Medical physicists in Germany have confirmed that medical staff are exposed to low levels of radiation during transarterial radioembolization (TARE) procedures, according to a study published March 17 in Radiology.
The finding fills a gap in knowledge concerning how much radiation staff members absorb in a real-world setting when handling yttrium-90 (Y-90) and holmium-166 (Ho-166) microspheres that emit high-energy beta particles, noted lead author Christian Kühnel, PhD, of Jena University Hospital in Jena, and colleagues.
“Ho-166 poly-L-lactic acid microspheres led to the highest body doses, while Y-90 resin microspheres generated the highest hand doses, with interventional radiologists receiving the highest overall doses,” the group wrote.
TARE is a procedure to treat liver cancer that involves radiopharmacists, medical physics experts, interventional radiologists, nuclear medicine physicians, radiologic technologists, and nursing staff, all of whom are exposed to radiation, the authors explained.
While the procedure is rising in popularity, the researchers noted that data on occupational radiation exposure during TARE are sparse, specifically regarding the three microsphere types used: namely, Y-90 resin SIR-Spheres, Y-90 glass TheraSphere, and Ho-166 poly-L-lactic acid (PLLA) QuiremSpheres.
To bridge the gap, they monitored radiation exposure to five radiopharmacists, seven interventional radiologists, five medical physics experts, five nuclear medicine physicians, eight radiologic technologists, and six nurses during 60 TARE procedures. They used four types of dosimeters worn by the staff to measure skin surface doses on hands, body doses on the chest, maximum procedural dose rates, and exposure times per step, as well as compared microspheres.
Photographs show an example of a Y-90 resin microsphere transarterial radioembolization (TARE) procedure using the generation 2 system. (A) Manual portioning by radiopharmacists of therapeutic radioactivity on a laminar flow bench meeting International Organization for Standardization class 5 cleanroom standards and equipped with lead shielding. (B) Single components of the application box. (C) Assembling by the medical physics expert of application box components and vials according to respective manuals. (D) Application box in angiography intervention room with application lines connected to the microcatheter while the nuclear medicine physician administers the microspheres. (E) Storage of empty vials and waste in an acrylic glass bin by the nuclear medicine physician. (F) Measurement of dose rates on the patient’s liver surface immediately after TARE. RSNAAccording to the analysis, mean radiation doses were generally low, with body and hand doses under 5 µSv (0.005 mSv) and under 350 µSv (0.35 mSv) per procedure. Given that approximately 70 TARE procedures are performed yearly at their hospital, the estimated staff exposure annually is far below the legal maximum in Germany (body: 20 mSv/year; hand: 500 mSv/year), the researchers noted.
Other key findings included the following:
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Ho-166 PLLA generated the highest body doses (maximum, 17 µSv), while Y-90 resin generated the highest hand doses (maximum, 309 µSv) due to procedural handling.
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Interventional radiologists received the highest body (mean, 2.5 to 4.5 µSv per procedure) and hand (mean, 146 to 309 µSv per procedure) doses among all occupations as a result of additional angiography.
“Medical staff exposure to transarterial radioembolization radiation was generally low,” the group wrote.
Nonetheless, as a note of caution, the authors recommended that since Y-90 resin microspheres result in high hand doses due to procedural handling, their portioning, assembly, and application should be performed with optimal efficiency by trained staff using long tweezers.
“Further studies are required to evaluate the impact of fingertip-to-base distance for beta particles, and subsequent studies with greater sample sizes are required to validate the results of this study,” the researchers concluded.
The full study is available here.