background: identify the optimal technique of radiotherapy for patients with high grade glioma. our initial year of experience with rapidarc radiation therapy. materials and methods: planning ct scans of 50 patients with grade iv glioma were reviewed and three plan sets by 3d conformal radiotherapy (3dcrt), intensity modulated radiotherapy (imrt) and rapid arc (ra) were generated and the plans ...

The capability of the TrueBeam treatment system to deliver step and shoot IMRT plans at low dose rates was evaluated. Beam characteristics during low dose rates (5 to 100 MU/min) were evaluated for consistency using a planar ion chamber array. MU constancy, linearity, and beam profile symmetry were all found to be equivalent within 0.5%. The response of the Scandi Dos Delta 4 system was also ev...

A common way to solve intensity-modulated radiation therapy (IMRT) optimization problems is to use a beamlet-based approach. The approach is usually employed in a three-step manner: first a beamlet-weight optimization problem is solved, then the fluence profiles are converted into step-and-shoot segments, and finally postoptimization of the segment weights is performed. A drawback of beamlet-ba...

In inverse planning for intensity-modulated radiation therapy (IMRT), the dose specification and related weighting factor of an objective function for involved organs is usually predefined by a single value and then iteratively optimized, subject to a set of dose-volume constraints. Because the actual dose distribution is essentially non-uniform and considerably affected by the geometric shape ...

Introduction: Whole breast radiotherapy after breast-conserving surgery decrease the risk of local recurrence. this study investigates the dosimetric aspects of intensity modulated radiotherapy (IMRT) compared to conventional tangential wedge-based beams techniques (CTT) of the whole breast in early stages breast cancer patients.   Materials and Methods: Co...

Intensity-modulated radiation therapy (IMRT) can be delivered inefficiently using the movable jaws of a linac. The efficiency can be much improved by delivering IMRT with the movable jaws together with a relocatable mask below the jaws (Webb 2002 Phys. Med. Biol. 47 257-75). This paper extends the modelling work by showing that a much simpler relocatable mask than previously conceptualized can ...

The recent development of intensity modulated radiation therapy (IMRT) allows the dose distribution to be tailored to match the tumour's shape and position, avoiding damage to healthy tissue to a greater extent than previously possible. Traditional treatment plans assume that the target structure remains in a fixed location throughout treatment. However, many studies have shown that because of ...

The quantitative comparison of two-dimensional dose distributions (e.g., calculated versus measured) has become a key issue in intensity-modulated radiotherapy (IMRT) QA. We proposed a new evaluation method referred to as modified dose difference (MDdiff) evaluation. Hereinafter, features and effectiveness of the MDdiff evaluation method will be described. In this work, the formalism of MDdiff ...

Highly attenuating radiation treatment couches are no longer useful in the present era of radiotherapy utilizing IMRT and IGRT. Carbon fibers couch tops with its high tensile strength and low density present a useful alternative. The objective of the current study was to quantify the attenuation of megavoltage photons through a Brainlab imaging couch top and headrest at various angles and field...

We consider Pareto surface based multi-criteria optimization for step and shoot IMRT planning. By analyzing two navigation algorithms, we show both theoretically and in practice that the number of plans needed to form convex combinations of plans during navigation can be kept small (much less than the theoretical maximum number needed in general, which is equal to the number of objectives for o...