NAPAC2016 - List of Authors (Vassiliev, O.N.)

Paper	Title	Page
TUPOA54	Examination of Out-of-Field Dose and Penumbral Width of Flattening Filter Free Beams in Medical Linear Accelerators	396
	L.C. Bennett, O.N. Vassiliev M.D.A.C.C., Houston, Texas, USA
	Medical linear accelerators (LINACS) have traditionally used a flattening filter to ensure that the photon spectrum entering the patient was homogeneous within a given field size. Recently, leading manufacturers of medical accelerators have begun including an option for Flattening Filter Free (FFF) beams on their accelerators. These beams are characterized by a softer spectrum (lower average energy), peaked profiles, and less side scatter. Previous work with Monte Carlo models has shown that the elimination of the flattening filter from the beam path has the potential to greatly reduce scatter in regions immediately adjacent to the primary field (Kry 2010); however, systematic in-depth investigation of these effects has yet to be done using actual measurements from a linac equipped with FFF beams. We have examined and compared measurements of different energy pairings of FFF and FF beams from the Varian TrueBeam accelerators and found reductions of peripheral dose at upwards of 30% for the FFF beams and nearly 5% reduction in penumbral width at nearly all depths and field sizes; reductions were greatest for shallow depths and small field size. Kry et al. Out-of-field photon dose following removal of the flattening filter from a medical accelerator. Physics in Medicine and Biology. vol. 55, no. 8, 2010. pp 2155-2166.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA54
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Paper

Title

Page

Examination of Out-of-Field Dose and Penumbral Width of Flattening Filter Free Beams in Medical Linear Accelerators

396

L.C. Bennett, O.N. Vassiliev
M.D.A.C.C., Houston, Texas, USA

Medical linear accelerators (LINACS) have traditionally used a flattening filter to ensure that the photon spectrum entering the patient was homogeneous within a given field size. Recently, leading manufacturers of medical accelerators have begun including an option for Flattening Filter Free (FFF) beams on their accelerators. These beams are characterized by a softer spectrum (lower average energy), peaked profiles, and less side scatter. Previous work with Monte Carlo models has shown that the elimination of the flattening filter from the beam path has the potential to greatly reduce scatter in regions immediately adjacent to the primary field (Kry 2010); however, systematic in-depth investigation of these effects has yet to be done using actual measurements from a linac equipped with FFF beams. We have examined and compared measurements of different energy pairings of FFF and FF beams from the Varian TrueBeam accelerators and found reductions of peripheral dose at upwards of 30% for the FFF beams and nearly 5% reduction in penumbral width at nearly all depths and field sizes; reductions were greatest for shallow depths and small field size.
Kry et al. Out-of-field photon dose following removal of the flattening filter from a medical accelerator. Physics in Medicine and Biology. vol. 55, no. 8, 2010. pp 2155-2166.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA54

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)