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British Journal of Radiology 75 (2002),249-252 © 2002 The British Institute of Radiology

Full Paper

Paediatric personnel extremity dose study

J M C Gallet, PhD1,2,3 and M H Reed, MD2,3

1 Department of Medical Physics, CancerCare Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba, Canada R3E 0V9, 2 Winnipeg Children's Hospital, Department of Paediatric Radiology, 840 Sherbrooke Street, Winnipeg, Manitoba, Canada R3A 1S1 and 3 University of Manitoba, Department of Radiology, College of Medicine, Winnipeg, Manitoba, Canada R3A 1S7


   Abstract
Top
 Abstract
Introduction
 Materials and method
 Results
 Discussion and summary
 References
 
Concern has been expressed in paediatric radiology regarding the magnitude of the extremity dose received by attending personnel during routine fluoroscopic procedures and CT. Common procedures that may be of short duration in adults can be quite the opposite in paediatric patients. The extremities of attending personnel are more likely to be exposed to the primary beam and for a longer period of time owing to a variety of reasons such as assisting in the procedure or physically restraining the patient during the examination. During the period mid 1998 to mid 2000, two paediatric radiologists, four senior radiographers and two paediatric nurses were monitored using ring thermoluminescent dosemeters (TLDs). Each participant wore the ring TLD on either the left or right ring finger, depending on which hand the individual favoured. Left/right asymmetrical studies were not conducted, nor were records kept of whether an examination used a grid or gridless technique. Initial apprehension about higher paediatric fluoroscopic and CT extremity doses was dispelled as a result of this quantitative dosimetric study.


   Introduction
Top
 Abstract
 Introduction
Materials and method
 Results
 Discussion and summary
 References
 
In the Paediatric Radiology Department at the Winnipeg Children's Hospital, dose to the patient, care-givers and radiographic personnel is kept as low as possible given the conditions of the imaging equipment without compromising diagnostic image quality. In paediatric fluoroscopy and CT, it is always a concern, whether real or perceived, that because the studies are not always as straightforward as the equivalent adult ones, particularly in terms of restraining the patient, the occupational dose received during fluoroscopy or CT by attending radiologists, nurses and radiographers will be higher. In addition, contributing to the uneasiness is a heightened awareness throughout the radiology community of higher doses owing to lengthy fluoroscopic procedures. The current body of published literature is focused principally towards an adult patient population, and interventional or cardiological dosimetric studies [1–23]. In this study we have concentrated exclusively on a paediatric population during CT and fluoroscopic examinations.

Two concerns were expressed at our institution that initiated this study. The first was the general concern of radiographers who, because their duties required them to be in close proximity to paediatric patients and thus to the imaging equipment, believed they might be receiving high extremity doses. Radiographic personnel do not wear lead-lined gloves during the normal course of any fluoroscopic procedure. The second concern was perhaps not as substantiated but nevertheless was a cause of anxiety for radiographers. The fluoroscopy equipment at our institution is 10 years old and shows increasing mechanical and technical problems. It has been shown in the literature that suboptimal fluoroscopic equipment can be directly correlated with higher exposure levels [24]. This unit has also been identified through our quality assurance (QA) card tracking system as described in a previous publication [25]. As a consequence, image quality is also questionable and exhibits variations as measured with a dedicated contrast/detail phantom. The performance of the equipment over time has resulted in the present concern expressed by radiographers. It was suggested at one of our regular QA meetings that dosimetric ring badges might be used to better monitor personnel and thus address any subsequent problems regarding exposures more promptly.

Monitoring at eye level was considered but, since the radiographers were of the opinion that their hands were receiving not only scattered radiation but also primary radiation, it was decided that only ring badges would be used at this time. It should also be noted that at this time the Paediatric Radiology Department does not have a dedicated CT unit, which means that only paediatric radiologists and nurses are attendant at CT, but not radiographers. With the arrival of our own dedicated CT unit near the end of 2001, paediatric radiographers will perform CT examinations.


   Materials and method
Top
 Abstract
 Introduction
 Materials and method
Results
 Discussion and summary
 References
 
In mid 1998, two full-time paediatric radiologists, one paediatric nurse and four senior radiographers were recruited into this study. During the calendar year 1999, one radiologist (Radiologist 1 in the data set) left the department to take on new responsibilities and duties. There were no other changes to the monitored personnel in calendar year 1999. One part-time paediatric nurse (Paediatric Nurse 2 in the data set) was added in the calendar year 2000.

Senior radiographers attend to the paediatric patient during fluoroscopic studies. This may be to comfort the patient, or as an aid in the procedure. Also, during the course of 1999, radiographers began to perform voiding cystourethrography on older children in accordance with the transfer of function protocol in our hospital. Of the senior radiographers in the monitored group, one was used as a control. His duties were mainly concentrated in angiocardiology where he would receive little or no radiation exposure to the hands.

Thermoluminescent dosemeters (TLDs) in the form of ring dosemeters were obtained from the National Dosimetry Services (NDS) of Canada. The NDS has been licensed in Canada according to Regulatory Standard S-106(E) [26]. The ring dosemeters were worn on either the right or left ring finger. They were worn daily and exchanged for new rings at the end of each month. Dosimetric reports were also generated monthly. In addition, all study participants wore the regulation TLD under their lead apron as outlined in Health and Welfare Canada Safety Code 20-A [27]. The TLD worn under the lead apron was read on a quarterly basis and is that used for an estimate of whole body dose [28]. Although each participant wore a thyroid shield during fluoroscopic studies, at this institution it is not customary to wear an exterior collar dosemeter. In general, for small children and infants, lead eyewear is not worn by the attending radiographers, as these patients can be disturbed or agitated upon seeing radiographers wearing this type of glasses. Left/right asymmetry as well as grid or gridless technique were not recorded separately for this dosimetric study. Of the female participants, none were or became pregnant during the study period. As data readings were to be used as a benchmark, the ring TLDs were stored away from any ionizing radiation sources to prevent anomalous evaluations as much as possible, as has been reported in the literature [29]. The revised Canadian regulations in force since May 2000 stipulate that dose to a nuclear energy worker for a 1-year period must not exceed 500 mSv to the hands and feet [30]. A nuclear energy worker has been defined as "a person who is required, in the course of the person's business or occupation in connection with a nuclear substance or nuclear facility, to perform duties in such circumstances that there is a reasonable probability that the person may receive a dose of radiation that is greater than the prescribed limit for the general public" [30]. The prescribed limit for the general public is 1 mSv whole body per year [30].

Paediatric Radiologist 1 was engaged in CT as well as interventional and basic fluoroscopic studies. Paediatric Radiologist 2 was principally engaged in basic fluoroscopic studies such as barium studies and voiding cystourethrography. The duties of the paediatric nurses required them to restrain or hold patients when necessary, administer intravenous contrast medium, and assist in CT and interventional fluoroscopic studies.


   Results
Top
 Abstract
 Introduction
 Materials and method
 Results
Discussion and summary
 References
 
The study group has been monitored since May 1998. As shown in Figure 1Go, Radiologist 1 received the highest extremity dose (130.8 mSv) for the monitored period of 1998. This is 79.4 mSv, or almost 61%, higher than the next participant, Paediatric Nurse 1, with a reading of 51.4 mSv. If one extrapolates the reading of Radiologist 1 to a full year, a value of approximately 196 mSv is determined, representing approximately 39% of the yearly extremity dose allowed. Although this value is within the regulatory limit, it remains a concern to the group as it is considered to be an unacceptable personnel dose level in paediatrics. This high value should also be further investigated as it may be indicative of malfunctioning equipment. Also, in 1998 Nurse 1 received almost five times higher dose than Radiographer 2, and in 1999 twice as much as the next highest, again Radiographer 2.



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  		Figure 1. Histogram representing the complete dataset from mid 1998 to mid 2000, showing all of the participants in the study and their yearly extremity dose exposure. N1, Nurse 1; C, control; N2, Nurse 2; R1, Radiographer 1;RAD1, Radiologist 1; R2, Radiographer 2; R3, Radiographer 3; RAD2,Radiologist 2.

 

   Discussion and summary
Top
 Abstract
 Introduction
 Materials and method
 Results
 Discussion and summary
References
 
Staffing rotations, increased staffing levels and changes in patient protocols contributed to extremity dose levels of less than 10 mSv. Therefore, monthly extremity dosimetric monitoring was shown not to be warranted in paediatric radiology. Dose as quantitatively measured by the finger TLDs indicated that in general the radiographic personnel were not exposed to more radiation than initially recorded by their corresponding quarterly whole body dose estimates. It was also decided that the wearing of lead gloves was not required. If procedures or protocols change, then the wearing of lead gloves should be revisited.

The paediatric radiologist with the highest extremity dose levels was found, in further discussions, to be holding paediatric patients at CT. He was advised to decrease the frequency of this duty and preferably to discontinue this practice entirely. It is not the policy of the department to encourage holding of patients unless there is no viable alternative.

At the beginning of 2000, a multi-detector row CT unit was installed, replacing an older single row detector system. The subsecond rotational speed of this new unit is sufficient to result in less holding of the patient being necessary, thus decreasing the extremity dose to Paediatric Nurse 1. Coupled with the fact that there are currently two nurses sharing responsibilities and duties in the Paediatric Radiology Department, each nurse is now receiving minimal extremity dose readings. Over the course of 1999 and into 2000, several more radiographers shared the duties of performing voiding cystourethrography with Radiographers 1, 2 and 3 in this study, leading to a decrease in the exposure readings of Radiographers 1, 2 and 3.

In conclusion, although the initial study was initiated by staff anxieties relating to old fluoroscopic equipment and longer examination times, in summary all personnel involved were not receiving more than the maximum allowed, that is 500 mSv per year, in any of the monitored years. This is not to imply that action will not be taken by the department unless the regulatory limit is reached by an individual. On the contrary, dose audits will be conducted on a regular basis. Also, audits are performed when new equipment is installed or when changes or new protocols warrant a review. The department has benchmarked extremity doses, which will be periodically reviewed as part of our quality improvement programme.

Received for publication March 6, 2001. Revision received August 14, 2001. Accepted for publication September 17, 2001.


   References
Top
 Abstract
 Introduction
 Materials and method
 Results
 Discussion and summary
 References
 

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This Article
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Right arrow Articles by Gallet, J M C
Right arrow Articles by Reed, M H

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