Section 1.4  Page 18
Radio waves have a longer wavelength than X rays, therefore, they have a lower frequency and less energy.  When radio waves strike an object, they do not damage it.  X rays have a much shorter wavelength than radio waves, and therfore have a higher frequency and much more eenergy.  When X rays strike soft objects like human tissue, they can cause damage.
The human eye can detect wavelengths in the visible range (400-700 nm).
When white light is directed through a prism, it separates into different colours.  If white light did not consist of different colours, it would remain white when passed through a prism.
A continuous spectrum is an uninterrupted pattern of colours observed when  a beam of white light is passed through a prism.   An example of a continuous spectrum is a rainbow.  A line spectrum is discontinuous.  The lines, produced when light emitted by an element is directed through a prism, are separated by space with no colour.  Hydrogen gas has a line spectrum.
a)   It is not safe for the technician to be in the same room during an X ray because the technician would be exposed to X rays each time an X-ray scan is taken: as many as several hundreed scans per year.  This amount of exposure exceeds the recomended levels of X-rays exposure for an iindividual.  Patients are only exposed during thier X-ray scan, therefore the risks are minimal.

b)   Only the desired area to be X-rays is exposed; the rest of the body is covered with a lead apron, which X rays cannot penetrate.  technicians wear badges that measure the radiation levels in the radiation areas, and keep detailed records of their cumulative lifetime dose.