Technology Overview
Millimeter-Wave (MMW) imaging has been developed for a variety of applications including security screening and body measurements. In addition to these applications, real-time MMW imaging could be used to support physicians who are administering radiation therapies to treat cancer patients.
Currently, during radiation therapy, optical techniques are used to track motion but, unlike MMW, they cannot see through clothing. For Radiation Oncology, physicians need the ability to accurately track respiratory motion in cases where tumors in the lower chest and upper abdomen move as the patient breathes.
PNNL’s patent-pending 3D MMW technology could increase the efficacy of radiation therapy, reduce ionizing radiation exposure to healthy tissue, and improve patient comfort. It also could lead to reduced imaging artifacts in security screening and other applications.
Advantages
During radiation therapy, optical alignment and tracking methods are used to enable visual alignment with skin marks, but the process requires removing clothing, blankets, and any superficial covering or bandages. Oncology patients are frequently anemic and hypersensitive to cold temperatures, even a partial disrobing can be very painful and uncomfortable.
Even when using CT or MRI for alignment, it is generally correlated with fiducial markers on the skin and these still need to be visualized by the technologist when aligning the patient. Worse, if the patient moves or coughs after treatment has started, a fixed displacement may be introduced that is not readily detectable. Finally, respiratory gating generally just turns the beam off and on as the lesion moves out of, and back into, the treatment field. There is not a good means to redirect the beam during even a portion of the respiratory cycle.
With PNNL’s technology, real-time radar imaging of the surface of the patient’s skin together with CT (or MR) imagery can be used to create a map representing the most likely position of the target within the body relative to the skin surface at various depths of inspiration/expiration. This allows a patient to remain fully-clothed and blanketed while receiving radiation therapy and may reduce the degree of external restraint needed to ensure correct dose delivery.