JA, et al. Radiation exposure to personnel obtaining equine appendicular radiographs using a handheld generator. J Equine Vet Sci 2019;73:7074.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 11.

    Widmer WR, Shaw SM, Thrall DE. Effects of low-level exposure to ionizing radiation: current concepts and concerns for veterinary workers. Vet Radiol Ultrasound 1996;37:227239.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 12.

    Doll R, Wakeford R. Risk of childhood cancer from fetal irradiation. Br J Radiol 1997;70:130139.

  • 13.

    Milacic S. The incidence of malignant neoplasms in individuals working in areas of ionizing radiation in hospitals. J BUON 2008;13:377384.

    • Search Google Scholar
    • Export Citation
  • 14.

    Hupe O, Ankerhold U. Dose to persons assisting voluntarily during X-ray examinations of large animals. Radiat Prot Dosimetry 2008;128:274278.

  • 15.

    Stewart FA, Akleyev AV, Hauer-Jensen M, et al. ICRP publication 118: ICRP statement on tissue reactions and early and late effects of radiation in normal tissues and organs—threshold doses for tissue reactions in a radiation protection context. Ann ICRP 2012;41:1322.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 16.

    Dauer LT, Ainsbury EA, Dynlacht J, et al. Guidance on radiation dose limits for the lens of the eye: overview of the recommendations in NCRP Commentary No. 26. Int J Radiat Biol 2017;93:10151023.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 17.

    Ainsbury EA, Bouffler S, Dorr W, et al. Radiation cataractogenesis: a review of recent studies. Radiat Res 2009;172:19.

  • 18.

    Phillips B, Duran EB. Rejection criteria for defects in lead apparel used for radiation protection of x-ray workers. Vancouver, BC, Canada: British Columbia Centre for Disease Control, 2003;27.

    • Search Google Scholar
    • Export Citation

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