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One of the first objective analytical comparisons between single-arc IMRT (RapidArc), standard IMRT (S-IMRT) and TomoTherapy was recently published in the journal Physics in Medicine and Biology.

The note is titled “Single-Arc IMRT?” and was authored by Prof. Thomas Bortfeld and Prof. Steve Webb. Their analysis clearly illustrates the fundamental differences between the three techniques in terms of angular spacing of beams and ability to modulate the beam from each direction. Bortfeld and Webb provided the following conclusions:

“We find that Tomotherapy provides the greatest flexibility in shaping intensity landscapes and that it allows one to deliver IMRT in a way that comes close to the ideal case in the transverse plane.”
“Only in relatively simple cases that do not require substantial intensity modulation will Single-Arc be dosimetrically comparable to Tomotherapy.”
“In terms of treatment planning, Single-Arc poses a more challenging optimization problem than Tomotherapy or standard IMRT.”
“Because Single-Arc delivers an irregularly shaped but unmodulated treatment field from each gantry angle, it is actually not IMRT in the strict sense that requires each field from a given direction to be spatially modulated.”
“Tomotherapy has, by design, a much greater flexibility of shaping dose distributions in transverse slices than both S-IMRT and Single-Arc: it allows full intensity modulation per beam direction (like S-IMRT but not Single-Arc), and beams can come from practically all (co-planar) directions (like Single-Arc but not S-IMRT).”
This work can be accessed in its entirety by visiting the electronic journals section of the Institute of Physics website: http://www.iop.org/EJ/toc/0031-9155/54/1

Professor Thomas Bortfeld is Chief of Physics, Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, USA; Professor Steve Webb is Chief of Physics, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Sutton, UK. Both authors have been major contributors to the development and implementation of IMRT over the past two decades and are extremely well-published in this and other areas of radiation oncology.

TomoTherapy had no involvement or sponsorship relating to this analysis or paper publication.

About TomoTherapy Incorporated

TomoTherapy Incorporated has developed, markets and sells the TomoTherapy® Hi·Art® treatment system, an advanced radiation therapy system for the treatment of a wide variety of cancers. The Hi·Art treatment system combines integrated CT imaging with conformal radiation therapy to deliver sophisticated radiation treatments with speed and precision while reducing radiation exposure to surrounding healthy tissue. The company’s stock is traded on the NASDAQ Global Select Market under the symbol TOMO.

Source: TomoTherapy Incorporated