The strength of Intensity Modulated Radiation Therapy (IMRT) is that it treats the disease, but spares more healthy tissue. This is especially important in treating areas such as the prostate where you wish to spare the rectum and bladder to minimize complications associated with treatment. To spare healthy tissue, IMRT treats with smaller margins around the tumor. Smaller margins require more accuracy in localizing the target. Localization is made even more complicated due to organ motion and change in organ shapes that are seen at the time of each treatment. This makes delivering the planned treatment accurately to the target a significant challenge and can result in a geographical miss of the target organ, or over-treatment of critical structures. To accomplish this demand for increase in the accuracy of radiation delivery, Oakwood Cancer Center (Oakwood) offers the most sophisticated, state-of-the-art, target localizing tool: Image-Guided Radiation Therapy (IGRT).
There are different forms of IGRT currently available in Radiation Therapy. Oakwood offers to its patients the next generation in IGRT system, the X-ray Volume Imaging (XVI) by Elekta. This is a new technology designed to improve the precision and effectiveness of cancer treatments by giving doctors the ability to target and track tumors more accurately. Oakwood Cancer Center is not only the first in Central Pennsylvania, but also one of the first centers in the United States to be able to offer this technology to patients.
The XVI unit is integrated with the high energy linear accelerator, allowing for accurate localization of treatment site at the time of treatment. Unlike other types of IGRT systems, the XVI system acts in a similar way to a CT scanner, allowing images that view the soft tissue. A scan, taken at the time of treatment, is compared to a reference scan. The patient is moved to correct any differences in position allowing accurate treatment delivery to be performed.
Traditionally, imaging technology has been used to produce three-dimensional scans of the patient’s anatomy to identify the exact location of the cancer tumor prior to treatment. However, difficulty arises when trying to administer the radiation, since cancer tumors are constantly moving within the body (for example, from movement caused by breathing). Hence, the exact location of the tumor may have changed between the time of scan and actual treatment.
An automated system for IGRT, the XVI, allows physicians to locate the tumor before each dose is administered while the patient is in the treatment position. This minimizes the volume of healthy tissue exposed to radiation during treatment.
“IGRT addresses an important clinical challenge. As we understand more about tumor motion, we now realize that we cannot position patients purely on the basis of marks or tattoos on their external anatomy. Dynamic Targeting – IGRT – gives us the ability to see exactly where a tumor is, and how it is moving every day just prior to treatment – even during treatment. This makes it possible to use radiation therapy to treat tumors that were not readily treatable before.”