The Future of Radiological Protection


Influence of Different Operating Modes (High, Normal and Low) and FOV Sizes on Air Kerma Rate in Different Interventional Radiology Equipment

Author(s): Arícia Ravane Pereira Da Cruz 1, Tiago da Silva Jornada 2
( 1 Universidade Federal de Pernambuco; 2 Hospital das Clínicas da Universidade Federal de Pernambuco)


Interventional Radiology is one of the diagnostic and therapeutic specialties that provides the highest levels of exposure to ionizing radiation for both patients and medical and technical staff. Minimizing the probability of harm to health with processes to optimize radiological practices is necessary. The fact that the manufacturers of Angiographics and C-Arm equipment have numerous technological resources provides a vast field for dose reduction. However, when we approach interventional radiology, a limiting factor is the lack of technical operating parameters and their relationship with the optimization of the dose rate used in the examination. Therefore, we aim to assess the influence of only two of these parameters. One is the different Exposure Modes and the other is the Field of View Size (FOV) dimensions of the image intensifier or flat panel. We assessed the patient's skin entrance kerma rate on six angiographs and four C-arms. We simulated a typical patient with 3-mm-thick copper attenuators and used a solid-state radiation detector for data collection. By means of irradiations performed under automatic exposure control, kerma rate values were obtained in low, medium, and high modes for the protocols and all field sizes available in the equipment. As expected, when changing the operating mode from high to normal and then to low the dose delivered to the patient decreases. However, when comparing equipment from the same manufacturer, each one presented its own behavior and there was also no relationship in the reduction between exposure modes when comparing all tested equipment. Another expected behavior was that the kerma rate would decrease as the FOV increases, in addition, it was expected that the radiation dose rates for equipment equipped with flat panel detectors would increase at a rate of 1/FOV and that for those with image intensifiers this rate was 1/(FOV)2. Most equipment followed this behavior, however, the largest discrepancies between the nominal and calculated values were observed for angiographers, whose maximum variation was 83% in the air kerma rate. The data corroborate the importance of characterization in the behavior of the technical parameters of operation, evaluated in this study, and its relationship with the dose of ionizing radiation used. In addition to the fact that equipment with the same brand and model may have different behavior. We highlight the need for future work to evaluate other functionalities of ionizing radiation emitting equipment used in interventional radiology.

Keywords: Interventional Radiology; Dose rate; Optimize; Angiographics; C-Arm