X-rays Flashcards
What are X-rays?
High frequency short wavelength electromagnetic waves
How do they work?
They are transmitted by (pass through) healthy tissues and are absorbed by denser materials like bones and metal
How do they produce a photo?
They affect photographic film in the same way as light so they can be used to take a photo
The brighter parts of the photo is where less light gets through this is a negative image
What can X-rays be used to diagnose?
Many medical conditions such as bone fractures or dental problems
How can X-ray images be formed electronically?
Using CCD’s
What is a CCD?
Silicon chips about the size of a stamp that are divided up into a grid of millions of identical pixels
What do CCD’s do?
They detect X-rays and produce electronic signals which are used to from high resolution images (same technology as in digital cameras)
What is a CT scan?
Computerised axial tomography scans
What do CT scans do?
They use X-rays to produce high resolution images of soft and hard tissues
How does a CT scan work?
Patient inside cylindrical scanner
X ray beam is fired through the body from an X-ray tube and picked up by detectors on the opposite side
X ray tube and detectors are rotated during the scan
Computer interprets the signals to from a 2-d image and multiple of these are put together to make a 3D image
What is ionisation?
High doses of X-rays will kill living cells
How can X-rays kill cancer?
They have to be carefully focussed at just the right dosage to kill cancer cells but not normal
X-rays are focused on tumour using a wide beam
The beam is rotated round the patient with the tumour at the centre
This minimises the exposure of normal cells to radiation
What precautions do radiographers take to minimise radiation dose?
Wear lead aprons, stand behind a lead screen, or leave room while scan takes place
Lead is hard to shield areas of patients body that aren’t being scanned and exposure time is kept to a minimum
What’s an advantage of X-rays?
Produces clear images of the bones and metal
What’s a disadvantage of X-rays?
They are ionising and can cause cancer if you’re exposed to too high of a dose
