SPECT Imaging Techniques

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Questions and Answers

What is the main limitation of conventional planar gamma imaging?

Loss of depth information and reduced contrast (correct)
High cost of equipment
Low sensitivity
Long exposure times

What is the purpose of using a parallel hole collimator in SPECT?

To improve the resolution of the image (correct)
To reduce the number of counts acquired
To rotate the camera slowly in a circular orbit
To increase the scanning time

How many views are taken in a SPECT scan?

60 views (correct)
90 views
30 views
120 views

What is the total scanning time required for a SPECT scan?

30 minutes (D) Signup and view all the answers

How many counts are acquired in a SPECT scan?

3 million counts (D) Signup and view all the answers

What are the two methods of emission tomography?

SPECT and PET (C) Signup and view all the answers

What is the benefit of using a dual- or triple-headed camera in SPECT?

Halved image acquisition time or improved sensitivity (B) Signup and view all the answers

What is the purpose of using an elliptical orbit in SPECT?

To reduce the gap between the collimator and the patient (B) Signup and view all the answers

What is a useful rotation option in cardiac tomography in SPECT?

180° (D) Signup and view all the answers

What is a major use of SPECT?

Thallium studies of myocardial infarctions and ischaemia (D) Signup and view all the answers

How can SPECT studies be presented?

Either as a series of slices or as a three-dimensional display (C) Signup and view all the answers

What is the effect of persistence of vision in SPECT image display?

Reduces image noise (B) Signup and view all the answers

What is the purpose of testing for radionuclide purity in radiopharmaceuticals?

To prevent unnecessary dose to the patient (D) Signup and view all the answers

How is the patient administered a radiopharmaceutical in planar imaging?

Intravenously, through an injection (C) Signup and view all the answers

What is the ideal function of a radiopharmaceutical in planar imaging?

To concentrate in the organ or tissues of interest (C) Signup and view all the answers

What is the purpose of testing for radiochemical purity in radiopharmaceuticals?

To detect free pertechnetate in a labelled compound (D) Signup and view all the answers

What is the purpose of testing for chemical purity in radiopharmaceuticals?

To detect the presence of alumina (B) Signup and view all the answers

What is the purpose of the dose calibrator in radiopharmaceuticals?

To measure the activity of the radiopharmaceutical (B) Signup and view all the answers

What percentage of nuclides in the world are stable?

Nearly 100% (D) Signup and view all the answers

What is the main reason for innovation in nuclear medicine diagnostic imaging over the last century?

Development of new equipment and techniques (A) Signup and view all the answers

What is the significance of Röntgen’s discovery of X-rays?

It started the innovation in diagnostic imaging (D) Signup and view all the answers

What is the requirement for practicing nuclear medicine safely?

Clear understanding of the behavior and principles of radiation sources and radiation detection (C) Signup and view all the answers

What is unique about the nucleus of ordinary hydrogen?

It has a single proton (D) Signup and view all the answers

What is the general trend in the composition of stable lighter nuclei?

They have nearly equal numbers of protons and neutrons (A) Signup and view all the answers

What is the result of forcing an additional neutron into a stable nucleus?

A neutron excess (A) Signup and view all the answers

What is the result of a positive beta particle coming to the end of its range?

It combines with a negative electron (A) Signup and view all the answers

What is the purpose of a cyclotron in producing radionuclides?

To accelerate positively charged ions (A) Signup and view all the answers

What is the energy of each photon emitted during the annihilation of a positive and negative electron?

511 keV (D) Signup and view all the answers

What is the characteristic of the half-lives of radionuclides produced in a cyclotron?

Short-lived, ranging from less than a minute to a couple of hours (D) Signup and view all the answers

What type of radiation is emitted when an electron from an outer shell fills a created vacancy in the K-shell?

X-ray radiation (D) Signup and view all the answers

Why are medical minicyclotrons designed to be located near hospital sites?

To enable the use of short-lived radionuclides in medical imaging (B) Signup and view all the answers

What is the result of forcing an additional proton into a stable nucleus?

An increase in atomic number (A) Signup and view all the answers

What is the characteristic of gamma rays emitted during radioactive decay?

A line spectrum of specific energies (B) Signup and view all the answers

What is the process by which a nuclide with a neutron deficit decays?

K-electron capture (C) Signup and view all the answers

What is the total number of known radionuclides?

More than 2700 (C) Signup and view all the answers

What is the result of the combination of a positive and negative electron?

The neutralization of opposite charges (D) Signup and view all the answers

What is the decay process in which a radionuclide with a neutron excess loses energy and becomes stable?

Beta minus decay (C) Signup and view all the answers

What is the name of the radionuclide that is produced from the decay of Molybdenum-99?

Technetium-99m (C) Signup and view all the answers

What is the energy of the gamma ray emitted during the decay of Technetium-99m to Technetium-99?

140 keV (B) Signup and view all the answers

What is the change in the atomic number of Iodine-131 during its decay to Xenon-131?

Increases by one (C) Signup and view all the answers

What is the process by which a radionuclide in an excited state returns to its ground state with the emission of a gamma ray?

Isomeric transition (B) Signup and view all the answers

What is the name of the radionuclide that is produced from the decay of Germanium-68?

Gallium-68 (B) Signup and view all the answers

What is the result of adding a neutron to the nucleus of Molybdenum-98?

The atomic number of the nucleus remains unchanged, but its mass increases by one (D) Signup and view all the answers

What happens when an additional proton is forced into a stable nucleus in a cyclotron?

A neutron is knocked out of the nucleus, resulting in a neutron deficit (B) Signup and view all the answers

What is a characteristic of radionuclides produced in a cyclotron?

They have short half-lives, ranging from less than a minute to a couple of hours (D) Signup and view all the answers

What is a medical application of radionuclides produced in a cyclotron?

They are used in medical imaging, such as in the production of fluorine-18 (A) Signup and view all the answers

What is a method of producing radionuclides?

Extracting radioactive fission products from spent fuel rods of nuclear reactors (B) Signup and view all the answers

What is a characteristic of radionuclides obtained from generator systems?

They are daughter products obtained from a longer-lived radioactive parent (D) Signup and view all the answers

Study Notes

Image Acquisition and SPECT

Image acquisition time can be halved or sensitivity improved by using a dual- or triple-headed camera.
The camera must move on a sufficiently large circular orbit to avoid the patient's shoulders.
An elliptical orbit can be used to minimize the gap between the collimator and the patient, improving resolution.
A 180° rotation is a useful option, especially in cardiac tomography.

SPECT Studies and Display

SPECT studies can be presented as a series of slices or as a 3D display.
The 3D display is particularly effective when rotated continuously on the computer screen, reducing the effect of image noise.

Applications of SPECT

Thallium studies of myocardial infarctions and ischaemia are major uses of SPECT.
SPECT can be used in dynamic imaging where short exposure times are necessary, accepting poorer resolution.

Collimators

Medium-energy collimators have thicker septa (1.4 mm) and fewer holes, resulting in lower sensitivity.
They are used up to 400 keV, e.g., with 111In, 67Ga, and 131I.

Tomography with Radionuclides

Conventional planar gamma imaging produces a 2D projection of a 3D distribution of a radiopharmaceutical.
The images of organs are superimposed, losing depth information and reducing contrast.
Emission tomography addresses these deficiencies.

Types of Emission Tomography

There are two methods of emission tomography: Single-Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET).

SPECT Process

In its simple form, a gamma camera with a parallel hole collimator rotates slowly in a circular orbit around the patient.
Every 6°, the camera halts for 20-30s and acquires a view of the patient.
60 views are taken from different directions, each with fewer counts than in conventional static imaging.

SPECT Scanning

Approximately 3 million counts are acquired in an overall scanning time of around 30 minutes.
This technology reduces the radiation exposure of the staff.

Radiopharmaceuticals and Quality Control

Quality control includes testing for:
- Radionuclide purity
- Radiochemical purity
- Chemical purity
- Response of the radionuclide calibrator

Radiation and Decay

Radionuclides with a neutron excess may lose energy and become stable by a neutron changing into a proton plus an electron.
The electron is ejected from the nucleus with high energy and is referred to as a negative beta particle.
Isomeric transition can occur in some radionuclides, where the gamma ray is not emitted until an appreciable time after the emission of the beta particle.

Introduction to Nuclear Medicine

The technologies used in nuclear medicine for diagnostic imaging have improved over the last century.
Each decade has brought innovation in the form of new equipment, techniques, radiopharmaceuticals, advances in radionuclide production, and better patient care.
All such technologies have been developed and can only be practiced safely with a clear understanding of the behavior and principles of radiation sources and radiation detection.

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Description

Learn about the techniques used in Single-Photon Emission Computed Tomography (SPECT) imaging, including camera orbit and rotation options to improve image acquisition and resolution.