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Nuclear Chemistry in Conjuction with Cancer Patients

Radiation
by

Cyrus Ghaznavi

on 26 April 2011

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Transcript of Nuclear Chemistry in Conjuction with Cancer Patients

Cancer Patients & Radiation Therapy To really understand the rest of the Prezi, we need to have established an adequate definition for the phrase "radiation therapy." We may throw it around, but do we actually know what it means? According to the National Cancer Institute (NCI), radiation therapy is a method in which a cancer patient undergoes high level radiation so as to kill cancer cells via attacking their DNA [1]. In this case, high level radiation refers to both x-rays and gamma rays. Both x-rays and gamma rays are comprised of photons, or particles of light. When the DNA of a cancer cell is damaged, the genetic information used for cell multiplication is destroyed. This thus makes the cell unable to divide, or simply die (dead cells are removed via natural body processes). What does the radiation do? It is also possible that the radiation work indirectly by creating charged particles, also known as free radicals, within cancer cells, which would destroy the genetic information. Radiation therapy can come via an external source or via radioactive material placed inside the body. External-Beam Radiation [1] A linear accelerator delivers the radiation by utilizing electricity to create a stream of photons. The next eight slides will refer to other types of external-beam radiation. Intensity Modulated Radiation Therapy Collimators, or beam-shaping devices, are utilized in the hundreds to dose tumors. They can move during treatment, allowing certain areas associated with the tumor to get different doses of radiation. Image-Guided Radiation Therapy This is the process in which several images (whether they be from CTs, MRIs, or PETs) are taken to monitor the tumor's size and location, therefore adjusting the therapy in accordance with the observations. Tomotherapy To treat a patient with tomotherapy is to use a machine which is comparable to a mixture of a CT scanner and an external-beam radiator. While radiating the patient, images are taken for precise dosage to accurate locations. Stereotactic Radiosurgery This type of radiotherapy also takes advantage of images to deliver doses of radiation to small tumors without fuzzy edges (especially brain and spinal tumors). Stereotactic Body Radiation Therapy SBRT deals with small, local tumors (isolated). As opposed to Stereotactic Radiosurgery, it doesn't deal with cerebral or spinal tumors, but rather those throughout the rest of the body, especially the lungs and the liver. Proton Therapy The use of protons, or positively charged particles (+1), rather than photons to deliver radiation is called proton therapy. They deposit most of their energy at the end of their paths, also known as the Bragg Peak. Electron Beam Electron beams are comprised of negatively charged particles and are primarily used for superficial tumors because they cannot penetrate very far through tissue. Skin cancer pairs well with this type of treatment. 3-dimensional Conformal Radiation Therapy The linear accelerator is used in conjunction with precise computer software so as to have very accurate doses of radiation. Internal Radiation Therapy This type of radiation therapy involves placing a radioactive source internally, so as it decays, it kills cancer cells. This is certainly a more direct means of treatment. Also known as brachytherapy, pellets of radioactive isotopes are surgically implanted near the cancer, and deliver either a high or low dosage of radiation, depending on the situation. Systemic Radiation Therapy [1] Much like internal radiation therapy, the systemic version involves placing a radioactive isotope internally. However, the radioactive substance, in this case, is bound to a monoclonal antibody. The main radioactive isotopes used are iodine-131, samarium-153, and strontium-89. What is a monoclonal antibody? [3] This is a laboratory-made molecule, designed with the purpose of killing/shrinking cancer cells. It does this in three ways:
They bind to cancer cells, making them more visible to the immune system, which now attaks the unwanted cells.
The antibodies stop the growth signals sent by the cancer cells by blocking the receptors.
Tumors attract blood vessels in order to attain an oxygen and nutrient supply. Monoclonal antibodies block the signals sent by the cells that attract the blood supply. Iodine-131 [4] This isotope is used commonly with thyroid cancer because thyroid cells naturally absorb the iodine. Iodine-131 decays via beta radiation and has a half-life of about 8 days. Samarium-153 [5] This radioactive isotope is used in conjunction with lexidronam; it comes in the form of an injection. The formula is . The samarium has a half-life of 46.3 hours and decays via beta radiation. Strontium-89 [6] This drug is called QUADRAMET. In this case, the radioactive isotope of strontium is bonded to a chloride ion, in a drug called Metastron, which is intravenously dosed. It decays via beta radiation. It has a half-life of 50.5 days. Both Quadramet and Mestastron are palliative drugs, meaning they aren't cures, they just lessen the pain. They are used on patients whose cancers have matastasised to the bone. [7] Iodine-131 is bonded to tositumomab in a drug called Bexxar, administered in an injection. Tositumomab is a monoclonal antibody composed of various amino acids. It is a matter of weighing risks and benefits [1] You may be thinking, what's the catch? Unfortunately, radiation therapy doesn't only kill cancer cells, it also kills normal tissue. There is a long list of side effects, some of which are:
fatigue
pain
nausea
mouth sores
hair loss
decreased blood cell count
vomiting Texts Cited Radiation Therapy for Cancer." National Cancer Institute . National Cancer
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Mar. 2011. Mayo Clinic. "Monoclonal antibody drugs for cancer treatment: How they work."
Mayo Clinic. Mayo Foundation for Medical Education and Research, 5 Nov.
2010. Web. 3 Apr. 2011. "Iodine." US EPA. US EPA, 24 Mar. 2011. Web. 3 Apr. 2011. <http://www.epa.gov/
rpdweb00/radionuclides/iodine.html>. "QUADRAMET®." RxList. RxList Inc., 2011. Web. 4 Apr. 2011.
. "Metastron." Drugs.com. Drugs.com, 2011. Web. 4 Apr. 2011.
. "BEXXAR® ." RxList. RxList, 2011. Web. 4 Apr. 2011. 1 2 3 4 5 6 7 Images Cited "Bristol-Myers Squibb to Buy Monoclonal Antibody Maker Medarex." BioJob Blog.
LexBlog, 23 July 2009. Web. 3 Apr. 2011. Dave. "What you need to know about laptop radiation." Geek With Laptop.
Prelovac, 14 Sept. 2008. Web. 27 Mar. 2011.
. Pidwirny, Michael, and Scott Jones. "The Nature of Radiation." Physical
Geography. University of British Columbia Okanagan, 29 July 2009. Web.
27 Mar. 2011. "Quadramet." Drugs.com. Drugs.com, 2011. Web. 4 Apr. 2011.
. "Rituximab Failures Show Promising Results with Bexxar." Cancer Watch. N.p.,
Jan. 2001. Web. 4 Apr. 2011. Monoclonal Antibody Pic Radiation Symbol Pic Radiation Spectrum Pic Quadramet Structure Pic Bexxar Pic
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