多切片電腦斷層掃描小兒參數之最佳化

多切片電腦斷層掃描之掃描速度增快，可大幅減少檢查造影時間並且可提升Z軸之影像解析度，已成為臨床診斷之一大利器，然而小兒對輻射較為敏感，因此在針對小兒接受多切片電腦斷層檢查時，宜更加謹慎。目前小兒接受臨床多切片電腦斷層檢查時，大部份是使用成人的掃描條件，或根據成人的掃描條件而修改，因此本研究目的為建議最佳化之小兒多切片電腦斷層掃描參數，可降低小兒劑量，並能維持影像品質以供診斷。本研究以直徑10~32 cm的五種圓柱型假體模擬小兒體型，改變管電壓與管電流時，比較體中央與表面的劑量與影像品質。結果顯示，管電壓從120 kVp降低至80 kVp時，劑量會降低為原來的的0.3~0.7倍，成人劑量約為小兒的1.4~2.5倍。假體中央的影像雜訊約高於邊緣處兩倍，假體直徑越大其差異越明顯，因此可提高管電流使雜訊降低，隨之也提高對比雜訊比。由本研究可知小兒多切片電腦斷層檢查在管電壓與管電流對劑量與影像品質的影響，暸解假體邊緣與中央之劑量衰減與影像品質之關係，進而利用系統化的方法分析影像品質，提出小兒檢查的臨床技術條件參考建議表，在可提供臨床醫師足夠的影像資訊以進行診斷判讀之前提下，合理抑低小兒輻射劑量，減少輻射致癌機率風險。

關鍵字

多切片電腦斷層掃描；小兒劑量；影像品質

並列摘要

Multislice CT scanners have short scanning duration between every scan and improve the Z-axis resolution. Pediatric patients need to be taken more care due to they are highly radiosensitive. However, most of the pediatric scanning protocols are currently adjusted according to adult parameters. Previous studies indicated that scanning parameters should be as low as reasonable reduced. The purpose of this study is to recommend an optimal protocol for pediatric CT scanning according to the habitus of pediatric patients. The results indicated the relationship between radiation dose and image quality was affected by the tube voltage and tube current. The pediatric radiation dose was 0.3~0.7 times lower than that of adults when we decreased tube voltages. The adult doses were 1.4~2.5 times higher than that of pediatrics under the same exposure condition. Increasing the tube current can reduce the image noise, and then the contrast-to-noise ratio was improved. The optimal pediatric CT examination protocol has been recommended for clinical uses since it can reduce pediatric doses and the probabilities of cancerous risk without interfering the diagnostic image quality.

並列關鍵字

multislice computed tomography ； pediatric dose ； image quality

國際替代計量

多切片電腦斷層掃描小兒參數之最佳化

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