Edmonton Review Course

Question 1

Thyrotoxicosis vs hyperthyroidism

Answer 1

Thyrotoxicosis
The clinical manifestation of the presence of excess thyroid hormone overproduction
abnormal release of hormone from gland
extra-thyroidal sources of hormone

Hyperthyroidism
thyrotoxicosis specifically related to autonomous overproduction of thyroid hormone by the thyroid gland

Question 2

Three medications that can cause thyroiditis

Answer 2

Amiodorone

Lithium

Tyrosine kinase inhibitors

Question 3

I131 empiric dosing for Graves and TMNG

Answer 3

Graves - 10 to 15 mCi

TMNG - 10-20 mCi

Question 4

Ideal radiopharmaceutical properties for therapy

Answer 4

High dose to target organ/tumour

Low dose to non-target organs

Long enough physical half life to match biologic half life

No carrier added/high specific activity

Stable decay products

Question 5

General characteristics of therapeutics

Answer 5

Alpha:
5-9 MeV; Range 40-100 um; LET 80 keV/um

Beta:
50-2300 kev; Range 0.05 - 12 mm; 0.2 keV/um

EC/IC:
Non energetic electrons; ev-keV; 2-500 nm; 4-26 keV/um

Question 6

Therapy dose reduction for Y90 microsphere threrapy

Answer 6

Lung shunt ratio:
< 10 = no reduction
10-15 = 20% reduction
15-20 = 40% reduction

Question 7

RCB bleed scan diagnostic criteria

Answer 7

Focal site of increased activity
Conforms to bowel anatomy
Increases with time
Moves anterograde or retrograde

90% sn; 95% sp

Question 8

False negative GI bleed

Answer 8

Too low bleeding rate
Intermittant bleeding
Attenuation by barium or contrast
Overlapping blood pool structures

Question 9

Causes poor RBC labeling

Answer 9

Meds (heparin, penicillin, IV contrast)
Generator ingrowth time > 24 hrs
Excess tin
Injection through IV tubing

Question 10

Delayed gastric empyting cutoffs

Answer 10

> 90% retention at 1 hr
60% retention at 2 hrs
10% retention at 4 hrs (>20% = moderate; > 35% = severe)

Question 11

Easy conversion for pediatric dose

Answer 11

1/100 adult dose/kg, min of 10 kg

Question 12

Homsy’s sign

Answer 12

Functionally significant high grade obstructed induced by high flow rate

Renogram begins to clear then rises as flow rate peaks

Question 13

Classic Ps of pheochromocytoma

Answer 13

Pain (HA)
Palpitations
Perspiration
Pallor
Pressure (HTN)

Question 14

MEN2A features

Answer 14

MTC, pheo, hyperparathyroidism

Question 15

MEN2B features

Answer 15

MTC, pheo, multiple neuromas

Question 16

Initial fracture risk on BMD

Answer 16

Determined from white female database for both sexes

Uses only femoral neck

Question 17

BMD categories < 50

Answer 17

> -2.0 Within expected range for age

<= -2.0 Below expected range for age

Question 18

Amino acid synthesis tracers

Answer 18

C11-methionine

F18-FET

Question 19

Only 3 approved and marketed PET radiopharmaceuticals in Canada

Answer 19

FDG
Rb82
F18-florbetaben

F18-NaF (approved for sale but limited to clinical trials)

Approved for use but not yet for sale 13N-NH3

Question 20

Describe Gates method

Answer 20

Measure syrginge counts pre and post injection
Inject DTPA, image for 6 minutes
Create TAC, correct for background and linear depth attenuation
Convert to clearance

Question 21

Causes of R to L shunt

Answer 21

Cardiac
Pulmonary AVM
Capillary telangiectasia
ECMO

Question 22

L to R shunt study technique

Answer 22

Pertechnetate 74 MBq, rapid IV bolus
Parallel hole high sensitivity collimator
2-4 frames per sec x 25 sec
128 x 128 matrix 
140 keV peak + 20% window
FOV on lungs

Create pulmonary time activity curve

Question 23

SSB repair

Answer 23

1. Base excision repair - removal of base and sugar, replacement of base
2. Nucleotide excision repair

Question 24

DSB repair

Answer 24

1. Nonhomologous end joining - end recognition (no sister chromatid)
2. Homologous recombination repair - normal DNA strand as template (sister chromatid)

Question 25

Doubling dose

Answer 25

Dose that doubles the spontaneous mutation rate in one generation (in Gy)

Question 26

Thyroid cancer risk factors

Answer 26

``` Age Female FH Exposure to ionizing radiation Obesity Smoking is protective ```

Question 27

Papillary TC mets

Answer 27

Lymphatics | Distant less common (lung, bone, mediastinal nodes)

Question 28

Follicular TC mets

Answer 28

Lower survival rate than papillary Hematogenous spread Lungs, bones, brain

Question 29

Role of RAI therapy in TC

Answer 29

1. Low risk - Total thyroidectomy. RAI not normally given, if so, then 30 mCi. If subtotal thyroidectomy, RAI not given. 2. Moderate risk - consider RAI 3. High risk - do RAI

Question 30

ATA low risk features

Answer 30

Papillary with no mets, no aggressive histology Follicular - intrathyroidal, well differentiated

Question 31

ATA intermediate risk features

Answer 31

Microscopici invasion of tumour into perithyroid tissues Aggressive histology

Question 32

ATA high risk

Answer 32

Gross ETE Incomplete resection Distant mets Any lymph node > 3 cm

Question 33

RAI remnant ablation dose

Answer 33

30 mCi

Question 34

RAI dose suspected microscopic residual disease

Answer 34

Dose up to 150 mCi

Question 35

RAI dose lung mets, bone mets

Answer 35

100-200 mCi empiric Can do dosimetry to limit 2 Gy to marrow

Question 36

Inpatient iodine treatment

Answer 36

If activity remaining < 300 Mbq and dose rate at 2 m < 4uSv/hr, no hospitalization and minimal precautions If activity remaining < 1100 Mbq and dose rate at 2 m < 16 uSv/hr, precautions needed whether hospitalized or discharged if activity remaining > 1100 Mbq and dose rate at 2 m > 16 uSv/hr, inpatient isololation and precautions

Question 37

Purpose of post therapy scan for thyroid

Answer 37

Additional staging information Document avidity of any residual structural disease