Radiation Therapy to Treat Head and Neck Cancers
The goal of radiation therapy is to accurately and aggressively treat a cancerous tumor without hurting nearby tissue. There are several options that help us to do that.
Each of the following treatment approaches rely on imaging to tailor the therapy to a given problem. Each has its own strengths in terms of where they’re best applied. These precision technologies provide treatment options that weren’t possible in the past, especially for complicated cancers of the head, neck and skull base. That allows us to customize radiation therapy to each patient.
- IMRT — Intensity-Modulated Radiation Therapy (IMRT) was one of the first forms of conformal treatment in which the radiation dose conforms closely to the tumor without harming nearby tissue or structures. IMRT essentially breaks up the beam that delivers the radiation dose into several different angles. That means the beam can be carefully aimed and the intensity of the dose can be adjusted so it delivers the strongest dose to the tumor and low or no dose to surrounding tissue. Avoiding nearby tissue means that many side effects of radiation therapy can be minimized or eliminated. IMRT can be especially effective in covering a region — lymph nodes, for example — where tumor cells are suspected, but where it’s difficult to tell precisely which node contains the cancer.
- TomoTherapy Hi-Art® System — TomoTherapy takes IMRT technology further by adding CT imaging. TomoTherapy allows clinicians to take a CT image of the patient in the treatment position to verify the position of the tumor. A current image of the tumor – right before treatment — means radiation can be accurately delivered where it’s needed while avoiding healthy tissue and organs.
TomoTherapy also builds on IMRT by increasing the number of angles at which the radiation dose enters the body. The radiation beam is broken up into different angles covering 360 degrees. Each angle can be tailored to deliver more or less of the radiation depending on the location of the tumor, allowing a much more precise delivery.
- Gamma Knife (Stereotactic Radiosurgery) — the Gamma Knife isn’t a knife at all, but a precise way to deliver highly concentrated radiation to tumors located inside the skull. The Gamma Knife uses precise imaging and a three-dimensional grid to identify the exact size, shape and location of tumors within the brain. It then can deliver a highly concentrated radiation dose — 201 converging beams of radiation — to the tumor while delivering much lower doses to surrounding healthy brain tissue.
Because of the precise nature of Gamma Knife technology, an external head ring is attached to the patient’s skull to hold the head perfectly still and ensure they are in the same position for the diagnostic imaging and for treatment. Using precise coordinates, the radiation can then be delivered right to the edge of the tumor, while the dose falls off dramatically even millimeters away from the tumor.
- CT-On-Rails™ — this new technology expands on IMRT and TomoTherapy by improving the quality of the imaging. Like TomoTherapy, CT-On-Rails™ allows imaging the patient first, then putting them back in the exact same position for the planning scan. The CT-On-Rails™ has a CT machine on one end and the treatment machine on the other. The table can swing 180 degrees to do a CT scan, and swing the patient back into position. The images are fused very quickly to compare the tumor’s position. With this new software, clinicians are able to quickly fuse the daily diagnostic CT image with the original treatment planning scan — a great advantage in targeting the precise location of the tumor, especially with certain smaller tumors.
We always strive to develop improved image-guided therapies to have the tools to deliver conformal treatment across the spectrum of head, neck and skull base cancers. We know that future developments will allow clinicians to become even more precise in treating difficult tumors, and we’ll be there, leading the way.