A Sensitivity-Driven Greedy Approach to Fluence Map Optimization in Intensity-Modulated Radiation Therapy

AIM To examine the impact of beam rate on dose distribution in IMRT plans and then to evaluate agreement of calculated and measured dose distributions for various beam rate values. BACKGROUND Accelerators used in radiotherapy utilize some beam rate modes which can shorten irradiation time and thus reduce ability of patient movement during a treatment session. This aspect should be considered ...

Planning and delivery in HN-IMRT has been challenging for the Elekta linac because of numerous machine limitations. Direct aperture optimization (DAO) algorithms have had success in simplifying the planning process and improving plan quality. Commercial adaptations of DAO allow for widespread use in many clinics; however clinical validation of these methods is still needed. In this work we eval...

PURPOSE Volumetric modulated arc therapy (VMAT) is a specific type of intensity-modulated radiation therapy (IMRT) in which the gantry speed, multileaf collimator (MLC) leaf position, and dose rate vary continuously during delivery. A treatment planning system for VMAT is presented. METHODS Arc control points are created uniformly throughout one or more arcs. An iterative least-squares algori...

This paper attempts to provide an answer to some questions that remain either poorly understood, or not well documented in the literature, on basic issues related to intensity modulated radiation therapy (IMRT). The questions examined are: the relationship between degeneracy and frequency response of optimizations, effects of initial beamlet fluence assignment and stopping point, what does filt...

In step-and-shoot IMRT plans, aperture-based optimization (or one-step optimization) has been considered as a means of improving monitor unit (MU) efficiency compared to fluence-based optimization (or two-step optimization). However, the extent of improvement on MU efficiency varies, depending on the implementation and design of one-step optimization. In this paper, we attempted to investigate ...

PURPOSE/OBJECTIVE(S) IMRT allows dose escalation for large lung tumors, but respiratory motion may compromise delivery. A treatment plan that modulates fluence predominantly in the transversal direction and leaves the fluence identical in the direction of the breathing motion may reduce this problem. MATERIALS/METHODS Planning-CT-datasets of 20 patients with Stage I-IV non small cell lung can...

Innovation/Impact: We propose a novel delivery method for intensity modulated radiation therapy (IMRT) that significantly reduces treatment delivery times by delivering dose during both inhale and exhale windows. We developed an inverse treatment planning method for developing inhale and exhale IMRT fluence maps that produce a final dose (the summed inhale and exhale doses) that meets clinical ...