Optimization of sliding windows IMRT treatment planning

Abstract

Intensity-modulated radiation therapy (IMRT) with sliding windows is a form of radiation therapy that delivers precise radiation dose to a tumor/target region. It uses a multi-leaf collimator (MLC) to move pairs of unidirectional tungsten leaves across a radiation emitting region to conform the shape of the radiation beam to the target regions. This is a dynamic treatment approach which aims to deliver adequate radiation dose to target regions while minimizing radiation delivery to healthy tissues. This paper proposes a linear optimization model for IMRT with sliding windows. This model directly incorporates a number of deliverability constraints to conform to physical limitations of the LINAC, including the required distance between leaves through the treatment process and restrictions on leaf interdigitation. We demonstrate the viability of this model using patient data and discuss the leaf motion proposed by our model. Such a model can be embedded in treatment planning systems to improve both the quality of the treatment and the efficiency of the treatment planning process.

Keywords:

• Linear programming
• radiation therapy
• sliding windows IMRT
• dose-volume histogram
• optimization

Additional information

Funding

This work is supported in part by the Natural Sciences and Engineering Research Council of Canada (NSERC), grant number: RGPIN 50503-10205.