Completed notes of the course

Page 1

COMPUTED AIDED SURGERY XRAY Roentgen found X-rays by chance making electrical experiments. He called x because not know what they are, a new form of energy. The found medical application of this new scoperta very soon. X rays are located in the spectrum of electromagnetic radiation, they are high frequency and small wave length that can penetrate easily the human body being attenuated in deferent way by the the different living organism (bone, soft tissue (like water), and air). Xray tube (Roentgen tube). We need to have high energy electrons colliding against a target with very high atomic number (tungstenus usually). In order to have this collision that in the end produce the X-ray exiting the tube we need to exite applying potential difference between the cathode and anod. The cathode will be a filament where we produce a cloud of electron by termoionic excitation. The anod is the high atomi c number element. We apply a potetional difference of a lot of kV, the anod is typically put in rotation because the collision produce a lot of heat so putting it in rotation we distribuite the heat in the all target. According to what we need to have everything is putted in a vacuum tube where everything takes place. The efficiency is very low and proportional to the potential difference applied and the atomic number. We need to cool down all the machine otherwise everything will burn down. Potential difference (100 kV) applied and energy of X-rays we obtain, once filtered, have a relationship -> and it’s expressed in electron V. If I apply 100kV I will obtain a X-ray beem with an average on the spectrum if 100 KeV which is typically the energy required to penetrate the human body structure because they have to pass the human body and enter the hit the detector in order the map. Photo…