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Answer to the question (19:35): The half-life for Re-188 is about 17 hours. After 10mins, more than 99% of initial activity still remains. So, we can assume the activity unchanged. Now we can easily multiply the activity by the sensitivity of collimator to obtain the total counts per second of Re-188: Total counts/sec = 10 MBq * 0.9 * 10^-4 = 900. Now we can calculate the number of 155 keV gamma rays counted per second which is 15.6% of the total counts: 900 * 15.6% = 140.4. If we continue counting for 10 mins, we will count a total of 140.4 * 10 * 60 = 84240 gamma rays with 155 keV of energy.
Just discovered your channel. I'm doing my PhD in radiopharmacology and greatly appreciate the breadth and depth of your videos. Thank you so much. Keep up the good work!
from what i understand, c is the constant that represents the speed of light. so for E=mc^2, energy is equal to the mass of an object multiplied by the speed of light squared. in other words if you have a mass of something that is 1kg, then its energy is going to be 1 * the speed of light squared (alot of energy)
A photon cannot give all its energy to an electron if its free. This is because of conservation of energy and momentum and the key point is that the photon wont exist anymore. Assume that the free electron is at rest before collision and the energy of the photon is less than 511 keV not to make a relativistic situation. If the photon gives all its energy to the electron, it wont exist after collision. Therefore, the total energy of the photon must be taken by the electron. => conservation of energy: Eph = 1/2 mv^2. Moreover, the momentum of the system must remain unchanged. => conservation of momentum: Eph/c = mv. By these two equations you will see that mvc = 1/2 mv^2 => v = 2c. We know that it is not possible for a particle to move faster than light. Now we understand why it is impossible to have a photoelectric effect if the electron is free. The same reason governs why in Compton scattering a photon cannot give all its energy to an electron.
hello, thank you for making this video. But I have a question about the estimation of SUVr. Is the SUVr a literally true equal to 1 in all examples even if a body mass is 1kg, 2kg, or 10kg? I don't think so and these SUVr meaning has to be different from each others.
