ORIGINAL ARTICLE

Occupational Exposure of Orthopaedic Trainees to Radiation

Martin P Laird*,John Tawfik *, Timothy J Small *,Brett Courtenay **

*Australian Orthopaedic Association (AOA) Advanced Surgical Trainees
**St Vincent’s Hospital Sydney, Australia

Address for Correspondence:

Martin Laird
Postal Address
PO Box 32
Randwick NSW 2031
Phone : +61 431 050945
Email: mlaird@gmp.usyd.edu.au

Abstract:

Background
Current orthopaedic practice involves an increasing use of operative fluoroscopic screening and radiation exposure. The Australian Orthopaedic Association (AOA) publication entitled “Radiation safety for orthopaedic surgeons” outlines the risks. There is a disparity between guidelines and actual clinical practice for trainee registrars.
The aims of this study are

1. To measure trainee fluoroscopy usage with and without consultants present.
2. To audit trainees and hospitals adherence to the guidelines

Methods

A retrospective review of data routinely kept by the operating theatre staff of a tertiary referral hospital was conducted. This included Procedure, Operating Surgeon, Assistant and the presence or absence of the Consultant. Fluoroscopic Exposure Time was also recorded.
Procedures were grouped and times compared according to supervision of consultant for trainee registrar.

42 cases were performed by an orthopaedic registrar with the consultant assisting and 76 were performed in the absence of the consultant.
A questionnaire based on the AOA guidelines was produced and distributed to NSW advanced Orthopaedic trainees.

Results

Difference of 32.18 seconds in mean screening time / case (p-value 0.0069)
One registrar was exposed to 8131 seconds of radiation in 6 months. Without the use of lead protection, the trainee would have exceeded the annual limit of whole body exposure by 2-fold.

Conclusion

Dramatic decreases in exposure can be achieved by better discipline with the usage of II. This needs to be a fundamental part of registrar training. 

The survey shows trainees are not aware, or fail to adhere to current guidelines and that hospitals are not providing appropriate safety equipment and not insisting that staff exercise safe practices.
( ABSTRACT WORD COUNT 250)

J.Orthopaedics 2011;8(4)e6

Keywords:

Cancer; Ionising radiation; Radiation protection; Surgeon; Training

Introduction:

Orthopaedic practice increasingly involves the use of fluoroscopic screening thus increasing radiation exposure to surgical and nursing staff in the operating theatre.

The incidence of certain forms of cancer appears to be higher in orthopaedic surgeons than in the general population, with one survey of members of the Australian Orthopaedic Association (AOA) revealing an increased incidence of thyroid carcinoma among Orthopaedic Surgeons (1).  Thyroid carcinoma has been shown to occur as a direct result of exposure to ionising radiation with a low-exposure dose being significant and without a defined specific minimum exposure. (2).
The biological effects of radiation exposure can be classified as either deterministic or stochastic.  Deterministic effects are those for which the severity of the effect varies with the dose, and for which a threshold exists (3). Above the threshold level, the extent of the damage increases with dose. Examples include non-malignant damage to the skin, cataract of the ocular lens, and gonadal cell damage leading to infertility. These effects do not occur for absorbed doses less than a threshold level (2Gy) (4), which is far greater than the doses encountered in common orthopaedic procedures.  The assumption regarding deterministic effects, is that the rate of “injury” is low enough for cells to be able to repair themselves (5).

Stochastic effects, such as the induction of cancer, may be induced even in doses close to zero. It is the probability rather than the severity of such effects that increases with increasing radiation exposure.  Stochastic effects have no threshold dose and the assumption is that the damage from radiation is cumulative over a lifetime (5).

Radiation exposures, commonly occurring in radiological procedures, have been reported as being associated with zero probability for induction of deterministic effects but a non-zero probability for cancer or genetic effects (4).  Ionising radiation may also be a risk factor in the development of childhood leukemia in the offspring of individuals exposed to low-level preconception radiation (5).  The effect of exposure to high levels of radiation has been directly linked to increasing the incidence of cancers, whereas the effect of low-level radiation remains uncertain (6).

The AOA has published a booklet entitled Radiation Safety for Orthopaedic Surgeons in a bid to raise awareness among surgeons about the specific dangers associated with ionising radiation (3). The document lists specific guidelines to be followed by orthopaedic surgeons when using ionising radiation in surgical procedures (3). However, we believe there is a disparity between AOA guidelines and actual clinical practice for trainee registrars for the use of ionising radiation in orthopaedic surgery.

The two principle aims for this paper are firstly, to assess if the supervision of a consultant surgeon in the operating theatre reduces fluoroscopic radiation exposure time for orthopaedic trainees and, secondly to assess orthopaedic trainee’s awareness of and adherence to AOA radiation safety guidelines.

Methods :

All elective and emergency surgical procedures performed by a single orthopaedic advanced training registrar in a 6 month period requiring fluoroscopic screening were included in the study. The operations were performed in the operating suite of St Vincent’s Hospital, NSW between January 2006 and July 2006. The trainee was the primary surgeon for all cases included in the study.

Data was collected and recorded by nursing staff in the theatre log book. This included procedure, operating surgeon and presence or absence of the consultant surgeon at the time of operation. All intraoperative screening was conducted using a Shimadzu Opescope 50N Image Intensifier. Fluoroscopic exposure time (seconds) of the image intensifier was recorded in a logbook by the radiographer. These records were used to calculate the data presented in the study.

The main outcome measure was a comparison of the Orthopaedic Registrar’s mean fluoroscopy exposure time between cases performed in the presence and absence of a consultant surgeon. An anonymous questionnaire based on the AOA guidelines for the use of ionising radiation was produced and distributed to all NSW advanced trainees in Orthopaedic Surgery.

Data was expressed as mean with 95% Confidence Intervals and statistical analysis was performed using an unpaired t-test for exposure time.

Results :

Overall, 118 cases met the inclusion criteria for the study. Fourty two cases were performed by the trainee with the consultant present and 76 were performed in the absence of the consultant.
The overall mean exposure time was significantly greater in cases performed by the registrar alone (70.4 seconds) compared to those in which the consultant was present (38.2 seconds; p = 0.007).

Table 1: Summary data of orthopaedic trainee intraoperative radiation exposure time in the presence and absence of the treating consultant surgeon

Table 3: Questionnaire distributed to all NSW orthopaedic trainees

Thirty one of the 51 Orthopaedic trainees completed the anonymous questionnaire.
 
Discussion :

Over the last 2 decades, fluoroscopy has been increasingly utilised for interventional and surgical procedures. This has resulted in increasing exposure of health care workers to low-dose ionising radiation. The effects of this career-long exposure to health care professionals and potentially even to their offspring, may not manifest for many years. The health related risks of chronic low-dose ionising radiation remain essentially unknown, and are therefore unpredictable. Hence, it is essential to highlight the potential risks and minimise occupational radiation exposure (7)
The American National Council on Radiation Protection recommends whole body exposure to radiation be limited to 50 mSv / year. The International Commission of Radiological Protection and Australian National Occupational Health and Safety Commission (NOHSC) recommend whole body exposure to radiation be limited to 20mSv/year. All agree that maximum exposure to hands be 500mSv/year (8,9). These recommended limits have been revised downward at least five times since 1934 (5). This shows there is no agreement on what is a safe limit of low-dose ionizing radiation exposure in the workplace and one must practice using radiation levels as low as reasonably achievable. (9)

Three variables have been described to limit exposure to radiation during the use of fluoroscopy.

1. Mechanical factors (fluoroscopic unit, direction of the radiation beam and duration of exposure). 2. Use of protective devices. 3. Working distance between the surgical team and the fluoroscopic unit (6).

Mechanical protection begins with the fluoroscopic unit. The use of pulsed imaging during fluoroscopy has been shown to reduce overall exposure by 20 – 75% (7). Fluoroscopic beam collimation has also been shown to reduce radiation exposure by reducing the amount of scattered radiation (7,10). The use of last image hold on multiple screens and biplanar memory mode has been shown to decrease the length of fluoroscopy screening time by as much as 60% (6). Other settings that help to reduce radiation output include use of the low dose option, using a laser guide to ensure images are centered and avoidance of image magnification (11). To ensure that these features are functioning optimally, the fluoroscopic unit should be subject to periodic inspection, quality control testing and calibration by a medical physicist (12,6). In our survey, 97% of trainees were not aware of the maintenance and inspection schedules of radiation-generating and protection equipment.

Correct placement of the C-arm in surgery is important for minimising radiation exposure to patient and surgeon. When the beam is activated, it enters tissue and produces scatter in the direction of the transmitter. In pinning of hip fractures the image receptor of the image intensifier should be as close as possible to the patient. This reduces the entrance skin dose to the patient, allows greater use of collimation to area of interest and provides less geometric distortion (3).  The image receptor should be above the patient in the anteroposterior projection, reducing scatter to the head and neck of the surgeon. In the lateral projection, the image receptor should be on the same side as the surgeon reducing the amount of scatter directed towards the surgeon (3). In hand, foot and elbow surgery, a table should be used and the x ray tube positioned below the table in order to minimise scatter to the eyes and thyroid of the surgeon. Our survey showed that 97% of trainees have practiced the incorrect technique of using the image receptor of the image intensifier as an operating table. 

Figure 1: Correct positioning in the lateral view

Radiation exposure can be decreased by reducing exposure time (5,6). Our results show that the presence of the consultant surgeon in the operating theatre reduces mean radiation exposure time by over 45%. This suggests that the consultant’s expertise allow them to achieve adequate outcomes with less exposure, but also their experience allows them to appreciate that reductions do not have to be absolutely anatomical to produce equivalent clinical outcomes. We believe that aiming for a perfect x ray alignment for no clinical benefit is common practice amongst orthopaedic trainees. This may be due to lack of experience or fear of criticism when the x-ray film is reviewed by the treating consultant or other orthopaedic colleagues. We found that 65% of trainees use continuous fluoroscopic screening to demonstrate successful fixation of a fracture and 65% take unnecessary II shots to ensure the perfect x-ray picture.

Previous studies looking at experience versus radiation exposure have shown that less experienced surgeons receive higher radiation doses (13). Giannoudis et al showed that the radiation exposure for Surgical House Officers was much greater than the radiation exposure of a Registrar and operations involving radiographers with less than 5 years experience recorded higher levels of radiation dose and screening time (14).

With the introduction of Surgical Education and Training (SET) in Australia, Orthopaedic trainees are more junior in terms of surgical experience. We believe that it is essential that there is adequate supervision and education by consultants to prevent excessive exposure when using fluoroscopy during surgical procedures.

The AOA guidelines for radiation safety for orthopaedic surgeons states that during fluoroscopy  "the operating team must wear a lead gown that covers the front and back of the torso, a thyroid shield and lead impregnated glasses. These items should be of 0.5mm lead equivalent" (3). The use of a lead apron has been shown to cover 82% of the active bone marrow in the body (4) and can reduce the x-ray intensity of both primary and scattered radiation by 90% (3). Our survey showed that 32% of trainees wore no thyroid protection, 87% no eye protection and 100% used no head and hand protection.

The guidelines recommend surgeons to "wear a radiation monitor inside the lead protective apron, and ensure that a lifetime record of exposure is maintained". Our survey revealed that only 4% of trainees complied with this guideline. The guidelines also state that surgeons should "never assume protection (or allow others to assume protection) by standing behind a protected person". In contrast to this, 100% of trainees have assumed protection by standing behind a protected person.

Lead gowns must be handled carefully and not thrown down and crumpled as the protective lining will crack and be ineffective. It is recommended that gowns must be visibly inspected before each wearing and regularly checked by the radiology department and the date of the last check marked on the gown. These inspections should be at least annually and ideally every six months (15). Our survey showed 97% of trainees were unaware of the maintenance schedule for lead gowns.

Exposure rates for the orthopaedic surgeon using a regular C-arm, are estimated to be as high as 0.2 mSv/min to the torso and 0.3mSv/min to the hand (5). Exposure to the surgeon’s hands tends to be the greatest given their proximity to the Fluoroscopic Image Intensifier.  Exposure to the hands can be reduced by 33% with the use of radiation gloves (7). Singer showed that surgeon’s hands were exposed to an average of 0.20 +/- 0.123 mSv/case. A routine chest x ray exposes a patient to 0.20mSv (8).

Singer showed that intramedullary nailing and locking of femoral fractures requires an average of 6.26 minutes of fluoroscopy time and results in an average exposure of 1 mSv per operation (5). The Australian recommendation for maximum occupational exposure is 20mSv/year. Based on this study, this limit may be reached after just 10 operations in 6 months. The Orthopaedic Registrar in our study performed 13 intramedullary nailings of the tibia and femur during the 6 month period and was exposed to a total of 8131 seconds of fluoroscopic exposure during the 6 month rotation. Based on these figures, the training registrar may have potentially been exposed to 27.1 mSv to the torso and 40.66 mSv to the hands in 6 months. Without the use of Personal Protection Equipment the training registrar would have exceeded the annual Australian and International limit of whole body exposure (20mSv/year) by more than 2-fold.

Intramedullary locked nailing systems are often associated with long ionising radiation exposures. Proceeding to an open procedure rather than persisting with closed manipulation has been recommended if there is difficulty in introducing the guide wire (15). In our survey we found that 39% of trainees did not consider performing a limited open reduction when they encountered difficulty passing the guide wire using closed means. With locked nailing systems radiation dose can be reduced by using only one cross locking screw if stability is not compromised (15). Our study found that 32% of trainees never considered this option.

This paper highlights the potential risks and dangers of fluoroscopic ionising radiation in surgical procedures. Our findings demonstrate that there is a marked discrepancy between AOA guidelines and actual clinical practice in the use of ionising radiation during surgical procedures performed by orthopaedic trainees.  Radiation exposure to orthopaedic trainees can be significantly reduced with improved supervision and education by the treating consultant.  

Reference :

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2. Dewey P, Incoll I.  Evaluation of thyroid shields for reduction of radiation exposure to orthopaedic surgeons.  ANZ J Surg 1998; 68:635-636
3. George S, Dewey P, Beh H, Gray A. Radiation safety for orthopaedic surgeons, 2nd edition, Australian Orthopaedic Association
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6. Herscovici Jr. D, Do RW, Sanders MD. The Effects, Risks, and Guidelines for Radiation Use in Orthopaedic Surgery. Clinical Orthopaedics And Related Research 2000; 375:126-132
7. Rampersaud RY, Foley KT. Radiation exposure to the spine surgeon during fluoroscopically assisted pedicle screw insertion. Spine 2000; 25(20): 2637-2645
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11. Mahesh M. The AAPM/RSNA physics tutorial for residents, 2001. Available from: http://www.rsna.org/Education/archive/aapm.cfm
12. Perisinakis K, Damilakis J, Theocharopoulos N. Patient effective dose and radiogenic risks from fluoroscopically assisted surgical reconstruction of femoral fractures. Radiation Protection Dosimetry, Radiation Protection Dosimetry 2004; 108:65-72
13. Bahari S, Morris S, Broe D, Taylor C, Lenehan B, McElwain J. Radiation exposure of the hands and thyroid gland during percutaneous wiring of wrist and hand procedures. Acta Orthopaedica Belgica. 2006; 72(2):194-8
14. Giannoudis PV, McGuigan J, Shaw DL. Ionising radiation during internal fixation of extracapsular neck of femur fractures. Injury, pp 469-72, 1998.
15. Dewey P, George S, Gray A. Ionising radiation and orthopaedics (mini Symposium) Current Orthopaedics 2005; 19:1–12

This is a peer reviewed paper 

Please cite as :Martin P Laird,Occupational Exposure of Orthopaedic Trainees to Radiation.

J.Orthopaedics 2011;8(4)e6

URL: http://www.jortho.org/2011/8/4/e6