nucmed_basic instrumentation

scintillation camera (gamma/anger camera)

> a device that produces projected images of the distribution of radioactivity in the body

> acts as a dectector

a) lead collimator

b) scintillator

a) gamma rays emerging from the patient pass through a ___

b) this allow photons travelling parallel to the collimator holes to reach the ___

spatial information

the collimators are essential for providing ___ in Planar Nuclear Medicine Imaging:

NaI (sodium iodide) crystals

the gamma rays that pass through the collimator interacts with ___, which produce many light photons:

10%

approximately [%] of gamma ray energy is converted to light:

array of photomultiplier tubes

the light output from NaI crystals is detected by an ___ and converts it into electrical signals:

lead shielding

scintillation cameras have ___ to prevent unwanted background radiation from the room or other areas of the patient from contributing artifacts to image formation:

collimator

a device that is made up of lead and contains multiple holes:

septa (singular: septum)

the lead strips between the holes of the collimator:

parallel hole collimator

> this projects the same object size onto the camera

> FOV does not change with distance

> most commonly used

converging collimator

> this produces a magnified image

> FOV decreases with distance

> used in small organs

diverging collimator

> this projects an image size that is smaller than the object size

> FOV increases with distance

pinhole collimator

> this projects an image that is magnified and inverted

> cone-shape with a single hole at the apex

larger holes and lower resolution

high sensitivity:

smaller holes and lower sensitivity

high resolution:

Low Energy General Purpose (LEGP) collimator

> has a thinner septa

> used for Tc-99m and Tl-201 radionuclides

> Low Energy High Resolution (LEHR)

> technetium-99m (Tc-99m) radionuclide

> thallium-201 (Tl-201) radionuclide

the LEGP collimator is used for:

Low Energy High Resolution (LEHR)

> most frequently used

> cardiac scan

> Tc-99m scan

Medium Energy General Purpose (MEGP) collimator

> has a thicker septa than LEGP collimator, LEHR

> used for Ga-67 and In-111 radionuclides

> gallium-67 (Ga-67) radionuclide

> indium-111 (In-111) radionuclide

the MEGP collimator is used for:

> 93 keV

> 3.26 days

the energy and half-life of Ga-67:

> tumors

> inflammation

> acute and chronic infection

Ga-67 is used for:

> 247 keV

> 67 hours

the energy and half-life of In-111:

> platelets labelling

> thrombus detection

In-111 is used for:

High Energy General Purpose (HEGP) collimator

> has the thickest septa

> used for I-131 radionuclide scan

iodine-131 (I-131) radionuclide scan

the HEGP collimator is used for:

> 364 keV

> 8 days

the energy and half-life of I-131:

> whole body survey

> pre- and post-RAI (Radioactive Iodine) Therapy

I-131 is used for:

sodium iodide (Na-I) crystals

they detect gamma rays emerging from the patient and subsequently converts them into light photons:

Pulse Height Analyser (PHA)

> Analyzer sa net

> an electronic device used to determine which portion of the detected spectrum is used to create an image

> can be set to allow only selected energies to be counted

> reduces the number of Compton scatter photons in the image

Compton scatter photons

PHA reduces the number of ___ in the image:

Planar Nuclear Medicine Imaging

> nuclear images can be viewed in real time during acquisition

> uses ADC to generate digital information

> typical matrix size is 128 x 128

128 x 128

the typical matrix size used in Planar Nuclear Medicine Imaging:

64 x 64

the matrix size used for a cardiac study:

1204 x 1204

the matrix size used for whole body imaging:

Single Photon Emission Computed Tomography (SPECT)

> a NM imaging technique that provides computed tomographic views of the 3D distribution of radioisotopes in the body

> physiology and anatomy

parallel hole collimator

the type of collimator used in SPECT:

180° or 360°

in SPECT, the scintillation cameras move ___ around the patient:

every 3° or 6°

in SPECT, the projection images are obtained at selected angles which is typically ___:

small

a fast scan can be achieved using a [small/large] matrix size:

10 thyroid scans

1 x-ray scan is equal to ___:

calcium tungstate (CaWO₄) crystals

they emit blue light:

rare earth crystals

they emit green light:

360°

the degrees used by the Single Headed PET Camera:

180°

the degrees used by the Dual Headed PET Camera:

Positron Emission Computed Tomography (PET)

> a NM imaging technique wherein detectors are coupled to photomultiplier tubes to detect light produced in each detector

> image metabolic processes based on glucose uptake

> without biopsy

PET camera

a device that contains rings of detectors (scintillators) surrounding the patient:

photomultiplier tube (PMT)

> where detectors are coupled in PET

> detects light produced in each detector

dose calibrator

> measures the amount of activity present

> volume does not affect radioactivity

> can be used for determining half-life without using the equation

> saline is mixed with radioactive materials

5~7 mCi

the amount of activity present in the thyroid:

Radio-Iodine Fume Hood

> expels iodine fumes safely into the atmosphere

> located at the highest point of the infrastructure

> where iodine is also prepared

lead glass

the Radio-Iodine Fume Hood is made of ___:

gamma well counter

> instrument that measures the radioactivity of gamma-emitting samples

> used for blood testing or anything related to blood

> equivalent to radio-immunoassay lab

> used every friday or once a week

> detects gamma-photon emissions from radionuclides

Geiger-Muller counter (survey meter)

> measures the amount and presence of radioactivity

> detects beta and gamma

> has uptake probe

1) first detection - GAMMA

> place plastic on probe