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5

Lead : 1.65 €/kg, Gold : 35,000€/kg, Uranium (even depleted) : cost unknown, with possible radioactive contamination. So I think it's just a question of cost and practical use. Lead is cheap and available.


3

During proton therapy, most of the damage is actually done in the last few mm before the beam stops - at the point called the Bragg Peak Yes, the penetration distance is largely determined by the energy above a few MeV; as the particle slows down, it starts to dump more energy per unit length. Quoting from "The physics of protons for patient treatment" (...


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I pulled out my notes from a shielding class and found that the absorption cross section per atom follows a rule: $$\sigma_a\sim\frac{Z^p}{E^3},$$ where $z$ is the atomic number of the absorber atom, $E$ is the energy of the photon, and $p$ is an energy dependent value between 3 and 5. For most x-rays, $p\simeq 4$. While the cross-section per atom does ...


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Let's suppose you have swallowed one of the Po-210 sources from this student kit. Its activity is 3700 Bq (0.1 μCi). Based on the Table 6 in the meta-study [1], it is probably safe to ingest up to 0.02 MBq/kg of the Po-210. This means, that for 80 kg person, it is probably safe to ingest 1.6 MBq of the Po-210, so you "need" to eat approx. 400 of these ...


2

Yes, it is essentially just the Coloumb interaction. Sometimes, this will strip electrons from atoms. However, those electrons might have been responsible for a bond in a molecule, so this will have effectively destroyed the molecule. Other mechanisms include having a nucleus recoil from a proton (perhaps imparting enough energy to break a bond), or ...


1

Maybe there are some missunderstanding in question and/or answers about what "slice" means for each people. At each view angle, what is theoretically taken is a 2D image, like a classical photo. Of course a given pixel shows the superimposition of opacities all along a column. Then the angle of view (+source) is turned, and numerous 2D images are ...


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The output is a series of slices because this is the clearest way to view the three dimensional tissue in sufficient detail. Think about a loaf of bread, if there was something inside and you didn't take appropriately thin slices then you might miss something when compared to a non-sliced imaging. In addition this method allows rapid reconstruction of ...


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See if this argument works - I am making this up on the spot so there is definitely space for argument... Most of the interactions with the electrons will not be "head-on collisions" but rather electrostatic interactions. If we get to a certain distance of an electron, it will feel the force and undergo acceleration. If the time of the interaction is short, ...


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Here is what wiki has to say about Polonium radiological toxicity: By mass, polonium-210 is around 250,000 times more toxic than hydrogen cyanide (the LD50 for 210Po is less than 1 microgram for an average adult (see below) compared with about 250 milligrams for hydrogen cyanide[66]). The main hazard is its intense radioactivity (as an alpha ...


1

Let me start off with something that should be obvious but I feel the huge need to say it -- I am not trained in the biomedical field and what I put in my answer should not be construed as definitive and ready-for-use in actual patients. I will do my best and present what I think is correct, but I am not a doctor and don't even pretend to play one on TV. ...


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Sound waves are pressure waves. We measure it as a logarithmic ratio of intensity. Sound intensity is a useful parameter to measure because it's related to the energy incident on a surface which can be easy to measure. Sound intensity is proportional to pressure squared. When calculating decibels we would have to handle that like so: \begin{equation} I = p^2/...



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