骨盆腔攝影照相使用柵板之劑量評估

Dose Estimation of the Grid in Pelvic A-P Radiography

陳怡光(Y. G. Chen) ； 許芳裕(F. Y. Hsu) ； 林佳妮(J. N. Lin) ； 毛敏莉(M. L. Mao) ； 吳志行(T. H. Wu)

《中華放射線技術學雜誌》 28卷2期 (2004/12) Pp. 101-109

https://doi.org/10.30045/CJRT.200412.0001

摘要

在急診外傷的一般X光檢查中，骨盆正面照相(pelvic A-P projection)常被用以作為診斷有無嚴重骨折的首要篩檢方式，本研究在影像結果不影響急診醫師之正常判讀前提下，測量並比較患者在不使用柵板、直接放置攝影片匣在骨盆下，與使用柵板、放置攝影片匣時的不同攝影條件下，兩種作業模式所產生的輻射劑量差異，並提供相關攝影條件之劑量參考，以利對骨盆攝影之X光檢查方式做客觀評估。本研究採用了放射診斷技術中用以度量低劑量範圍的TLD-100H作為劑量計，置放於擬人假體(Rando phantom)之體內度量各器官之劑量與皮膚表面劑量(ESD)。TLD在測量前需先進行篩選與校正，以確保計讀數據的穩定與準確性。利用假體實驗所得之ESD與體內各器官劑量的關係，可再進行臨床實際作業中病患的ESD劑量度量，藉以轉換成臨床病患之生殖腺與其他重要器官的吸收劑量。經參考ICRP 60號報告所建議之13個重要器官之組織加權因數，可評估使用柵板與不使用柵板進行骨盆檢查之有效劑量(effective dose)。60位患者（分成兩組）的各攝影條件計算後所得平均ESD為2.40 mSv（使用柵板）與1.01 mSv（不使用柵板），二者之比值約為2.4。測量劑量由最小體厚13 cm的0.67 mSv至最大體厚22 cm的4.35 mSv之間呈逐漸昇高。本研究的劑量度量方法評估出了柵板在使用上所造成之劑量差距。結果顯示無柵板的攝影方式，是降低受檢者輻射劑量的簡易可行方式，值得採用；不過，無論如何，對於骨盆過大患者而言，在攝影時仍要加上柵板才足以濾除過多散射線，以取得足夠好之影像品質。

關鍵字

熱發光劑量計 ； 柵板 ； 骨盆攝影

並列摘要

The examinations with and without grid in pelvic A-P radiography are performed on emergency patients with trunk-injury frequently. Low gonad dose and acceptable image quality are the goals of this study. Optimization for the use of the grid was assessed in this work to maintain the diagnosis value and to reduce the radiation dose in pelvic A-P radiography. High sensitivity thermoluminescence dosimeters (TLD), TLD-l00Hs, were placed in a RANDO phantom and on the entrance surface of clinical human bodies. Stability and dose calibration of TLDs were performed in advance. The relations between entrance surface dose (ESD) and organ doses in phantom give the organ dose conversion factors, with and without grid, for the pelvic A-P radiography. According to the conversion factors and ESDs, clinical organ doses of a human can be estimated. ICRP-60 report gave the recommendations for tissue weighting factors of 13 important tissues and organs. As an index, the doses of these important organs were estimated and compared in the conditions of with and without grid in the pelvic A-P radiography. The ESDs of 60 clinical pelvic A-P cases were measured in this work. All these cases were chosen in the thickness ranged from 13 to 22 cm. Examinations were performed half with grid and half without grid in contrast. The ratio of average ESD of with grid and without grid in clinical radiography is 2.4. Our work gives the suggestions in the optimized use of grid in the pelvic A-P view examinations. In most cases, the doses decrease in the radiography without grid, and increase with grid. However, a grid is still needed in some special cases, such as larger pelvic, for the image quality.

並列關鍵字

TED ； grid ； pelvic radiography