The primary controlling factor for contrast in film-based imaging is kilovoltage or kV. Kilovoltage controls the energy or is the penetrating power of the primary beam. The higher the kV, the greater is the energy and the more uniformly the x-ray beam penetrates the various mass densities of all tissues. Therefore the higher kV produces less variation in attenuation (differential absorption), resulting in lower contrast.
Kilovoltage (kV) is also a secondary controlling factor of density. Higher kV, resulting in both more numerous x-rays and greater energy x-rays, causes more x-ray energy to reach the IR, with a corresponding increase in overall density. A general rule of thumb states that a 15% increase in kV will increase film density similar to doubling the mAs.
Other factors may affect radiographic contrast. The amount of scatter radiation the film-screen receives influences the radiographic contrast. Scatter radiation is radiation that has been changed in direction and intensity as a result of interaction with patient tissue. The amount of scatter radiation produced is dependent on the intensity of the x-ray beam, the amount of tissue irradiated and the type/thickness of the tissue. Close collimation of the x-ray field reduces the amount of scatter produced, thereby increasing contrast. Close collimation also reduces the radiation dose to the patient and the technologist.
Hi mam, I included the Radiologic Technology Prayer in my 6th book to encourage all radiographers to pray always. Thank you so much and God Bless
hello sir…really? that’s a good idea…thank you…
God Bless You also…^_^