Physics A 1

Question 0

What are CT scans?

Answer 0

Computerised axial tomography scans use X-rays to produce high resolution images of soft and hard tissue.The patient is put inside a rotating cylindrical scanner and an X-ray beam is fired through the body and picked up by detectors on the side

Question 1

What are X rays and why do x ray images work

Answer 1

X ray images are high frequency short wavelength EM waves. They are transmitted by healthy tissue and are absorbed by materials like bone and metal
As they affect photo film in the same way light does they can be used to create images

Question 2

How can X-ray’s be used to treat cancer and what safety precautions are taken during these procedures?

Answer 2

To treat cancer the X-rays are focused on the tumour using a wide beam

This beam is rotated around the patient with the tumour at the centre

This minimises the exposure of normal cells and reduces the chances of damaging the rest of the body

Precautions consist of : -lead aprons - lead screens - lead shield on the areas of the patients body that aren’t being scanned

Question 3

Define Ultrasound

Answer 3

Sound with a higher frequency that human hearing

< 20000 hz

Question 4

Define partial reflection

Answer 4

When a wave passes from one medium to another some of the wave is reflected of the boundary between the two media and some is transmitted and refracted

Question 5

What is an Oscilloscope used for?

Answer 5

It is used to find boundaries within waves

S (Distance) = V (Speed) * T (Time)

Question 6

Name two uses of Ultrasound

Answer 6

Breaking down kidney stones by concentrating High energy waves at the kidney stones which turns it into sand like particles.

Pre natal scanning as they pass through the body but some is reflected back and detected by a sensor

Question 7

Summarise safety between Ultrasound X-ray imaging and CT scans

Answer 7

Ultrasound are non ionising and as far as as any one can tell, safe. Ultrasound images are typically fuzzy.

X-rays are ionising. They can cause cancer if your exposed to high doses. They produce clear images of bones and metal.

CT scans use lot more X-ray radiation that standard X-ray photographs. They produce detailed images that can be used to diagnose complicated illnesses.