Avaliação dos procedimentos de segurança e exposição ocupacional para procedimentos de radiologia intervencionista em embolização de artéria uterina

Abstract

Uterine fibroids can be defined as benign tumors that affect almost half of women of reproductive age. It can be classified as asymptomatic or symptomatic. Among the myoma treatment techniques, uterine artery embolization, studied in this work, stands out. The embolization consists of a procedure performed in a minimally invasive manner, bringing advantages such as shorter hospital stay, lower infection risk and preservation of the reproductive system. The entire procedure is performed in a hemodynamic room with X radiation to guide the catheter to the desired location. The radiation doses may vary according to the professional's experience, the quantity and location of these tumors, the collimation of the radiation beam and the total duration of the procedure. In this work the equivalent and effective dose values for the IOE and the patient were computationally obtained, using the Monte Carlo method, with the MCNPX code. A hemodynamic room was simulated with 3 female virtual anthropomorphic phantoms (FASH) representing the physician, medical assistant and patient. Three projections were simulated: PA, LAO45, RAO45, with field sizes 20 × 20 cm², 25 × 25 cm² and 32 × 32 cm², and tube voltages of 70 kV, 80 kV, 90 kV and 100 kV generated with the IPEM SRS 78 software (tungsten target and 2.1 mmAl filtration). To verify the efficiency of the protective equipment, scenarios were simulated in which workers were not wearing protective equipment and scenarios in which lead curtains, brain and thyroid protectors, aprons and lead glasses were used. It was observed that with higher field sizes and tube voltages, higher doses were received by the patient and staff, reinforcing the importance of collimating the beam and reducing the tube voltages whenever possible. The projection that provided the highest doses for the patient was the PA, and the highest effective dose, 3.64E3 µSv (±0.08%), was obtained with a field size of 32 × 32 cm² and a tube voltage of 100 kV. The organs that received the highest equivalent dose were the uterus 2.20E4 µSv (±0.09%), bladder 1.79E4 µSv (±0.11%), ovaries 1.36E4 µSv (±0.20%), which are the organs closest to the primary radiation beam. The organs that received the lowest doses were the eye lenses 4.25E-1 µSv (±17.86%), followed by the salivary glands 1.15E1 µSv (±1.85%), and the remaining tissues 5.49E1 µSv (±0.01%). Considering the scenario without the use of protective equipment, the LAO45 projection provided the highest doses, with a field size of 32 × 32 cm² and a tube voltage of 100 kV. The highest effective dose was received by the physician 4.57E2 µSv (±0.15%), and the medical assistant received 4.11E2 µSv (±0.13%). However, when all protective equipment was used, the doses reduced to 1.57 E1 µSv (±1.02%) and 1.45E1 µSv (±0.80%), for the physician and medical assistant respectively. It was possible to conclude that for the scenario without the protective equipment, the physician received a dose 9% higher than the medical assistant, as it is closer to the patient. For the scenario with PPE, the medical assistant received a 9.3% higher dose than the physician, mainly due to the fact that its location in the room is not protected by the lead curtain. When the physician does not wear the personal protective equipment, a dose increase of 317% was noticed. In this situation, the medical assistant received a 382% higher dose.