Our study provides essential information on the spectral differentiation of tissue, urinary stones, and relevant endoscope components. The measurements indicate that differentiation using fluorescence is possible for all relevant stone types.

No abstract

We investigate heteronuclear collisions in isotope mixtures of laser-cooled metastable ( 3 P2) neon. Experiments are performed with spin-polarized atoms in a magnetic trap for all two-isotope combinations of the stable neon isotopes 20 Ne, 21 Ne, and 22 Ne. We determine the rate coefficients for heteronuclear ionizing collisions to β21,20 = (3.9 ± 2.7) × 10 −11 cm 3 /s, β22,20 = (2.6 ± 0.7) × 10 −11 cm 3 /s, and β21,22 = (3.9 ± 1.9) × 10 −11 cm 3 /s. We also study heteronuclear elastic collision processes and give upper bounds for heteronuclear thermal relaxation cross sections. This work significantly extends the limited available experimental data on heteronuclear ionizing collisions for laser-cooled atoms involving one or more rare gas atoms in a metastable state. I. INTRODUCTIONDue to their high internal energy which surpasses the ionization energy of almost all neutral atomic and molecular collision partners, metastable rare-gas atoms (Rg*) prepared by laser cooling techniques [1] present a unique class of atoms for the investigation of cold and ultracold collisions [2]. With lifetimes ranging from 14.73 s (neon)[3] to 7870 s (helium) [4], the first excited metastable states present effective ground states for applying standard laser cooling techniques. The resulting extremely low kinetic energy of the laser-cooled atoms (≈ 10 −10 eV) stands in strong contrast to the high internal energy between 8 eV (xenon) and 20 eV (helium). This offers unique conditions not accessible with samples of lasercooled alkali-metal atoms. In particular, the high internal energy of the metastable state allows for Penning (PI) and associative (AI) ionizing collisions,to dominate losses in trapped Rg* samples at high densities. Since direct detection of the collision products (using electron multipliers) as well as of the remaining Rg* atoms is possible with high efficiency, detailed studies of homonuclear ionizing collisions have been carried out for all rare gas elements (see [1] for an overview). Additional motivation for these investigations arises from the fact, that favorable rate coefficients for inelastic but also for elastic collisions are essential for the achievement of quantum degeneracy which for Rg* atoms so far has only been demonstrated for 4 He [5-8] and 3 He [9]. For unpolarized Rg* samples, two-body loss rate coefficients for PI [10] between β = 6 × 10 −11 cm 3 /s for 132 Xe [11] and β = 1 × 10 −9 cm 3 /s for 22 Ne [12] have been measured. Spin polarizing the atoms to a spin-stretched * gerhard.birkl@physik.tu-darmstadt.de state may suppress PI: In a collision of atoms in spinstretched states the total spin of the reactants is larger than the total spin of the products. Thus, if spin is conserved, PI collisions should be significantly reduced. In the case of He* in the 3 S 1 state, a suppression of four orders of magnitude has been observed [7,13]. For the heavier rare gases, however, the metastable state 3 P 2 is formed by an exited s electron and a p 5 core with orbital momentum l = 1. This leads to an anisot...

Introduction and objective Thermal injuries associated with Holmium laser lithotripsy of the urinary tract are an underestimated problem in stone therapy. Surgical precision relies exclusively on visual target identification when applying laser energy for stone disintegration. This study evaluates a laser system that enables target identification automatically during bladder stone lithotripsy, URS, and PCNL in a porcine animal model. Methods Holmium laser lithotripsy was performed on two domestic pigs by an experienced endourology surgeon in vivo. Human stone fragments (4–6 mm) were inserted in both ureters, renal pelvises, and bladders. Ho:YAG laser lithotripsy was conducted as a two-arm comparison study, evaluating the target identification system against common lithotripsy. We assessed the ureters’ lesions according to PULS and the other locations descriptively. Post-mortem nephroureterectomy and cystectomy specimens were examined by a pathologist. Results The sufficient disintegration of stone samples was achieved in both setups. Endoscopic examination revealed numerous lesions in the urinary tract after the commercial Holmium laser system. The extent of lesions with the feedback system was semi-quantitatively and qualitatively lower. The energy applied was significantly less, with a mean reduction of more than 30% (URS 27.1%, PCNL 52.2%, bladder stone lithotripsy 17.1%). Pathology examination revealed only superficial lesions in both animals. There was no evidence of organ perforation in either study arm. Conclusions Our study provides proof-of-concept for a laser system enabling automatic real-time target identification during lithotripsy on human urinary stones. Further studies in humans are necessary, and to objectively quantify this new system’s advantages, investigations involving a large number of cases are mandatory.

No abstract