High-Yield Radiology & Imaging: X-Ray, CT & Mammography Made Easy | NEET PG | FMGE | INI-CET

Added: 2026-06-04

[00:00:00]Now let's come to basics of CT and x-rays. So basic x-ray tube is like this. There is a cathode and there is an anode. So cathode is negatively charged. This is cathode.

[00:00:14]And positively charged one is anode.

[00:00:17]Now cathode emits electrons which hit the anode and the x-rays are produced. Now question comes, what is cathode made of? So cathode is made of tungsten plus thorium. We remember it by cathode, tungsten and thorium.

[00:00:35]Whereas anode target is made of tungsten and rhenium. So again, rat.

[00:00:42]Tungsten is common in both. Rat means rhenium.

[00:00:46]Cat means thorium.

[00:00:49]Now the window, the glass window through which the x-rays pass, it is made of glass. And below the x-ray beam, there is a filter which filters the low energy x-rays. What is it made of? Aluminum and copper.

[00:01:03]And finally this filtered beam falls onto the patient. Now the difference between the cathode, the potential difference between the cathode and the anode is KVP or kilovolt potential. And the current flowing into the cathode is known as MAS.

[00:01:18]Now question recently asked in FMG exam, that what is the mechanism of formation of x-rays at the target anode? So there are two types of mechanism. One is known as Bremsstrahlung radiation or the breaking radiation and characteristic radiation.

[00:01:37]Now characteristic radiation as the name suggests, they are specific to the element of the target.

[00:01:43]So they are specific energy x-rays and they're specific to the element that is target.

[00:01:49]Whereas Bremsstrahlung radiation or a breaking radiation are a continuous spectrum of x-rays. Right? So if this is the continuous spectrum of X-rays, these are the breaking radiation or the Bremstrahlung radiation and specific energy X-rays overlapping these, these will be known as characteristic radiations.

[00:02:13]Now, important here is to note what is the difference between KVP and MAS and how does that impact our image quality.

[00:02:21]So, KVP as we have read is the potential difference between cathode and anode. It determines the quality or the energy of X-rays.

[00:02:29]And MAS is the current flowing into the cathode. More current, more X-rays. It is the quantity of X-ray produced. And mainly MAS determines the radiation dose. Very, very important.

[00:02:41]Now, what is the relation of image contrast with KVP? We have read image contrast is inversely proportional to KVP. If I reduce KVP, image contrast improves.