Radiation therapy is delivered to patients externally or internally to treat various forms of cancer. External radiation therapy uses high-energy X-ray or electron beams delivered by a linear accelerator and aimed at specific points on the body where the tumor is located. Internal radiation therapy involves the implantation of radioactive material directly into the body. A radiation oncologist is a physician who specializes in the treatment of cancer patients using radiation therapy.
External Beam Radiation Therapy
A linear accelerator provides external radiation therapy to cancer patients. Linear accelerators deliver standard doses of radiation to cancer tumors. Intensity Modulated Radiation Therapy (IMRT) is an advanced form of noninvasive radiation treatment enabling radiation oncologists to precisely target tumor cells. IMRT uses computed tomography (CT) to create 3D images and treatment plans to deliver targeted radiation beams of varying intensity to cancerous tumors. The addition of image-guidance technologies to IMRT allows radiation oncologists to localize treatment to the affected area, minimizing damage to surrounding tissue.
Image-Guided Radiation Therapies (IGRT) technologies provide image-guidance and verification capabilities during radiation treatment allowing for a more accurate delivery of radiation to the tissue target. IGRT involves imaging during the course of radiation treatment. A computer compares the images taken at the time of treatment to images taken during the planning phase. Through this process, IGRT is able to account for changes in the patient’s body or position that may shift the exact location of the cancer. This allows increased accuracy of very complex treatment approaches. It also provides documentation of the degree of accuracy. IGRT is used in conjunction with external beam radiation, three-dimensional conformal radiation therapy (3D-CRT), or intensity modulated radiation therapy (IMRT).
Stereotactic Radiosurgery (SRS) & Stereotactic Body Radiotherapy (SBRT) are advanced types of radiation technology. SRS uses a computer-guided therapy system to treat tumors and other abnormalities of the brain. SRS is ideal for otherwise inoperable tumors, such as those in the brain that cannot be treated by traditional surgical methods. SRS is a non-surgical procedure that delivers precisely-targeted radiation at much higher doses than traditional radiation therapy with minimal damage to surrounding healthy tissue.
SBRT is used to treat malignant or benign small to medium size tumors in the body, including the lung, liver, abdomen, spine, prostate, and head or neck. SRS and SBRT are important alternatives to invasive surgery, especially for patients who are unable to undergo surgical interventions for tumors and abnormalities.
SRS and SBRT work in the same way as other forms of radiation treatment. The process does not actually remove the tumor, but the radiation causes it to shrink. By damaging the DNA of tumor cells, these cells cannot reproduce. Malignant and metastatic tumors may shrink more rapidly, even within a couple of months. When treated with radiosurgery, arteriovenous malformations (AVMs) begin to thicken and close off slowly, typically over several years. Specific technology is required to deliver SRS and SBRT treatments. Three-dimensional imaging is used to locate the tumor within the body and define the exact size and shape. This imaging guides the treatment plan and positioning of the patient for treatment. A linear accelerator is used to deliver treatment. Using this technology has significant advantages over earlier generation technology because it utilizes a larger X-ray beam, which enables the uniform treatment of larger tumors.
AccuBoostTM is a treatment for breast cancer patients that utilizes the real-time image guidance of IGRT to precisely target the boost dose of radiation for breast cancer treatment, making it more accurate for each treatment. This precision allows little or no exposure to surrounding healthy tissue, ensuring a better cosmetic outcome, and eliminating the variability that radiation oncologists face for similar treatments. The AccuBoostTM system targets the dose precisely to where it needs to go and minimizes the side effects of radiation.
Internal Radiation Therapy
Low Dose Rate (LDR) Brachytherapy Radioactive Seed Implants
LDR brachytherapy treatment involves the use of radioactive materials inserted into body tissue in close proximity to the tumor to deliver high dose radiation in a permanent or temporary application. LDR brachytherapy is most often used to treat prostate and gynecologic cancers.
High Dose Rate (HDR) Brachytherapy
HDR brachytherapy utilizes radioactive material inserted into applicators within body cavities or tissues in close proximity to the tumor, allowing for a high dose of radiation to be delivered precisely to the tumor. HDR brachytherapy is a temporary implant conducted in an outpatient setting and minimizes treatment time. Imaging tools such as CT (computed tomography) verify the exact catheter or applicator placement, resulting in a radiation dose with one-millimeter accuracy that significantly spares radiation exposure to surrounding healthy tissue and critical organs.
- Breast Cancer Treatments
MammoSite® delivers a high daily dose of HDR brachytherapy to the area where breast cancer is most likely to recur after a lumpectomy. The radiation can kill any remaining cancer cells. MammoSite® works from inside the body via a discreet balloon catheter system implanted in the breast lumpectomy cavity. The system is in place for five days with treatments given twice a day, versus other treatments that may take five to seven weeks.
- ConturaTM Balloon
The ConturaTM Balloon delivers a high daily dose of HDR brachytherapy via five channels for the radioactive source. These channels allow clinicians to shape the radiation and administer radiation only where it is needed, thus protecting healthy tissue. Treatment time is decreased to just five days versus up to seven weeks.
The SAVITM applicator delivers a high daily dose of HDR brachytherapy via multiple catheters that allow clinicians to contour the radiation and protect nearby healthy tissue. This approach provides greater flexibility in the delivery of radiation.
- Gynecologic Cancer Treatment
- HDR Brachytherapy
High dose radiation is used to treat gynecologic cancers by delivering radiation internally and precisely targeting the tumor. This precision minimizes the impact on the surrounding healthy tissue and limits side effects. The radiation is delivered through an applicator that is inserted internally and is removed once treatment is complete. Treatment time is significantly reduced to three to six treatments that last 10 to 20 minutes each.
- Prostate Cancer Treatment
- HDR Brachytherapy
Prostate HDR brachytherapy involves temporarily implanting flexible needles within the prostate to allow the delivery of treatment using radioactive materials. Treatment time is reduced to one and a half days and it is an alternative treatment option for qualifying patients as compared to external beam treatments, which last five to seven weeks.
Treatment Planning and Simulation
Simulation is the first step in the radiation oncology treatment process and involves consultation with your physician and radiation therapy team during which every part of your treatment is planned. Planning includes determining the correct body position for treatment, taking imaging scans, making reference marks for the positions on the skin, and conducting virtual simulation.
- Body Positioning: The team will determine the best position for a patient’s body to receive radiation treatment. Immobilization devices may be used to ensure the patient is in the exact position during each subsequent treatment.
- Imaging: Once the correct position is determined, images are taken to determine where on the body the radiation will be focused. This may include traditional X-rays or PET (positron emission tomography)/CT (computed tomography).
- Marking: To ensure that all treatments are delivered to the right place on a patient’s body, the skin may be temporarily or permanently marked.
- Virtual Simulation: During virtual simulation, the patient images are used to create a 3D model of a patient’s anatomy, including the tumor and its location. This helps augment an oncologist’s ability to plan the optimal course of treatment.
Research Collaboration with Radiation Therapy Oncology Group®
Through its affiliation with US Oncology Research, Texas Oncology participates in clinical trials through the Radiation Therapy Oncology Group® (RTOG®). The RTOG trials at Texas Oncology are conducted by principal investigator Vivek Kavadi, M.D. Recognized for its leadership in working to increase survival and improve the quality of life for cancer patients, RTOG is a key clinical research component of the American College of Radiology (ACR) and serves as a multi-institutional, international clinical cooperative group funded primarily by the National Cancer Institute.
RTOG continues to be the leading multicenter research organization systematically testing novel radiotherapy approaches against cancer and pursuing fully integrated translational and quality of life research to support and further this effort. RTOG is also a leader in formally evaluating the integration of optimized radiotherapy with new classes of anti-cancer therapies and has completed and conducted a number of practice- and paradigm-changing trials. RTOG maintains a roster of 40 active studies devoted to the group's primary disease sites.
- Brain Tumors: RTOG found that oligodendroglioma and anaplastic oligoastrocytoma patients with missing chromosome arms 1p and 19q were more likely to respond to aggressive treatment with chemotherapy and radiotherapy and their progression-free survival increased by almost five years.
- Brain Metastases: RTOG improved survival by more than 33 percent for patients with a single brain metastasis by using whole brain radiotherapy followed by stereotactic radiosurgery instead of whole brain treatment alone.
- Head and Neck Cancer: In a study for patients with high-risk head and neck cancer, RTOG discovered that participants who received chemotherapy together with radiotherapy after surgery were far less likely to have a recurrence of cancer.
- Lung Cancer: RTOG found that healthier patients with inoperable non-small-cell lung cancer had better results if they received chemotherapy during their course of radiotherapy rather than before radiotherapy.
- Pancreatic Cancer: An intergroup trial led by RTOG showed significantly improved survival for patients with advanced pancreatic adenocarcinoma when they received the drug, gemcitabine, in addition to standard therapy after surgery.
- Prostate Cancer: RTOG determined that radiotherapy combined with long-term hormone suppression significantly improves survival for men with high-grade prostate cancer (Gleason score 8-10). However, men with locally advanced prostate cancer (Gleason score 2-6) benefit most from hormonal suppression prior to their radiotherapy.
RTOG trials currently open at Texas Oncology-Sugar Land Cancer Center in association with Memorial Hermann Hospital Sugar Land and Texas Oncology-Radiation Oncology Center at Memorial Hermann Memorial City include:
- Breast Cancer
- Endometrial Cancer
- Esophageal Cancer
- Head and Neck Cancer
- Prostate Cancer
- Brain (metastasis)
For more information about RTOG, please visit www.rtog.org.
Texas Oncology Radiation Oncology Cancer Treatments Centers: