FLASH Dose Rate Helium Ion Beams: First In Vitro Investigations.

Purpose: To establish and investigate the effects of dose, linear energy transfer (LET), and O concentration on biologic response to ultrahigh dose rate (uHDR; FLASH) helium ion beams compared with standard dose rate (SDR) irradiation.

Methods And Materials: Beam delivery settings for raster-scanned helium ions at both uHDR and SDR were tuned to achieve >100 Gy/s and ∼0.1 Gy/s, respectively.

Fluence inhomogeneities due to a ripple filter induced Moiré effect.

At particle therapy facilities with pencil beam scanning, the implementation of a ripple filter (RiFi) broadens the Bragg peak, so fewer energy steps from the accelerator are required for a homogeneous dose coverage of the planning target volume (PTV). However, sharply focusing the scanned pencil beams at the RiFi plane by ion optical settings can lead to a Moiré effect, causing fluence inhomogeneities at the isocenter. This has been experimentally proven at the Heidelberg Ionenstrahl-Therapiezentrum (HIT), Universitätsklinikum Heidelberg, Germany.

Status of high current ion source operation at the GSI accelerator facility.

Vacuum arc ion sources, Penning ion sources, and filament driven multicusp ion sources are used for the production of high current ion beams of a variety of metallic and gaseous ions at the GSI accelerator facility. For accelerator operation, the ion sources have to provide a stable beam over a long period of time with an energy of 2.2 keV/u and a maximum mass over charge ratio of 65.

Characterization of atherosclerotic plaques in human coronary arteries with 16-slice multidetector row computed tomography by analysis of attenuation profiles.

Rationale And Objectives: We investigated if 16-slice multidetector row computed tomography (MDCT) allows correct classification of coronary plaques into calcified or noncalcified and further subclassification of noncalcified plaques into either lipid-rich with a necrotic core or fibrous.

Materials And Methods: Coronary arteries of 30 isolated hearts were filled postmortem with a contrast medium and scanned with a 16-slice MDCT imager (Light Speed 16 pro, GEMS, Milwaukee, WI). Imaging parameters: collimation 16 x 0.