慈濟技術學院放射技術系

摘　要

目前各醫院主要的放射攝影方法有三種，分別為數位攝影（DR）、電腦攝影（CR）與傳統底片攝影，其成像原理並不相同，X光機的管電壓、管電流與照射時間等條件也有些差異，因此，一次攝影給予病人的劑量也不相同。本研究利用花蓮慈濟醫院醫學影像部的放射設備，研究DR、CR與底片胸腔攝影給予病人各器官的等價劑量及與全身輻射風險相關之有效劑量。本研究以高靈敏度片狀氟化鋰熱發光劑量計為輻射偵檢器，以女性RANDO擬人化假體模擬女性病人的軀體，以花蓮慈濟醫院實際攝影時所訂的X光機曝射條件，評估CR、DR與底片攝影給予病人的劑量。實驗結果顯示，DR、CR與底片胸腔攝影給予病人的有效劑量分別為20.68微西弗、29.99微西弗與32.30微西弗，DR、CR與底片攝影給予病人的入射表面劑量分別為0.122毫西弗、0.195毫西弗與0.197毫西弗。三種攝影方法給予病人的入射表面劑量，都遠低於國際原子能總署建議的胸腔PA攝影不得超過0.4毫西弗的劑量指引水平。本研究也參考國際輻射防護委員會第60號報告的輻射機率效應風險係數，評估病人因一次胸腔射影伴隨之機率效應風險約為1.68×10^-6。

關鍵字：熱發光劑量測定術、X光劑量、有效劑量、入射表面劑量

Shann-Horng Yeh、Ying-Yai Tsai and Ming-De Ding

Department of Radiological Technology

Tzu-Chi College of Technology

Abstract

There are three major radiographic methods in hospital, i.e., digital radiography（DR）, computed radiography（CR）and film radiography.  The exposure parameters of X-ray machine such as tube voltage, tube current and exposure time are different for these methods.  Therefore the patient’s absorbed doses are different and need to be evaluated.  This research study the patient dose for these three radiographic methods by utilizing the radiographic equipments of Buddhist Tzu Chi General Hospital in Hualien.  The equipments used in this study include high sensitivity TLD-LiF and female RANDO phantom.  The exposure parameters（kVp and mAs）adopted at Tzu Chi General Hospital are utilized in this research to evaluate patient’s organ dose and effective dose.  The research results reveal that patient’s effective dose for DR, CR, and film radiography are 20.68 μSv, 29.99 μSv and 32.30 μSv respectively.  The entrance surface doses（ESD）for DR, CR, and film radiography are 0.122 mSv, 0.195 mSv and 0.197 mSv respectively.  The ESD for these three radiographies are quite lower than the guidance levels recommended by International Atomic Energy Agency.  Finally this research evaluates the patient’s radiation risk for the lung radiography also.  The radiation risk is about 1.68 × 10^-6.

Keywords：thermoluminescent dosimetry, X-ray dose, effective dose, entrance surface dose