Physics P3-A

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X-Rays In Medicine

X-rays are typically used in hospitals 

X-rays are high frequency, short wavelength electromagnetic waves. Their wavelength is roughly the same size as the diameter of an atom.

They are transmitted by (pass through) healthy tissue and are absorbed by denser material like bone or metal.

They are affected by photographic material in the same way as light so they can be used to take photos. X-rays can be used to identify health problems such as bone fractures or breaks or dental problems such as broken teeth.

X-ray images can be used to form images using charged coupled devices which are silicon chips about the same size of a postage stamp and are made up of a grid of millions of identical pixels. CCD's (Charged Coupled Devices)can detect and produce X-rays and capture a digital image in a high resolution similar to the technology used in digital cameras.

In an X-ray image the brighter parts of the image are where fewer X-rays have been absorbed. This is known as a negative image. The plate of the image starts off all white.

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CT Scans and Cancer Treatment

CT Scans

Computerised axial tomography scans or CT scans use X-rays to produce images of soft and hard tissue. The patient is put into a cylindrical scanner where X-ray beams are fired into the body. Detectors in the back of the machine pick up signals from the beam and the both the detectors and X-ray tubes rotate around the patient and intepret an image of the inside of the body. Multiple scans can also be used to make a three dimensional image rather than the bog standard two dimensional.

Treatment for cancer

X-rays can also cause ionisation which means they can kill off cells. Doctors use them to kill cancer and with the right dosage it doesnt cause damage to the rest of the body although the beam has to be very carefully focused as to not kill other cells. To treat cancer they: 

  • Focus the rays using a wide beam,
  • The beam is rotated on the tumor at the centre,
  • This minimises the exposure of normal cells to radiation
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