[Monitoring Radiation Exposure During Surgery with Real Time Measurements: Opportunities and Limitations]. / Überwachung der Strahlenexposition im OP mit Echtzeitmessungen: Möglichkeiten und Grenzen.

BACKGROUND: In Germany, staff exposed to radiation is monitored with official individual dosimeters. Commercially available real-time dosimeters (RTD) can be used as radiation protection dosimeters. They are worn over the apron and display the radiation dose being measured at the desired location at intervals of one second. These real-time radiation exposure measurements enable the surgical staff to take suitable measures to reduce the radiation during the operation. The objective of our study was to monitor the accuracy of the measurements taken from the real-time dosimeter and to determine the radiation scatter for individual members of the surgical staff. MATERIALS AND METHODS: Prospective measurements of the operating team's exposure to radiation were carried out using a real-time dosimeter system in an operating room for vascular surgery equipped with a C-arm. Firstly the calibration of the RTD at the operating table was checked using a water phantom. Subsequently, measurements were taken during vascular interventions and surgery. RESULTS: When calibrated, the values of the individual RTD revealed internal significant deviations, thus a corrective factor was calculated for each RTD. In total 55 interventions on 53 patients were studied. The average dose for the RTD of the surgeon during endovascular aortic repair (n = 11) amounted to 9 ± 9 µSv (range 3.6 - 50 µSv) and during thoracic endovascular aortic repair (n = 6) 35 ± 49 µSv (3.8 - 190.3 µSv). In the case of percutaneous transluminal angioplasty of the pelvis and of the lower extremities (n = 20), the average dose for the RTD of the surgeon was 7 ± 7 µSv (1.2 - 35 µSv) and for the angiographies of the lower extremities (n = 12) at 2 ± 3 µSv (0.2 - 15.9 µSv). The real-time dosimetry provided data which contributed to the operating team changing their behaviour in the operating room. DISCUSSION: Since the dose values determined by the official dosimetry are generally very low, it is not possible to optimise the behaviour and thus the radiation protection using these dose values. This can be achieved with the radiation protection dosimeter and the dose reference levels can be defined in the new Radiation Protection Ordinance (StrlSchV). Instant feedback of the current dose rate at the place where the RTD is worn can lead to both the individual adjusting his or her personal behaviour and to optimisation of the individual's radiation protection. It is only possible to compare the measured data obtained with the RTD when calibration is carried out in advance.