A Study on Radiation Dose in Dental Radiography Measured on Human Body and Phantom

牙科X光攝影術對人體及假體的放射線劑量的研究

印憶恒(Yat-Hang Yan) ； 林立民(Li-Min Lin) ； 黃湧澧(Yeong-Lei Huang) ； 連熙隆(Shi-Long Lian) ； 許彬杰(Pin-Chieh Hsu) ； 翁寶山(Pao-Shan Wang)

《The Kaohsiung Journal of Medical Sciences》 3卷3期 (1987/03) Pp. 182-191

https://doi.org/10.6452/KJMS.198703.0182

摘要

由於醫學科技的發展及牙科治療方法的進步、在一般醫療及診斷過程中，X光扮演著非常重要的角色。為協助牙醫師對病人的病情診斷，治療計晝的安排及治療結果的評估：病人接受X光檢查成為一項不可或缺的步驟。為提昇醫療品質，病人接受X光檢查的機會也相對增加。故評估病人在做過X光檢查後，有多少放射線劑量被身體的敏感器官所吸收，並造成可能的傷害，成為今日一項熱門的課題。國外曾有很多這方面的報告，但大多是用假體(Phantom)或是作全口14張根尖片照射的放射線劑量的分析，少有單張X光的劑量報告。國內這方面資料相當缺乏。本研究主要的目的是在測定一般常用的牙科X光攝影術，測量被眼球，甲狀腺，性器官和脊髓等器官所吸收之劑量。以熱發光劑量計(thermoluminescent dosimeter，TLD)置於假體的各個需要測量器官內及相對的體表位置上，以不同的方法照射，包括口內不同位置的牙根尖片，上顎和下顎的咬合片。利用清華大學原子科學研究所的Harshaw 2000 B&C型的TLD測定器計讀其劑量。然後在志願待測者的相對體表位置上貼TLD，利用數學的原理，計算出待測者實際上各器官所吸收的放射線劑量。結果顯示眼球的吸收劑量主要是受主射線的入射角度和受測器官與主射線的距離有關；甲狀腺主要與主射線角度和X光底片暴射時間有關。性腺的吸收劑量主要是受射線角度，受測器官的距離和X光底片暴射時間等因素有關。脊髓的吸收劑量和射線的距離有穩定的關係，但因為不同的射線角度而有所差別。本研究所有的結果和其他報告比較都顯得低，這可能與目前X光機性能的改良，X光片敏感度的提昇等因素有關。雖然本研究中各器官所接受的劑量很低，且在原子能委員會所規定的範圍內，然而為符合輻射線保護的原則，對於受檢者的眼球、甲狀腺和性腺等都應加以防護，如鉛衣、鉛頸布、鉛眼罩等都可以減少受檢者的輻射劑量。以期在對病人造成最少傷害的情況下得到最大的診斷價值。

並列摘要

Dental radiography is a very important diagnostic tool in modern dentistry. It also provides additional information for setting the procedure for the patient's future treatment. Dental radiography belongs to the low radiation dose class. The magnitude of the risk remains uncertain. This study provides for an informed selection in terms of the risk of these procedures. The thermoluminescent dosimeter (TLD) and a Rando phantom were used to detect the radiation dose on various organs including the optic lens, thyroid gland, gonad and spinal cord. The TLD was also placed on the skin surface of the volunteers corresponding to that of the phantom. The dose to the organs in their real position was calculated mathematically. We found that the dose on the lens was greatly affected by both the direction of the main beam of radiation and the distance between the exposed site and the organ. But the dose on the thyroid gland was mainly related to the direction of the ray and the exposure time. Gonadal dose may be related to the angulation of the central beam and the distance between the central beam and gonadal organ. In addition, the time factor may also be related. For the spinal dose, it may be mainly attributed to the target-organ distance and the angulation of the beam. In view of the angulation of the central ray and distance between the exposed site and the organ, the results showed that all the radiation doses were lower than those of previous reports. Possible reasons for these results including the improvement of collimator, beam filtration, increased kilo-voltage, sensitivity of the film, increased focal-film distance and other related factors have been discussed.

並列關鍵字

thermoluminescent dosimeter TLD ； phantom ； radiation dose