The difference of molybdenum target, rhodium target and tungsten target
Molybdenum target refers to that the anode of X-ray tube is made of molybdenum (Mo). The relative energy of molybdenum target ray is relatively low, which is "soft" ray. Under the condition of lower tube voltage required by mammography, it is especially suitable for mammary glands with more adipose tissue and lower density of parenchyma, or with smaller thickness and higher density of parenchyma.
Rhodium target refers to that the anode of X-ray tube is made of rhodium (Rh). Rhodium target rays are similar to molybdenum target rays. The characteristic peak energy level of rhodium target is slightly higher than that of molybdenum target. The appropriate increase of rhodium target energy can be applied to the thicker and denser mammary gland. However, under the irradiation of low energy X-ray, the photoelectric effect increases the dose absorbed by the tissue.
Tungsten target means that the anode of X-ray tube is made of tungsten (W). Under lower tube voltage, tungsten target ray is a kind of "hard" ray, that is, continuous ray, and no identification ray appears.
The linear response range of the traditional screen breast camera to the signal is narrow, which can match the X-ray of molybdenum target or rhodium target after penetrating the tissue, and obtain the breast X-ray image with excellent contrast. However, the exposure characteristic curve of the digital flat panel detector is linear and has a wide dynamic range, and it can respond well to the penetrating ray information in all energy ranges. The "hard" ray produced by the tungsten target is continuously at a higher photon frequency, which is compatible with the dynamic sensing range of the flat panel detector, and has stronger penetrability. Even if the tissue incident dose is slightly higher, the tissue absorbed dose is lower than that of the molybdenum target X-ray Therefore, the re application of mammography from tungsten target to molybdenum target to tungsten target is driven by the progress of digital technology and the actual clinical needs.
