5 ways to improve your equine X-ray image
Below are our top 5 tips for improving your Equine X-ray Images!
1. Appropriate Exposure Settings
Exposure settings will vary depending upon your generator, your processing equipment, and the patient. Each practice or set of equipment should therefore have a unique exposure chart, which is a record of the optimal kV and mAs values for each region and/or view (e.g. foot, hock, or caudocranial stifle) of a standard sized horse. Exposure settings can then be altered appropriately for larger or smaller patients. Using an exposure chart will help to ensure good quality images every time, thereby increasing efficiency and decreasing exposure to staff and/or owners.
Kilovoltage (kV) determines the energy of the photons generated. The energy of the photons determines the penetrative capacity, i.e., whether a photon is absorbed by the patient or reaches the detector, and therefore influences image contrast. Higher energy X-ray beams produce images with poorer contrast, for example lack of soft tissue detail, or overexposure of fine osseous detail (Image 1).
Milliampere-seconds (mAs) is a measure of radiographic density, which is a function of the amount of radiation produced (mA) over a length of time (s). Altering the mAs will essentially determine the amount of radiation reaching the detector. A lack of sufficient mAs will lead to an underexposed and poorly detailed image, and on digital radiographic systems a grainy appearance known as ‘quantum mottle’ is commonly seen (Image 2).
2. Consistent Film-Focus Distance
Incorrect film-focal distance (FFD) is probably the most common reason for failure of an otherwise correct exposure chart to deliver a well exposed image. The FFD is the distance between the generator and the detector (cassette or plate); ensuring correct FFD is just as important as selecting the appropriate kV and mAs settings. Incorrect FFD will negatively affect image quality by influencing the exposure.
On most modern generators there should be a tape measure or a laser which allows you to accurately judge the distance and ensure that it is correct.
3. Small Area of Collimation
With all systems it is advisable to collimate down to the area of interest only. The benefits of good collimation are twofold: improved signal-to-noise ratio and therefore higher image quality, and improved radiation safety. These effects are particularly noticeable in thick areas of anatomy such as the neck, back, and stifle.
4. Perfect Patient Positioning
Superimposition of structures can significantly hinder the readability of images. A poorly positioned radiograph is often non-diagnostic because it may both mask and mimic pathology (Image 3). Time spent carefully positioning the area being radiographed is usually recouped through reduced number of retakes. Sedated horses are usually easier to position and will stay in position for longer, leading to better quality images.
When processing images, make sure that you pick the right body part and therefore the right algorithm. The algorithms linked to the view enables you to achieve the best possible image for that body part. With direct digital radiography (DR) systems, the body part under which the image is stored cannot be changed once the shot has been fired – this is for legal reasons. Processing images with incorrect algorithms can greatly undermine image quality.
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