Nuclear Medicine

Question 1

what is the main radionuclide used in nuclear medicine

Answer 1

Technetium (Tn)

Question 2

how is technetium produced

Answer 2

Tn is produced in a generator from Molybdenum

Question 3

what process is involved in Tn production

Answer 3

isomeric transition

Question 4

what is isomeric transition

Answer 4

the production of a gamma ray without any change in atomic mass or number

Question 5

In Nuclear Medicine, what does the generator consist of

Answer 5

the generator is a lead lined container with the parent radionuclide

Question 6

how is the carrier free daughter eluted from the generator

Answer 6

this is done by passing a solvent like saline over the column

Question 7

the eluate from a technetium generator is called?

Answer 7

sodium pertechnetate

Question 8

what are some advantages of technetium

Answer 8

6hr half life
pure gamma emitter
easy to shield
combines well with other chemicals used in bone scans and renal imaging
non-toxic

Question 9

what is molybdenum breakthrough

Answer 9

tiny amounts of molybdenum in solution of sodium pertechnetate

Question 10

how is Mo breakthrough measured?

Answer 10

comparing eluate activity with and without Pb shielding

Question 11

what is the main imaging device in NM

Answer 11

gamma camera

Question 12

what is the gamma camera combined with

Answer 12

a collimator

Question 13

what is the purpose of the collimator

Answer 13

the purpose of the collimator is to establish a relationship between the distribution of the isotope in the patient and the position at which the gamma rays are detected in the crystal

Question 14

what is the gamma camera made of

Answer 14

sodium iodide doped with thalium

Question 15

what effect does crystal thickness have on detector efficiency and spatial resolution

Answer 15

thicker the crystal, greater detector efficiency but lower spatial resolution

Question 16

the amplitude of the signal detected in the PM tube is proportional to what?

Answer 16

the amplitude of the signal detected is proportional to the amount of light emitted

Question 17

the light emitted is proportional to what?

Answer 17

the light emitted is proportional to the energy of the gamma ray

Question 18

what is the Z pulse?

Answer 18

the summation of the PM tube outputs provides an energy, which is proportional to the total light produced in the crystal

Question 19

where does the Zpulse go

Answer 19

to the pulse height analyser

Question 20

what does the pulse height analyser do

Answer 20

PHA selects the isotope peak

Question 21

what is the Z pulse proportional to

Answer 21

the z pulse is proportional to the total light output from one scintillation

Question 22

what happens if z pulse is accepted

Answer 22

the positional circuitry is triggered to locate the gamma ray interaction

Question 23

what is the PHA purpose

Answer 23

choice of photo peak
exclude compton scatter

Question 24

what is the energy spectrum

Answer 24

the number of measured events with a given energy plotted as a function of energy

Question 25

what is the goal of NM

Answer 25

To map the distribution of radiotracers

Question 26

what renders gamma rays not useful for accurate measurement of radionuclide location?

Answer 26

when gamma rays scatter in the body first and change direction

Question 27

what does the collimator design effect

Answer 27

spatial resolution sensitivity size of FOV magnification/minification

Question 28

what does spatial resolution depend on

Answer 28

diameter of holes in the collimator length of holes septal thickness distance of pt from collimator surface intrinsic resolution of detector

Question 29

what is the point spread function (PSF)

Answer 29

a profile of measured counts as a function of position across a point source

Question 30

line spread function

Answer 30

profile of measured counts as a function of position across a line source

Question 31

what is the modulation transfer function

Answer 31

MTF is one way to more completely characterise the ability of a system to reproduce spatial frequencies

Question 32

how is the MTF calculated

Answer 32

it is calculated as the fourier transform of the PSF or LSF and is a plot of the response of a system to different spatial frequencies

Question 33

what is the relationship between resolution and sensitivity

Answer 33

if resolution is increased by a factor of 2, the sensitivity is decreased by a factor of 4

Question 34

`what is the unit of radioactive decay?

Answer 34

Becquerel (in NM, we use MBq)

Question 35

what has replaced lung perfusion with technetium

Answer 35

CT pulmonary angiography

Question 36

what is the annual whole body dose limit for a member of the public

Answer 36

1mSv

Question 37

what is the limit for the lens of the eye

Answer 37

15mSv

Question 38

what is the whole body dose limit for a category B worker?

Answer 38

6mSv

Question 39

How is Tc predominantly excreted?

Answer 39

via urine

Question 40

what is encouraged to lower body dose?

Answer 40

frequent bladder emptying

Question 41

what is the typical whole body dose in a bone scan

Answer 41

5mSv