| Summary: | 碩士 === 中臺科技大學 === 醫學影像暨放射科學系暨研究所 === 105 === Purpose: The purpose of this study was to evaluate scatter radiation dose of family member of patient during routine chest CT at different positions around the gantry and to investigate the degree of dose reduction for them when using lead apron.
Materials and Methods: Acrylic phantom that simulated family member was put at 4 positions around the gantry: in front of gantry and 300 from isocenter, in front of gantry and 450 from isocenter, in the back of gantry and 300 from isocenter, in the back of gantry and 450 from isocenter. All 4 measurement points were in the left side of the CT couch and 80cm away from patient isocenter. Semiconductor was attached to the phantom at the height equal to CT table to evaluate Entrance Skin Dose. There were 2 scenarios were implied: with and without wearing lead apron (0.5mm Pb). Routine chest CT protocol was applied at a teaching hospital with constant kVp (120) and scan length (320mm) but changing Dose Length Product (DLP) from 378mGy*cm to 629.9mGy*cm in 2 increments.
Results: Scatter doses in front of gantry were higher than in the back of gantry (32.44%) in both scenarios. Doses at 450 from isocenter were higher than at 300 (12.13%) for both in the back and front of gantry, with and without lead apron. However, the differences between doses among measurement points were not consistent with different DLPs. Using protective apron can reduce original dose to 6.8%.
Conclusion: standing at 300 or at 450 from patient isocenter at the same distance were acceptable due to unsignificant different doses between them. Wearing lead apron can reduce secondary radiation significantly, therefore it is strongly recommended in clinical application.
Keywords
Computed tomography, acrylic phantom, semiconductor dosimeter, scatter radiation
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