物理phy~~~~~~~~~~!

(a) Similaritiy - both x and gamma rays are high frequency (short wavelength) electromagnetic waves.

Difference - gamma rays are generally more penetrating than x-rays

(b) The radation beam, which is hard x-rays from a linear acelerator of energy above 10 MeV, is made to rotate around the patient's body. This is equivalent to shooting several beams towards the tumour, with all the beams intersecting at the tumour location. As such, the tumour receives the highest radiation dose, but other tissues receive less.

(c) The three precautions are:
(i) There should not be any person, except the patient under examination, present in the room when diagnostic or therapeutical procedures are taken. If the presence of medical personnel is required inside the room, lead aprons should be worn by them.
(ii) Any irradiating apparatus should be operated by qualified personnel.
(iii) Suitable room design and shielding should be made to protect members of the public outside the room where irradiating apparatus is in operation.