Radiotherapy
Since the development of X-ray technology, medical professionals have embraced the concept of radiation as a diagnostic and therapeutic tool. This nuclear science, called radiotherapy, utilizes radioactive particles and elements for diagnosis and treatment of a variety of illnesses. Because X-ray radiation can only image dense materials such as bone, it has limited in application and overexposure can be harmful. Diagnosing certain disorders in soft tissue is now possible through the use of radionuclides, or radioactive tracers which are introduced into the body by way of an injection called a radiopharmaceutical. According to the type of radionuclide, the tracer will collect in one or more areas of the body. As the isotope emits radiation it is easily detected by a Geiger counter or scanning device so physicians are able to follow its path, checking the organs under surveillance. The radionuclide is flushed out of the body like any ordinary waste product. Radioactive trace elements are becoming a preferred method of diagnosis for two reasons. First, they can be used to target individual organs, such as the kidneys or the thyroid. Second, they emit radiation from the body while X-ray radiation is absorbed by the body; thus, the amount of radiation to which the patient is exposed is much lower. Trace elements are also often used to replace riskier and more traumatic procedures such as contrast arteriography.
Advances in radiotherapy are increasing its application in disease detection, diagnosis, and treatment, particularly of certain types of cancers. 3-dimensional conformal radiotherapy uses CAT (CT) or magnetic resonance imaging (MRI) scans to detect disease and permit precise treatment targeting of tumors. Treatments may consist of either a well-defined beam of radiation from a high-voltage "linear accelerator," neuron or proton beam therapy, or implants of radioactive "seeds" of iodine or palladium. For example, treatment of early prostate cancer may involve the insertion of Iodine-125, a low-energy, gamma-emitting isotope, directly into the prostate gland. Implanted under ultrasound guidance, this one-day, cost-effective, and convenient form of treatment--called prostate brachytherapy--appears to control local disease as effectively as external beam therapy. Brachytherapy is also used for gynecological, head and neck, and soft tissue cancers.
Stereotactic radiosurgery, an extremely complicated therapy, delivers multiple converging beams of high-dose radiation directly to the target lesion minimally affecting surrounding tissue. Used primarily to treat brain tumors, it is also used for vascular malformations, certain recurring head and neck tumors, and lesions at the base of the skull. Total skin electron irradiation (TSEI), a complex treatment for certain types of cutaneous lymphomas, uses an electron (as opposed to photon) beam to treat the entire skin surface. Because penetration of the electron beam is superficial, underlying tissue remains relatively unaffected. Intraoperative radiotherapy involves the insertion of an electron cone into the bed of a surgically removed tumor which has a high risk of recurrence. Radiation is therefore delivered to the tumor bed only. In a July 1997 article in The Lancet, British researcher Dr. Michele Saunders and colleagues released a study of a radiotherapy regimen called continuous hyperfractionated accelerated radiotherapy (CHART), found to increase the survival rate of patients with non-small-cell-lung cancer. Still in its experimental stages, this unique radiotherapy schedule delivers more than one treatment each day, delivering the same total dosage in approximately 12 days as compared to the normal treatment time of four to six weeks. This accelerated dose schedule reduces the problem of radiation resistance encountered in traditional therapy.
The person most responsible for the acceptance of nuclear medical procedures is American radiologist Edith Quimby. Quimby was the first to precisely measure the amount of radiation necessary for tracing within the body, and later determined exact dosages required for therapy. In addition to diagnostic and therapeutic applications, nuclear radiation is used to sterilize medical equipment, making the old method of sterilization through steam practically obsolete. Because it can be administered at low temperatures, radiation can be used to sterilize plastic instruments that would be destroyed by steam and reaches small crevices that steam would often miss.
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