RF acceleration of ultracold electron bunches.

The ultrafast and ultracold electron source, based on laser cooling and trapping of atomic gas and its subsequent near-threshold two-step photoionization, is capable of generating electron bunches with a high transverse brightness at energies of roughly 10 keV. This paper investigates the possibility of increasing the range of applications of this source by accelerating the bunch using radio frequency electromagnetic fields. Bunch energies up to 35 keV are measured by analyzing the diffraction patterns generated from a mono-crystalline gold sample.

Subpicosecond Ultracold Electron Source.

We present the first observation of subpicosecond electron bunches from an ultracold electron source. This source is based on near-threshold, two-step, femtosecond photoionization of laser-cooled rubidium gas in a grating magneto-optical trap. Bunch lengths as short as 735±7  fs (rms) have been measured in the self-compression point of the source by means of ponderomotive scattering of the electrons by a 25 fs, 800 nm laser pulse.

SAFESTEREO: phase II randomized trial to compare stereotactic radiosurgery with fractionated stereotactic radiosurgery for brain metastases.

Background: Stereotactic radiosurgery (SRS) is a frequently chosen treatment for patients with brain metastases and the number of long-term survivors is increasing. Brain necrosis (e.g.

Impact of PTV margin reduction (2 mm to 0 mm) on pseudoprogression in stereotactic radiotherapy of solitary brain metastases.

Purpose: To determine the influence of PTV-margin (0 mm versus 2 mm) on the incidence of pseudoprogression (PP) and local tumour control (LC) in patients treated with stereotactic radiotherapy (SRT) for solitary brain metastases.

Methods: Patients were treated on Novalis LINAC. Three dose schedules were used depending on the PTV-size.