Gamma photons are the most energetic photons in the electromagnetic spectrum. Gamma rays (gamma photons) are emitted from the nucleus of some unstable (radioactive) atoms.
3 Gamma Radiation
What are the properties of gamma radiation
Gamma radiation is very high-energy ionizing radiation.
Gamma photons have no mass and no electrical charge--they are pure electromagnetic energy.
4 Gamma Radiation
Because of their high energy gamma photons travel at the speed of light and can cover hundreds to thousands of meters in air before spending their energy. They can pass through many kinds of materials including human tissue
5 Gamma Radiation
What is the difference between gamma rays and x-rays
Gamma rays and x-rays like visible infrared and ultraviolet light are part of the electromagnetic spectrum. While gamma rays and x-rays differ in their origin. Gamma rays originate in the nucleus. X-rays originate in the electron fields surrounding the nucleus.
6 Gamma Radiation
How do we use gamma emitters
The penetrating power of gamma photons has many applications. Gamma rays penetrate many materials they do not make them radioactive. The three radionuclides by far most useful are cobalt-60 and cesium-137 and technetium-99m.
7 Gamma Radiation
Uses of Cesium-137
Uses of Cobalt-60
sterilize medical equipment in hospitals
8 Gamma Radiation
Uses of Technetium-99m
TC-99m is the most widely used radioactive isotope for diagnostic studies. (Technetium-99m is a shorter half-life version of technetium-99.) Different chemical forms are used for brain bone liver spleen and kidney imaging and also for blood flow studies.
9 Radioactive Measurements
1. Competitive Binding Assays
2. Time Dependent Measurements
3. Radio Nucleotide Imaging
Gamma Camera scintillation camera
10 1. Competitive Binding Assays
No radioactive substance is given to the patient
Blood from a patient is mixed with a radioactive substance in the laboratory
Thyroid Hormone and Iron Binding Sites most common.
11 1. Competitive Binding Assays 12 2. Time Dependent Measurements
Radioactive Tracers are to the patient administered.
Allows the volume of a compartment to be measured.
13 Intravenous Pyelogram
An Intravenous Pyelogram (IVP) is an x-ray examination of the kidneys ureters and urinary bladder.
14 Intravenous Pyelogram 15
This is a test done to diagnose obstruction of the bile ducts (for example by a gallstone or a tumor) disease of the gallbladder and bile leaks.
16 Cardiac Angiography
Coronary angiography is performed to detect obstruction in the coronary arteries of the heart. During the procedure a catheter is inserted into an artery in your groin and then threaded carefully into the heart. The blood vessels of the heart are then studied by injection of contrast media through the catheter. A rapid succession of X-rays is taken to view blood flow.
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The arrow indicates a blockage in the right coronary artery.
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This image taken before angioplasty This patient had episodes of weakness leading to the angiogram. The angiogram shows a very narrowed artery supplying the right side of brain. This vessel is within the skull on the surface of the brain
Cerebral angiogram taken after angioplasty The narrowing is less severe and the branches beyond the narrowing fill better
23 3. Radionucleotide Imaging
Image is generated using radioactive decay from an organ
Usually a function of time.
Provide functional information
24 3. Radionucleotide Imaging
Single detectors are used for thyroid studies.
25 3. Radionucleotide Imaging
Shows two dimensional data
Studies physiologic function
Ventilation-Perfusion Scan of a lung looking for a blood clot.
A bone scan is used to find bone problems such as cancer infections or fractures to check joint replacements and to find joint problems such as arthritis.
A small amount of injected radioactive matter (tracer) and a camera to form an image.
Bone scan looking for
metastatic bone cancer.
Looking for fibrous dysplasia that is a congenital non-hereditary skeletal disorder
Patients are often asymptomatic. Others experience pain pathologic fractures and bone deformity
Imaging of Acute Osteomyelitis in the Diabetic Foot
A 65 year old male with a history of non-insulin dependent diabetes mellitus alcohol abuse and severe peripheral vascular disease presented with a non-healing ulcer of the left first toe.
This Indium White Blood Cell Scan demonstrates areas of infection in the abdomen after surgery for colon cancer.
31 4. Tomography
The fourth class of imaging is the tomographic reconstruction of body slices.
The use of a brain SPECT scan is based on the principal of blood flow.
Areas of increased blood flow take up more Radioactive tracer than areas of less blood flow.
Blood flow in the brain is directly related to brain activity.
COMMON DISEASES EVALATED BY SPECT
Attention Deficit Hyperactive Disorder
Autism Aspergers syndrome
Unipolar and Bipolar Depression
Anxiety states - Panic
Epilepsy and Non-epileptic seizure equivalents
Post Traumatic Stress Disorder
Migraine and common headaches
Dementia and memory loss- Stroke- Multiple Sclerosis- Parkinsons Disease
35 SPECT Image 36
Blood flow to the brain is represented on a color scale dark areas have no flow and bright yellow areas have good blood flow.
The dark butterfly-shaped area in the center of the brain is normal but the dark area on the right of each picture is the region of impaired blood supply (ischemia) that corresponds to the patients acute stroke.
Prior to t-PA the SPECT scan showed a large area of the brain that has lost its blood supply (arrow).
Several hours after treatment with t-PA the blood flow has dramatically improved although there is still a small area ischemia (arrow).
38 PET Scanner 39
Image of heart which has had a mycardial infarction. The arrow points to dead myocardial tissue. Therefore the patient will not benefit from heart surgery but may have other forms of treatment prescribed.
Normal PET scan of a heart.
PET image showing malignant breast mass that was not revealed by conventional imaging techniques such as CT MRI and mammogram
PET image of same patient with enlarged left axillary lymph nodes (indicated by arrows) which through biopsy were found to be metastatic. The whole body scan reveals a mass in the left breast (indicated by arrow) that was malignant and subsequently removed
Image of the brain of a 9 year old female with a history of seizures poorly controlled by medication. PET imaging identifies the area (indicated by the arrows) of the brain responsible for the seizures. Through surgical removal of this area of the brain the patient is rendered seizure-free.
PET measurements of cerebral blood flow (CBF) and oxygen extraction by the brain (OEF) before (top row)and after (bottom row) angioplasty of a focal severe stenosis of an artery at the base of the brain (supraclinoid internal carotid artery).
65 year old male with brain tumors imaged
here with a PET scan.
44 (No Transcript) 45 Treatment of Cancer
Radioactivity is very effective in the treatment of certain cancers.
The choice is basically do you administer the radiotherapy externally or internally.
46 External Beam Therapy
External beam therapy (EBT) is a method for delivering a beam of high-energy x-rays to the location of the patients tumor.
The beam is generated outside the patient and is targeted at the tumor site.
These x-rays can destroy the cancer cells and careful treatment planning allows the surrounding normal tissues to be spared.
These cancers are commonly treated.
Colorectal Cancer (Bowel Cancer)
Head and Neck Cancer
48 (No Transcript) 49 High Energy X-Rays 50 Linear Particle Accelerator 51 (No Transcript) 52
Zapping Cancer Proton Beam Therapy Proves Effective in Targeting Tumors Aug. 17 2004 A new kind of radiation is proving effective in the fight against cancer. Proton beam therapy according to doctors zeroes in on tumors with impressive results and without the devastating side effects of traditional radiation therapy.
We can shape the beam more accurately hitting targets with more precision said Dr. Jerry Slater clinical director of Loma Lindas Proton Therapy Center in Southern California.
You dont feel any pain said Ron Leuck who is being treated for prostate cancer with the new therapy.
During the treatment a rotating scaffold three stories high aims computerized ray guns directly at his tumor.
53 Proton Beam Radiotherapy
This form of external beam irradiation involves directing radiation through the front of the eye in order to reach the intraocular tumor.
When compared to low-energy eye-plaque radiation therapy It is easier to treat tumors that are surrounding the optic nerve with protons.
Brachytherapy is where radioactive seeds or sources are placed in or near the tumor itself giving a high radiation dose to the tumor while reducing the radiation exposure in the surrounding healthy tissues.
The term brachy is Greek for short distance.
Brachytherapy is not new. Throughout this century several types and routes of implantation of radioactive seeds have been used to treat cancer.
Radioactive Iodine seeds were widely used during the 1970s and 1980s.
Brachytherapy sources can be divided into permanent and temporary groups.
Permanent sources tend to have lower energy and shorter half-lives.
The advantage of these lower energies is enhanced safety.
The disadvantage is that anatomical adjustments cannot be made once the sources are placed.
Currently temporary implants consist primarily of 192Ir and 137Cs.
Currently the 2 most common permanent radioactive sources for brachytherapy seeds are 125I and 103Pd.
The lower the energy emitted by the photons the higher the energy transfer.
The higher the energy transfer the higher the radiobiologic effect which can lead to lower total doses.
59 Prostate Cancer
The prostate gland is just beneath the male bladder.
Cancer is common.
The prostate gland can be felt with a digital rectal exam Cancer is sometimes detected this way.
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67 year old male with metastatic prostate cancer.
Iridium 192 is used for highdose rate treatment of prostate cancer. During the implantation hollow needles are inserted transperineally. The needles are then connected to an automated remote-controlled loading machine. The total irradiation time is usually only 5-10 minutes.
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Temporary seed placement is shown here.
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