Advanced Technology

Radiation therapy

• 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.

Radiology

• PET/CT — PET/CT combines positron emission tomography (PET) with a high-quality CT scanner in one machine. A PET scan is a nuclear medicine study which detects the metabolism of a tumor. The PET scan uses a glucose solution “labeled” with a radioactive tracer. The glucose goes to the most metabolically active areas, and tumors tend to be very metabolically active. So, even if a tumor might be hard to see in other scans, the PET scan can detect its metabolic activity. The patient can have both scans (PET and CT) done on the same table, which improves accuracy, and the images can be quickly fused to create a more comprehensive picture of the tumor.
  
  PET/CT is especially effective when the primary tumor is unknown, when dealing with adenopathy (abnormal lymph nodes), and when evaluating for metastatic disease (cancer that has spread from somewhere else). The PET/CT scan is also helpful after treatment to see how the tumor is responding to treatment and to evaluate recurrence in certain situations.
  
  
• 64-Slice Multidetector CT – The latest CT (computed tomography) technology available, the 64-slice multidetector CT, allows clinicians to take very high quality, thin section images very quickly. Known as the LightSpeed VCT, or volume CT, this scan gives a highly detailed look at the anatomy, and can be especially effective in detecting head, neck and skull base cancers. The VCT also allows technicians to do more with images in post processing. The images can be reformatted in any plane, creating images that are helpful for planning surgical and radiation therapy treatments.
  
  Froedtert & The Medical College of Wisconsin have three dedicated, specially trained technologists working in a separate 3-D computer workroom. These skilled technologists do all of the post work on the VCT studies, and can produce a higher level of processing. They work closely with physicians to highlight important anatomy and produce detailed views. This allows the physicians to answer specific questions and develop optimal therapies.
  
  
• MRI – Magnetic resonance imaging (MRI) plays an important role in diagnosing head, neck and skull base cancers. MRI can effectively differentiate soft tissue, map the extent of tumors and evaluate the spread of a tumor along nerves. When tumors spread into the skull, MRI is superior for evaluating the extent of that spread. Froedtert & The Medical College of Wisconsin have a 3 Tesla MRI scanner, the highest field strength used in clinical practice. (The tesla is the unit used to measure the strength of a magnetic field.)

Author: Joan Cotter Pike

Date: Nov. 15, 2007