1. The actual focal spot refers to the physical size of the area on the anode target where the electrons hit to produce X-rays. The effective focal spot, on the other hand, is the size of the focal spot as it appears to the patient. This is determined by the angle of the X-ray beam and the distance between the focal spot and the patient.
2. As SID (source-to-image distance) increases, size distortion or magnification decreases. This is because, as the distance between the X-ray source and the image receptor (such as the film or digital detector) increases, the divergence of the X-ray beam decreases. This results in less magnification and more accurate representation of the object being imaged.
3. High kilovoltage (kVp) leads to low contrast and a long scale of contrast. This is because high kVp X-rays have higher energy and can penetrate through the tissues more easily. As a result, there is less attenuation of the X-ray beam, leading to less contrast between the different structures in the image. The long scale of contrast refers to a wide range of gray shades on the image, making it more difficult to differentiate between different tissues or structures.
4. Increasing collimation, which means reducing the field size, decreases radiographic density. This is because a smaller field size restricts the amount of X-ray photons that reach the image receptor, resulting in decreased exposure and reduced radiographic density. On the other hand, decreasing collimation or widening the field size allows more X-ray photons to reach the image receptor, leading to increased exposure and higher radiographic density.
5. Developer is a chemical solution used in the photographic processing of X-ray films. It contains reducing agents that convert the exposed silver halide crystals on the film into black metallic silver, forming the visible image.
6. The purpose of fixer in image formation is to remove the unexposed and undeveloped silver halide crystals from the film. It does this by dissolving the silver halide in the film emulsion, leaving only the developed silver as the final image. Fixer also hardens the emulsion, making it more resistant to physical damage.
7. The preservative chemical commonly used in fixer is sodium sulfite. It helps to prevent oxidation and prolongs the shelf life of the fixer solution.
8. Two examples of reducing agents used in developer are hydroquinone and Elon. These chemicals help to convert the exposed silver halide crystals into metallic silver during the development process.
9. Sodium carbonate is used for maintaining the proper pH level in the developer solution. It acts as a buffer, keeping the solution acidic, which is necessary for the development process.
10. A safelight is a type of lighting used in the darkroom to provide illumination while working with X-ray films. It emits a specific color of light that does not expose or fog the film. The purpose of a safelight is to allow visibility in the darkroom without affecting the sensitivity of the X-ray film.
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