Technology
Proton Therapy
M. D. Anderson has offered proton therapy since May 2006. Patients can be treated on three different passive modulation beam lines, which treated approximately 12 hours per day. The expected benefits of proton therapy, including fewer treatment side effects, are being observed daily. M.D. Anderson's Proton Therapy Center is the only treatment facility of its kind in the Southwest.
Gamma Knife
The Gamma Knife is a 30-ton machine that contains a cylindrical cone made of the world's largest piece of tungsten with lead shielding. The machine has 192 Cobalt-60 radiation sources that are shaped by eight sectors that surround the patient's head.
Intensity Modulated Radiation Therapy (IMRT)
A type of 3-dimensional conformal radiotherapy that focuses multiple radiation beams directly on the tumor itself. Beam intensities vary, so that the highest possible doses can be used to destroy cancerous tissue. Proper positioning of the patient is crucial to the success of IMRT. Radiation oncologists use special planning software to determine the most accurate treatment.
Dynamic multi-leaf collimator (DMLC)
A device that uses metal "leaves" to modulate the intensity of radiation beams. By visualizing the shape and location of the tumor, radiation oncologists determine the necessary beam angles for treatment. Beam intensity is regulated by calculating the size of the space between the leaves and how long they remain open. This delivers a lethal dose to the tumor, while protecting nearby critical organs.
Brachytherapy
Using ultrasound, dozens of tiny "seeds" containing radioactive iodine (I-125) are placed at the tumor site with a special needle. The seeds release their radiation over a period of time. Brachytherapy is particularly effective for prostate cancer, destroying the tumor while sparing the urethra, bladder and other nearby organs.
CT-Driven Virtual Simulation
M. D. Anderson has several CT (computed tomography) scanners dedicated to simulating radiation treatments for each individual patient. These simulations are used to test various treatment fields and devices used to immobilize the patient during therapy. Data from the simulators ensures that patients get the appropriate dose of radiation before treatment begins.
Dedicated OR Suite
A dedicated OR suite is a special amphitheater where surgery and radiation therapy can be performed in a single procedure. A special treatment unit contains a high dose rate iridium (lr-192) source capable of delivering radiation while the treatment area can be easily accessed and nearby organs can be moved out of the way. This technique is used to treat many malignancies, especially pelvic and abdominal tumors.
Digital Portal Imaging
Allows for real-time viewing of radiotherapy images, which helps oncologists position the patient by tracking their movements, and to design blocks for protecting healthy tissue. Images can be viewed one at a time, superimposed, or in a movie loop for optimum treatment planning.
Gating
Intra-fraction motion is a major concern in treating patients with tumors in the lung or upper abdomen. Currently two different gating approaches are being evaluated. Other systems are being considered. Gated simulations and treatments are being performed on selected patients.
Linear Accelerator/In-Room CT
A treatment room which contains both an accelerator and a CT unit. The same treatment table is used for both imaging and treatment, allowing for unique treatment applications, such as treating metastasis to the vertebral bodies and the comparison of various imaging techniques in their ability to locate different targets.
On-Board Imaging
The on-board imager is an automated system for image-guided radiation therapy that provides high-resolution X-ray images to pinpoint tumor sites. The on-board imager is mounted on the treatment machine via robotically controlled arms that can be positioned for the best possible view of the tumor. The image detector shows radiologists exactly how a tumor will move during treatment due to breathing or other patient movements. This technology also gives physicians the ability to incorporate a unique 150 kV X-ray tube designed for generating CT-quality images from a moving gantry.
PET/CT
The Radiation Treatment Center has a specially designed PET/CT simulator combines PET (positron emission tomograpy) images with CT images, which will make substantial contributions to the process of defining treatment targets.
Stereotactic Radiosurgery
Stereotactic radiosurgery involves a single, high-dose application of radiation to the tumor, instead of the many smaller doses given in standard treatment. Several radiation beams are precisely aimed to converge upon a small tumor. The patient lies on a couch that rotates 180 degrees for maximum targeting, without harming surrounding tissues. This technique is used to treat brain tumors and other intracranial cancers.
Stereotactic Radiotherapy (SRT)
The dedicated linear accelerator is also used to treat SRT patients with a mMLC or with the more traditional circular cones. Patients receiving such treatments include those with tumors in the central nervous system and head and neck regions.
Stereotactic Spine Radiotherapy
Stereotactic guided radiation is combined with CT guidance for the highest possible dose to spinal tumors while minimizing harmful side effects. A computed tomography (CT) machine is in the same treatment suite as the linear accelerator, so that radiation oncologists can instantly adjust radiation beams to account for any changes in tumor location, no matter how small. Patients remain immobilized on the same treatment table while the CT moves on rails around the table to confirm tumor location.
- View a video of this procedure
Stereotactic Body Radiation Therapy (SBRT)
SBRT combines elements of three-dimensional conformal radiotherapy (3D-CRT)/intensity-modulated radiation therapy (IMRT), which links CT scans of the tumor site with treatment-planning software to determine optimum photon radiation beam direction and intensity, and image-guided radiation therapy (IGRT) techniques that cope with tumor motion and anatomy changes during the course of radiotherapy.
SBRT allows the delivery of ablative dose of radiation to the target in significantly shortened treatment time, individual treatments, called "fractions" have been reduced from 35 to fewer than 5 in this approach, while minimizing damage to normal tissues in the tumor region. This approach has been used in patients with early stage or isolated recurrent/metastatic cancer in the lung, liver and other sites.
At M. D. Anderson, we perform 4-dimensional CT based simulation for SBRT treatment plan for all patients to evaluate the motion of tumor and critical structure, to make sure the target is covered and all critical structures are spared. In addition, we conduct a re-simulation CT using CT on-rail or cone beam CT before each fraction of SBRT treatment to verify the position and target coverage.
Among more than 360 patients with early stage or recurrent/metastatic lung cancer treated with SBRT at M. D. Anderson to date, preliminary data shows more than 95% local control with minimal toxicity. This data represents the first such report for recurrent lung cancer, as well as for lesions close to critical healthy structures such as the heart, bronchial tree, spinal cord and major vessels. A randomized clinical study to compare SBRT results with surgery in operable, early-stage lung cancer is ongoing.