Time-related study on external exposure dose of 2-deoxy-2-[F-18]fluoro-D-glucose PET for workers' safety

Commissioning of the first hospital-based PET radiopharmaceutical cyclotron in Greece: personnel dose assessment

The role of18F-fluoro-deoxy-glucose in positron emission tomography (PET) imaging is well established in diagnosis and management of cancer patients. Installations of on-site self-shielded mini cyclotrons are increasing. The Dose on Demand Biomarker Generator BG-75 was installed at Metaxa Cancer Hospital, Greece, in May 2021 and is the first hospital-based PET radiopharmaceutical cyclotron in the country. Personnel expected external exposure was established during commissioning; internal exposure is not expected. Personnel dose was estimated with two methods: survey meter measurements in various locations combined with the time spent in each location, and direct measurement using electronic personal dosemeters. Gamma and neutron radiation readings outside the cyclotron vault were at background levels. Inside the cyclotron vault, the highest recorded radiation readings by the target were 18μSv h-1for both gammas and neutrons with cyclotron in operational mode; at one meter, the values were 5μSv h-1and 4μSv h-1, respectively. The annual expected whole body dose per cyclotron operator is 0.6 mSv, and the respective extremity dose 16 mSv. The annual expected whole body and extremity dose for the radiochemist is 0.3 mSv and 25 mSv, respectively. The respective annual dose estimates for the medical physicists are < 1 mSv. The expected personnel doses are well below the regulatory limits and local as low as reasonably achievable (ALARA) levels. With experience and a robust ALARA program, personnel exposure could be further reduced.

Exposure Doses to Technologists Working in 7 PET/CT Departments

Objective:

The aim of this study was to measure occupational exposure doses of technologists who dispense and inject radiopharmaceuticals in 7 positron emission tomography/computed tomography (PET/CT) departments. This was done with the goal to help improving protective designs in PET departments and/or establishing national protection standards.

Method:

Common LiF thermoluminescence dosimeters (TLDs) were placed on the chest and necklace of the technologists to monitor whole-body and thyroid doses, respectively. Ring TLDs were also worn on both index fingers to measure individual hand doses. All TLDs were assembled and measured once every 3 months for a total of 12 months. Additionally, we measured and compared the dose of TLDs attached to both the inside and the outside of the technologist’s lead coat.

Results:

Technologists received relatively high exposures, which accounted for 64% to 94% of the collective dose in their respective departments. Their thyroid doses ranged from 1.2 to 1.7 mSv/a; some technologists’ hand doses exceeded 500 mSv/a. Use of a lead coat reduced the average dose by 8%.

Conclusion:

Technologists working in PET/CT departments were the main population exposed to radiation. This work underscores the need for enhanced protective measures for these workers to better reduce their exposure, particularly for their hands.