Search results for "TRIPS"

STUDIES OF WIRE GAIN AND TRACK DISTORTION NEAR THE SECTOR EDGES OF THE ALEPH TIME PROJECTION CHAMBER

1986

Abstract The materials used to hold the wires at the sector edges in a large Time Projection Chamber (TPC) inrtoduce distortions of the electric drift field near those edges. These distortions degrade tracking information and sometimes cause large changes in wire gain near the edge. We have studied these two problems for the ALEPH TPC and have found that both can be greatly reduced by the addition of two field correction strips held at appropriate voltages.

Development of a High Precision Axial 3-D PET for Brain Imaging

2009

We describe a PET device based on a novel method to extract the coordinates of the interaction point of the 511keV γ rays from 100 mm long and thin LYSO (Lutetium Yttrium OxyorthoSilicate) scintillator bars, positioned axially in the tomograph. The coordinate along the hit crystal is measured by using a hodoscope of Wave Length Shifting (WLS) plastic strips mounted perpendicularly to each plane of scintillators. As photodetectors, new Geiger mode Avalanche PhotoDetectors (G-APDs) with integrated electronics are being used to detect both the hit crystal in a block (x and y coordinates) and the interaction point in the crystal (z coordinate) through the light escaping from the crystal and tra…

The AX-PET Concept: New Developments And Tomographic Imaging

2011

The Axial PET (AX-PET) concept proposes a novel detection geometry for PET, based on layers of long scintillating crystals axially aligned with the bore axis. Arrays of wavelength shifting (WLS) strips are placed orthogonally and underneath the crystal layers; both crystals and strips are individually readout by G-APDs. The axial coordinate is obtained from the WLS signals by means of a Center-of-Gravity method combined with a cluster algorithm. This design allows spatial resolution and sensitivity to be decoupled and thus simultaneously optimized. In this work we present the latest results obtained with the 2-module AX-PET scanner prototype, which consists of 6 radial layers of 8 LYSO crys…

Sub-kelvin current amplifier using DC-SQUID

2000

Abstract We have set up a system where a low-noise DC-SQUID is used as a current amplifier. The SQUID output is read using a wide band electronics unit based on the noise cancellation scheme. The SQUID has been installed in a compact Nanoway PDR50 dilution refrigerator, and superconducting transitions of Ti/Au thermometer strips for X-ray calorimeter applications have been measured. We can operate at 100 mK using a SQUID with Pd shunt resistors. Noise and bandwidth results of the setup are presented.

Physics of Shock-wave Lithotripsy

2018

Sialolithiasis. Proposal for a new minimally invasive procedure: Piezoelectric surgery

2014

Sialolithiasis is the presence of stones in the ducts of the salivary glands. Most episodes are unique, and 60-80% are located exclusively in the main excretory duct. The main clinical manifestations are swelling and pain typically before, during or after meals that decreases if the obstruction is not complete. The highest prevalence of lithiasis is in the submandibular gland -87%-, whose secretion is more viscous, followed by the parotid gland -10%- and finally the sublingual gland -3%-. The most significant consequences are caused by the prolonged blockage of the duct by a stone, which can produce a persistent ductal dilatation with a swelling that does not subside, and could lead to the …

Assessment of a Modified Acoustic Lens for Electromagnetic Shock Wave Lithotripters in a Swine Model

2013

The acoustic lens of the Modularis electromagnetic shock wave lithotripter (Siemens, Malvern, Pennsylvania) was modified to produce a pressure waveform and focal zone more closely resembling that of the original HM3 device (Dornier Medtech, Wessling, Germany). We assessed the newly designed acoustic lens in vivo in an animal model.Stone fragmentation and tissue injury produced by the original and modified lenses of the Modularis lithotripter were evaluated in a swine model under equivalent acoustic pulse energy (about 45 mJ) at 1 Hz pulse repetition frequency. Stone fragmentation was determined by the weight percent of stone fragments less than 2 mm. To assess tissue injury, shock wave trea…

Ureteral Stones: Shockwave Lithotripsy or Ureteroscopy, Which is Best?

2021

Background Renal stone disease is common and can cause emergency presentation with acute pain due to ureteric colic. International guidelines have stated the need for a multicentre randomised controlled trial (RCT) to determine whether a non-invasive outpatient (shockwave lithotripsy [SWL]) or surgical (ureteroscopy [URS]) intervention should be the first-line treatment for those needing active intervention. This has implications for shaping clinical pathways. Objective To report a pragmatic multicentre non-inferiority RCT comparing SWL with URS. Design, setting, and participants This trial tested for non-inferiority of up to two sessions of SWL compared with URS as initial treatment for ur…

Gender differences in bicycle sharing system usage in the city of Valencia

2021

Abstract Bicycle sharing systems (BSS) in cities are an environmentally friendly alternative to fossil-fuel-based transport. Among the different factors that influence its use, the scientific literature points out that there are gender differences in the frequency of trips made. The present study analysed the movements of men and women who use the BSS in the city of Valencia during weekdays. Our database contained a total of 5,300,328 trips by users over a period of 4 years. Ridership networks were constructed through user's trips (arcs) between the bicycle exchange stations (nodes). Different parameters of centrality and density of the generated networks were calculated, and the Voronoi sp…

AX-PET: A novel PET detector concept with full 3D reconstruction

2009

We describe the concept and first experimental tests of a novel 3D axial Positron Emission Tomography (PET) geometry. It allows for a new way of measuring the interaction point in the detector with very high precision. It is based on a matrix of long Lutetium-Yttrium OxyorthoSilicate (LYSO) crystals oriented in the axial direction, each coupled to one Geiger Mode Avalanche Photodiode (G-APD) array. To derive the axial coordinate, Wave Length Shifter (WLS) strips are mounted orthogonally and interleaved between the crystals. The light from the WLS strips is read by custom-made G-APDs. The weighted mean of the signals in the WLS strips has proven to give very precise axial resolution. The ach…