Background:
Radioactive: An element is radioactive if it has an imbalanced charge due too many protons or neutrons. The nucleus will undergo a change to become more balanced. (8)
-Alpha particle: ejection of two protons and two neutrons (8)
-Beta particle: the neutron will convert to a proton by emitting an electron (8)
-Gamma ray: an excited nucleus will release a photon (8)
Definition of Nuclear Medicine: Part of the emerging medical field of molecular imaging. Nuclear medicine is the combination of small amounts of radiation in radiopharmaceuticals and imaging equipment to get a examine process inside of the body. It is used to detect and to treat diseases and medical issues. (2)
What is Nuclear Medicine: The use of high-energy radiation rays like X-rays or gamma rays to shrink tumors and kill cancer cells. It can come in two ways externally, delivered by a machine, or internally, through an injection. (5)
How: The radiation kills the DNA cells the carry genetic information that carries on through generations of cells. The radiation will damage the DNA or produce particles within the cell that will damage the DNA. When a cancer cells DNA is to damaged to reproduce/keep living it will die, the cells will break down and eventually eliminated from the body. Radiation damages normal, healthy cells too. (5)
Why: Usually, doctors hope that when they give patients radiation it will kill the cancerous tumor or the cancer cells. It can be used on its own as a treatment or it can be used with surgery or chemotherapy. However, sometimes it is used just to relieve some of a patient’s symptoms. (5)
Scans:
-Radioactive compounds attaches to tumor cells (3)
-Imagining technology is used to see were the radioactive substances concentrate (3)
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-PET (3)
-Positron Emission Tomography
-Capture chemical changes that happen in tissue
-The patient receives a dose of sugar and radioactive sugar
-Cancer cells take in the sugar more rapidly then other organs
-Locates the sugar
-Takes about 1 hour for the sugar to travel to the tumor
-Scanner goes over body 6-7 times
-Scan is used to show where the sugar traveled to
-Can show if the tumor is cancerous
-However, only good at detecting tumors more then 8mm and that are very aggressive
-Not good at showing smaller and less aggressive tumors
-Can check for 3 things
-If treatment is working (if the tumor is dying by absorbing less sugar)
-Detect cancer that other (more common) scans won’t show
-Show if the cancer is reoccurring
Check out this video too(1)!
-SPECT (3)
-Single Photon Emission Computed Tomography
-Very similar to PET scan
-Use radioactive material and scanners to create images
-IMAGES CAN BE 2 OR 3D
-Injected into the vein
-Scanner creates images on where the sugar has accumulated
-Gives info about blood flow and chemical reactions like metabolism
-The antibodies that are injected are stick to the tumor cells
Check this video out about why SPECT scans are important!(12)
X-Ray (4)
-X-Ray beams pass through the body-Bones either absorb or block the rays depending of the density of the bone and this process creates shadows that is picked up by a sensor on the other side of the beam -Bones (white), muscle/tissue (grey), air (black)
-Commonly used to show bone factures/breaks arthritis, scoliosis, tumors, osteoporosis, fluid in the lungs, and infections
-Are exposed to a small amount of radiation and can cause caner and birth defects
Computed Axial Tomography CT or CAT(6):
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-Combination of X-rays and computer calculations to produced detailed cross-section images of organs and tissue.-X-rays are moved completely around the person and move through the tissue as detectors measure the images.
-The computer then combines the images and produces a new highly detailed one.
-When the different images are stacked a 3-D image of the area is made
-Can distinguish between solids and liquids, allows for the examination of the type and extent of the damage.
-When dye is injected the images become of higher quality
-These scans can show kidney tumor and masses
CT vs. X-ray vs. Nuclear medication (2):
-Nuclear medicine scans: show where the radiation compound has gone in the body and how it interacts. Find disease by biological changes in the tissue
-CTs and X-rays: uses machines to send radiation throughout the body. Find changes through changes in the anatomy
-CTs, X-rays and nuclear imaging scans are some of the safest test
-Each use around the same amount of radiation
Treatment (5) :
Radiation can come from three sources external beam radiation (from a machine), brachytherapy (where radioactive material is put inside of the body near the sick area) or systematic radiation is when the radioactive material is injected into the body either through a vein or is ingested and goes through the blood stream and into the infected tissue.
-External Beam radiation: X-rays and gamma rays most commonly used, gamma rays have the most energy while x-rays have the least. Most of the time the rays are created in a linear accelerator machine (LINAC). Using electricity fast-moving subatomic particles are formed, which creates radiation.Intensity-Modulated Radiation Therapy- A collimator, which shapes the radiation beams, can move or be stationary and give off different intensity’s of rays. The controlling of intensity makes so different areas of the tumor/tissue receive different amounts of radiation. It is unique because it is planned in reverse, the doctor choices the amount of radiation and a computer calculates the number of beams and the angles needed. This form of treatment is good because it exposes the needed parts with as big of a dose as possible and decreases the amount healthy areas are exposed to.Image-Guided Radiation Therapy (IGRT): During this course of treatment repeated imaging scans, like CTs, MRIs or PETs, of the area are taken allowing seeing if the tumor has shrunken during the treatment. This type of treatment allows for the dose of radiation to be adjusted during the procedure, which can limit the amount of radiation a patient is exposed to.
Proton Therapy: They deposit energy into living tissue in the cancerous area; they deposit less energy in healthy areas during their journey there. This type of therapy is still in trials, but in theory it should not expose as much of the healthy tissue to radiation.
-Internal Radiation Therapy is when radioactive materials are put into the body. Radioactive isotopes are placed into tiny sealed “seeds” and then injected into the patient. While they decay they give off radiation, damaging the cancer cells. Over time the isotope will decay for a few months while all of the radiation is given off and the “seed” will be left in the body since it is not harmful.
-It is able to deliver high doses to affected areas and not harm the healthy tissue.
-High dose: Tubes connected to a machine carry the radiation to the tumor and then after the treatment is over are removed from the body
-Low dose: The radioactive material is carried to the tumor through tubes, which are then taken out after treatment
-Temporary v. Permanent: Temporary can be both low and high dose and tubes with the radiation are placed in the body during treatment. Permanent is only low dose and the source of the radiation is surgically put into the patient.
-There are several methods of doing this like Interstitial, where the radiation source is put inside of the tumor, Intracavitary, where the radiation is put inside a (surgical or body) cavity and placed near the tumor or Episcleral which attaches the source of the radiation to the tumor.
-Can be used with external radiation to give the tumor additional radiation.
Systematic Radiation Therapy: Swallowing or injection of the radioactive material, usually radioactive iodine or a monoclonal antibody bounded to a radioactive substance.
-The antibody helps move the compound to the tumor and then kill it.
-An antibody is a protein that identifies and “neutralizes” foreign objects in the immune system (7).
-There are many different types of drugs used to treat tumors
Side Affects(5):
-Can cause both short and long term affects
-Some long-term affects can occur years after the treatment
-Depends on dose, area of the body, frequency, other treatments and conditions
-Acute (short-term) is caused by the rapid division of cells
-These affects end when treatment does and there are preventive drugs like Ethyol
-Hair loss
-Skin irritation
-Damage to the salivary glands
-Urinary problems
-Fatigue
-Nausea
-Chronic (long-term)
-Fibrosis: formation of scar tissue
-Damage to the bowels: diarrhea and bleeding
-Infertility
-Memory loss
-Seldom a second cancer can arise from treatment
Uses(13):
On radiochemistry.org I found a very extensive list of many isotopes and their functions in medicine, here are a couple I found interesting! ( the numbers in parenthesis are the element's half lives).
Technetium-99m (6 h): Used in to image the skeleton and heart muscle in particular, but also for brain, thyroid, lungs (perfusion and ventilation), liver, spleen, kidney (structure and filtration rate), gall bladder, bone marrow, salivary and lacrimal glands, heart blood pool, infection and numerous specialised medical studies.
Cobalt-60 (10.5 mth): Formerly used for external beam radiotherapy.
Holmium-166 (26 h): Being developed for diagnosis and treatment of liver tumors.
Iodine-125 (60 d): Used in cancer brachytherapy (prostate and brain), also diagnostically to evaluate the filtration rate of kidneys and to diagnose deep vein thrombosis in the leg. It is also widely used in radioimmuno- assays to show the presence of hormones in tiny quantities. Iodine-131 (8 d): Widely used in treating thyroid cancer and in imaging the thyroid; also in diagnosis of abnormal liver function, renal (kidney) blood flow and urinary tract obstruction. A strong gamma emitter, but used for beta therapy.
Iridium-192 (74 d): Supplied in wire form for use as an internal radiotherapy source for cancer treatment (used then removed).
Lutetium-177 (6.7 d): Lu-177 is increasingly important as it emits just enough gamma for imaging while the beta radiation does the therapy on small (eg endocrine) tumours. Its half-life is long enough to allow sophisticated preparation for use.
Palladium-103 (17 d): Used to make brachytherapy permanent implant seeds for early stage prostate cancer.
Rhenium-186 (3.8 d): Used for pain relief in bone cancer. Beta emitter with weak gamma for imaging.
Carbon-11, Nitrogen-13, Oxygen-15, Fluorine-18: These are positron emitters used in PET for studying brain physiology and pathology, in particular for localising epileptic focus, and in dementia, psychiatry and neuropharmacology studies. They also have a significant role in cardiology. F-18 in FDG has become very important in detection of cancers and the monitoring of progress in their treatment, using PET.
Gallium-67 (78 h): Used for tumour imaging and localisation of inflammatory lesions (infections)
Iodine-123 (13 h): Increasingly used for diagnosis of thyroid function, it is a gamma emitter without the beta radiation of I-131.
Rubidium-82 (65 h): Convenient PET agent in myocardial perfusion imaging.
1)http://www.youtube.com/watch?v=cd1UHRb54hw&feature=relmfu
8)http://answers.com/Q/What_makes_an_element_radioactive
9)http://chemo.net/023PACXR.jpg
10)http://www.riversideonline.com/source/images/image_popup/fl7_brainct.jpg
12)http://www.youtube.com/watch?v=RV1Ql3rDJlE&feature=related
13http://www.radiochemistry.org/nuclearmedicine/radioisotopes/01_isotopes.shtml
