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您请求的操作仅限于组中的用户:== " '胶片和/或处理错误的潜在区域'' == #鞋跟效应-由于机器释放的x射线不均匀，与x射线产生有关的视觉误差来源。x光机有两个端，阴极端和阳极端。阴极端比阳极端释放出更多的光子，这就导致了阴极端薄膜的过度曝光和阳极端的曝光不足。由于这个事实，技术人员将把病人放在手术台上，这样被研究的身体区域最厚的部分被放置在离阴极端最近的地方，而较薄的部分被放置在离阳极端最近的地方。伪影- x光片视觉图像感知错误，通常被视为异常发现或异物。当存放x射线底片的磁带接触到指纹或小碎片时，就会出现伪影。曝光——电离辐射量的测量，由三个因素决定:时间、x射线能量和x射线光子的数量。技师可以操纵曝光来突出感兴趣的结构。过度穿透往往会提高骨骼的可见度，而穿透不足则会提高软组织的可见度。#移动-在x光曝光的瞬间，由于患者的移动导致图像模糊。 # Film processing – An error that occurs during the processing of the film can result in disturbances in the contrast, detail, or density of the image displayed. # Radiodensity is a representation of the relative tissue density, based on the appearance of the tone of the tissue (white, gray, or black). The following structures may be found on a medical radiograph (in order of increasing radiodensity) # Air – black appearance, often seen in structures such as the lungs, bowels, trachea # Fat – dark grey appearance, often seen in structures such as thicker adipose tissue # Muscle, tendon, organ tissue – appears “neutral” or mid-grey # Bone – cancellous bone appears as light grey, while cortical bone appears as white # Contrast media - white appearance # Meta'''l''' – white appearance, often seen in structures such as jewellery, dental fillings, or orthopaedic hardware Caution to the radiograph viewer/interpreter – There is an inherent error that occurs when a 2-dimensional image is created to depict 3-dimensional structures that are often superimposed on one-another. Due to this fact, radiographic studies of specific body regions often include 3 or more views from different angles.Biederman, R. E., Wilmarth, M. A., & Editor, C. M. D. T. (n.d.). Diagnostic Imaging in Physical Therapy Avoiding the Pitfalls. Diagnostic Imaging. '''Four principle sources of radiographic error''' # Enlargement occurs because the x-ray beams exit the machine in an expanding conical pattern (similar to a flashlight beam). As a result, objects placed closer to the beam source appear larger than objects placed further away from the beam source. # Elongation is produced by the increased beam angle at the periphery of the x-ray beam cone. As a result of the increased beam angle, objects in the periphery of the x-ray beam appear smeared or spread compared to objects in the centre of the beam. # Foreshortening is the opposite effect of elongation. This occurs when the body region to be studied is placed at an angle to the primary x-ray beam, resulting in the appearance of decreased length. # Superimposition occurs because anatomic structures are often stacked on one another, forcing the x-ray beam to penetrate multiple structures before arriving at the film plate. Superimposition can create the appearance of increased density of structures, or the appearance of novel structures altogether.

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