NM

Question 1

how is Tc-99M produced- type of production, parent nucleide, and by which decay reaction

Answer 1

radionuclide generator
from Molydenum-99 undergoes beta minus decay, makes Tc-99M

Question 2

what is the half life of molybdenum-99

Answer 2

67 hrs

Question 3

what is the beta minus decay equation?

Answer 3

Question 4

what is the half life of technetium 99m

Answer 4

6hrs

Question 5

what type of decay does technetium 99m undergo

Answer 5

isomeric transiton- gamma ray production

Question 6

what the the photo peak of technetium 99m

Answer 6

140keV

Question 7

how is molybdenum-98 turned to molybdenum-99

Answer 7

cyclotron- bombardment

Question 8

what kind of collimator is used for Tc-99m imaging
a) low energy
b) medium energy
c) high energy

Answer 8

low- septal thickness 0.3mm. works for photon energies up to 150keV

Question 9

increasing the distance of the patient from the gamma camera causes ___ in spatial resolution

Answer 9

decrease

Question 10

a high spatial resolution gamma camera collimator has what effect on image acquisition and quality?
a) increased resolution, reduced count rate, increased acquisition time
b) increased resolution, increased count rate, the same scan time
c) increased resolution, reduced count rate, generally shorter scan time

Answer 10

A

Question 11

in a gamma camera, which layer is important for turning the gamma photons to visible and UV light?

Answer 11

NaI scinillator- fluorescence

Question 12

in a gamma camera, which layer is important for increasing the number of electrons that reach the final anode?

Answer 12

photomultiplier tube -similar to image intensifier in fluoroscopy

Question 13

how does NaI crystal thickness affect spatial resolution in a gamma camera?

Answer 13

thinner crystal, better spatial resolution

Question 14

what causes the comptom band in the voltage pulse graph in a gamma camera
a) Compton reactions within the patient
b) Compton reactions within the scintillator
c) Compton reactions within the scintillator and patient

Answer 14

C
The gamma photon energy absorbed by the scintillation crystal depends on its interaction with that photon which results in a spectrum of Z values.
1. All energy absorbed: gamma photon interacts with crystal via photoelectric effect
2. Part of the energy absorbed: photon undergoes one or more Compton interactions (when a high-energy photon (like X-rays or gamma rays) hits a loosely bound electron in an atom, transferring some of its energy, causing the photon to scatter in a new direction with less energy, and ejecting the electron (a Compton electron)

Question 15

what is the role of the collimator in a gamma camera
a) scatter rejection
b) spatial mapping
c) amplification and channelling of electrons from the photocathode
d) Reduces dose to radiation workers

Answer 15

B

The collimator acts as a lens to reject photons that have a path that means they do not hit the camera in a location that corresponds to their original location i.e. its purpose is for spatial mapping. It does not reject scatter. (different to XR)

Question 16

which gamma camera is most common?
a) Parallel hole
b) Diverging hole
c) Converging hole image
d) Pinhole

Answer 16

A

Question 17

which gamma camera collimator is for magnifying images of small objects?
a) Parallel hole
b) Diverging hole
c) Converging hole image
d) Pinhole

Answer 17

D

Question 18

which gamma camera collimator is for minifying images?
a) Parallel hole
b) Diverging hole
c) Converging hole image
d) Pinhole

Answer 18

B

Question 19

what is the half life of iodine 123

Answer 19

produced by cyclotron, emits gamma radiation, half life 13.2 hrs

Question 20

what is iodine 123 used for?

Answer 20

Assess thyroid function and thyroid cancer mets

Question 21

what is the energy of the gamma photons emitted by iodine 123

Answer 21

Energy 159keV 83%
Decays by electron capture
Replaced I-131 for diagnosis as lower dose.
Too few neutrons but not enough energy for β+ decay

Question 22

what is the half life of iodine 131

Answer 22

8.6 days

Question 23

what types of radiation are emitted by iodine 131

Answer 23

emits gamma and beta

gamma- imaging 364-keV photon used for imaging
beta- for treatment

Question 24

what energy are the gamma rays from iodine 131

Answer 24

364- very high
Resolution and detection efficiency are poor due to high energy of photons

Question 25

how is iodine 131 generated

Answer 25

in a nucear reactor

Question 26

which radio-isotopes can be used in thyroid imaging?

Answer 26

TC- pertechnetate- taken up as a monovalent ion, not organified, uptake proportional to thyroids metabolic state. I 123 I 131

Question 27

how is Tc pertechnetate used for imaging portosystemic shunts

Answer 27

transplenic or per rectal administration, image the first pass blood supply.

Question 28

what is technetium MDP used for. how does it work?

Answer 28

three phase bone scans pulmonary mineralisation studies binds to hydroxyapatite crystals

Question 29

how is tc- pertechnetate uptake by the thyroid gland affected by methimazole?

Answer 29

Uptake of pertechnetate is not affected by antithyroid medication except METHIMAZOLE (increased radionuclide uptake)

Question 30

when imaging a cat after pertechnetate, where can you find high physiological levels of uptake?

Answer 30

salivary glands, stomach, kidneys, urinary bladder, thyroid (always more than in plasma) Up to 30 x [X] of that in plasma in a normal gland 300 – 500 x [X] of that in plasma in an abnormal gland.

Question 31

how long after IV injections should you image feline thyroid glands after pertechnetate? a) immediately b) after 10 mins c) 20-30 mins d) 1 hr

Answer 31

20-30 mins Use of pertechnetate in thyroid imaging measures uptake, not organification (assessment of thyroid morphology, vascularity and function)

Question 32

how is Tc pertechnetate excreted in cats and dogs?

Answer 32

kidneys, (GI)

Question 33

which is true about per- rectal Tc perchecnetate? a) there is efficient active absorption of Tc pertechnetate across the colonic wall b) direct portosystemic shunt visualisation is possible if imaged after 3 minutes c) imaging will show higher uptake in the heart and lungs, before the liver, in a dog with a PSS d) trans-splenic injection is less efficient, requiring higher doses, but allows better shunt visualisation.

Answer 33

C Per-rectal = dose of radionuclide is administered per-rectum, Follow by active transport across the intestinal wall occurs via a bicarbonate/Cl exchange pump Under ideal conditions only ≃ 14 % of the colonic dose is absorbed, necessitating large doses Absorption rate is variable. Presence of shunting can be determined, but direct visualization of the portal system is typically not achieved immediate imaging and repeat imaging until the compound reaches the heart. In normal animals, radioactivity first appears in the liver 10-15s after rectal administration, then 8-12s delay before radioactivity seen in the heart Trans-splenic portal scintigraphy (TSPS) is generally considered superior to per-rectal portal scintigraphy (PRPS) due to better image quality, lower radiation exposure, and improved ability to determine shunt anatomy, which aids surgical planning.

Question 34

how soon after injection should you image patients for a bone phase scan after Tc MDP? a) 10 mins b) 30 mins c) 1 hr d) 2-4hrs Picture of you for ehpss

Answer 34

2-4 hrs Indications Indicated as a skeletal imaging agent to delineate areas of abnormal osteogenesis (in metastatic bone disease, arthritic disease, osteomyelitis, and fractures) 3-phase scanning can be used to distinguish between cellulitis and osteomyelitis Vascular phase = images acquired immediately, while the radionuclide remains in the blood system ( dynamic scans obtained every 1-2 secs from 20-70 secs after administration, for up to 90 secs). Diagnostic information can be gained by the presence of either ↗︎ (e.g. acute inflammation infectious osteitis/osteomyelitis) or ↘︎ flow (infarcts, severe soft tissue trauma, laminitis) Soft tissue phase = represents distribution of nuclide in the capillary bed and ECF (though it’s almost impossible to completely avoid imaging some early bone uptake - e.g. in particularly acute lesions) => this phase wll last from ≃ 2 min to 10-30min post-administration. Not very sensitive to soft tissue injuries Bone phase = should begin 2-3 hours post-administration  normally, good bone penetration and reasonable clearance from soft tissues

Question 35

how is Tc MDP eliminated?

Answer 35

Elimination of non-bone bound radionuclide is primarily renal For nuclide bound to bone, activity remains => horses must be kept isolated until reasonable decay has occurred - Route of excretion: o Primarily renal: ≈ half of the dose retained by skeleton and half excreted in urine by 24h, o 10% of the dose remains in the blood 1h post-injection o Small quantity secreted from the sweat glands (horses)

Question 36

how soon after administration can you image the thyroid after I 123 is given? a) 10 mins b) 30 mins c) 2-4 hr d) 4-6hr

Answer 36

D Used for diagnosis  imaging performed 4-6 hours post administration Indicated for evaluation of thyroid function +/- morphology Uptake determined by Nal (TI) thyroid probe

Question 37

how is I 131 and I 123 eliminated?

Answer 37

Urinary tract mainly. git, sweat, tears, Also secretion into breast milk and across the placenta with secretion Also into the saliva

Question 38

what is the normal thyroid to salivary gland ratio for pertechnetate in cats?

Answer 38

1.5:1 6.4:1 for background

Question 39

where can circulating iodide become trapped?

Answer 39

o Circulating iodide is also trapped by the salivary glands, gastric mucosa, choroid plexus of the brain, placenta, ciliary body of the eye, lactating mammary tissue; may be secreted in milk and can be actively accumulated by foetal thyroid tissue

Question 40

what factors can reduce radioactive iodine uptake by the thyroid?

Answer 40

antithyroid drugs iodine supplementation (or high amounts in the diet, contrast media) before the study/ treatment

Question 41

what is the half life of F18

Answer 41

109.7mins

Question 42

which areas show normal physiological uptake of radioisotope in techetium but not iodine 123? a) choroid plexus b) lacrimal glands c) gastric mucosa d) salivary glands

Answer 42

B howeverr PET study with I 124 showed uptake in lacrimal glands (and others VRU 2022 page 36)

Question 43

18 flt pet ct usually accumulates where cats

Answer 43

3'-deoxy-3'-[(18) F]fluorothymidine ((18) FLT), a proliferation tracer, has been found to be a useful tool for characterizing neoplastic diseases and bone marrow function in humans in normal cats: Notable areas of uptake included hematopoietic bone marrow, intestinal tract, and the urinary and hepatobiliary systems