Kim Sangroh, Yoshizumi Terry T, Toncheva Greta, Yoo Sua, Yin Fang-Fang
Duke University, Durham, NC 27705, USA.
Radiat Prot Dosimetry. 2008;132(3):339-45. doi: 10.1093/rpd/ncn305. Epub 2008 Dec 13.
In recent years, wide beam computed tomography (CT) technique has become standard in radiation oncology whereas there is little information about radiation dose assessments for the technique. A point dose measurement method was employed to assess the radiation doses of cone beams CT (CBCT) and multi detectors CT (MDCT). The radiation doses of both modalities were measured using thermoluminescence dosemeters (TLDs) in head and body CT phantoms. Four TLD chips were placed at the centre and each peripheral channel to measure the doses. From the measurements, the weighted CT dose index for CBCT (CTDI(w)(CBCT)) and volume CT dose index for MDCT (CTDI(vol)(MDCT)) were derived. In the results, the CTDI(w)(CBCT) was 89.7 +/- 4.0 mGy and the CTDI(vol)(MDCT) was 137.0 +/- 7.4 mGy for the head scan. For the body scan, they were 37.9 +/- 1.4 and 74.3 +/- 5.3 mGy, respectively. In conclusion, CTDI(w)(CBCT) for the head scan was 35% lower than CTDI(vol)(MDCT), and CTDI(w)(CBCT) for the body scan was also 49% lower than CTDI(vol)(MDCT).
近年来，宽束计算机断层扫描（CT）技术已成为放射肿瘤学的标准技术，然而关于该技术的辐射剂量评估信息却很少。采用点剂量测量方法来评估锥形束CT（CBCT）和多探测器CT（MDCT）的辐射剂量。使用热释光剂量计（TLD）在头部和体部CT体模中测量这两种模式的辐射剂量。将四个TLD芯片放置在中心和每个外周通道以测量剂量。通过测量，得出了CBCT的加权CT剂量指数（CTDI(w)(CBCT)）和MDCT的容积CT剂量指数（CTDI(vol)(MDCT)）。结果显示，头部扫描时CTDI(w)(CBCT)为89.7±4.0 mGy，CTDI(vol)(MDCT)为137.0±7.4 mGy。体部扫描时，它们分别为37.9±1.4和74.3±5.3 mGy。总之，头部扫描的CTDI(w)(CBCT)比CTDI(vol)(MDCT)低35%，体部扫描的CTDI(w)(CBCT)也比CTDI(vol)(MDCT)低49%。
