1.1 本规程详细介绍了通过评估个体检测不同射线噪声、对比度和清晰度的线性图像的能力来确定射线照相口译员低对比度视力的程序。没有就这些图像的适用性作出任何声明，以评估射线照相口译员的能力。在实际射线照相检查中，这些狭缝模型图像与检测裂纹或其他线性特征的能力之间没有相关性。 该测试程序遵循1981年6月发布的NBS技术说明1143中由国家标准与技术研究所执行的工作。 1.2 视力测试集由五个单独的平板组成，每个平板包含一系列0.5的射线图像 在里面(12.7 mm）薄金属垫片中的长缝。使用各种吸收体、几何参数（不清晰度、狭缝宽度）和源参数（kV、mA、时间）生成用于准备插图的原始射线照片，以生成不同噪声、对比度和清晰度的图像。 每个射线照相图像的背景密度为1.8±0.15。在射线照相解释环境中查看图像，用于评估生产射线照相胶片，例如，指南中所述的照明器和背景照明 E94 和规格 E1390 ，并且没有光学放大。 1.3 每个视力测试板由25个单独的图像区域组成。图像按5行5列排列，如所示 图1 . 每个图像区域为2 在里面 x 2 在里面(51 毫米x 51 毫米）。所有标识均位于铭牌背面。可以从四个方向中的任何一个方向查看每个平板（即，可以在照明器上的任何四个边缘“向上”的情况下查看）。由于该组中有五个不同的图版，因此总共可以查看20种不同的图案。在任何给定的测试中，可以通过背面的标识来确定五块板中的哪一块以及四个方向中的哪一个。 图1 视力测试板布局 1.4 在图像区域内，狭缝图像可能出现在五个位置中的任何一个，即图像区域的四个角中的任何一个，或靠近中心。任何一个图像区域中不会出现超过一个狭缝图像。狭缝图像可以是水平、垂直、向左倾斜或向右倾斜。几个板包括一个或多个图像区域，其中没有狭缝图像。 1.5 使用本标准需要购买辅助测试板。 1.6 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.7 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 4.1 本规程用于评估射线照相解释人员在射线照相解释环境中辨别低对比度狭缝图像的能力。射线照相查看器，如规范所述 E1390 ，以及查看环境，如指南中所述 E94 强烈建议。任何给定应用中的最低可接受测试分数取决于应用的要求。使用方应制定并维护其测试结果的记录，以指导其应用程序可接受测试分数的确定。 （参见 注1 .) 注1: 在与经验丰富的射线照相口译员进行循环测试期间，76 % 四分之一的口译员得了85分 % 或更高，95 % 取得80分 % 或更高。平均得分为90.7分 %, 标准差为6.7 %. 在2017年的第二项研究中，认证放射技师和非认证人员的平均和标准偏差为90.4±4.0 % 非持证人员为88.4±4。 9 %. 我们发现，在每个测试页面上有3到4个图像，每个图像的平均分数低于80 % 正确，其余图像的得分均大于80分 % 平均而言。对少数公众进行了检查，其中平均得分为75.0±3.3 %. 4.2 试验管理 4.2.1 本规程中描述的测试程序旨在确定射线照相解释器在微光环境中检测低对比度图像的能力。 应允许适当的暗适应时间。至少1 建议最小值；然而，一些用户可能需要更长的暗适应时间。 4.2.2 测试应由测试管理员管理或在其指导下进行（参见 3.2.4 ). 试验前，受试者不应知道板的标识或方向。 4.2.3 在答题纸上记录对平板上25个图像区域中每个区域的解释， 图2 ，通过在该图像区域中绘制与狭缝图像的位置和方向相对应的线。 如果未检测到直线图像，则应在答题纸上与未检测到狭缝图像的图像区域相对应的区域内绘制一个圆。评分表示例如所示 图3 ，说明了典型的线路位置和方向，并说明了标记答案的方法。样品计分表中所示的标记并非取自任何实际测试板；然而，它们说明了狭缝图像的典型分布。 图2 本练习的答案可以复印以提供答卷，或者使用组织可以自行生成合适的答卷。 在任何情况下，答题纸必须具有记录25个图像位置中每个位置指示的位置和方向的规定。 图2 视力测试评分表 图3 完整的视力测试分数表示例 4.2.4 显示标记的顺序并不重要。读者可以按顺序标记指示，或者可以标记较容易的图像并返回到较难的图像。 4.2.5 评分表完成后，测试管理员应确定所读铭牌的标识和方向，并使用适当的答案键对答案进行评分。

1.1 This practice details the procedure for determining the low-contrast visual acuity of a radiographic interpreter by evaluating the ability of the individual to detect linear images of varying radiographic noise, contrast, and sharpness. No statement is made regarding the applicability of these images to evaluate the competence of a radiographic interpreter. There is no correlation between these images of slit phantoms and the ability to detect cracks or other linear features in an actual radiographic examination. The test procedure follows from work performed by the National Institute of Standards and Technology presented in NBS Technical Note 1143, issued June 1981. 1.2 The visual acuity test set consists of five individual plates, each containing a series of radiographic images of 0.5 in. (12.7 mm) long slits in thin metal shims. The original radiographs used to prepare the illustrations were generated using various absorbers, geometric parameters (unsharpness, slit widths), and source parameters (kV, mA, time) to produce images of varying noise, contrast, and sharpness. Each radiographic image has a background density of 1.8 ± 0.15. The images are viewed in a radiographic interpretation environment as used for the evaluation of production radiographic films, for example, illuminators and background lighting as described in Guide E94 and Specification E1390 , and without optical magnification. 1.3 Each visual acuity test plate consists of 25 individual image areas. The images are arranged in 5 rows and 5 columns as shown in Fig. 1 . Each image area is 2 in. x 2 in. (51 mm x 51 mm). All identification is on the back side of the plate. Each plate can be viewed from any of the four orientations (that is, it can be viewed with any of the four edges “up” on the illuminator). Since there are five different plates in the set, this makes for a total of 20 different patterns that can be viewed. The identification of which of the five plates and which of the four orientations were viewed in any given test can be determined from the designation on the back side. FIG. 1 Layout of Visual Acuity Test Plate 1.4 Within the image areas, the slit image may appear in any of five locations, that is, in any of the four corners of the image area, or near the center. No more than one slit image will appear in any one image area. The slit image may be horizontal, vertical, slant left, or slant right. Several of the plates include one or more image areas in which there is no slit image. 1.5 Use of this standard requires procurement of the adjunct test plates. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 4.1 This practice is used to evaluate the ability of a radiographic interpreter to discriminate low contrast slit images in a radiographic interpretation environment. A radiographic viewer, as described in Specification E1390 , and a viewing environment, as described in Guide E94 , are strongly recommended. The minimum acceptable test score in any given application depends on the requirements of the application. Using parties should develop and maintain records of their test results to guide the establishment of acceptable test scores for their applications. (See Note 1 .) Note 1: During round robin testing with experienced radiographic interpreters, 76 % of the interpreters achieved a score of 85 % or higher, and 95 % achieved a score of 80 % or higher. The average score was 90.7 %, and the standard deviation was 6.7 %. In a second study from 2017, with both certified radiographers and uncertified personnel, the average and standard deviation among certified radiographers was 90.4 ± 4.0 % and among uncertified personnel was 88.4 ± 4.9 %. It was found that on each test page there are 3 or 4 images where the average score for each was less than 80 % correct and the remainder of the images all individually scored greater than 80 % on average. A limited number of the general public was examined, and the average score among these was 75.0 ± 3.3 %. 4.2 Administration of the Test 4.2.1 The test procedure described in this practice is intended to determine the ability of a radiographic interpreter to detect low contrast images in a low light level environment. Appropriate dark adaptation time should be permitted. A minimum of 1 min is recommended; however, longer dark adaptation times may be required by some users. 4.2.2 The test shall be administered by or under the direction of a test administrator (see 3.2.4 ). The individual being tested shall not know the identification of the plate or orientation prior to the test. 4.2.3 The interpretation of each of the 25 image areas on a plate is recorded on an answer sheet, Fig. 2 , by drawing a line corresponding to the location and orientation of the slit image in that image area. Where no line image is detected, a circle should be drawn on the answer sheet in the area corresponding to the image area in which no slit image was detected. An example score sheet is given in Fig. 3 , illustrating typical line locations and orientations and illustrating the method for marking answers. The markings shown in the sample score sheet are not taken from any of the actual test plates; however, they illustrate typical distributions of slit images. Fig. 2 of this practice may be photocopied to provide answer sheets, or the using organization may generate their own suitable answer sheet. In any case, the answer sheet must have provisions for recording both the location and orientation of the indication in each of the 25 image locations. FIG. 2 Visual Acuity Test Score Sheet FIG. 3 Example of Completed Visual Acuity Test Score Sheet 4.2.4 The order in which the indications are marked is not important. The reader may mark the indications in order, or may mark the easier images and return to the more difficult images. 4.2.5 Once the score sheet is completed, the test administrator shall determine the identity and orientation of the plate that was read and score the answers using the appropriate answer key.