Imaging

Question 0

X-ray imaging requires three things…..

Answer 0

An X-ray source
Object to be imaged - A patient
A radiation detector

Question 1

A shorter wavelength and therefore higher energy results in a greater ionising ability, enabling…..

Answer 1

Tissue penetration.

Question 2

Limitations of planar (2D) X-rays….. (3)

Answer 2

It is a 2D image of a 3D object.
Some structures can be hidden behind others.
Not possible to judge the depth of an object in the body.

Question 3

Chest X-rays are used to screen for TB because….. (2)

Answer 3

They are rapid.

They show shadows and nodules in the lung.

Question 4

A disadvantage of chest X-rays for TB screening

Answer 4

They are not very sensitive.

Question 5

If chest X-ray screening is positive, the patient should….

Answer 5

Be sent for a diagnostic test to confirm results.

Question 6

How does an X-ray source work?

Answer 6

An X-ray tube of two electrodes is heated, emitting electrons which are accelerated towards to positive electrode through the application of a voltage.
The electrons collide with the positive electrode and an X-ray is generated.

Question 7

The three stages of X-rays ……

Answer 7

X-ray generator - sample - detector

Question 8

When an X-ray is generated in the source it forms from two processes…..

Answer 8

X-ray fluorescence and bremsstrahlung

Question 9

X-ray fluorescence occurs when…..

Answer 9

A high energy electron knocks and inner electron from the electron shell. An electron from a higher energy falls to fill the vacancy, resulting in the emission of X-rays.

Question 10

Bremsstrahlung occurs when…..

Answer 10

An electron of high energy is scattered by a high atomic number nucleus and energy is lost. Most of it is lose as heat, around 1% goes into X-ray production.

Question 11

In an X-ray source, the acceleration can be varied to create X-rays of different energies and therefore of…..

Answer 11

Varying wavelength, depending on the tissue to be imaged.