Chapter 1 - Physics

Question 1

What is the difference between direct and indirect ionization?

Answer 1

Direct - when a CHARGED particle interacts with a molecule through columbe forces and creates an ion creating biological or chemical changes

Indirect - uncharged particle or EM interacts with a molecule causing the release of a charged particle which then goes on to create an ion creating biological or chemical change through columbe force

Question 2

What particles are directly ionizing?

Answer 2

Alpha
Beta
Protons
Heavy particles
Electrons

Question 3

What particles or energy are indirectly ionizing?

Answer 3

Neutrons
EM
NO CHARGE SO NO COLUMBE forces

Question 4

What is the difference between direct action and indirect action?

Answer 4

Direct action: cause breaks in DNA its

Indirect: Creates free radicals - hydroxyl (most common from H20) which in turn causes DNA damage.

Question 5

What energies produce direct actions?

Answer 5

Any form of radiation can cause direct if large enough.

Alphas, neutrons, protons and nuclear fragments are most likely

Question 6

What energies produce indirect actions?

Answer 6

Normally EM (photons) or electrons.

Question 7

Number one reaction for creation of free radicals?

Answer 7

H20 –> H20+ + H20 —-> H30+ + OH

OH is hydroxyl which interacts with DNA and breaks it.

**2/3 of damage by Medical imaging are due to this!

Question 8

How long does the inital ionization take (physics part of indirect action)? how long do free radials stay around (chemistry part of indirect action)? How long does the biological affects take to be seen?

Answer 8

10 to the -15
10 to the -5
Day, weeks, years, generations

Question 9

How long does it take biologic expression happen after DNA is damaged

Answer 9

Day, weeks, years, generations

Question 10

Free radical scavengers help reduce the effect of direct action or indirect action?

Answer 10

INDIRECT cause it deals with free radicals

Does nothing for Direct action