Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Technology > Nuclear Medicine > Flashcards

Nuclear Medicine Flashcards

1
Q

PET scanning mechanism

A

tracer accumulates in tissues of interest
radioactive tracer emits positrons during decay
positron travel short distance before annihilating with electron in the surrounding tissue

this creates energy in the form of 2 back to back / DIAMETRICALLY OPPOSITE 511 kiloeletronvolt gamma photons emitted in opposite directions
circle of gamma detectors measure pairs of gamma photons -i.e. arriving in the same small period nanoseconds of time - said to be in coincidence
locating exact position of collision
the positron assumed to met electron somewhere along the line of response
millions of lines of response recorded to map out 3 d distribution of positron emitting radionucleotide in the body
reconstruction gives pixel values proportion to radioactivity concetration in area of bodu

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q 
definition
nuclide
istope
radioisotope
radionuclide
radiopharmaceutical
A

nuclide
atom with arrangement of protons, neutrons and electrons

isotope
nuclide with same number of protons, atomic number - neurtrons and protons and chemical properties

radioisotope
unstable isotope, emits radiation as nuclei undergo rearrangament more stable form

radionuclide
radioactive atom
nomenclature element plus atomic mass number

radiopharmaceutical = combination radionuclite with compound with physiological properties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what does gamma camera detect

A

distribution of radioactive substances in vivo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

half life of technetium 99m
what is m
what is radiation emitted

A

6 hours
m is for metastable
emits gamma ray

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

why is Tc99m suitable

A 
non toxic
no immune response
no pharm ation in isolation
can mix with range of compounds
eg Tc99m colloid for sentinel LN biopsy
Tc99m MDP bone scan
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is used for glomerular filtration

A

chromium Cr 51 edetate (Cr 51-ethylenediamine tetraacetic acid; Cr 51-EDTA)

Tc-99m DTPA (diethylene-triamine-pentaacetate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

how to do radiopharm scan

A

adequate hydration
bladder empty
sitting/prone gamma camera to back
inject radiopharmaceutical and acquire images 20-40 minutes
empty bladder to reduce dose to pelvic organs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

3 phases of renogram

A

vascular phase
first few seconds,
phase should be removed from generated renogram

uptake phase from 1 min onwards
rate rises porportional to kidney function
2-5 min peak, rapid rise

transit phase
renal handling tracer gradual slope

elimination phase
any time after 3 min
after reaches peak
balance between uptake and elimination

rising curve uptake exceeds elimination
horizontal curve uptake and elimination balanced

1st Phase

Rapid uptake by tubular cells
(isotope reaches kidney within approx 15 seconds)
Reflects speed of injection and renal blood flow

2nd Phase – Renal handling

The transfer of tracer across tubular cells into lumen of nephron

3rd Phase – Excretory phase
Reflects efficiency of excretion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

DTPA

where excreted

A

inert
90% excreted by glomeruli
no secretion or filtration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

MAG 3 excretion

A

95% tubular secretion
can measure effective renal plasma flow as surrogate of GFR

MAG-3 principally excreted by tubular secretion 90%; 10% filtered

MAG3 is cleared by a combination of glomerular fi ltration and tubular
secretion, so it has greater kidney uptake, leaving less in the blood background. It is
therefore the preferred radiopharmaceutical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

DMSA

A

better for function as has cortical parenchymal activity

anterior and posterior views

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

dose of furosemide

when to give

A

0.5 mg/kg up to 40mg

can give at T+20 if not emptied by 20 minutes
data acquisition for another 15 mins

if equivocal response then maximal diuretic response can be F-15

if venous access difficult eg in children, furosemide give immediately before radioactive tracer through same cannula F+0

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

types of renogram curve

A

type 1 normal
type 2 obstructed
type 3 a hypotonic - normal drainage from hypotonic renal pelvis, rises initially but rapid fall with diuretic
type 3b equivocal = rises initially but neither falls rapidly nor continues to rise following injection of furosmide

type 4 Homsy sign
transient response to diuretic, represents obstruction, VUR can look similar, represents intermittent hydronephrosis, giving -15 diuretic eliminates homsy sign

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

bone scan compound

A

methylene diphosphonate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is energy of gamma rays emitted from pet

A

two of 511kEV gamma rays emitted in opposite directions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

fdg

A

18F flurodeoxyglucose
This is an analogue of glucose, which is trapped
within cells following phosphorylation by hexokinase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

half life of 18F

A

110 minutes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

half life of 18F

A

110 minutes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

half life 11C

A

20 minutes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

11C pet vs 18F FDG pet for prostate ancer

A

FDG - low metabolic rate of prostate cancer

C11 better as map to lipid metabolism/cell membrane integrity

21
Q

what is SUV

A

pixel values from pet scan expressed as units of kBq/kl normalised to injected activity and patient body weight to produced standardised uptake values SUV

22
Q

how is renogram performed

A

patient well hydrated
drink 300-500mls water prior
empty bladder imm before test

positioned seated with back to camera to aid normal gravitational drainiage or supine with camera underneath couch
injection of radiopharmaceutical
immediately gamma camera starts acquiring dynamic series of images
one frame every 20s for 30-40 minutes
if kidney not drained by 40 min, and patient lying down, patient asked to stand up and final static image acquired
then patient empties bladder and post mic image acquired

23
Q

drawing regions of interest

A

around kidney and other area for background activity

24
Q

use of background curves

A

used to subtract background contribution from each kidney curve, resulting curve is the renogram

25
Q

how is relative function calculated from mag 3

A

from first 1-3 minutes of renogram, rutland plot most accurate

26
Q

Homsy’s sign

A

If the renogram curve initially starts to fall after
furosemide but then begins to rise again after a few minutes, this is known as
Homsy’s sign (Fig. 22.1d ). It is indicative of intermittent obstruction which only
occurs at high urine fl ow rates. In these cases, an F-15 renogram will probably
appear obstructed.

27
Q

F-15 renogram curve when will have max diuresis

A

will have max diuresis by time renogram started
if curve rises mean ob at high flow
however no indication how kidney handles normal urine flows

28
Q 
how DMSA scan is done
name
where bind
emitting radiation
where accumulates
how long wait
which images taken
A 
dimercaptosuccinic acid 
gamma emitting
binds to PCT
accumulates slowly renal cortex
only small amount excreted
patient waits for 2-4 hours to sufficient cortical uptake

supine on imaging couch
static views from kidney posterior anterior left posterior oblique and right posterior oblique

each view takes about 5 mins to get 200,000 to 500,000 counts

29
Q

gamma camera in dmsa scan
using
how long per image
how calculate geometric mean

A

Gamma camera: detects gamma rays and their position, via collimator and photomultiplier
LEHR collimator, approx 5 mins per image (200,000-500,000 counts)
Static views from posterior, anterior, LPO and RPO
Region of interest around each kidney, exclude non-renal background
Relative function calculated from posterior and anterior view (geometric mean)

30
Q

what is megabecquerel

A

1MBq = million atoms disintegrating/sec

31
Q

1Gray

A

absorption of 1J of energy/kg (=100rads

32
Q

Effective radiation dose (Sv)

A

Gy x type of radiation x tissue type/volume/time

33
Q

MAG 3
how many mBq
mSV
secretion and filtration

A

Mercaptoacetyltriglycine
Renography
99Tm, 100MBq, 0.7mSv
90% tubular secretion, 10% filtered

34
Q

why need geometric mean in dmsa

A

geometric mean adjusts for differential distance of kidneys from gamma camera

35
Q

in patient with stone disease what level function consider nephrectomy

A

Depends on a number of factors including age / fitness for relative interventions, overall renal function, particular condition
<10% function usually nephrectomy
>20% renal preservation
10-20% depends on above factors

36
Q

principle of radioisotope renography

A

Radioisotope imaging involves labelling of organic compounds with a radioactive isotope that emits gamma irradiation.
Gamma rays penetrate through tissues and get detected by a gamma camera.

36
Q

principle of radioisotope renography

A

Radioisotope imaging involves labelling of organic compounds with a radioactive isotope that emits gamma irradiation.
Gamma rays penetrate through tissues and get detected by a gamma camera.

37
Q

picture taking interval MAG 3 scanr

A

Images are collected onto a film at 30s intervals for the first 3 mins and then at 5 min intervals
total 40 mins

38
Q

radiation dose MAG 3

A

0.7mSV

39
Q

what is mag3 renogram represent

A

Relationship between supply and excretion is known as the time-activity curve aka ‘Renogram’

2/3 of MAG-3 taken up by kidney with each passage of blood through the kidney

Peak of activity is reached when MAG-3 delivery to the kidney via renal artery is equivalent to excretion

40
Q

technetium 99
decay half life
daughter nuclide of
produced in a generator and extracted by

A

Decay half life of 6 hours- Daughter nuclide of Mo 99 by decay in a metastable state.

Produced in generator and extracted by column chromatography

41
Q

half life of Cr51

A

27 hours

42
Q

dose of MAG3 given

A

50-70MBq of agent is given iv (flush with saline)

43
Q

how is bone scan performed

radiation dose

A

Injection of Tc99 Methylene Diphosphonate IV, Wait 3 hours. Gamma camera scan. AP, PA and other views PRN. 3.6mSv (equivalent to 180 CXRs and similar to an IVU).

44
Q

MDP binding site

A

The phosphonate compounds bind to bone by chemo-adsorption to the hydroxyapatite crystal

45
Q

release of gamma rays by Tc 99

A

Technetium 99m decays by releasing 140-kV gamma rays, which are detected by a gamma camera.

The appearance of activity on the scan usually reflects osteoblastic activity in bone.

46
Q

causes of superscan

A 
Diffuse metastatic disease
Prostate carcinoma
Breast carcinoma
TCC
Multiple myeloma
Lymphoma
47
Q

dose DMSA scan

A

0.8mSV - 1mSV

vs MAG3 0.4-0.7mSV

48
Q

gamma camera

A

gamma rays hit scintillation crystal
which make scintillation light which is collected by photomultiplier tubes
converted to volts which make up picture

Technology (24 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions