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題 名 | 站立式鉛柵焦距改變對影像品質影響的探討=Evaluation of Image Quality by Grid Focus Change of Standing Bucky |
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作 者 | 林彥良; 汪珮如; 張詩屏; 劉尤娜; 王美文; 王世堯; 陳韻如; | 書刊名 | 中華放射線技術學雜誌 |
卷 期 | 36:1 2012.03[民101.03] |
頁 次 | 頁39-43 |
分類號 | 416.12 |
關鍵詞 | 鉛柵焦距; 焦距切斷; 影像背景均勻度曲線; 影像品質; Grid focus; Focus-grid distance decentering; Cut off; Background-uniformity diagram; Image quality; |
語 文 | 中文(Chinese) |
中文摘要 | 站立式鉛柵機一般使用於胸部、頭部、頸椎、腹部及膝關節等攝影,目前大多數診斷用X光機的鉛柵機多使用聚焦式鉛柵板(focused grid),對於多功能型的一般X光攝影室,鉛柵板的選擇非常重要,因鉛柵板有其固定的鉛柵焦距,隨攝影部位的不同,會有180cm和100cm不同的攝影距離(focal-film distance),若採用不適當的鉛柵容易因鉛柵焦距產生焦距切斷(focus grid distance decentering, cut off)的情況,所以我們使用150cm和170cm兩種不同焦距的鉛柵板,在兩種不同的攝影距離下取得影像,利用影像呈現出的像素值(Pixel values)不同來評定影像品質,最後依照測量結果得知,焦距150cm的鉛柵同時在180cm和100cm攝影距離下所得之影像,其背景均勻度曲線圖皆呈現較平整的曲線(最高與最低落差分別約306 pixel values和102 pixel values),再經由放射科專科醫師判別對影像判讀之影響後,所得的統計數據與測試結果相同,即鉛柵焦距150cm的鉛柵板在拍攝180cm及100cm攝影距離的影像時,同時對兩種距離之影像品質的不良影響率較小,顯示其有較佳的影像品質;由此可知,焦距150cm的鉛柵板是最適合運用於一般攝影室必須兼顧180cm及100cm攝影距離的站立式鉛柵。 |
英文摘要 | Standing bucky generally uses in the chest, head, cervical spine, abdomen, knee radiographies and so on. Most bucky grids of diagnostic x-ray systems usually use focused grid. For the general multi-type X-ray systems, it is very important to choose the grid focus. Because each one focused grid has its specific focal range. According to different body parts of radiographies, the specific focus-film distance (180 cm or 100 cm) is used. If improper focused grid is used, the focus-grid distance decentering (cut off) can easily occure. Therefore, we used the two different focused grids (150 cm and 170 cm) to obtain radiographic images at two different focal-film distances (180cm and 100cm). The image quality of these images are evaluated by pixel values. Finally, based on the pixel-value measurement result, it reveals smooth curves of the background-uniformity diagram when the images use 150cm focused grid at both focal-film distances of 180cm and 100cm(The highest and the lowest difference approximately 306 pixel values and 102 pixel values). Image quality of the images were assessed by radiologists, too. The result is identical with the pixel-value measurement result. Consequently the images using 150cm focused grid at both focal film distances of 180cm and 100cm have minimum impact on the fraction defective and better image quality. It can be seen that 150cm focused grid is the most suitable to be applied to standing bucky of general x-ray system, it can give consideration to the image quality at both focus-film distances of 180cm and 100cm. |
本系統中英文摘要資訊取自各篇刊載內容。