CAT scans and probably other things one day

why are CAT scans better than x-rays?

• CAT scans create 3D images but x-rays only do 2D ones, so CAT scans give a better idea of size, shape and position of tumour so easier to treat

• CAT scans can also see cross-sections of tumour

• CAT scans can differentiate between materials of similar densities and attenuation coefficicents but x-rays can’t

why are CAT scans not better than X-rays?

• CAT scans are longer so patient receives more ionising radiation and will be more uncomfortable

• CAT could damage their cells more because they receive several years of background radiation

• patient has to stay still for a long period of time in CAT scans

what does CAT stand for?

• computerised axial tomography

• it records a large number of 2D x-ray images from different angles and assembles them into a 3D image using software or something

• the computer controls the scanning process and analysis of electrical signals

how does a CAT scan work?

• patient lies on back in a horizontal table that can slide in/out of gantry

• gantry has x-ray tube on one side and an array of electronic x-ray detectors on opposite side (both rotate)

• the x-ray tube produces a fan-shaped beam of x-rays 1-10mm thick

• the detectors record the intensity of the transmitted x-rays and send electrical signals to a computer

• every time 360 rotation, a two-d image or slice is acquired and the table moves 1cm through the ring, then the beam irradiates the next slice of the patients body

• radiographer can view each 2D slice and make a 3D image