Radioguided Surgery With F18 FDG Exposes Staff to Radiation

A recent study set out to determine the average radiation dose received by operating room (OR) personnel from radiosurgical procedures performed on patients administered F18 FDG

The study was published in a recent issue of European Journal of Nuclear Medicine and Molecular Imaging.

While the annual dose limit for radiation workers is 50 mSv, and the dose was found to be below that threshold, it is important to know that adhering to the ALARA principle requires additional dose reduction if practical.

The Study
10 patients participated in this study.

Methodology
Each was administered an average of 700 MBq of F18 FDG approximately 2 hours before being brought to the OR, and 3 hours before beginning surgery.

During surgery, a handheld detector was used to guide the surgeon in finding abnormal tissues requiring resection. Average duration of the procedure was 4 hours.

Radiation measurements were obtained from optically stimulated luminescence (OSL) dosimeters provided to the nursing staff; who managed the patient before, during, and after the procedure as well as other OR staff.

The OR staff included the scrub technologist, anesthetist, and surgical physicians.

Surgical physicians included all attending surgeons, plus the first and second assistant surgical residents. Dose measurements averaged over the 10 procedures were reported along with the standard deviations for each of the OR staff members.

Results
Surgeons received the highest average radiation exposure per case (0.16 mSv), followed by the anesthetist (0.12 mSv) and the scrub technologist (0.09 mSv).

The nursing staff received a mean dose of approximately 0.05 mSv per case.

Using the US Nuclear Regulatory Commission’s (USNRC) 50 mSv per year limit, surgeons could participate in about 300 cases per year.

That would be reduced to 120 cases per year if International Commission on Radiological Protection limits (20 mSv) were considered. The ALARA principle, that of keeping radiation levels As Low As Reasonably Achievable, was not discussed.

Conclusions
The absorbed dose to the OR personnel from a single patient’s F18 FDG radiosurgical procedure is low. They believe that with monitoring, up to 300 procedures could be performed annually without exceeding USNRC radiation worker limits.

Reviewer’s Comments
The authors do a thorough evaluation of the radiation dose delivered to OR personnel from F18 FDG. Their estimates of the number of procedures that can be performed within the limits USNRC guidelines are reasonable; but they ignore the ALARA concept, which is also part of the regulation.

Reasonable measures must be implemented to keep the exposure of radiation workers below the regulatory limits. Typical ALARA levels of 10% to 25% of the 50-mSv limit would substantially reduce the number of procedures any team could participate in.

Potential solutions to this problem include reducing the amount of administered activity, providing increased shielding of the uptake room, and spreading the case load among the operating staff.

Another related concern that is not discussed in this paper is the exposure to uncontrolled areas where the annual limit is only 1 mSv per year.

Since the operating room area is likely to be uncontrolled, substantial (and expensive) shielding may be required to comply with regulatory limits.

Author: Mark T. Madsen, PhD

Reference:

Povoski SP, Sarikaya I, et al. Comprehensive Evaluation of Occupational Radiation Exposure to Intraoperative and Perioperative Personnel From 18F-FDG Radioguided Surgical Procedures. Eur J Nucl Med Mol Imaging; 2008;35 (November): 2026-2034.