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The impact of peer-based training on reducing radiation doses from x-ray operations in an interventional pain management clinic.

INTRODUCTION

Although physicians have sought to relieve their patients' pain for centuries, pain management as a specific medical discipline began with the founding of the International Association for the Study of Pain in May 1973. (1) During the last decade, pain management has evolved into an essential part of patient care. Physician specialists, such as physiatrists, are medical doctors who specialize in physical medicine and rehabilitation with a special interest in musculoskeletal conditions. Some physiatrists have advanced training in interventional pain management (IPM). (2) In this specialized subfield of pain management, procedures such as diagnostic and therapeutic nerve blocks, sympathetic blocks, discography, peripheral nerve blocks, and radiofrequency denervation are performed. Additionally, fluoroscopy is an integral part of IPM and is primarily used to ensure target specificity and accurate delivery of the injectate. (3-6)

In 2002, Walter Reed Army Medical Center, a large US Army teaching hospital, began the operation of an IPM clinic. There are 3 separate populations that could possibly receive exposure to ionizing radiation as a result of this clinic's activity: staff, patients, and the general public. There have been multiple studies to characterize the exposure of the IPM specialist to ionizing radiation. (3-8) However, it is much more difficult to characterize the radiation dose to a patient during a fluoroscopic procedure. Since the primary method of exposure to the physician performing a fluoroscopic procedure is scattered radiation from the patient, the relative dose to the patient can be inferred from the measurement of the physician's dose. This idea of inferring a relative dose to the patient from a direct measurement of the physician's dose assumes a proportional relationship between the two; therefore, a decrease in the physician's dose is equivalent to a proportional decrease in the patient's dose. In order for a relative dose based on a physical dose measurement to be meaningful, it must be compared to a similar measurement (eg, dose measurements before and after a training event). The 2 relative doses must also have equivalent proportionality to the base measurements. In the case of fluoroscopy, a proportionality based on scattered radiation would change if the geometry between the patient and physician, or if the presence of shielding material changes significantly. If these requirements are satisfied, it is valid to assume that comparing 2 similar exposure scenarios would yield comparable relative dose assessments.

It is impractical to directly measure the dose to each member of the general public that might be exposed to ionizing radiation as a result of this clinic's activity. The most practical way to estimate these doses is to measure the ambient radiation levels around the IPM clinic and extrapolate these measurements to conservative estimates of the doses to the general public.

The mission of the Health Physics Office at our facility is to maintain the doses resulting from any medical use of ionizing radiation as low as reasonably achievable (ALARA). During an annual review of our dosimetry program at the end of calendar year 2003, the dosimetry custodian noticed an average increase in the total effective dose equivalent (TEDE) to those personnel who are occupationally exposed to ionizing radiation and are issued personnel dosimetry. The increase was not large (from 0.60 mSv to 0.80 mSv), but a quick review of the dosimetry data revealed a large discrepancy in the average dose received by the physicians, residents, and fellows in the IPM clinic as compared to personnel working elsewhere in the facility. In order to reduce these doses, a special training program focused on the proper use of fluoroscopic x-ray equipment by the IPM clinic staff was implemented to supplement the regular annual radiation safety training. This paper describes the measurement and characterization of the radiation exposure to the 3 populations listed above as a result of the operation of an IPM service, as well as the effectiveness of this new training program in reducing radiation doses in the clinic.

MATERIALS AND METHODS

X-Ray Source

The fluoroscopic x-ray systems used in our facility's IPM clinic (photo on page 47) are the General Electric Model OEC 9800 (GE Healthcare Systems, Waukesha, Wisconsin). This c-arm style unit has many features that are designed to limit both the user's and the patient's radiation exposure while maintaining acceptable image quality. Despite these features, the carm units have the ability, if not used properly, to produce an x-ray field capable of delivering significant levels of exposure to both patient and user alike. This fact became evident during an annual x-ray safety compliance survey of these units when the maximum exposure level at 30 cm from the focal spot was measured to be 128 roentgens per minute with an MDH ion chamber (Radcal Corporation, Monrovia, California).

Dose to Patients and Staff Members

In the US Army, all personnel who are occupationally exposed to ionizing radiation and may exceed 10% of the occupational dose limit of 5 rems (50 mSv) per year are issued dosimetry. (9) The US Army uses a thermoluminescent dosimetry (TLD) system to measure and characterize this exposure. The TLD system is provided by the US Army Dosimetry Center, Redstone Arsenal, Alabama. This center is accredited by the National Voluntary Laboratory Accreditation Program for the determination of TEDE using a dosimetry system manufactured by Panasonic (Secaucus, New Jersey). This dosimetry system consists of a Panasonic model UD-802AS dosimeter in a model UD-874AT holder and a model 710 reader.

In order to determine the TEDE, a combination of 2 dosimeters is used. One is worn on the trunk of the body under any lead shielding and the second is worn at neck level outside of any lead shielding. The TEDE is calculated from the deep (depth of 1.0 cm in tissue) dose determined from each dosimeter using the following formula (10):

TEDE = 1.5 x Body + 0.04 x Neck

where Body and Neck refer to the deep dose determined from the dosimeter worn on the trunk of the body and at the neck level respectively.

Fluoroscopy Training Program

The need for physician training programs on the effective use of fluoroscopic x-ray equipment has been presented in the literature. (11,12) However, the methods used to provide this training can vary significantly. Within the US Army Medical Department, the individual Radiation Safety Officers at different medical facilities have employed varied training methodologies ranging from instruction by the health physics staff to internet-based training. The selected methodology used at our facility was peer training. In August 2004, a training class in the proper use of fluoroscopy was given to the IPM clinic staff by an experienced, board certified interventional radiologist. All personnel in the IPM clinic using fluoroscopy were required to attend the training. The class included the following topics: pulsed and low dose fluoroscopy; fluoroscopic magnification modes; use of last image hold; time, distance, and shielding concepts; recognition of the x-ray field size; and proper wear of dosimetry.

In order to determine the effectiveness of this training program, the cumulative TEDE to the staff of the IPM clinic was compared before and after the training. The dosimetry for the personnel in this department is exchanged monthly. The cumulative TEDE for the clinic was tallied using all individual monthly dose readings for 2 equal time periods (July 2003 through September 2004 and October 2004 through December 2005) immediately before and after the described training. It is important to note that no new personnel joined the clinic staff during the period of this study.

Doses to Members of the General Public

Since x-ray operations are regulated by the individual states, there are no specific federal regulations that deal with the shielding of x-ray facilities. Despite this, there are multiple federal regulations limiting the dose from ionizing radiation to members of the general public. (13,14) The dose limit of 1 mSv per year is incorporated into the US national consensus standards used to determine the shielding requirements of x-ray facilities. (15) Additionally, the US Army has specific requirements for the shielding of x-ray facilities which are published in Technical Bulletin MED 521 (16) Paragraph 4-12 of this bulletin states that "... a qualified expert will ... ensure that the design [of the x-ray facility] is adequate to meet regulatory dose limits and keep doses to personnel ALARA." (16) (p4-10)

Due to the mobile nature of a c-arm fluoroscopic x-ray system, the facility design (eg, shielding) that normally accompanies the installation of a permanent x-ray system is not required. However, according to the National Council on Radiation Protection and Measurements: "If a mobile x-ray system is used in a fixed location, a qualified expert shall evaluate the need for structural shielding." (15) (p14) This is precisely the situation that occurred as a result of starting an IPM clinic at our facility. Originally, the clinic was to only be at its present location temporarily. However, when it was decided that the location would be permanent, the shielding of the rooms containing the x-ray units had to be evaluated. In order to do this, 14 Panasonic model UD-802AS dosimeters in model UD-874AT holders were placed both inside and outside of each protective barrier in the patient treatment rooms, patient waiting area, and the hallway adjacent to the patient treatment rooms. The dosimeters were left in place for a period of 2 months in early 2004.

RESULTS AND DISCUSSION

Dose Reductions From Training

The cumulative dose to a member of the IPM clinic staff before the implementation of the new training program was 18.14 mSv. After the training, the cumulative dose dropped to 9.55 mSv. This marked decrease demonstrated that the new training program was effective in reducing the dose to the staff of the IPM clinic. Since the doses to the staff are proportional to the doses patients receive, the training program was effective in reducing the patient exposure as well. Discussions with the staff revealed that the primary procedural change that occurred as a result of the training were the use of the last image hold and the low dose mode. Therefore the relative doses had equivalent proportionality to the direct measurements both before and after the training event.

It was recognized that changes in fluoroscopic procedures due to the new training program are not the only potential cause for a reduction in staff doses. Workload changes could also affect the measured cumulative doses. However, since beginning operations in 2002, the workload at our facility's IPM clinic has seen a slight increase and has subsequently stabilized at around 5000 fluoroscopic procedures annually. This includes the time period considered during this study.

Shielding Evaluation

Only 4 of the 14 dosimeters that were used in determining the shielding properties of the barriers in the IPM clinic showed a measured deep dose greater than background (as measured with control TLDs). The 4 dosimeters were all located within the 2 treatment rooms and recorded monthly deep doses of 0.10 mSv, 0.25 mSv, 0.28 mSv, and 0.30 mSv respectively. All dosimeters in patient waiting areas and the hallway showed no discernable exposure above background. The Panasonic dosimeters used in this study have a minimum detectable dose of 0.01 mSv. (17) Therefore, a dose of up to 0.12 mSv per year would not be detectable in the areas measured. It was determined from these results that no additional shielding was required for the IPM clinic to be in compliance with Army regulations.

CONCLUSION

The operation of an IPM clinic exposes clinic staff, patients, and members of the general public to ionizing radiation. With a few simple precautions, the radiation exposure to all 3 populations can be maintained below regulatory limits and in accordance with the ALARA principle. It was not necessary to make any shielding enhancements to our IPM clinic to protect the members of the general public. The primary method of reducing dose to the staff and patients was through the implementation of a peer-based training program focused on effective use of the c-arm fluoroscopes. Using an experienced interventional radiologist in the training process worked very well as evidenced by the significant reduction (by a factor of two) in the total doses to the clinic staff after the peer-based training program.

[ILLUSTRATION OMITTED]

REFERENCES

(1.) Meldrum ML. A capsule history of pain management. JAMA. 2003;290:2470-2475.

(2.) Thomas SA. Role of the pain management specialist. Spineuniverse.com web site. Available at http:// www.spineuniverse.com/displayarticle.php/ article3337.html. Accessed July 25, 2006.

(3.) Botwin KP, Freeman ED, Gruber RD, Torres-Ramos FM, Bouchlas CG, Sanelli JT, Hanna AF. Radiation exposure to a physician performing fluoroscopically guided caudal epidural steroid injections. Pain Physician. 2001;4:343-348.

(4.) Manchikanti L, Cash KA, Moss TL, Pampati V. Radiation exposure to the physician in interventional pain management. Pain Physician. 2002;5:385-393.

(5.) Manchikanti L, Cash KA, Moss TL, Pampati V. Effectiveness of protective measures in reducing risk of radiation exposure in interventional pain management: a prospective evaluation. Pain Physician. 2003;6:301-305.

(6.) Zhou N, Singh N, Abdi S, Wu J, Crawfor J, Barach P. Fluoroscopy radiation safety in interventional pain procedures. 24th Annual Scientific Meeting, American Pain Society; March 30, 2005; Boston, MA. Poster 775.

(7.) Botwin KP, Fuoco GS, Torres FM, Grubber RD, Bouchlas CC, Castellanos R, Rao S. Radiation exposure to the spinal interventionalist performing lumbar discography. Pain Physician. 2003;6:295 300.

(8.) Zhou N, Singh N, Abdi S, Wu J, Crawfor J, Furgang FA. Fluoroscopy radiation safety for spine interventional pain procedures in university teaching hospitals. Pain Physician. 2005;8:49-53.

(9.) Department of the Army Pamphlet 385-24: The Army Radiation Safety Program. Washington, DC: US Dept of the Army; August 24, 2007.

(10.) Department of the Army Pamphlet 40-18: Personnel Dosimetry Guidance and Dose Recording Procedures for Personnel Occupationally Exposed to Ionizing Radiation. Washington, DC: US Dept of the Army; June 30, 1995.

(11.) Castronovo FP. A fluoroscopic credentialing/safety program at a large research hospital. Health Phys. 2004;86 (suppl2):S76-S79.

(12.) Archer BR, Wagner LK. Protecting patients by training physicians in fluoroscopic radiation management. J Appl Clin Med Phys. 2000;1:32-37.

(13.) Federal Radiation Protection Guidance for Exposure of the General Public. 69 Federal Register FRL-5126 -7 (1994).

(14.) Radiation Dose Limits for Members of the General Public. 56 Federal Register 23398 (1991) (codified at 10 CFR Part 20 Subpart D).

(15.) Report No. 147--Structural Shielding Design for Medical X-Ray Imaging Facilities. Bethesda, MD: National Council on Radiation Protection & Measurements; 2004.

(16.) Technical Bulletin MED 521: Occupational and Environmental Health Management and Control of Diagnostic, Therapeutic, and Medical Research X-Ray Systems and Facilities. Washington, DC: US Dept of the Army; February 26, 2002.

(17.) Product Manual: New TLD "TL Badge System". Secaucus, NJ: Panasonic Industrial Company; 2006.

MAJ Christopher D. Pitcher, MS, USA

COL Mark A. Melanson, MS, USA

MAJ Pitcher is Deputy Chief of the Chemical, Biological, Radiological, Nuclear, and High-Yield Explosives Branch, Department of Preventive Health Services, Academy of Health Sciences, US Army Medical Department Center and School, Fort Sam Houston, Texas. During the period covered by this paper, he was the Operations Branch Chief, Health Physics Office, Walter Reed Army Medical Center, Washington, DC.

COL Melanson is Director, Armed Forces Radiobiology Research Institute, Bethesda, Maryland, and the Radiological Hygiene Consultant to The Army Surgeon General.
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Author:Pitcher, Christopher D.; Melanson, Mark A.
Publication:U.S. Army Medical Department Journal
Article Type:Report
Geographic Code:1USA
Date:Apr 1, 2010
Words:2538
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