- 學位論文
台灣電腦斷層掃描劑量參數調查與國民平均年有效劑量評估
The investigation on parameters of dose of computed tomography in Taiwan and assessment of population of average annual effective dose
摘要
台灣衛福部統計資料顯示從2000年到2013年，CT檢查人數每年以8.1%的比例增加，2013年的檢查人數已是2000年的2.7倍。因電腦斷層檢查增速快，且有效劑量貢獻比例大，實有必要探討台灣目前因電腦斷層掃描造成的國民有效劑量。本研究蒐集全台28家醫療院所，登錄其臨床電腦斷層掃描檢查的劑量資訊，以建立台灣電腦斷層資料庫。資料庫中收集了30台電腦斷層掃描4407筆的資訊。本研究將掃描部位分成頭、頸、胸、腹、骨盆、其它六種範圍，檢查人數比例依序是頭部(39.8%) >腹部(26.7%) >胸部(23.3%)>骨盆(4.8%)>頸部(3.9%)>其它(1.6%)。我們以此比例當成是台灣2013年1,896,494人次的掃描比例。 本研究使用劑量長度積(DLP) 評估電腦斷層造成有效劑量。由自建資料庫分析得六種部位每單次掃描的DLP (mGy-cm)分別是：頭(902190)、頸(591330)、胸(452318)、腹(542226)、骨盆(770388)、其它(858572)。而平均每人施做掃描的次數(次/人)，分別是：頭(1.19)、頸(1.87)、胸(1.60)、腹(2.43)、骨盆(1.60)、其它(1.64)，其中以腹部的掃描次數最多。結合以上數據，我們可得自建資料庫中每人在六種部位的DLP (mGycm)，若再乘上DLP轉換有效劑量因數(k值)，則可得平均台灣施做六種部位CT造成的有效劑量。本實驗以熱發光劑量計(TLD)實驗以獲取k值，並以二套軟體模擬驗證之。六種部位實驗的k值(mSvmGy-1cm-1)分別是：頭(0.0016)、頸(0.0077)、胸(0.0142)、腹(0.0138)、骨盆(0.0095)、全身(0.0050)。以上是二台電腦斷層配合台灣臨床掃描範圍，實驗得之結果，此數據介於二套軟體模擬值之間。其它部位的k值難以確認，本研究採用全身的k值。由2013年衛福部的掃描人數、自建資料庫每人的DLP分佈、與實驗得之k值，可分析得台灣2013年因電腦斷層掃描造成的國民有效劑量為0.72 mSv per capita。
並列摘要
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.