There's too much about radiation to be dealt with in a simple blog like this - after all, it's a science of its own, and a subject that we still don't know everything about.
In the two previous posts, I tried to cover the most basic things about the effects of radiation on the human body, but I realize, and apologize for it, that I forgot to explain the very basics of radioactivity itself; what it is and how it occurs.
Radioactivity is the result of the process of spontaneously decaying atom nuclei emitting ionizing radiation. Alpha, beta, and gamma radiation are the most common types of radiation.
Alpha radiation is constituted of so called alpha particles, like nuclei of Helium atoms: Two neutrons and two protons. This kind of radiation is easily blocked by other matters - just a sheet of paper is enough - and can for example not penetrate the outer skin layer. Thus, alpha radiation is only dangerous if in direct contact with living cells, which may happen through ingestion on alpha contaminated food or inhalation of alpha radiationg particles.
Beta radiation and beta particles consists of electrons and/or positrons formed during beta decay. If ingested, it's less dangeous than alpha radiation, as a beta particle has lesser mass than an alpha particle. Beta radiation has the ability to penetrate human tissue with a reach of 1 cm (which, if you've read the previous post, you remember may cause severe burns). This kind of radiation can also change the structure of struck molecules and mutate them. A few millimeters of Aluminium will shut out beta radiation.
Gamma radiation consists of photons and is also recognized as the electromagnetic radiation emitted by atom nuclei. Gamma rays are the most penetrative kind of rays connected to radioactivity. It may be blocked out by a concrete wall or lead. Gamma radiation is what causes what we refer to as radiation sickness. It causes damage throughout the body and increase the risk of cancer to occur.
Now we know more about what may happen if exposed to radiation in different doses, but if exposed to a degree where it becomes a health problem, how can it be treated?
ARS symptoms don't develop immediately, as it takes time for the mutated DNA to produce enough proteins to make an obvious change in body chemistry and structure, and unfortunately there is no known way to treat this, as doctors and scientists are unable to repair damaged DNA. All they can do is treating the symptoms.
Concerning cancer inflicted by radiation, it's treated just like cancer with no connection to radioactive exposure, by cytotoxin or more commonly, by radiotherapy.