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Advances in Therapeutic Radiology
Like all medical specialties, the field of therapeutic radiology continues to make advances in knowledge and technology. Many newer radiation modalities are being used and studied to find more effective treatments for cancer and other conditions which may be treated with radiation.
Some newer therapeutic radiation therapies are described below:
- Radiation and chemotherapy in combination. It has been discovered that radiation may, in some cases, improve the effects of chemotherapy, and that chemotherapy, in some cases, may improve the effects of radiation. Research continues in this area to establish treatment protocols which may provide the greatest efficacy of chemotherapy and radiation.
- Intraoperative irradiation. Intraoperative irradiation is the use of external beam radiation therapy or other types of radiation therapy during surgery to treat cancerous tumors or certain other forms of cancer. Benefits of intraoperative irradiation include a decreased area of irradiated tissue, as the target area is directly visible, and a more effective dose of radiation may be used. The use of intraoperative irradiation, when used in conjunction with surgery, external beam therapy, and/or chemotherapy, has been shown to improve the outcome of cancer treatment in certain situations.
- Stereotactic irradiation (radiosurgery). The use of stereotactic irradiation has added an important new treatment modality to the area of brain cancer treatment. Stereotactic irradiation is the use of a single high dose of radiation sent into the diseased tissue with very narrow beams of radiation. The two main forms of stereotactic irradiation are linear acceleration and the gamma knife. The precision, as well as the lower amount of invasiveness offered by stereotactical surgical procedures has been shown to lower the length of hospital stays and the associated costs for certain brain cancers and conditions.
- Particle radiation therapy. Particle radiation therapy is the use of higher-energy radiation particles in cancer therapy. This type of radiation therapy offers benefits related to the individual cells under treatment. Types of radiation particles used in radiation therapy include neutrons, protons, ions, and antiprotons.
Proton therapy is the most widely used type of particle therapy. Fast neutron therapy may be used in the treatment of certain inoperable or recurrent tumors. There are only a few centers in the US which offer fast neutron therapy.
Antiproton therapy is the newest type of particle radiation therapy under investigation. It is considered to have promise for use in radiosurgery techniques.
Internal hadron therapy is another type of particle radiation therapy. One example of this type of therapy is boron neutron-capture therapy. In boron neutron-capture therapy, a boron compound is given to the patient by injection. The boron accumulates in the tumor or cancerous tissue. A reaction occurs in the tumor when a beam of neutrons is sent into the tumor, destroying the cancerous cells. The advantage of internal hadron therapy is that it can be used to treat cancer that is more widely-spread throughout the body.
- Three-dimensional (3D) conformal radiation therapy. Before the development of computed tomography (CT), exact targeting of a lesion or tumor for radiation therapy was difficult. CT provided a 2-dimensional means of visualizing the treatment area. However, a 3-dimensional visualization is necessary to define all borders of the lesion or tumor for the most precise treatment planning and implementation.
Protocols and techniques for 3-dimensional conformal radiation therapy have been developed and are being refined to improve the application and outcomes of radiation therapy.
- Intensity-modulated radiation therapy (IMRT). Similar in concept to 3D conformal radiation therapy, intensity-modulated radiation therapy, or IMRT, uses varying intensity within individual radiation beams in order to achieve "organ sparing" treatment (minimizing the amount of radiation to normal tissues surrounding the area being treated).
- Thermoradiotherapy (hyperthermia). The use of elevated temperatures at the site of treatment has been shown experimentally to improve the response of certain cancers to other forms of radiotherapy, as well as to chemotherapy.
Because of the difficulty in delivering adequate doses of heat to tissues located deep inside the body, hyperthermia is most often used to treat melanoma (a type of skin cancer) and breast cancer.
- Focused ultrasound (FUS). Focused ultrasound is a type of thermoradiotherapy. FUS was first used many decades ago. However, until the development and wide-spread use of magnetic resonance imaging (MRI) occurred in the latter part of the twentieth century, FUS was not used widely because of difficulty in targeting the area for treatment.
FUS uses ultrasound waves to heat the tissue under treatment. FUS has shown promise in treating benign prostatic hyperplasia (a condition in which the prostate gland becomes enlarged), uterine fibroids (benign tumors in the uterus), and bleeding. FUS is not commonly employed in the United States at this time, although its use is fairly common in Europe. The safety and effectiveness of FUS are being studied.
- Radioimmunotherapy. Radioimmunotherapy is a type of radiation therapy that involves using antibodies "tagged" with a radiopharmaceutical substance. These tagged antibodies recognize tumor cells and bind with them, thus bringing the radiopharmaceutical directly to the tumor tissue. The tagged antibodies may be administered intravenously, directly into an artery, under the skin, or directly into a body cavity such as the uterus.
One advantage of radioimmunotherapy is that it may be used to treat metastases (sites away from the original lesion or tumor to which cancer has spread) that are not visible by diagnostic means, thus helping to eliminate the spread of the disease.
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