1. RADIOBIOLOGY Prof.Dr.Tarek Elnimr L 8 Presented to the Biology Departments in Faculty of Sciences on February 15 , 2009

2. Interactions of radiation with Matter

3. Interaction with beta Electrons excited or kicked off. ionization Energy dissipated as heat. As Z of material increases, so does bremsstrahlung. Note that range is different from path .

4. Interaction with gamma Photon travels until it hits something, either an electron or a nucleus. Several types of interactions have been observed.

8. Pair production and annihilation Two gamma collide, convert to a positron and a negatron. Complete energy to matter conversion These two betas collide, converting to 2 gammas with equal energy of 511 kev. Complete matter to energy conversion. www.mhhe.com/.../fix/ student/images/26f14.jpg

14. More on calculating REM LET (keV per µm) Q example 3.5 and less 1 X-rays, β ,  7 2 neutrons 23 5 53 10 175 and over 20 alpha

15. Comparing old, SI units Rad = 100 ergs/gram; Rem = rad x Q; 1 Gray = 100 Rads, 1 j/kg; 1 Sievert = 100 rem; Old SI Radioactive material curies becquerels Deposited energy Rads Grays Dose to humans Rems Sieverts Units of energy in air Roentgens none