PubMed · 15417385
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
F MAGANO. 1950. [Conjectures].. https://pubmed.ncbi.nlm.nih.gov/15417385/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Advances in medicine have enabled more craniopagus twins to survive separation, but the ultimate goal, to have both twins emerge from their separation with full neurologic function and a chance at leading independent and productive lives, remains elusive. The authors were contacted to evaluate craniopagus conjoined male infant twins for separation. Once it was determined that the brains were separate, they reviewed the literature and elected to design an open-ended multistaged separation. Four major stages over 9 and a half months led to the successful separation and preservation of neurologic function. To the authors' knowledge, this is the first such outcome in such a case. This article reviews the pertinent literature and discusses the authors' rationale and methodology.
Dose assessment in computed tomography (CT) is challenging due to the vast variety of CT scanners and imaging protocols in use. In the present study, the accurateness of a theoretical formalism implemented in the PC program CT-EXPO for dose calculation was evaluated by means of phantom measurements. Phantom measurements were performed with four 1-slice, four 4-slice and two 16-slice spiral CT scanners. Firstly, scanner-specific nCTDIw values were measured and compared with the corresponding standard values used for dose calculation. Secondly, effective doses were determined for three CT scans (head, chest and pelvis) performed at each of the ten installations from readings of thermoluminescent dosimeters distributed inside an anthropomorphic Alderson phantom and compared with the corresponding dose values computed with CT-EXPO. Differences between standard and individually measured nCTDIw values were less than 16%. Statistical analysis yielded a highly significant correlation (P < 0.001) between calculated and measured effective doses. The systematic and random uncertainty of the dose values calculated using standard nCTDIw values was about -9 and +/- 11%, respectively. The phantom measurements and model calculations were carried out for a variety of CT scanners and representative scan protocols validate the reliability of the dosimetric formalism considered-at least for patients with a standard body size and a tube voltage of 120 kV selected for the majority of CT scans performed in our study.
Inhomogeneous magnetic fields produce artifacts in MR images including signal dropout and spatial distortion. A novel perturbative method for calculating the magnetic field to first order (error is second order) within and around nonconducting objects is presented. The perturbation parameter is the susceptibility difference between the object and its surroundings (for example, approximately 10 ppm in the case of brain tissue and air). This method is advantageous as it is sufficiently accurate for most purposes, can be implemented as a simple convolution with a voxel-based object model, and is linear. Furthermore, the method is simple to use and can quickly calculate the field for any orientation of an object using a set of precalculated basis images.