Gamma Camera Gamma Camera TechnologyTechnology

Gamma CameraGamma Camera

Is a device used to image gamma Is a device used to image gamma radiation radioisotopes this radiation radioisotopes this technique is called also scintillation technique is called also scintillation camera.camera.

Gamma camera is used to view and Gamma camera is used to view and analyse images of the human body analyse images of the human body or the distribution of the medically or the distribution of the medically ingested, injected or inhaled ingested, injected or inhaled radionuclides. radionuclides.

Gamma CameraGamma Camera

Gamma Camera ComponentsGamma Camera Components 1-Collimators1-Collimators The collimator provides an interface The collimator provides an interface

between the patient and the between the patient and the scintillation crystal by allowing only scintillation crystal by allowing only those photons traveling in an those photons traveling in an appropriate direction. appropriate direction.

CollimatorsCollimators

CollimatorsCollimators

Types of collimatorsTypes of collimators

A) By the accepted energy.A) By the accepted energy.

B) By the geometric shape.B) By the geometric shape.

C) By the resolution. C) By the resolution.

CollimatorsCollimators

By the accepted energyBy the accepted energy

Low Energy Collimator

High Energy Collimator

Medium Energy Collimator

CollimatorsCollimators

By the geometric shape.By the geometric shape.

Parallel-Hole Diverging collimator

Converging collimator

Pin-Hole Collimator

CollimatorsCollimators

Parallel-HolePin-Hole (more resolution & magnification) hip,thyroid

Converging لألعضاء أفضل وتحديد الصورة البدين Divergingلتكبير المريض حالة في للتصغير

CrystalCrystal

Any Any damagedamage to the crystal results in to the crystal results in an inoperable scintillation camera an inoperable scintillation camera and requires costly replacement of and requires costly replacement of the crystal.the crystal.

The large surface area, as well as The large surface area, as well as the the hygroscopic hygroscopic and and brittle naturebrittle nature of of the crystal, calls for constant care to the crystal, calls for constant care to avoid puncturing the housing or avoid puncturing the housing or otherwise damaging the crystal. otherwise damaging the crystal.

CrystalCrystal

The chosen material for the crystal is The chosen material for the crystal is Na-I (Tl).Na-I (Tl).

The Na-I (Tl) crystal is stationary.The Na-I (Tl) crystal is stationary.

The crystal transform the gamma-ray The crystal transform the gamma-ray photon ------> Light photonphoton ------> Light photon

Photomultiplier tubePhotomultiplier tube

PhotocathodePhotomultiplier tube

DynodeConnected to High positive volt

Photomultiplier tubePhotomultiplier tube

The Photocathode transform the The Photocathode transform the lightlight photonphoton --- --- electron.electron.

The PMT multiplies the electron to be The PMT multiplies the electron to be a significant detected signal.a significant detected signal.

Other circuits Other circuits

1)Pre-Amplefier1)Pre-Amplefier

2) Amplifier2) Amplifier

Advantages of Gamma CameraAdvantages of Gamma Camera

The imaging time is only 1-2min.The imaging time is only 1-2min.

It can distinguish 2 sources about It can distinguish 2 sources about 5mm apart.5mm apart.

Types of imaging in Nuclear Types of imaging in Nuclear Medicine Medicine

Planar (Gamma Camera).Planar (Gamma Camera). Static.Static. Dynamic.Dynamic. Total Body.Total Body. Tomographic (SPECT).Tomographic (SPECT).

Static ImagingStatic Imaging

It is the basic type of imaging.It is the basic type of imaging. The patient is injected before imaging.The patient is injected before imaging. The camera head is located at the The camera head is located at the

organ of interest.organ of interest. For dual head cameras two images can For dual head cameras two images can

be acquired at the same time.be acquired at the same time. The stopping mechanism is either by The stopping mechanism is either by

CountCount or or Time.Time.

Static ImagingStatic Imaging

The matrix size is defined according to the The matrix size is defined according to the need from each exam starting from need from each exam starting from 64X6464X64 up to up to 1024 X 1024.1024 X 1024.

The zoom is defined according to the size of The zoom is defined according to the size of the organ of interest.the organ of interest.

Examples:Examples: Thyroid imagingThyroid imaging: : 500 Kc500 Kc acquisition count acquisition count

or or 5 Min5 Min acquisition time with injected dose acquisition time with injected dose of of 5 mCi5 mCi

matrix= matrix= 128 X128128 X128 Zoom = Zoom = 2 : 12 : 1

Static ImagingStatic Imaging

Bone imagingBone imaging: : 500 Kc500 Kc acquisition acquisition count or count or 5 Min5 Min acquisition time for acquisition time for each position with injected dose of each position with injected dose of 20 mCi20 mCi

matrix= matrix= 512 X512512 X512 Zoom = Zoom = 1 : 11 : 1

SPECT imagingSPECT imaging

What is SPECT ?What is SPECT ?

Single photon to Single photon to differentiate from differentiate from two annihilation two annihilation photonsphotons

Generation of cross - Generation of cross - sectional imagessectional images

Images from various Images from various angular projectionsangular projections

Collectively, the Collectively, the different different

projections projections contents contents

represent the represent the basic raw data, basic raw data, which is then which is then

mathematically mathematically reconstructed to reconstructed to

yield the yield the transverse transverse

section imagessection images

Dual head scannerDual head scanner Single head SPECTSingle head SPECT