A Longitudinal Computed Tomography Imaging in the Diagnosis of Gallbladder Cancer

Background/Aim. To assess whether the diagnostic power of longitudinal multiplanar reformat (MPR) images is superior to that of conventional horizontal images for gallbladder cancer (GBC). Methods. Between 2006 and 2010, a total of 54 consecutive patients with preoperatively diagnosed gallbladder neoplasms located in gallbladder bed were analyzed. These patients underwent cholecystectomy with resection of the adjacent liver parenchyma. The patients were divided into the GBC group (n=30) and the benign group (n=24). MPR images obtained by preoperative multidetector row CT (MDCT) were assessed. Results. Mucosal line was more significantly disrupted in GBC group than that in benign group (93% [28/30 patients] versus 13% [3/24], p<0.001). Maximum (9.3 [4.2–24.8] versus 7.0 mm [2.4–22.6], p=0.29) and minimum (1.2 [1.0–2.4] versus 1.3 mm [1.0–2.6], p=0.23) wall thicknesses on a single MPR plane did not differ significantly; however, the wall thickness ratio (max/min) differed significantly (6.8 [1.92–14.0] versus 5.83 [2.3–8.69], p=0.04). Partial liver enhancement adjacent to tumor on longitudinal images was more common in GBC (40.0% [12/30 patients] versus 12.5% [3/24], p=0.03). Mucosal line disruption was the most reliable independent predictor of diagnosis (odds ratio, 8.5; 95% CI, 5.99–28.1, p<0.001). Conclusion. Longitudinal MPR images are more useful than horizontal images for the diagnosis of GBC

Measurements of total reaction cross sections for 17Ne using a solid hydrogen target

We measured the energy dependence of the total reaction cross sections (σR) for the proton-drip-line nucleus, 17Ne, using a solid hydrogen target. We compared the experimental data with theoretical calculations using the Glauber model. We found that the theoretical cross sections overestimate the experimental ones in the low-energy region (∼100A MeV), whereas they significantly underestimate the experimental data in the intermediate-energy region (∼300-500A MeV). These trends are the same as those for σR for carbon–proton collisions, which were measured previously. We discuss several possibilities for resolving this discrepancy. This work demonstrates the necessity of additional careful investigations of the energy dependence of σR for various nuclei on proton targets in order to determine nuclear size properties precisely

Efficiency and timing performance of time-of-flight detector utilizing thin foils and crossed static electric and magnetic fields for mass measurements with Rare-RI Ring facility

We developed a time-of-flight (TOF) detector for mass measurements of rare radioactive isotopes (RIs) with a storage ring, called the Rare-RI Ring, in RIKEN. For successful mass measurements, a time resolution of less than 100 ps and a detection efficiency close to 100% are required. Additionally, the change of ion velocity in the detector should be as small as possible ( ). To satisfy these requirements, the TOF detector utilizes ion-induced secondary electrons emitted from a thin foil and the crossed static electric and magnetic fields to transport the electrons isochronously to the microchannel plate detectors. The TOF detector was tested in both offline test with an alpha source and online test with heavy ions. In the online test with 84Kr ions of 200 MeV/nucleon, a time resolution of 38.6(2) ps in sigma and a position-averaged detection efficiency of 95.2(2)% were achieved in the entire area of 45-mm-diameter aluminum-coated Mylar foil. This good performance is attributed to the electromagnetic field achieved, which is the strongest thus far for a detector with this design

Development and operation of an electrostatic time-of-flight detector for the Rare RI storage Ring

An electrostatic time-of-flight detector named E-MCP has been developed for quick diagnostics of circulating beam and timing measurement in mass spectrometry at the Rare-RI Ring in RIKEN. The E-MCP detector consists of a conversion foil, potential grids, and a microchannel plate. Secondary electrons are released from the surface of the foil when a heavy ion hits it. The electrons are accelerated and deflected by 90◦toward the microchannel plate by electrostatic potentials. A thin carbon foil and a thin aluminum-coated mylar foil were used as conversion foils. We obtained time resolutions of 69(1) ps and 43(1) ps (standard deviation) for a84Krbeam at an energy of 170 MeV/u when using the carbon and the aluminum-coated mylar foils, respectively. A detection efficiency of approximately 90% was obtained for both foils. The E-MCP detector equipped with the carbon foil was installed inside the Rare-RI Ring to confirm particle circulation within a demonstration experiment on mass measurements of nuclei around 78Ge produced by in-flight fission of uranium beam at the RI Beam Factory in RIKEN. Periodic time signals from circulating ions were clearly observed. Revolution times for 78Ge, 77Ga, and 76Zn were obtained. The results confirmed successful circulation of the short-lived nuclei inside the Rare-RI Ring