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BACKGROUND In general, the IMRT optimisation problem possesses many equivalent solutions. This makes it difficult to decide whether a result produced by an IMRT planning algorithm can be further improved, e.g. by adding more beams, or whether it is close to the globally best solution. RESULTS It is conjectured that the curvature properties of the objective function around any globally optimum...

Recently the compensator has been shown to be an in expensive and reliable dose delivery device for photon beam intensity-modulated radiation therapy (IMRT). The goal of IMRT compensator design is to produce an optimized primary fluence profile at the patient's surface obtained from the optimization procedure. In this paper some of the problems associated with IMRT compensator design, specifica...

There is a pressing need for clinically intuitive quality assurance methods that report metrics of relevance to the likely impact on tumor control of normal tissue injury. This paper presents a preliminary investigation into the accuracy of a novel "transform method" which enables a clinically relevant analysis through dose-volume-histograms (DVHs) and dose overlays on the patient's CT data. Th...

Inverse treatment planning for intensity-modulated radiotherapy may include time consuming, multiple minimizations of an objective function. In this paper, methods are presented to speed up the process of (repeated) minimization of the well-known quadratic dose objective function, extended with a smoothing term that ensures generation of clinically acceptable beam profiles. In between two subse...

In a radiotherapy department having more than one linear accelerator, it is rather common to match the dose output of all machines. In particular, the recently developed flattening filter free mode requires new investigations regarding the feasibility of matching and the consequences for quality assurance and workload. This refers also to the beam model of the radiotherapy treatment planning sy...

The purpose was to evaluate the effect of dose rate on discrepancies between expected and delivered dose caused by the interplay effect. Fifteen separate dynamic IMRT plans and five hybrid IMRT plans were created for five patients (three IMRT plans and one hybrid IMRT plan per patient). The impact of motion on the delivered dose was evaluated experimentally for each treatment field for differen...

In radiotherapy practice, one often needs to compare two dose distributions. Especially with the wide clinical implementation of intensity-modulated radiation therapy, software tools for quantitative dose (or fluence) distribution comparison are required for patient-specific quality assurance. Dose distribution comparison is not a trivial task since it has to be performed in both dose and spati...

Background: Radiation Pneumonia (RP) is one of the most extensive side effects in Stereotactic Body Radiotherapy (SBRT) of lung cancer. SBRT are performed by means of Intensity Modulated Radiotherapy (IMRT), Intensity Modulated Arc Therapy (IMAT), CyberKnife (CK) or Helical Tomotherapy (HT) treatment methods. In this study, we performed a plan study to determine the plan parameter such as the M...

Intensity-modulated radiotherapy (IMRT) has become an effective tool for cancer treatment with radiation. However, even expert radiation planners still need to spend a substantial amount of time manually adjusting IMRT optimization parameters such as dose limits and costlet weights in order to obtain a clinically acceptable plan. In this paper, we describe two main advances that simplify the pa...