نتایج جستجو برای: dosimetric audit absolute photon dose linacs
تعداد نتایج: 491847 فیلتر نتایج به سال:
Boron neutron capture therapy (BNCT) is a form of chemically targeted radiotherapy that utilises the high neutron capture cross-section of boron-10 isotope to achieve a preferential dose increase in the tumour. The BNCT dosimetry poses a special challenge as the radiation dose absorbed by the irradiated tissues consists of several dose components with different relative biological effectiveness...
BACKGROUND Intensity-modulated proton therapy (IMPT) has the potential to spare dose to organs at risk (OAR) when compared to intensity-modulated radiotherapy (IMRT) while maintaining excellent clinical outcomes. METHODS Ten patients with nasopharyngeal carcinoma (NPC) were identified for whom IMPT was planned; 9 patients also had a comparison photon-based IMRT plan generated. Dosimetric comp...
BACKGROUND AND PURPOSE The Medical Physics Division of the Portuguese Physics Society (DFM_SPF) in collaboration with the IAEA, carried out a national auditing project in radiotherapy, between September 2011 and April 2012. The objective of this audit was to ensure the optimal usage of treatment planning systems. The national results are presented in this paper. MATERIAL AND METHODS The audit...
PURPOSE To determine the potentialities of synthetic single crystal diamond Schottky diodes for accurate dose measurements in radiation therapy small photon beams. METHODS The dosimetric properties of a diamond-based detector were assessed by comparison with a reference microionization chamber. The diamond device was operated at zero bias voltage under irradiation with high-energy radiotherap...
BACKGROUND AND PURPOSE Absolute dose measurements for Intensity Modulated Radiotherapy (IMRT) beamlets is difficult due to the lack of lateral electron equilibrium. Recently we found that the absolute dosimetry in the penumbra region of the IMRT beamlet, can suffer from significant errors (Capote et al., Med Phys 31 (2004) 2416-2422). This work has the goal to estimate the error made when measu...
The aim of this paper is to analyze the positional accuracy, kinetic properties of the dynamic multileaf collimator (MLC) and dosimetric evaluation of fractional dose delivery for the intensity modulated radiotherapy (IMRT) for step and shoot and sliding window (dynamic) techniques of Varian multileaf collimator millennium 80. Various quality assurance tests such as accuracy in leaf positioning...
OBJECTIVES The impact of two multileaf collimator (MLC) systems for linear accelerator-based intracranial stereotactic radiosurgery (SRS) was assessed. METHODS 68 lesions formed the basis of this study. 2.5 mm leaf width plans served as reference. Comparative plans, with identical planning parameters, were based on a 5 mm leaf width MLC system. Two collimation strategies, with collimation fix...
One of the newest developments within radiotherapy is integration Magnetic Resonance (MR) scanners and Megavoltage X-rays from linear accelerators into new MR-Linacs. Some MR-Linacs are able to perform gated treatments based on continuously acquired 2D MR images taken during dose delivery, which has potential reduce margins required for tumor coverage. We have developed a dosimetry system that ...
In VMAT treatment delivery the ability of the linear accelerator (linac) to accurately control dose versus gantry angle is critical to delivering the plan correctly. A new VMAT test delivery was developed to specifically test the dose versus gantry angle with the full range of allowed gantry speeds and dose rates. The gantry-mounted IBA MatriXX with attached inclinometer was used in movie mode ...
A convolution-based calibration procedure has been developed to use an amorphous silicon flat-panel electronic portal imaging device (EPID) for accurate dosimetric verification of intensity-modulated radiotherapy (IMRT) treatments. Raw EPID images were deconvolved to accurate, high-resolution 2-D distributions of primary fluence using a scatter kernel composed of two elements: a Monte Carlo gen...
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