An optimized forward-planning technique for intensity modulated radiation therapy

Abstract

Intensity modulated radiation therapy (IMRT) has stirred considerable excitement in the radiation oncology community. Its objective is to make the dose conform to the tumor and spare other organs. Instead of resorting to the rather complex inverse-planning, the technique described here is an extension of the conventional treatment planning technique. The beam orientation and wedge angles are chosen in the conventional rule-based manner. However, within each conformal beam's eye view (BEV) field including margin, a number of sub-field openings are added. The smaller field openings are designed to irradiate the tumor, while sparing the normal tissue of the organs at risk (OARs) that intrude into the target region in the BEV. As the number of intrusions into the target BEV increases, the number of sub-fields for each beam increases. The Cimmino simultaneous projection method was employed to obtain the optimized weighting for each field of each beam. In cases where the dose constraints for the tumor and for the OARs are reasonable, it is possible to obtain a plan with a fairly small number of beams that satisfies the specified dose objectives. This is illustrated for the treatment of prostate cancer, where the rectum creates a concavity in the planning target volume. An advantage of this technique is that the quality assurance for the delivery of these plans does not require extensive special efforts.

Potential Effect of Robust and Simple IMRT Approach for Left-Sided Breast Cancer on Cardiac Mortality

“…PrecisePlan features an aperture-based IMRT approach that has been previously described in detail (24). The planning process started with choosing the appropriate beam angles.…”

The dose–volume constraint satisfaction problem for inverse treatment planning with field segments

“…It is instructive to place this particular model and the algorithm in a context of related computational methods (Xing and Chen, 1996;Shepard et al, 2000;Xiao et al, 2000;Starkschall et al, 2001;Xiao et al, 2003a). The SSP algorithm applied to the model without DVC functions, i.e., only with the dose limit constraints (DL-SSP), coincides with the well behaved Cimmino method of the simultaneous projections onto linear constraint sets (Censor and Zenios, 1997;Stark and Yang, 1998).…”

Intensity-Modulated Radiation Therapy (IMRT) with Different Combinations of Treatment-Planning Systems and Linacs

“…Alternatively, the user can manually create, shape and correct the segments. Optimization is performed for the weight of the segments (i.e., monitor units) based on dose-volume constraints (DVCs) given by the user [27].…”