中华放射肿瘤学杂志
中華放射腫瘤學雜誌
중화방사종류학잡지
CHINESE JOURNAL OF RADIATION ONCOLOGY
2010年
2期
139-142
,共4页
贺晓东%王成%张剑戈%赵红光
賀曉東%王成%張劍戈%趙紅光
하효동%왕성%장검과%조홍광
射野图像优化%小波变换%巴特沃斯高通滤波
射野圖像優化%小波變換%巴特沃斯高通濾波
사야도상우화%소파변환%파특옥사고통려파
Portal imaging optimization%Discrete wavelet transforming%Butterworth high pass filters
目的 通过在自研的放疗DicomRT处理平台上,对放疗实时验证图像的优化算法和参数条件进行研究,以获得具有较高对比度、骨结构及软组织结构清晰的兆伏级X线图像.方法 在加速器6 MV X射线和Portal Vision aSi500非晶硅射野影像系统等设备条件下,采用Las Vegas专用图像质量测试板图像中可见行数及行数中圆形个数作为判定标准,对各种拍摄条件下采集的射野图像进行可见行数的判定,以找出最合适的拍摄条件.在图像后处理中使用Matlab语言进行编程处理,采用的算法主要为对比度拉伸加直方图均衡化、小波变换、巴特沃斯高通滤波.结果 较合适的拍摄条件为复位数2～3,均帧数3～4,开机量4～5 MU.对采集的图像采用直方图均衡化处理后密度分辨率有一定提高;经小波边界处理后软组织结构和骨结构的边界分辨率均有显著提高;采用巴特沃斯高通滤波处理后使得密度分辨率有明显提高,已能明确分辨出骨结构和软组织结构.结论 虽然兆伏级X线图像在本质上是低组织密度分辨率的,但在选择合适拍摄条件、采用小波边界检测法或采用巴特沃斯高通滤波处理后仍能获得较佳密度分辨率的实时射野图像.
目的 通過在自研的放療DicomRT處理平檯上,對放療實時驗證圖像的優化算法和參數條件進行研究,以穫得具有較高對比度、骨結構及軟組織結構清晰的兆伏級X線圖像.方法 在加速器6 MV X射線和Portal Vision aSi500非晶硅射野影像繫統等設備條件下,採用Las Vegas專用圖像質量測試闆圖像中可見行數及行數中圓形箇數作為判定標準,對各種拍攝條件下採集的射野圖像進行可見行數的判定,以找齣最閤適的拍攝條件.在圖像後處理中使用Matlab語言進行編程處理,採用的算法主要為對比度拉伸加直方圖均衡化、小波變換、巴特沃斯高通濾波.結果 較閤適的拍攝條件為複位數2～3,均幀數3～4,開機量4～5 MU.對採集的圖像採用直方圖均衡化處理後密度分辨率有一定提高;經小波邊界處理後軟組織結構和骨結構的邊界分辨率均有顯著提高;採用巴特沃斯高通濾波處理後使得密度分辨率有明顯提高,已能明確分辨齣骨結構和軟組織結構.結論 雖然兆伏級X線圖像在本質上是低組織密度分辨率的,但在選擇閤適拍攝條件、採用小波邊界檢測法或採用巴特沃斯高通濾波處理後仍能穫得較佳密度分辨率的實時射野圖像.
목적 통과재자연적방료DicomRT처리평태상,대방료실시험증도상적우화산법화삼수조건진행연구,이획득구유교고대비도、골결구급연조직결구청석적조복급X선도상.방법 재가속기6 MV X사선화Portal Vision aSi500비정규사야영상계통등설비조건하,채용Las Vegas전용도상질량측시판도상중가견행수급행수중원형개수작위판정표준,대각충박섭조건하채집적사야도상진행가견행수적판정,이조출최합괄적박섭조건.재도상후처리중사용Matlab어언진행편정처리,채용적산법주요위대비도랍신가직방도균형화、소파변환、파특옥사고통려파.결과 교합괄적박섭조건위복위수2～3,균정수3～4,개궤량4～5 MU.대채집적도상채용직방도균형화처리후밀도분변솔유일정제고;경소파변계처리후연조직결구화골결구적변계분변솔균유현저제고;채용파특옥사고통려파처리후사득밀도분변솔유명현제고,이능명학분변출골결구화연조직결구.결론 수연조복급X선도상재본질상시저조직밀도분변솔적,단재선택합괄박섭조건、채용소파변계검측법혹채용파특옥사고통려파처리후잉능획득교가밀도분변솔적실시사야도상.
Objective Electronic portal imaging devices (EPIDs) are widely used as a replacement of portal films for patient position verification, but the image quality is not always optimal. Because of very low density resolution, the portal imaging is difficult to be used clinically. In this study, several transforming models and the optimization exposure or acquisition conditions were studied for optimization portal imaging, which based on DicomRT platform built by ourselves. Methods 6 MV X-ray from Varian 21EX linac was used to generate portal images by Portal Vision aSiS00 amorphous silicon detector image acquisition system. The density resolution study was based on the number of the lines which could be seen in the image of a special Las Vegas image quality test board. The optimization calculating models were focused on equalization after stretch transforming discrete wavelet transform (DWT) and Butterworth high pass filters. The calculation was performed in Matlab language. Results The optimal numbers of MU, average frames and reset number were 4 - 5,3 - 4 and 2 - 3, respectively. The density resolution of optimized imaging via equalization after stretch transforming, DWT and Butterworth high pass filter transforming was markedly improved. The bone structure could be definitely distinguished. The number of lines distinguished in Las Vegas image via equalization after stretch transforming, DWT and Betterworth high pass filter transforming was 3, 4 and 5, respectivly. Conclusions The proposed transforming systems, including DWT edge detection and Butterworth high pass filter transform, are suitable for improving density resolving power of MV X-ray portal image.
