# Tag Info

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.

2

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 ...

2

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 ...

1

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 ...

1

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, ...

1

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. ...

1

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: I = ...

1

I am a medical physicist working in a Radiation Oncology department. MLCs are used for both 3D and IMRT plans. In fact, very few hospitals have the ability to make/use the lead blocks anymore. The MLCs define the shape of the radiation field. 3D treatment plans are generated with the user (often the MD) defining the MLC shapes for each gantry angle, and ...

1

Percentage Depth Dose Curves (or PDDs) are used to determine how many Monitor Units (MU) a treatment machine needs to give (or how long the machine needs to be on) to deliver a particular dose to a particular depth. The depth at which the PDD curve peaks is referred to as dmax. Treatment machines are often calibrated so that 1MU = 1 cGy at dmax in water. ...

Only top voted, non community-wiki answers of a minimum length are eligible