Heat Unit abbreviated as HU is the heat capacity unit of the spherical tube in DR, CT and other medical equipments. e.g., the heat capacity of Varian spherical tube RAD14 is 300kHU. when the equipment is working, the two poles of the X-ray tube have to withstand a very high voltage between the poles and pass a certain amount of electric current, the high-speed electron beam impacts the target surface of the anode, and a lot of heat energy will be generated. the maximum permissible heat load of the X-ray tube is heat capacity. \x0d\hu is a unit of measurement for determining the density of a localized tissue or organ in the human body, often referred to as the Heinz unit (hounsfield unit , HU) \x0d\Ct value means: CT value represents the attenuation of the X-rays as they are absorbed through the tissue. \x0d\ In order to quantify the rate of absorption of X-rays by tissue, Hounsfield defined a new scale "CT value". \As a tribute to him, the unit of CT value has been designated as "H". \x0d\ CT value calculation: the CT value of a substance is equal to the substance's attenuation coefficient and the difference between the attenuation coefficient of water, and then with the ratio of the attenuation coefficient of water multiplied by 1000. i.e., the CT value of a substance = 1000 × (u-u water) / u water,, the unit name is HU (Hounsfield Unit), can be seen CT value is not an absolute value, but a relative value. The CT value is not an absolute value, but a relative value. The CT value of different tissues varies and fluctuates within a certain range. Bone has the highest CT value of 1000 HU, soft tissue has a CT value of 20-70 HU, water has a CT value of 0 (±10) HU, fat has a CT value of -50~-100, and air has a CT value of -1000 HU. In real-time fluorescence PCR, the ct value is the number of cycles that the fluorescence signal in each reaction tube undergoes to reach the set threshold
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