AbstractID: 8603 Title: Implementation of a Virtual Micro-Multi-Leaf Collimator in a
Treatment Planning System
Multi-leaf collimators have been used for more than a decade to conform the radiation treatment fields to the planning target volume.
However, since the projected leaf width of most commercially available multi-leaf collimators is of the order of 1 cm at the isocenter
plane, the radiation field edges have a step-like character to them. Recently, the development of the HD-270TM (by Siemens) permits
the splitting of a radiation treatment portal into sub-portals that are comprised of simultaneous static longitudinal shifts and leaf
adjustments. The sum of these sub-portals produces a dose distribution which is still conformal but whose penumbra is smoother1,2.
In this paper we present a comparison of the dose distribution for the sub-portals of the HD-270TM sequence obtained experimentally
using film and numerically by importing the sub-portals in a commercial treatment planning system using DICOM-RT. We find that
the calculated isodose distribution for the sum of the sub-portals is smoother than the calculated isodose distribution of the original
portal. We also find that the calculated isodose distributions for the HD-270TM sequence agree well with the corresponding measured
isodose distributions. In conclusion, we can incorporate the effect of the splitting of a radiation treatment portal by the HD-270TM into
our treatment planning system with the aid of DICOM-RT.
1
2
J.M. Galvin et al., Int. J. Radiat., Oncol., Biol., Phys. 35 (1), p89 (1996)
R. Mitra et al., presented at 43rd Annual AAPM Meeting (2001)