Practical aspects of implementation of helical tomotherapy for intensity-modulated and image-guided radiotherapy.

Aims: Image-guided radiotherapy (IGRT) and intensity-modulated radiotherapy (IMRT) represent two important technical developments that will probably improve patient outcome. Helical tomotherapy, provided by the TomoTherapy HiArt system, provides an elegant integrated solution providing both technologies, although others are available. Here we report our experience of clinical implementation of daily online IGRT and IMRT using helical tomotherapy.

Evidence of long-wavelength collective excitations in magnetic superlattices.

We report on a mechanism of dynamic dipolar coupling in magnetic superlattices via long-wavelength nonevanescent fields. In the spin excitation spectra of our heterophase stripe structures, such interactions mediate a singlet<-->doublet crossover in the frequency regime driven by the orientation of an external static field. This crossover is a new feature observed in collective behavior of superlattices, though there is some analogy of this phenomenon with birefringence taking place in optical superlattices.

Simple helium cryostat for Raman spectroscopy.

We describe a simple and inexpensive flowing gas helium cryostat which efficiently cools the surface of a sample and eliminates the need for good thermal contact between the sample and a substrate.

A double pass spectrometer for the far infrared.

A far ir spectrometer has been built which uses a double pass optical system to increase the spectral dispersion. Because of the energy limitations in this spectral range, this means of increasing the dispersion is an efficient way to improve the resolving power of a grating monochromator. The same optical system is also used to advantage in a lamellar grating interferometer where the increased dispersion improves the performance at higher frequencies.