The investigation on parameters of dose of computed tomography in Taiwan and assessment of population of average annual effective dose

• Main Authors: Yu-Cheng Chang, 張育誠
• Other Authors: Tou-Rong Chen
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/95668117069699853648

碩士 === 中山醫學大學 === 生物醫學科學學系碩士班 === 103 === The compound annual growth rate of CT examinations is 8.1% from 2000 to 2013 according to the Ministry of Health and Welfare in Taiwan. The frequency of CT examinations in 2013 is 2.7 times of that in 2000. Due to the rapid incensement of CT examinations, and a large contribution in the collective effective dose, it is a important and necessary to study the population effective dose caused by CT examinations in Taiwan. The database of this study includes scan information, the dose indexes and parameters of CT clinical examination, of 28 hospitals in Taiwan. The database is composited by data of 30 CTs and 4407 persons. The data is arranged and analized by six scan ranges, the head (39.8%)> abdomen (26.7%)> chest (23.3%)> pelvis (4.8% )> neck (3.9%)> Other (1.6%) in sequence with the percentage of CT examinations. We use this ratio as a proportion extending to total 1896494 CT examinations of Taiwan in 2013. The effective dose of CT examination is assessed by dose-length product (DLP) in the study. The DLP (mGycm) for a single scan on six scan ranges are: head (902190), neck (591330), chest (452318), abdomen (542226), pelvis (770388), and other (858572), respectively. The average scan frequencies of a person or procedure (scan/person) are: head (1.19), neck (1.87), chest (1.60), abdominal (2.43), and pelvis (1.60), respectively. The highest scan frequency per person is located on the abdomen range. We can estimate the effective dose on six scan ranges after using DLP (mGycm) values multiply to DLP converted to effective dose factors (k values). The study uses thermoluminescent dosimetry (TLD) to achieve the k values, and using two simulation programs to verify it. The k values (mSvmGy-1cm-1) of six scan region ranges are head(0.0016), neck (0.0077), chest (0.0142), abdomen (0.0138), pelvis (0.0095) and whole body (0.0050)。They are resulted by two CT instruments. The experimental k value is between the simulation k values by two programs. The k value of other region adopts the k value of whole body, because of difficult to verify. The population effective dose of Taiwan is 0.72 mSv per capita in 2013 assessed by scanned persons, DLP distribution, and experimental k values.