nuclear med basic principles

Question 1

tracers

Answer 1

a trace amount of active pharmaceutical that follows the pharmacological pathway without affecting physiology

observe(imaging) and treat(therapy)

Question 2

therapy

Answer 2

delivery of radiation to the area targeted by the pharmaceutical
eg. iodine 131

Question 3

nuclear medicine imaging
differences compared to xray

Answer 3

measures function/physiology not structure

contrast due to uptake/radiopharmaceutical not attenuation

source inside body not out

radiation flux lower

Question 4

atomic number Z

Answer 4

number of protons

Question 5

radioactivity

Answer 5

radioactive materials are unstable
insufficient BE
nucleus changes w time
result in emission of radiation

decay probability is characteristic of nucleus decomposition

Question 6

beta decay

Answer 6

beta minus:
neutron decays into proton, an electron and an antineutrino

beta plus:
a proton decays into a neutron, a positron and a neutrino

electron capture:
proton + electron decays into a neutron and neutrino

Question 7

alpha decay

Answer 7

2 protons and 2 neutrons

Question 8

radioactive emissions

Answer 8

beta minus decay
excess of neutrons

beta plus decay
if excess of protons

electron capture
excess protons leads to K-shell electron to be captured by proton
outer electron falls into vacant orbit
x-ray emitted

alpha decay
for natural radioactive elements heavier than lead

gamma emission
parent radionuclides go into a metastable state after previous beta or alpha
metastable daughter loses excess energy as a gamma photon to revert to ground state

Question 9

TC-99m decay scheme

Answer 9

decay of tc-99m to tc-99 is an isomeric transition

(metastable to ground state) change in isomers