Epithelia and mesenchyme interact during various physiologic and pathologic processes. Scatter factor is a mesenchyme-derived cytokine that stimulates motility, proliferation, and morphogenesis of epithelia. Recent studies suggest that scatter factor and its receptor (c-met) mediate mesenchyme/epithelia signalling and even interconversion. In this mini-review, we will discuss how scatter factor...

PURPOSE The purpose of this study is to investigate the dose-volume variations of planning target volume (PTV) and organs-at-risk (OARs) in prostate volumetric modulated arc therapy (VMAT) when using different collimator angles. It is because collimator angle awareness is essential for planner to produce an optimal prostate VMAT plan in a rational time. METHODS Single-arc VMAT plans at differ...

We present results of investigations of the clinical significance of variations in the value of the 4-mm-collimator output factor, OF(4/18). Changes in treatment volume, dose-volume histograms (DVHs), and isodose distributions were studied, by varying OF(4/18) up to 20%. The variations were performed on a sample of clinical patient treatment plans for which the 4 mm collimator was used. Althoug...

The angular deflection of a 28.5 GeV electron beam passing off-axis between the jaws of a collimator, generating a transverse wakefield, were measured in End Station A (ESA) at SLAC. In total, fifteen different configurations of collimator geometry and material were tested: some were chosen for compatibility with previous measurements while others served to study the effect of geometry and tape...

Single photon emission computed tomography (SPECT) is based on the measurement of radiation emitted by a radiotracer injected into the patient. Because of photoelectric absorption and Compton scatter, the gamma photons are attenuated inside the body before arriving at the detector. A quantitative reconstruction must consider the attenuation, which is usually nonuniform. Novikov has derived an e...

This work is focussed on developing a commissioning procedure so that a Monte Carlo model, which uses BEAMnrc's standard VARMLC component module, can be adapted to match a specific BrainLAB m3 micro-multileaf collimator (microMLC). A set of measurements are recommended, for use as a reference against which the model can be tested and optimized. These include radiochromic film measurements of do...

Recent advances in collimator design and detector size, combined with radiopharmaceuticals having high photon yield, have resulted in diagnostic tests that may deliver photon fluxes in excess of the levels at which scintillation cameras can process the data. Moreover, these high rates of photon input may im pair certain parameters of image quality (1 ,2). For certain diagnostic tests, such as c...