Image Guided Radiation Therapy (IGRT)
OVERVIEW
Image-guided radiation therapy, or IGRT as it is commonly known, evolved from IMRT. IMRT provides far greater beam shaping capabilities than 3D radiation therapy, thereby permitting far more sophisticated treatment. However, we continued to require a safety margin for error for all of our treatments because of the inherent uncertainty of tumor location (prostate location) each and every day. For example, the prostate moves in a multitude of directions each day depending on how full or empty the bladder and rectum are. In the past, even with IMRT, we would need to add a safety margin around the prostate to account for this day-to-day variability in prostate location. This added margin resulted in a larger target (prostate) to be treated with radiation and more of the bladder and rectum included within the radiation field, thereby, increasing the risk of damage to these healthy organs.
Trilogy System™
IGRT has changed all of this. IGRT does exactly what its name states: it uses the image of the target (prostate) to guide the delivery of radiation for each and every treatment. IGRT technology allows us to greatly reduce the added margin since the treatment machine can check the prostate location just moments before treatment. This is important for two reasons:
1) A reduced margin translates into less bladder and rectum within the radiation field. What this means to the patient is a significant reduction in the risk of damage to the immediately adjacent normal tissue (bladder and rectum).
2) Reducing the treated area also allows the increase of radiation dose that can safely administered. Again, the same rules that governed 100 years ago continue to apply: the greater the dose, the greater the chance for cure.
Our Trilogy™ systems utilize the marriage of IMRT planning with target tracking, resulting in the reduction in the size of the treated volume (prostate) and thereby reducing the risk of damage to the normal tissue (bladder and rectum). Fiducials are placed along the border of the prostate gland so that the imaging device can read the location of the prostate, communicate that information to the treatment computer, and then adjust the position of the patient so that the treatment is delivered precisely.