Ionising Radiation

If it is possible to reduce risk to staff by assigning them to other duties, then it should be done.

Background radiation is that radiation that is impossible to avoid as it is part of our natural environment. Potassium 40 and carbon 14 are two naturally occurring radionuclides that form part of the background radiation.

X-rays are emitted from the tube with a range of energies (a spectrum) which will range from mid-teens to low 20s of keV (depending on the amount of “filtration” that the photons pass through) up to the maximum value which will equal the accelerating voltage.

“Scattered” radiation has interacted with an atom in the medium, so it is diverted from the direction of the primary beam.

Ultrasound produces an oscillation in the particles of the body, but does not use ionising electromagnetic radiation.

If radiation deposits energy of 1 MeV along its path of 1 mm, more damage would be produced (the radiation would be more “effective”) than if the 1 MeV of energy deposited was spread out along a path length of 10 cm.

This is the best answer, although the daughter nuclei may themselves also be radioactive and so contribute to the radioactivity of the sample. When a nucleus decays, it (or the daughter nucleus) is still there, so choice D is wrong.

“Fractionation” of the dose allows the healthy tissue some time to recover between irradiations. It also allows the tumour to be targeted from another direction by passing the beam through a different part of the body.

Penetrating ability of electromagnetic radiation increases as energy does.

In brachytherapy, the radioactive isotope is placed adjacent to or within the structure to be irradiated, so healthy tissue receives less dose.