Syh J, Patel B, Syh J, Wu H, Rosen L, Durci M, Katz S, Sibata C
Willis-Knighton Medical Center, Shreveport, LA.
East Carolina University, Greenville, NC.
Med Phys. 2012 Jun;39(6Part11):3734. doi: 10.1118/1.4735193.
To evaluate the characteristics of commercial-grade flatbed scanners and medical-grade scanners for radiochromic EBT film dosimetry.
Performance aspects of a Vidar Dosimetry Pro Advantage (Red), Epson 750 Pro, Microtek ArtixScan 1800f, and Microtek ScanMaker 8700 scanner for EBT2 Gafchromic film were evaluated in the categories of repeatability, maximum distinguishable optical density (OD) differentiation, OD variance, and dose curve characteristics. OD step film by Stouffer Industries containing 31 steps ranging from 0.05 to 3.62 OD was used. EBT films were irradiated with dose ranging from 20 to 600 cGy in 6×6 cm field sizes and analyzed 24 hours later using RIT113 and Tomotherapy Film Analyzer software. Scans were performed in transmissive mode, landscape orientation, 16-bit image. The mean and standard deviation Analog to Digital (A/D) scanner value was measured by selecting a 3×3 mm uniform area in the central region of each OD step from a total of 20 scans performed over several weeks. Repeatability was determined from the variance of OD step 0.38. Maximum distinguishable OD was defined as the last OD step whose range of A/D values does not overlap with its neighboring step.
Repeatability uncertainty ranged from 0.1% for Vidar to 4% for Epson. Average standard deviation of OD steps ranged from 0.21% for Vidar to 6.4% for ArtixScan 1800f. Maximum distinguishable optical density ranged from 3.38 for Vidar to 1.32 for ScanMaker 8700. A/D range of each OD step corresponds to a dose range. Dose ranges of OD steps varied from 1% for Vidar to 20% for ScanMaker 8700.
The Vidar exhibited a dose curve that utilized a broader range of OD values than the other scanners. Vidar exhibited higher maximum distinguishable OD, smaller variance in repeatability, smaller A/D value deviation per OD step, and a shallower dose curve with respect to OD.
评估商业级平板扫描仪和医学级扫描仪用于放射变色EBT胶片剂量测定的特性。
在重复性、最大可分辨光密度（OD）差异、OD方差和剂量曲线特性等类别中，评估了Vidar Dosimetry Pro Advantage（红色）、爱普生750 Pro、中晶ArtixScan 1800f和中晶ScanMaker 8700扫描仪对EBT2 Gafchromic胶片的性能。使用了Stouffer Industries公司的OD阶梯胶片，包含31个阶梯，OD值范围从0.05到3.62。EBT胶片在6×6 cm的射野尺寸下接受20至600 cGy的剂量照射，并在24小时后使用RIT113和螺旋断层放疗胶片分析仪软件进行分析。扫描以透射模式、横向、16位图像进行。在几周内进行的总共20次扫描中，通过在每个OD阶梯的中心区域选择一个3×3 mm的均匀区域来测量平均和标准偏差模数（A/D）扫描仪值。重复性由OD阶梯0.38的方差确定。最大可分辨OD定义为其A/D值范围与其相邻阶梯不重叠的最后一个OD阶梯。
重复性不确定度范围从Vidar的0.1%到爱普生的4%。OD阶梯的平均标准偏差范围从Vidar的0.21%到中晶ArtixScan 1800f的6.4%。最大可分辨光密度范围从Vidar的3.38到中晶ScanMaker 8700的1.32。每个OD阶梯的A/D范围对应一个剂量范围。OD阶梯的剂量范围从Vidar的1%到中晶ScanMaker 8700的20%不等。
Vidar呈现出一条比其他扫描仪利用更宽OD值范围的剂量曲线。Vidar表现出更高的最大可分辨OD、更小的重复性方差、每个OD阶梯更小的A/D值偏差以及相对于OD更浅的剂量曲线。
