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Chapter 081. Principles of Cancer Treatment (Part 6)

Application to Patients Teletherapy Radiation therapy can be used alone or together with chemotherapy to produce cure of localized tumors and control of the primary site of disease in tumors that have disseminated. Therapy is planned based on the use of a simulator with the treatment field or fields designed to accommodate an individual patient's anatomic features. Individualized treatment planning employs lead shielding tailored to shape the field and limit the radiation exposure of normal tissue. Often the radiation is delivered from two or three different positions. Conformal three- dimensional treatment planning permits the delivery of higher doses of radiation to the. | Chapter 081. Principles of Cancer Treatment Part 6 Application to Patients Teletherapy Radiation therapy can be used alone or together with chemotherapy to produce cure of localized tumors and control of the primary site of disease in tumors that have disseminated. Therapy is planned based on the use of a simulator with the treatment field or fields designed to accommodate an individual patient s anatomic features. Individualized treatment planning employs lead shielding tailored to shape the field and limit the radiation exposure of normal tissue. Often the radiation is delivered from two or three different positions. Conformal three dimensional treatment planning permits the delivery of higher doses of radiation to the target volume without increasing complications in the transit volume. Radiation therapy is a component of curative therapy for a number of diseases including breast cancer Hodgkin s disease head and neck cancer prostate cancer and gynecologic cancers. Radiation therapy can also palliate disease symptoms in a variety of settings relief of bone pain from metastatic disease control of brain metastases reversal of spinal cord compression and superior vena caval obstruction shrinkage of painful masses and opening of threatened airways. In high-risk settings radiation therapy can prevent the development of leptomeningeal disease and brain metastases in acute leukemia and lung cancer. Brachytherapy Brachytherapy involves placing a sealed source of radiation into or adjacent to the tumor and withdrawing the radiation source after a period of time precisely calculated to deliver a chosen dose of radiation to the tumor. This approach is often used to treat brain tumors and cervical cancer. The difficulty with brachytherapy is the short range of radiation effects the inverse square law and the inability to shape the radiation to fit the target volume. Normal tissue may receive toxic exposure to the radiation with attendant radiation enteritis or cystitis in .