Physics A 1 Flashcards
What are CT scans?
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
What are X rays and why do x ray images work
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
How can X-ray’s be used to treat cancer and what safety precautions are taken during these procedures?
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
Define Ultrasound
Sound with a higher frequency that human hearing
< 20000 hz
Define partial reflection
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
What is an Oscilloscope used for?
It is used to find boundaries within waves
S (Distance) = V (Speed) * T (Time)
Name two uses of Ultrasound
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
Summarise safety between Ultrasound X-ray imaging and CT scans
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.
