Lower gastrointestinal endoultrasound
SummaryFollowing a brief history of transrectal ultrasonography, the author explains the fundamentals that led to his research on rectal echographic layers and then describes his theory as applied to the anatomical interpretation of these layers. Personal cases of preoperative staging with transrectal echography provide a basis for the critical evaluation of this method and its proposed role in clinical application.
Endoluminal ultrasonic scanning in the evaluation of rectal cancer: A preliminary report of 13 cases
In 13 patients with a verified tumor of the rectum, endoluminal ultrasonic scanning was performed to evaluate the degree of tumor infiltration in the muscular wall and the perirectal tissue. In 11 cases the degree of tumor infiltration found by ultrasonic scanning was in complete accordance with the histopathologic finding. In 2 cases the examination was incomplete because the ultrasonic probe could not pass the tumor. We believe that endoluminal ultrasonic scanning with further development of the equipment will be a valuable additional diagnostic tool in the evaluation of gastrointestinal tract tumors. It will make it possible to decide whether local excision of the tumor is possible, based on the diagnostic procedure.
Photoreflectance characterization of vanadium-doped GaAs layers grown by metalorganic vapor phase epitaxy
Abstract We characterized the vanadium-doped (GaAs:V) layers grown on GaAs substrate by metalorganic vapor phase epitaxy. The conductivity of the samples is checked by the Hall effect measurements, and it is n type with electrons concentration ranging from 2×10 13 to 2×10 17  cm −3 . We used the photoreflectance technique (PR) to study the effect of vanadium doping on the optical properties of GaAs. Our experimental results show that the built-in electric field F and the broadening parameter Γ 0 increase with V-doping concentration. Furthermore, the temperature dependence of the built-in electric field and the broadening parameter of GaAs:V samples have been investigated by PR. It has been observed that these parameters increase with increasing temperature. The decrease of the built-in electric field with decreasing temperature is due to the photovoltage effect.We characterized the vanadium-doped GaAs (GaAs:V) layers grown on GaAs substrate by metalorganic vapor phase epitaxy.