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1

What other names is there for nuclear medicine?

Nuclear Medicine
Radionuclide Imaging
Scintigraphy
Unclear Medicine
Molecular Imaging

2

What is nuclear medicine?

A modality which images the relative distribution of a radiopharmaceutical in the body or a particular organ

3

Steps in producing a Scintigram?

Select a suitable tracer (Radiopharmaceutical)
Administer to patient.
Acquire images with a GAMMA CAMERA
Process images with computer to give functional information.

4

What is Gamma Camera?

An instrument that produces quantitative images of the distribution of gamma emitting tracers within a patient.

5

A Scintigram can be in the form of:

Static images that reflect the uptake and therefore function of an organ.
Movie images that show the distribution of tracer as time passes.
Quantitative information e.g. graphs and uptake values.

6

Advantages of Nuc med:

Sensitive
Functional information
Low patient dose

7

Disadvantages of Nuc med:

Low specificity
Poor anatomical detail
Slow

8

With reference to the gamma camera:i.) What is the crystal made from?

Sodium Iodide

9

What is added to the crystal and why?

Thallium added to ensure that the scintillations are at the blue end of the visible spectrum.

10

iii) What is the relationship between the energy of a gamma ray and the size of the scintillation it produces.

The quantity of light being proportional to the energy of the incident photon. (unsure if correct)

11

Photons striking _____ interact by _____ or ______. Produce a ________: ____/UV light

Photons striking CRYSTAL interact by COMPTON or PE. Produce a scintillation: BLUE/UV light

12

What does a Light Guide do?

Provides optical coupling
between crystal and PM tubes

13

What are Photo Multiplier Tubes

Several PM tubes will detect each scintillation
Produce small electrical signal from each scintillation
Amplify it maintaining proportionality

14

What does a position computer do?

Produces x and y signals corresponding to the position of the event.

15

What does Pulse Height Analyser look at?

PHA “looks” at the z pulse corresponding
to each scintillation

16

ADC does what?

ADC processes the signal
into digital form

17

Information density means..

number of photons collected over region of interest

18

Spatial Resolution, what is it?

Ability to image two adjacent point sources
as separate points

19

What is it dependent on?

Dependent on:
Intrinsic resolution (Ri)
Collimator (Rc)
Scatter component (Rsc)

20

Scatter…..

Surrounding tissue produces Compton scatter
Some scattered photons will reach crystal.
Some will be within the 20% energy window.
Degrades the image
Worse at increasing depth

21

SPECT what is it? What is it?

What problem does it solve?

Problem-background activity in surrounding tissues and the increased amount of scatter limits the resolution and target to background ratio of the organ being imaged.

Solution-SPECT (Single Photon Emission Computed Tomography) Reconstruct using filtered back projection

22

Advantages of SPECT

Increased “pick up” of deep lesions
Localisation
Correlate with CT
Estimate volumes

23

Disadvantages of SPECT

Requires special equipment
Careful setting up
Strict QC
Patient Co-operation
Acquisition times 15-30 minutes

24

Uses for SPECT

Cardiac (myocardial Perfusion)
Brain
Bone-Hips-Spine
Kidney (DMSA)
Liver
Other

25

Gamma Camera Q.C. 3 parts;

Field Uniformity
Field Linearity
Centre of Rotation

26

What is Field Uniformity?

Field uniformity
Uniform response over whole field of view
Intrinsic (without collimator) Extrinsic (with collimator)

27

Whats linearity?

Linearity:Ability of a gamma camera to image a straight line in x and y planes

28

QC of centre of rotation

To ensure that the mechanical centre of rotation and the co-ordinates stored in the computer are the same.

29

Types of collimators? What are they called (2)?

High resolution &
High Sensitivity collimators.

30

Give one reason when you would use;i. High Resolutionii. High Sensitivity

- Hi Resolution……..Bone scans, SPECT- Hi Sensitivity…….Dynamic/ short frame times