Chapter 3: Deposition of Radiation Energy

Question 1

For nonionizing photon radiation, energy transfer occurs via _______________.

Answer 1

selective absorption in specific molecules such as chromophores

Question 2

The initial effect of radiation action on biological systems is the ________________.

Answer 2

transfer of energy to essential cellular components

Question 3

For ionizing radiation, ____________ energy transfer.

Answer 3

all constituents of the exposed medium

Question 4

Exposure is _____________.

Answer 4

charge liberated per mass element of air

Question 5

KERMA stands for ____________ and represents _____________.

Answer 5

kinetic energy released per mass
sum of the initial kinetic energies of all secondary particles per unit mass element

Question 6

Stopping power is defined as _______________.

Answer 6

energy loss of the particle per unit length in the matter or the transferred energy per unit length

Question 7

Linear energy transfer is defined as ______________. Locally means _______ corresponding to a range of 100 eV electrons.

Answer 7

the amount of locally absorbed energy per unit length.
5nm

Question 8

The higher the LET, the __________ likely cellular repair.

Answer 8

less

Question 9

Due to the role of secondary particles in energy deposition the dose maximum is found at ____________.

Answer 9

a certain distance from the entry surface.

Question 10

As LET increases, relative biological efficiency __________.

Answer 10

increases up to 100 KeV/um the decreases due to overkill because more energy than needed is deposited at critical sites and energy is wasted.

Question 11

Relative biological efficiency is defined as ___________.

Answer 11

dose of reference radiation/dose of test radiation
to produce the same biological effect.

Question 12

The biological effects of radiation action lies in the fact that _______ amounts of energy are deposited _____________ leading to ___________.

Answer 12

high
locally in very small volumes
alteration/destruction of individual biological molecules.

Question 13

In microdosimetry the local volume for the radiation event to occur is on the scale of __________.

Answer 13

micrometers

Question 14

The mean lethal dose for humans is ________.
The required energy to break a chemical bond is ________, which is ________ in water.

Answer 14

4 Gy
400 kJ/mol
2x10^7 J/kg