Glossary of Key Terms Related to Radiation Oncology
External beam radiation therapy
External beam radiotherapy is the most common form of radiotherapy. Radiation therapy typically is delivered as high-energy beams that are aimed directly at a patient’s tumor, so that normal tissues are affected as little as possible.
Conventional: Traditional external beam radiotherapy delivered to the patient delivered using clinical linacs. Usually a single beam of radiation delivered to the patient from several directions: often front or back and both sides. This technique offers the advantage that it waiting time is shorter that other more advanced techniques.
Dual energy based adaptive radiotherapy: This technique is based in multi-energy anatomical imaging to visualize the tumor at multiple times along the treatment sessions to evaluate the tumor response and to adapt the treatment delivery according to the tumor reduction. This is a novel technique and Methodist University Hospital is the only facility in the Memphis area providing this technique to head and neck and prostate cancer patients.
Image-guided radiation therapy (IGRT): The use of frequent imaging such as CT, ultrasound, or X-rays to guide and assure the localization of the tumors during the delivery of the radiotherapeutic beams.
Intensity-modulated radiation therapy (IMRT): High-precision radiation that can target concave malignancy shapes (for example when the tumor is wrapped around the spinal cord, a major organ, or blood vessel) and reduce the dose to the local organs to spare their functionality. In IMRT, tumor localization is performed using the imaging techniques used in IGRT.
Magnetic resonance imaging guided linear accelerator (MRI-LINAC) radiotherapy: Integration of the imaging from an MRI system and an external beam radiotherapy delivered by a clinical linac. The new modality termed as Magnetic resonance linac (MRL) is the latest paradigm in radiation therapy. MRL techniques also offer the capability to perform MRI based adaptive radiotherapy with an unprecedented sensitivity in determine the tumor response to treatment based in the combination of anatomical and functional imaging.
Stereotactic body radiation therapy (SBRT): Precise, high-dose radiation (usually one to five treatments) delivered with millimeter localization of the tumor using a specially designed to assure accurate dose delivery during treatment. SBRT is usually delivered in fewer treatment sessions which is convenient for patients who need to travel long distance to the treatment center.
Volumetric modulated arc therapy (VMAT): External beam treatment that is delivered by a clinical linac using a radiation machine that rotates around the patient in arcs delivering focused beams of radiation to the cancer while reducing radiation to normal tissue. VMAT has similar benefits as IMRT but it reduces the treatment times by one-half to two-thirds without compromising treatment quality and patient safety. In VMAT, tumor localization is performed using the imaging techniques used in IGRT.
Internal brachytherapy
Brachytherapy is a type of internal radiation therapy in which seeds, ribbons, or capsules that contain a radiation source are placed in or near the tumor. Brachytherapy is a local treatment and treats only a specific part of the body. This allows doctors to deliver very high doses of radiation directly to the patient’s tumor while limiting radiation exposure to healthy tissue.
Accelerated SAVI breast HDR brachytherapy: The Strut Adjusted Volume Implant (SAVI) applicator delivers a form of accelerated partial breast radiation (APBI) known as breast brachytherapy, which delivers radiation from inside the breast. This allows physicians to precisely deliver treatment to the tumor cavity and surrounding tissue, and offers two key advantages: it spares healthy tissue from unnecessary radiation and reduces treatment time to one week.
Breast HDR brachytherapy: Seeds inserted with catheters deliver high-dose radiation to the cavity and surrounding area and can reduce treatment time from five to seven weeks down to five days.
Eye plaque brachytherapy: This technique consists of surgically placing a small disc (or “plaque”) with radioactive sources in the eye near the tumor. The low energy of the sources assure that the radiation is localized in the eyeball. The plaque is removed after one week of the implant leaving no residual radiation. We offer this technique for ocular melanoma and other ocular malignancies.
Gynecologic high dose rate (HDR) brachytherapy: Delivery of high-dose radiation to a gynecological tumor using specialized applicators. Radiation is highly localized to the malignancy, so the dose to the normal tissue is minimum. High dose rate treatments are short and highly conformal. Methodist University Hospital offers specialized combined brachytherapy and external beam radiotherapy techniques for advanced gynecological cancers.
Prostate brachytherapy: This treatment is used for prostate cancer that has not spread beyond the prostate gland. Prostate seed implants – it consist in implanting radioactive seeds into the prostate to deliver highly localized irradiation of the affected anatomy without distressing normal tissue. This treatment is used for prostate cancer that has not spread beyond the prostate gland. For the treatment of cancer spread outside the gland we offer external beam radiotherapy such as IMRT of VMAT.