Created by Students

AbdulAziz AlMahmoud

AbdulRahman AlZaydi

Abdullah AlWeleyi

Contents:

First Speaker (AbdulAziz AlMahmoud)

A. Introduction

B. Radiopharmaceuticals

Second Speaker (AbdulRahman AlZaydi)

C. Gamma Camera

Third Speaker (Abdullah AlWeleyi)

D. Single Photon Emission Computed

Tomography (SPECT)

E. Conclusion

What is radiation?

Radiation is a type of energy,

which exists in our environment in

many forms and comes from both

natural and man-made sources.

Light that allows us to see and the

warmth we get from the sun or

from nature are natural forms of

radiation.

e.g. of man-made radiation

include the microwave radiation

that is used for cooking and radio

waves for communication over

long distances ionizing radiation

comes from both natural and

man-made sources.

What is nuclear medicine ?

This is a branch of medicine that

uses radiation from radioactive

tracers to provide information

about the function of specific

organs.

In some cases, radioactivity can

be used to treat certain conditions

such as an overactive thyroid.

Follow.. Nuclear medicine studies use ionizing radiation,

as do x-ray studies.

radioactive tracers or radiopharmaceuticals commonly used are quickly eliminated from the

body through its natural functions.

In addition, the tracers used rapidly lose their

radioactivity.

In most cases, the dose of radiation necessary for

a scan is very small.

For example, a patient having a lung scan is

exposed to the same dose of radiation they

would receive from eight return air flights

between Sydney and London.

What is pharmaceutical?

The radioactive materials administered to

patients are known as radiopharmaceuticals.

These consist of :

Chemical molecule which determines the

behavior of the radiopharmaceutical in the

body a radionuclide.

The radiation emitted by the radionuclide may

be detected from outside the body by a

radionuclide imaging device (a gamma

camera) or may be detected

In a sample of a body fluid (e.g. plasma or urine)

Radiopharmaceuticals

Diagnostic radiopharmaceuticals must

deliver the minimum possible radiation

dose to the patient while still obtaining

the required diagnostic information.

Therapy radiopharmaceuticals must

deliver the maximum radiation dose to

the diseased organ or tumor, while

minimizing the radiation dose to non

target tissues such as the bone marrow.

Ensure minimal irradiation of other parts.

What is a half-life?

Nuclear medicines used for diagnosis

or treatment generally have short half-

lives.

A half-life is the time it takes for the

level of radioactivity to drop to half the

starting level.

Nuclear medicines typically have a

half-life of several hours or days.

This means they rapidly lose their

radioactivity level within the

predetermined half-life.

GAMMA CAMERA

1-Principle:

The Gamma or Scintillation Camera is an imaging device

that is most commonly used in nuclear medicine. It is also

called the Anger Camera.

Gamma Cameras detect radiation from the entire field of view simultaneously and therefore are capable of

recording dynamic as well as static images of the area

of interest in the patient.

The gamma cameras usually consists of several

components: a detector, a collimator, PM tube, a

preamplifier, an amplifier, a pulsed-height analyzer

(PHA), an X-, Y-positioning circuit, and display or recording device.

GAMMA CAMERA

2-Operation:The gamma rays emitted by the

radiopharmaceutical (in the patient)

are first collimated (by a specific

collimator) and then detected by a

detector (usually scintillator)

Single Photon Emission

Computed Tomography

(SPECT)

Tomograms: a series of views

(profiles) are acquired at different

angles around

Filters: Fourier transform "Sampling

and correction

(SPECT)

SPECT is also widely used and the

process of injecting a radioactive tracer

is the same as the PLANAR technique.

Instead of being stationary, the gamma

camera moves around the body

providing a series of images. This takes

about 20-30 minutes.

SPECT and PLANAR imaging are highly

convenient technologies as they use

radiopharmaceuticals, which can be

easily distributed, stored and mixed

ready for use at nuclear medicine clinics

and hospitals.

Collimator

A collimator is a device that narrows a beam of

particles or waves. To "narrow" can mean either

to cause the directions of motion to become

more aligned in a specific direction (i.s.,

collimated or parallel) or to cause the spatial

cross section of the beam to become smaller.

Gamma rays are emitted isotropically (in all

directions)

Using only a detector would not result in an

image because there will be no relationship

between the position at which the gamma rays

hit the detector and the origin of the gamma

rays (in the patient)

Detector

Detector, by which increase the

thickness of a detector increase

probability of Complete

absorption of gamma ray.

Detector are used in gamma

camera, but this decrease the

sensitivity Of the camera, because

many gamma rays () may escape

from the detector without

interaction.

Detector ٠Spatial resolution: the smallest separation

required between two small objects to be detected and distinguished as two separated objects

٠Energy resolution: bill width half maximum(FWHM)

٠Non-Uniformity: the slightly different response of different areas of the detector of the camera to a uniform radioactive source

٠Spatial distortion: random or systematic error of determining event location

٠Counting-rate: counts / unit of time. It is assessed as the Observed count-rate (gamma camera) vs. True count-rate (source activity)

٠Sensitivity: count-rate / unit of radioactivity

References:

Books:

1_Nuclrear Medicine and PET/CT, sixth edition.

2_The Essential Physics of Medical Imaging, third edition.

3-Physics Radiobiology of Nuclear Medicine, third edition.

Others:

1_Nuclear Medicine.ppt

2_Introduction to Nuclear Medicine.ppt

3_Imaging with Radionuclides.ppt

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