ABSTRACT
Purpose: Several cases of inaccurate irradiation in brachytherapy have been reported, occurring similarly to external radiation. Due to a large dose per fraction in brachytherapy, inaccurate irradiation can seriously harm a patient. Although various studies have been conducted, systems that detect inaccurate irradiation in brachytherapy are not as developed as those for external irradiation. This study aimed to construct a system that analyzes the source dwell position during irradiation using computed tomography (CT) scout images. The novelty of the study was that by using CT scout images, high versatility and analysis of absolute coordinates can be achieved. Material and methods: A treatment plan was designed with an iridium-192 (192Ir) source delivering radiation at two dwell positions in a tandem applicator. CT scout images were taken during irradiation, and acquired under different imaging conditions and applicator geometries. First, we confirmed whether a source was visible in CT scout images. Then, employing in-house MATLAB program, source dwell coordinates were analyzed using the images. An analysis was considered adequate when the resulting source dwell coordinates agreed with the treatment plan within ±1 mm, in accordance with AAPM TG56 guidelines for source dwell position accuracy. Results: The source dwelling was visible in CT scout image, which was enlarged or reduced depending on applicator geometries. The applicator was enlarged by 127% when 130 mm away from the center of CT gantry. The analysis results using our in-house program were considered adequate; although, analysis parameters required adjustments depending on imaging conditions. Conclusions: The proposed system can be easily implemented for image-guided brachytherapy and can analyze the absolute coordinates of source dwell position. Therefore, the system could be used for preventing inaccurate irradiation by verifying whether brachytherapy was performed properly.
ABSTRACT
In June 2015, Japanese diagnostic reference levels (Japan DRLs 2015) was released by Japan Network for Research and Information on Medical Exposures (J-RIME). After six months the release of Japan DRLs 2015, we have conducted a questionnaire and received 222 responses from hospital staff regarding their perception level, and implementation on Japan DRLs 2015 at their facilities. 131 people (59.0%) were familiar with Japan DRLs 2015, of which 56 people (29.2%) were not currently implementation of them. A total of 66 people (30.1%) understood how to implement Japan DRLs 2015. There were 35 people (18.2%) who heard of diagnostic reference levels (DRLs) for the first time through this survey. Those are the levels of perception and implementation on Japan DRLs 2015 became clear. It is necessary to compare the dose levels used at each facility with Japan DRLs 2015 to optimize patient protection during medical exposure. It is essential to continue to grow the medical community's understanding of DRLs with the expanded perception and implementation of this survey as an opinion poll across Japan.
