利用自製假體對E.cam 取像之最佳化

Optimization of E.cam imaging quality

張白容(Pai-Jung Chang)

指導教授 ： 潘榕光

中臺科技大學/健康科學院/放射科學研究所/碩士(2009年)

https://doi.org/10.6822/CTUST.2009.00005

摘要

目的：臨床上做腫瘤檢查的方法有許多種，就影像的檢查來說最常使用的有Ga-67 scan與FDG-PET scan兩種檢查。PET的影像品質與解析度都非常的好，但是成本較高，而Ga-67相較之下比較便宜，但是影像品質與解析度都不是很理想。若可找出Ga-67在γ-攝影機造影時最佳影像品質之參數，即可對於無法實行FDG-PET檢查的病人於臨床檢查時有一定的幫助。
材料與方法：本實驗使用田口實驗設計法(Taguchi methods)。利用簡單的直交表實驗設計與簡潔的變異數分析，以自製的壓克力假體 (大小為20x30x2 cm3，表面有5 mm深、1 mm寬的雷射刻痕) ，利用田口博士所設計的L9(34)「直交表」與少量的實驗數據進行分析尋求Ga-67在γ-攝影機造影時之最佳影像品質。
結果：經過資料分析與變異分析(ANOVA)、考慮其交互作用(cross interaction)後，得到一組最佳參數組合。但經過驗證實驗、再次修正後，最終一組最佳參數組合為：使用中能量高解析度的準直儀(MEHR)、捨棄光子300 keV (所佔比例最小)、掃描速度為16 cm/min、Ga-67活度為250 μCi時，可以得到最佳的影像品質。
結論：田口方法是田口玄一(Taguchi Genichi)博士於1950年代所開發倡導。利用簡單的直交表(orthogonal arrays)實驗設計與簡潔的變異數分析(ANOVA)，以少量的實驗數據進行分析，可有效提昇結果之品質。本實驗中，影像品質優劣之因素主要取決於準直儀(collimator) 之選擇與能窗大小(window width)；但由控制因子分類之觀念中得知，雖說掃描速度(scan speed)與67Ga之放射活性(activity) 等控制因子對品質特性較無影響力，但仍可經由調整此類控制因子來使生產成本降至最低。例如：用最快之掃描速度使病患檢查時更舒適度；用最快之掃描速度使作業流程更順暢，而使用最少之67Ga可節省作業部門之藥劑成本、患者身上的吸收劑量與整個作業場所之環境背景值，且有效提昇67Ga造影結果之影像品質。對於設置PET center 有困難的核子醫學科，或是無法做FDG-PET 的檢查的病人於臨床檢查時有一定的幫助。

關鍵字

Ga-67 scan ； FDG-PET scan ； 田口實驗設計法 ； 直交表 ； 變異分析

並列摘要

Purpose：On clinical, we used Ga-67 scan and FDG-PET scan for the tumor inspection. PET scan had good image quality and resolution, but the cost is high. Ga-67 scan is quite comparatively cheap, but the quality and the resolution are not very ideal. Parameter of the best image quality for Ga-67 in gamma - camera, with helpful to the patient who can not implements the FDG-PET inspection in the clinical examination.
Materials and Methods：This experiment uses the Taguchi Methods with simple orthogonal arrays and the analysis of variance (ANOVA), by the indigenous plate phantom and the few empirical datum to seek the best image quality of Ga-67 in gamma-camera.
Results：Used the medial energy high resolution collimator (MEHR), rejection photon 300 keV (to account for proportion to be smallest), the scanning speed is 12 cm/min, the activity of Ga-67 is 250μCi, may obtain the best phantom quality.
Conclusion：Taguchi Method was developed by Dr. Taguchi in 1950s. By using the simple experiment design of orthogonal arrays and ANOVA and analyzed a few experiment data could raise the image quality effectively. In this experiment, the factors of image quality are determined by the choose of collimator and energy window width; with the conception of division control factor, the factors of scanning speed and activity of Ga-67 have less effect on quality characteristic but by adjusting those control factors to decrease the production cost. For example, to increase the patient comfort in scan is increase the scanning speed; using the fastest scanning speed to smooth scanning procedure and injecting the less activity of Ga-67 would decrease the production cost of the department、absorbed dose of patients、the background of the working environment and increase effectively the image quality of Ga-67 tumor survey. That would help those NM department who set up PET center in difficult and patients not received FDG-PET scan in clinical examination.

並列關鍵字

FDG-PET scan ； Ga-67 scan ； Taguchi Methods ； ANOVA ； orthogonal arrays

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