AbstractID: 6671 Title: Dosimetric Accuracy of Nucletron’s Inverse Treatment Planning
(ITP) Software
Intensity Modulated Radiation Therapy (IMRT) treatment planning software must meet
the same dose accuracy standards as conventional planning software despite the increased
complexity of intensity modulated dose delivery. This paper reports on the results of
testing the dosimetric accuracy of Nucletron’s new inverse treatment planning software
(ITP) for IMRT delivery on a Varian 2100C. The testing was done in three phases: 1)
dose accuracy of the beam model for calculating the absolute dose and the shape of the
dose profiles for 1x1, 2x2 and 10x10 cm fields, 2) Absolute dose accuracy for a 1 cm
wide 10 cm long gap dynamically swept across a 10 cm long field at 10 cm depth, and 3)
a series of 10 patient plans consisting of at least 5 beams each were analyzed. This
analysis included single beam fluence maps and coronal plane isodoses in a solid water
phantom. For each phase, measured (using film or ion chamber) and calculated results
were compared. The results indicate that the beam model accurately reproduces the small
fields, the calculated absolute dose for the sliding 1 cm wide gap is within 1% of
measured, calculated fluence maps agree well with measured, the absolute dose at
isocenter for total patient plans is consistently within 2%, and the agreement between
measured and calculated isodoses in a coronal plane in a phantom is typically within 3%
or 3 mm for over 90% of the region covered by isodoses above the 30% level. Nucletron
Corporation, Maryland supported this research.