TomoTherapy platform offers dosimetric advantage in treating both standard and complicated cases by utilizing integrated daily imaging and helical radiation delivery to accurately target tumors and spare surrounding structures and organs, according to a study from McGill University Health Centre (MUHC).
The study entitled ‘Standard and Nonstandard Craniospinal Radiotherapy Using Helical TomoTherapy,’ said: “Helical TomoTherapy delivers continuous arc-based intensity-modulated radiation therapy (IMRT) that gives high conformality and excellent dose homogeneity for the target volume. Helical TomoTherapy allows for differential dosing of multiple targets resulting in very elegant dose distributions.
“By its conformal nature, IMRT is sensitive to improper patient setup. The use of pretreatment megavoltage CT (MVCT) imaging with helical TomoTherapy allows for increased precision with respect to patient positioning and use of a reduced planning target volume (PTV) margin. Daily imaging of our patients has shown the technique to be very reproducible. We conclude that helical TomoTherapy is an excellent tool for planning and delivery of conformal IMRT for both standard and nonstandard CSI.”
The McGill study focused on four patients, three of whom had complicating circumstances, such as unusual anatomy, prior radiation treatment or multiple boost targets. The first was a standard case of CSI in a 19-year-old patient with recurrent myxopapillary ependymoma (MPE).
Two other patients received non-standard CSI via differential dosing one was a seven-year-old with recurrent medulloblastoma who had been treated before and required a simultaneous dose reduction to the posterior fossa, and the other was a 14-year-old with metastatic tumors throughout the craniospinal axis from MPE who required concurrent boosting of multiple sites. The fourth patient was a 21-year-old with neurofibromatosis and pronounced scoliosis who needed treatment of the whole spine for recurrent MPE.
The study also noted that “There exist dosimetric advantages over conventional techniques. Lacking from the [helical TomoTherapy] plan is the hotspot created in the abdomen when using traditional skin gap junctioning techniques for the posterior spine. In addition, the (TomoTherapy) plan is significantly better in terms of maximum dose delivered.
“In fact, the plan maximum dose is 106%, which occurs within the patient treatment volume. Because of the use of direct fields and prescription points that can be at several centimeters’ depth, it is not uncommon to see hotspots on the order of 130% posterior to the spinal cord and outside of the target volume when using conventional CSI techniques.”
Fred Robertson, CEO of TomoTherapy, said: “This study of CSI with helical TomoTherapy technology at McGill is an excellent example of the use of our system for the types of treatment for which it is uniquely suited. We are pleased that TomoTherapy can help pediatric and young adult patients, who may otherwise face limited treatment options because of prior radiation or other complicating factors.”
TomoTherapy Incorporated, maker of TomoTherapy technology, develops, markets and sells radiation therapy solutions that can be used to treat a wide variety of cancers, from the most common to the most complex.
The ring gantry-based TomoTherapy platform combines integrated CT imaging with conformal radiation therapy to deliver radiation treatments with speed and precision while reducing radiation exposure to surrounding healthy tissue.