The risk of radiation exposure to assisting staff in urological procedures: a literature review.
Key Words: Radiation, urology, fluoroscopy, extra-corporeal shock wave lithotripsy, percutaneous nephrolithotomy, uretero-renoscopy, ureteral stenting, nurse, risk, X-ray, recommendations.
Since the advent and advancement of endourology, fluoroscopy has become an integral part of urologic practice. Percutaneous nephrolithotomy (PCNL) and extracorporeal shock wave lithotripsy (ESWL) now form the first line of treatment for urinary calculi. Retrograde pyelography (RGP) is an essential part of urology, predominantly as a diagnostic procedure and an adjunctive to other urologic interventions, such as PCNL, ureteric stenting, and ureterorenoscopy (URS). This increased use of fluoroscopy has led to the risk of occupational exposure of the urologist and assisting staff to radiation and its hazards (Hellawell, Mutch, Thevendran, Wells, & Morgan, 2005; Kumar, 2008; Tonnessen & Pounds, 2011).
Fluoroscopy utilizes X-rays, which are high energy ionizing radiations. These ionizing radiations enter the human body, and by the virtue of their energy, cause cellular damage and even cell death. The amount of damage depends upon the total dose, duration of exposure, and the site of exposure. This damage can lead to biological effects, which may be stochastic (independent of the dosage received) or deterministic (dose-dependent effects) (Rehani et al., 2010).
Considering the risks associated with radiation exposure, numerous guidelines have been proposed that set the annual permissible limit for the amount of exposure. Some amount of radiation is present in the environment; thus, human beings are constantly exposed to radiation. Medical personnel, especially urologists, form a special group of individuals who, apart from this environmental exposure, are also exposed to radiation due to their profession. The major source of radiation is the C-arm, which is used to produce images for surgical guidance. The radiation exposure can be direct or indirect. Direct exposure is when the person is in the line of the radiation rays produced by the fluoroscopy machine. Indirect exposure occurs from scattered rays resulting from the interaction of the primary beam with the patient that disseminate in all directions (Kumari et al., 2006).
Review of the available literature describes numerous studies that assess the risk of radiation to the operating surgeon. However, the risk to assistants and nursing staff has not been given the necessary attention. This article presents results of a literature review conducted to determine the risk of radiation exposure during urologic procedures, with emphasis on data concerning assisting staff.
Quantification of Radiation Exposure
Many different units are used to quantify radiation. The most commonly used units are Systeme international d'unites (SI units) and conventional units. SI units are the standard units of measurement recommended by the International System of Units, and conventional units are often used by various authors for quantification of radiation. See Table 1 for details of the commonly used units.
Recommendations for Radiation Exposure
The International Commission on Radiation Protection (ICRP) recommends guidelines for radiation exposure. For medical personnel, it has been recommended that the exposure should not exceed 20 mSv per year. The maximum duration for which this level of exposure is allowed is 5 years, hence a maximal total body exposure over 5 years should not exceed 100 mSv. ICRP has also given organ-specific permissible limits for radiation exposure. The maximum permissible exposure recommended is 150 mSv for the eye and 500 mSv for the skin as well as the extremities. These values can be used for the subset of population whose specific organs are exposed to radiation rather than the whole body. ICRP also advocates the principle of "as low as reasonably achievable" (ALARA). The ALARA principle accepts that some amount of radiation exposure may be inevitable. ICRP recommends the radiation exposure should be based upon the principles of justification, optimization, and dose limitation. Measures should be taken to reduce the radiation exposure in the form of provision of shielding from radiation, limiting the time of exposure, and increasing the distance between the radiation source and the personnel. Therefore, a "reasonably" low level of radiation exposure should be attained. Medical personnel involved in radiation should be screened monthly or quarterly to quantify the radiation exposure, and the total exposure should not be allowed to exceed the annual permissible limits (Wrixon, 2008).
Materials and Methods
The databases of major search engines, such as PubMed, Highwire Press, Scopus, and Google scholar, were searched with the key words radiation, urology, risk, recommendations, X-ray, and fluoroscopy. All major articles found were analyzed. Emphasis was given to the articles where assistants and nurses constituted a significant part of the study population. Details regarding the site of exposure, total duration of exposure, and the amount of exposure received, if available, were recorded.
The method of measurement of radiation exposure varied in the literature. The majority of the studies employed the thermoluminescence dosimetry for quantification of exposure. Thermo luminescence dosimetry uses chips impregnated with crystals that can be worn by medical personnel. These crystals absorb radiation, which can subsequently be measured to quantify the amount of personal radiation exposure. The studies reviewed in this article used variable units for the description of radiation exposure. To provide homogenous data to facilitate comparison between the studies, the amount of exposure received has been converted to [micro]Sv for all studies.
A total of nine major studies were found in the English literature that addressed the issue of radiation exposure to the assistants and nurses. The studies, with their findings, are outlined in Table 2. PCNL was the most common urological procedure studied for the assessment of the radiation exposure. Only two studies assessed the risk of exposure during other procedures, such as ureterorenoscopy (URS), RGP, and stenting. One study addressed the issue of radiation exposure during ESWL. Some authors (Hellawell et al., 2005; Majidpour, 2010) mentioned organ-specific exposure, while others (Giblin, Rubenstein, Taylor, & Pahira, 1996; Kumari et al., 2006) calculated the whole body exposure.
The biological effects of radiation pose a serious threat to medical personnel. These can be dependent on the total dose (deterministic effects) or independent of dose (stochastic effects). It is evident that smaller doses of radiation, which are generally encountered in many diagnostic procedures, may not exceed the threshold dose for deterministic effects. However, a probability still exists for stochastic effects. Radiation exposure has been linked to self-limiting diseases, such as skin erythema and cataracts, as well as to life-threatening illnesses, such as cancer and leukemia (Rehani et al., 2010).
Data from this review of nine studies revealed the amount of exposure to assisting staff and nurses during urologic procedures was low. The average amount of exposure was less than 2 [micro]Sv per case. Assistants were exposed to higher levels of radiation as compared to nurses. One causative factor for this may be that assistants are placed more closely to the operating surgeon and the radiation source. They are therefore exposed to higher amounts of radiation. This effect has also been shown by Hellawell et al. (2005), who demonstrated the average distance of the surgeon, assistant, and the nurse was approximately 75, 90, and 150 cm, respectively, from the source of radiation. This resulted in a lower exposure to the nurse as compared to the surgeon and the assistant. Further, the thyroid and lower extremities of assistants were subjected to a higher amount of radiation as compared to other parts of the body. The exposure to the head was 0.05 [micro]Sv/case, while it was 0.01 [micro]Sv, 0.025 [micro]Sv, and 0.1 [micro]Sv to the eyes, the fingers, and the legs, respectively, per case (Majidpour, 2010). The exposure to thyroid was 2 [micro]Sv per case in another study (Tse et al., 1999). Considering ICRP recommendations, this exposure was well below the maximum annual permissible limits. Even if the assistant was exposed to a workload of 10 to 15 cases per week, the total amount of exposure remains well below the recommended level.
The review also indicated that radiation exposure was very high in older studies. The mean dose to which an assistant was exposed ranged from 21 to 40 [micro]Sv/case in the 1980s (Bush, Jones, & Brannen, 1985). In more recent studies, this exposure was shown to be less than 2 [micro]Sv/case (Hellawell et al., 2005). Probable reasons may include advancement in technology, increase in urologists' expertise to perform endourological procedures, lesser requirement of fluoroscopy during surgery, and better operating instruments. Decrease in fluoroscopy time, which was significantly higher in older studies as compared to recent studies, could also be an influencing factor. A single case of PCNL that earlier required the fluoroscopic guidance for approximately 20 minutes now requires only 4 to 6 minutes (see Table 2).
Even if results of this limited review appear to be reassuring, assisting staff should be aware of the potential risk of the stochastic effects of radiation. Necessary precautions are mandatory for personnel exposed to any amount of radiation. These include the use of lead aprons to shield the body, thyroid shields to protect the thyroid, and eye glasses to protect the ocular lens. Assistants should distance themselves as much as technically feasible from the site of radiation. If not actively involved in the procedure, assistants should withdraw behind the lead screens. This can help in reducing radiation exposure (Wrixon, 2008, Rehani et al., 2010). It is also recommended that all assisting staff wear dosimeters so individual radiation exposure can be recorded. It is important that technical staff perform periodic checks on the fluoroscopy machines so excessive radiation dosing is not delivered (Kumar, 2008).
Radiological protection is essential and should form an integral part of the instruction of urologists and allied medical personnel who use radiation routinely as per ICRP recommendations. Interventional procedures that depend on fluoroscopy are technically demanding. Clinicians, therefore, need to be well versed with these procedures and also be conscious regarding the requirements of proper radiological protection. At least 15 hours of training for urologists and allied staff in radiological protection have been recommended (Rehani et al., 2010).
Based on this literature review, assisting staff were well within the maximum permissible limits of annual radiation exposure during urologic procedures utilizing fluoroscopy. However, considering the ALARA principle, all measures should be taken to reduce radiation exposure. Assistants and nursing staff must be mindful of the deleterious effects of excessive radiation exposure and take an active role in reducing their exposure.
Baldock, C., Greener, A.G., & Batchelor, S. (1992). Radiation dose to patients and staff from Storz Modulith SL20 lithotripter. The Journal of Stone Disease, 4(3), 216-219.
Bush, W.H., Jones, D., & Brannen, G.E. (1985). Radiation dose to personnel during percutaneous renal calculus removal. American Journal of Roentgenology, 145(6), 1261-1264.
Giblin, J.G., Rubenstein, J., Taylor, A., & Pahira, J. (1996). Radiation risk to the urologist during endourologic procedures, and a new shield that reduces exposure. Urology, 48(4), 624-627.
Hellawell, G.O., Mutch, S.J., Thevendran, G., Wells, E., & Morgan, RJ. (2005). Radiation exposure and the urologist: What are the risks? Journal of Urology, 174(3), 948-952.
Kumar, P. (2008). Radiation safety issues in fluoroscopy during percutaneous nephrolithotomy. Urology Journal, 5(1), 15-23.
Kumari, G., Kumar, P., Wadhwa, P., Aron, M., Gupta, N.P., & Dogra, P.N. (2006). Radiation exposure to the patient and operating room personnel during percutaneous nephrolithotomy. Inernational Urology and Nephrology, 38(2), 207-210.
Lowe, F.C., Auster, M., Beck, T.J., Chang, R., & Marshall, F.F. (1986). Monitoring radiation exposure to medical personnel during percutaneous nephrolithotomy. Urology, 28(3), 221-226.
Majidpour, H.S. (2010). Risk of radiation exposure during PCNL. Urology Journal, 7(2), 87-89.
Rao, P.N., Faulkner, K., Sweeney, J.K., Asbury, D.L., Sambrook, P., & Blacklock. N.J. (1987). Radiation dose to patient and staff during percutaneous nephrostolithotomy. British Journal of Urology, 59(6), 508-512.
Rehani, M.M., Ciraj-Bjelac, O., Vano, E., Miller, D.L., Walsh, S., Giordano, B.D., & Persliden, J. (2010). Radiological protection in fluoroscopically guided procedures performed outside the imaging department. Annals of the ICRP, 40(6), 1-102.
Tonnessen, B.H., & Pounds, L. (2011). Radiation physics. Jouranl of Vascular Surgery, 53, 6S-8S.
Tse, V., Lising, J., Khadra, M., Chiam, Q., Nugent, R., Yeaman, L., & Mulcahy. M. (1999). Radiation exposure during fluoroscopy: Should we be protecting our thyroids? The Australian and New Zealand Journal of Surgery, 69(12), 847-884.
Wrixon, A.D. (2008). New ICRP recommendations. Journal of Radiological Protection, 28(2), 161-168.
Tarun Jindal, MS, is a Post-Doctoral Trainee in Urology, Department of Urology, Calcutta National Medical College, Kolkata, India.
Table 1. Quantification of Radiation Exposure: Details of the Commonly Used Units Unit Abbreviation SI/Conventional Definition Coulomb per SI Measures the amount of kilogram (C/kg) radiation exposure. It is the radiation required to create 1 coulomb of charge in 1 kilogram of matter. Roentgen (R) Conventional Measures the amount of radiation exposure. 1 Roentgen= 2.58x[10.sup.-4] C/kg Gray (Gy) SI It is the unit of radiation absorption. It is the amount of radiation required to deposit 1 Joule of energy in 1 kilogram of matter. Radiation Conventional Measures the amount of absorbed dose radiation absorbed by a target. (rad) A dose of 1 rad means the 100 ergs of radiation energy has been absorbed per gram of absorbing material/tissue. 100 rad = 1 Gy Sievert (Sv) SI It is the unit for equivalent absorbed radiation dose. It quantifies the biological risk of radiation exposure. 1 Sv = 1000 msv = [10.sup.6] [micro]Sv Roentgen Conventional It is the unit for equivalent equivalent absorbed radiation dose. man (rem) 100 rem = 1 Sv Note: SI = Systeme international d'unites. Table 2. Review of Major Studies Quantifying Radiation Exposure to the Assisting and Nursing Staff during Urologic Procedures Medical Number of Types of Number Author Personnel Procedures Procedures 1 Bush, Jones, & Assisting 77 PCNL Brannen, 1985 nurse 2 Lowe, Auster, Beck, Surgical 7 PCNL Chang, & Marshall, assistant 1986 Scrub nurse 7 PCNL Circulating 6 PCNL nurse 3 Rao et al., 1987 Scrub nurse 18 PCNL 4 Baldock, Greener, & Assisting Information ESWL Batchelor, 1992 staff not available 5 Giblin, Rubenstein, Assistant 5 PCNL Taylor, & Pahira, 1996 6 Tse et al., 1999 Scrub nurse 20 PCNL, RGP, stenting, URS 7 Hellawell, Mutch, Assistant 24 PCNL, RGP, Thevendran, Wells, stenting, & Morgan, 2005 URS Nurse 24 PCNL, RGP, stenting, URS 8 Kumari et al., Assisting 50 PCNL 2006 surgeon Technical 50 PCNL assistant Scrub nurse 50 PCNL Floor nurse 50 PCNL 9 Majidpour, 2010 Assistant 100 PCNL Circulating 100 PCNL nurse Medical Duration of Number Author Personnel Exposure 1 Bush, Jones, & Assisting 24 minutes Brannen, 1985 nurse (mean) 2 Lowe, Auster, Beck, Surgical 27.8 minutes Chang, & Marshall, assistant (mean) 1986 Scrub nurse 27.8 minutes (mean) Circulating Information nurse not available 3 Rao et al., 1987 Scrub nurse 21.9 minutes (mean) 4 Baldock, Greener, & Assisting Information Batchelor, 1992 staff not available 5 Giblin, Rubenstein, Assistant Information Taylor, & Pahira, not available 1996 6 Tse et al., 1999 Scrub nurse 63.1 minutes (for 20 cases) 7 Hellawell, Mutch, Assistant 0.1 to 22.9 Thevendran, Wells, minutes & Morgan, 2005 Nurse 0.1 to 22.9 minutes 8 Kumari et al., Assisting 6.04 minutes 2006 surgeon (range 1.8 to 12.16 minutes) Technical 6.04 minutes assistant (range 1.8 to 12.16 minutes) Scrub nurse 6.04 minutes (range 1.8 to 12.16 minutes) Floor nurse 6.04 minutes (range 1.8 to 12.16 minutes) 9 Majidpour, 2010 Assistant 4.5 minutes (range 1 to 8 minutes) Circulating 4.5 minutes nurse (range 1 to 8 minutes) Medical Number Author Personnel Mean Dose 1 Bush, Jones, & Assisting 40 [micro]Sv/case Brannen, 1985 nurse (measured at the level of the neck) 2 Lowe, Auster, Beck, Surgical 37 [micro]Sv/case to neck Chang, & Marshall, assistant and 25 [micro]Sv/case to 1986 right and left hand Scrub nurse 12 [micro]Sv/case (measured at the level of the neck) Circulating 19 [micro]Sv/case nurse (measured at the level of the neck) 3 Rao et al., 1987 Scrub nurse Information not available Measurement done for eyes and hands 4 Baldock, Greener, & Assisting 4800 [micro]Sv annually Batchelor, 1992 staff 5 Giblin, Rubenstein, Assistant 500 [micro]Sv/hour Taylor, & Pahira, 1996 6 Tse et al., 1999 Scrub nurse 40 [micro]SV (for 20 cases) to the thyroid 7 Hellawell, Mutch, Assistant 2.1 [+ or -] 0.5 to 120 Thevendran, Wells, [+ or -] 30 [micro]Sv/ & Morgan, 2005 case Higher dose to legs Nurse 0.5 [+ or -] 0.1 to 24 [+ or -] 6 [micro]Sv/case Higher dose to legs 8 Kumari et al., Assisting 12 [micro]Sv/case 2006 surgeon Technical 2.6 [micro]Sv/case assistant Scrub nurse 0.3 [micro]Sv/case Floor nurse 0.16 [micro]Sv/case 9 Majidpour, 2010 Assistant 0.05, 0.01, 0.025, and 0.1 [micro]Sv to the head, eye glasses, fingers, and legs, respectively, per case Circulating Zero (0) nurse Notes: PCNL = percutaneous nephrolithotomy, ESWL = extra corporeal shock wave lithotripsy, URS = ureterorenoscopy.
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|Title Annotation:||Systematic Review of the Literature|
|Date:||May 1, 2013|
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