What is TomoTherapy?
TomoTherapy® Highly Integrated Adaptive Radiotherapy (HI-ART) shares a lot of technology with CT scanners, otherwise known as computerized tomography. The machine even looks like a CT scanner. Some of its capabilities are:
- TomoTherapy will do a quick CT scan before each treatment starts, to ensure the patient is correctly aligned.
- A thin beam rotates around the body, entering from many directions. This results in thousands of little beamlets of different intensities entering the body, converging on the tumors.
- A powerful multiple-processor computer calculates the treatment plans and coordinates treatment delivery.
- TomoTherapy can treat large or small tumors, single or multiple tumors, one region of the body or several regions, to the same dosage in every area or to multiple different dosages.
- TomoTherapy can avoid certain organs. We can miss the salivary glands and treat the throat tumor, miss the spinal cord and retreat the spinal bone, miss the kidneys and treat the pancreas.
When is TomoTherapy Used?
TomoTherapy is actually a form of intensity modulated radiation therapy (IMRT). TomoTherapy has been particularly valuable for the following conditions:
- Retreating previously irradiated areas of the body
- Treating multiple metastases simultaneously
- Treating all metastases throughout the body simultaneously
- Treating lung cancers, breast cancers, and prostate cancers
Many radiation oncologists are reluctant to give repeat radiation to the same part of the body that has already received radiation in the past. It can be dangerous to re-irradiate, because you could risk complications such as excessive scarring, ulceration or pain. However, TomoTherapy is a natural choice for retreating tumors that have already been irradiated. Because TomoTherapy is so targeted, it can make it safer to re-irradiate, because the surrounding healthy tissues will receive less radiation dose.
TomoTherapy at CTCA
CTCA cancer experts have years of experience retreating tumors with radiation, whether they be in the brain, lung, bone, breast, or other organ.
We will typically start with a PET/CT scan to determine exactly where the recurrent active cancer is. This is important, because sometimes it is difficult to distinguish between scar tissue from the previous radiation, and actively growing cancer. We usually only want to treat the active cancer. A PET scan can distinguish between the two. We do the PET scan as a "simulation," meaning we plan the radiation treatment directly from the PET/CT images.
We also frequently add amifostine (Ethyol) as a radioprotectant drug during retreatment, to help reduce the amount of additional scarring or damage we might cause.We choose a radiation dose that balances safety and cancer control.
With standard radiation therapy, often a different radiation therapy plan has to be created for each separate tumor treated. With TomoTherapy, it is easier to treat multiple tumors simultaneously, whether they be in the brain, liver, lungs, bones, or in several organs.
TomoTherapy can be used to treat prostate cancer. Many men have heard about using IMRT (intensity modulated radiation therapy) for prostate cancer, and TomoTherapy is a very advanced form of IMRT. We will use TomoTherapy in two ways to treat prostate cancer: either by itself, or in conjunction with high-dose rate (HDR) brachytherapy. TomoTherapy plus HDR brachytherapy is an aggressive treatment combination. It may be an appropriate option for patients with aggressive tumors or men who want the most intense treatment that we offer.
TomoTherapy can be used instead of gamma-knife, cyberknife, or stereotactic radiosurgery to treat brain tumors. TomoTherapy is more flexible than these therapies in that it can treat multiple tumors at the same time, can treat large or complex shaped tumors, and can be easily divided up into a series of daily treatments.
Before IMRT and TomoTherapy, there was no easy way to boost multiple brain tumors or large tumors. Now with TomoTherapy, the radiation oncologist merely outlines all the tumors on a computer screen and the computer will design a treatment composed of thousands of tiny radiation beamlets which intersect on all the tumors. We can use TomoTherapy to treat different stages of brain cancer, including primary brain tumors (glioblastoma multiforme), metastatic brain tumors, and recurrent brain metastases.
We frequently treat lung cancer with our PAT treatment regimen. P.A.T. stands for PET scan, amifostine, and TomoTherapy. We use a PET scan to determine where all the cancer is, TomoTherapy to target it, and add amifostine (Ethyol) as a "radioprotectant" to protect the lungs against some of the damage that can be caused by radiation therapy.
After a lumpectomy (partial mastectomy), radiation therapy is usually given to the breast, to eliminate any cancer cells that may still be present. For early stage cancers, we often use breast brachytherapy, which takes only five days, and treats only a portion of the breast. For more advanced breast cancers, or for women who do not want brachytherapy, we use external beam irradiation.
When TomoTherapy is used, we are able to contour the high dose region much more precisely to the breast tissue. The high dosages can be kept off the lungs and heart. If lymph nodes, such as the internal mammary nodes are also being included in the treatment, TomoTherapy can result in an even more dramatic reduction in unwanted radiation. With TomoTherapy, we can also give a higher dose each day to the area of the breast where the tumor used to be. This can shorten the length of radiation therapy from seven weeks down to five weeks.
Head and Neck Cancer
IMRT is revolutionizing the way that head and neck cancers are irradiated. With cancers of the tongue, throat, and larynx, often all the lymph glands of the neck have to be radiated along with the primary tumor. This usually results in permanent damage to the salivary glands and dry mouth, also known as xerostomia. TomoTherapy, which is a special form of IMRT, it became possible to treat the neck lymph nodes and avoid the salivary glands. Amifostine is also frequently added to radiation to increase the tolerance of the salivary glands to radiation, helping to prevent the symptom of dry mouth.
We always evaluate every patient's cancer uniquely to determine whether radiation therapy is appropriate, to what dose, and with what kind of radiation. Sometimes, a tumor is best treated with basic 3D conformal radiation. Sometimes, the best choice will be IMRT. Other times, with TomoTherapy, which often gives us the ability to treat (and retreat) cancers that would not have been possible or safe with other forms of radiation.