Radiation all Around Us

Radon gas, cosmic rays, medical x-rays, food and body chemicals

• I dose = amount of radiation absorbed• Measured in grays (Gy)• 1 Gy = i joule of radiation energy absorbed by

1kg of body• Alpha particles however, do 20x as much

damage to cells as same dose of beta, gamma or X-rays

• Thus talk in dose equivalents measured in Sieverts (Sv), where

• Dose equivalent = absorbed dose x Q(Sv) (Gy)

where Q = 1 for beta, gamma and x-rays 20 for alpha

Protection against radiation?

• How can you reduce your exposure to radiation?

• Read txtbook pages196- 197 answer questions 1-5

Radiotherapy

• Treatment of cancer with high energy ionising radiation

• Cancer is the uncontrollable division of cells, forming a tumour

• Benign – does not destroy surrounding tissues or spread to other organs

• Malignant – destroys surrounding tissue; cells often break away and spread to other sites; referred to as cancer

How does radiotherapy work?

• Gamma rays, electrons or a beam of high energy X-rays

• Electrons often used externally – do not penetrate well

• X-rays have higher energy and penetrate tissues more easily and travel further. Used to treat tumours inside body

• Can be use on own, or in conjunction with surgery and chemotherapy

• Normal cells also damaged but they quickly recover

• Cancer cells are dividing quickly, however and radiation will damage cells beyond repair when they are in mitosis

• Radiation beams carefully focussed on area to be treated

• Healthy tissue receives minimum of radiation• Curative or Palliative• Lesson 5 Radiation\An insight into Radiotherapy.

avi• Read txtbk pages 198- 199 answer questions 1-6

Alternatives to radiotherapy?

• Boron Neutron Capture Therapy (BNCT)

• Reserach and produce a summary of the basic principles of BNCT .

• What is its current status as a cancer therapy• To be completed for HW