Describe how X-rays interact with matter using the photoelectric effect, Describe the Compton effect and pair production. Define intensity and use the intensity and absorption equation. Describe the use of X-rays in imaging internal body structures Describe the operation of a CAT scanner. Describe the nature of X-rays. Describe how X-rays are produced. Describe ways of obtaining better X-ray images. Explain how soft tissue such as the intestines can be imaged using a barium meal. Describe the advantages of a CAT scan compared with an X-ray image. X Rays A C E

The p.d. between the anode and the cathode can be varied. A good vacuum is needed for X-rays to be produced. X Rays A discharge tube

How do we know that X rays are Electromagnetic Waves ? X Rays X Rays can be polarised X rays can be diffracted through crystals – wavelength between m and m

A modern X-ray tube X Rays Four Significant Features ………………………………………… ………………………………………… ………………………………………… ………………………………………… ………………………………………… ………………………………………… ………………………………………… ………………………………………… ………………………………………… ………………………………………… …………………………………………

The Energy of an X ray Photon X Rays 90,000 V Energy Gained by Electron =eV = 1.6 x x 90, 000 = 1.44 x 10 – 14 J Max Frequency of X ray = 1.44 x 10 – 14 / 6.6 x 10 – 34 = 2.2 x Hz Energy Gained by Electron = Energy of Photon = hf

A graph showing how the intensity of X-rays varies with wavelength for a particular anode and accelerating p.d. X Rays Significant Features ………………………………………… ………………………………………… ………………………………………… ………………………………………… ………………………………………… ………………………………………… ………………………………………… ………………………………………… ………………………………………… ………………………………………… …………………………………………

X Rays and the Photoelectric Effect X Rays Photoelectric Effect X Ray Emission What’s the difference ? …………………………………………………………………………………………… …………………………………………………………………………………………… ……………………………………………………………………………………………

An X-ray photon hitting a free electron and being deflected by it. The greater the deflection, the greater the loss of energy of the photon, and hence the bigger its wavelength becomes. X Rays The Compton Effect

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An X-ray beam from a point source obeying the inverse square law for intensity and a collimated X-ray beam whose intensity remains constant X Rays

X Ray Absorption X Rays I = I o e -μx

The intensity of X-rays decreases as they pass through any substance X Rays

Image enhancement X Rays 3 Ways of enhancing an X ray …………………………………… …………………………………… …………………………………… …………………………………… …………………………………… …………………………………… …………………………………… …………………………………… …………………………………… …………………………………..

A point source of X-rays will display a sharp shadow of a break in an arm bone; an extended source of X-rays will show only a blurred shadow of the same break. X Rays

Angiograms X Rays

The fan-shaped slice of X-rays used in a CAT scan X Rays

CAT Scans X Rays

X-ray source has width x and is a distance y from the detail of size d to be observed. X Rays