Nuclear medicine 2

Question 1

features of PET scan

Answer 1

• artificially made from proton-rich isotopes, may decay via positron emission (b+)
• positron causes formation of 2 511KeV
• short distance of 1mm

Question 2

features of SPECT scan

Answer 2

often uses 2 gamma cameras acquired in 3D volume
- takes 64 to 128 static images

Question 3

PHA

Answer 3

pulse height analyser

Question 4

purpose of collimators

Answer 4

removes scatter

Question 5

purpose of photomultiplier tube array

Answer 5

receive light from crystal and amplify energy = increase in electrons

Question 6

purpose of NaI crystals

Answer 6

absorb gamma rays and emits flashes of light

Question 7

purpose of PHA

Answer 7

selects signal arising from gamma ray energies coming from isotope

Question 8

effect of more electrons

Answer 8

the more number of electrons produced the more signal produced

Question 9

what does the crystal do in the digital display

Answer 9

• decay process is multi-directional
• sorts out gamma rays we want and dont want
• slab of lead with holes
• size of hole determines resolution and sensitivty

Question 10

purpose of scintillation crystals

Answer 10

• gamma ray converted to pulse of light
• flash of light caused by absorption of gamma ray photons

Question 11

what do surfaces tend to do

Answer 11

reflect the light

Question 12

What’s the next stage after PMT catches light

Answer 12

Passed onto the next stage which is photomultiplier tubes
- can catch light and turn it into an electrical pulse
- incoming pulse is very small

Question 13

What happens when radiation detector detects proton

Answer 13

Electrical pulse
PHA receives pulse and processes them
Categorises them based on amplitudes (amplitude relating to energy of proton)