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The characteristics of a novel, very high resolution film/screen system for mammography are compared with those of a conventional film/screen system for mammography. The image quality characteristics of these systems are measured in terms of Wiener spectra, MTF and sensitometry. These parameters then determine the signal-to-noise (SNR) transfer properties of these systems in terms of the contrast transfer function (CTF), the detective quantum efficiency (DQE) and the noise equivalent quantum efficiency (NEQ). Furthermore, the SNR transfer characteristics are modeled and rationalized by means of the light scattering properties of the intensifying screens and the scintillation spectra of the phosphor. The new system displays superior SNR properties ascribable to its x-ray absorption attributes and the light scattering properties of the phosphor coating.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Conclusions 1. With the advent of the information age the United States has lost the "sanctuary" that it has enjoyed for over 200 years. In the past ordinary citizens and businesses could be protected by control of the airspace, land, and the seas. Now an attack may be launched directly against a citizen passing right through (or around) all our traditional lines of defense. 2. The environment for developing and implementing national security policy is neither designed nor equipped to deal with events resulting from sources not rooted in the temporal or physical restrictions of the past. 3. Today's interagency approach to national security is not compatible with the speeds of the information age. Current government and civil institutions led by the Federal Emergency Management Agency (FEMA) are not designed to deal with attacks and natural disasters that move at the speed of light, crossing geographic and legal boundaries with impunity. 4. The National Security Council (NSC) needs to define the boundaries that separate technology-based attacks that are merely a nuisance from those that constitute national security threats. The Emerging Threat We have entered an era of immense global change and we must recognize that protection of the public during domestic emergencies has taken on new meanings with new consequences. A new process needs to be developed that defines the specific responsibilities of federal and state governments for technological disasters. The DOD has taken the initiative and has established new educational and training programs focused on Information Warfare and Strategy, Command and Control Warfare, and Information Operations. But solutions to the problem are larger than the DOD and other organizations must be engaged. Issues involving information technology, national security, and civil defense cross many if not all of the traditional governmental boundaries thus ultimately requiring a truly holistic solution. Vice President Al Gore's announcement of a National Information Infrastructure was a harbinger of things to come rather than a fait accompli. Economic and public policy theorists widely tout the emergence of a "Global Economy," with its components inextricably linked as result of rapidly advancing communications technology. The nature of these linkages will help define economic, diplomatic, and military relationships well into the next century. Modern societies (particularly the United States) increasingly rely upon the kind of information infrastructures that have enabled the emergence of the Global Economy. Infrastructures that do not and cannot stand alone but by their very nature must remain interconnected to function and survive are the dominant features of this new economy. The international banking and telecommunications industries are two obvious examples of vital internetted global systems that are essential for day to day governmental and commercial operations. Both the public and the private sectors have been slow to acknowledge and deal with information age deliberate attacks, unintended consequences, accidents or natural disasters. The fact that hackers have gained access to sensitive government and commercial computer systems is common knowledge with small cults developing around some of the more charismatic. While steps have been undertaken to develop greater security for these systems, timely detection of intrusions and effective responses have yet to be achieved. Recent instances of service interruption affecting electrical grids, air traffic control and financial transfer systems have been interpreted by some as a warning of impending disaster resulting from the very linkages among our systems previously heralded as the key to progress. Leveling the Field Underlying this worldwide expansion in communications and computer networks is a global technological leveling that already draws theorists to discussion of information age battlefields consisting of databases, financial networks, as well as manufacturing and service centers. …

Models for characterizing the signal-to-noise ratio for radiographic imaging systems typically ignore the human interface. In this work, images of a calibrated mammographic step wedge and a very low contrast paper step wedge were made with mammography film-screen systems and with direct x-ray exposures. Large and small density differences between adjacent steps were thus obtained over a wide range of film optical densities. Experienced viewers determined large-area threshold contrast sensitivity as a function of film density and viewbox luminance at constant low ambient illuminance with masking to exclude transmission of bright viewbox light through any area other than that portion of the step-wedge image being examined. Then, at high and low levels of viewbox luminance, threshold contrast sensitivity was determined at four different levels of ambient illuminance ranging from lower to higher than levels ordinarily used in clinical practice. threshold contrast sensitivity with and without masking was determined for viewing on a typical radiographic viewbox at a constant luminance level. The resulting data give strong qualitative support to the conclusion that viewing conditions (viewbox luminance, masking, and ambient illuminance) typically used in clinical practice are insufficient for optimum detection of the diagnostic information that can be recorded and displayed with modern mammography film-screen systems.

Although laparoscopic procedures are currently in vogue in general surgery, the role of this approach in children has not been prospectively evaluated in the United States using the new instrumentation now available to us. To assess the value of laparoscopic appendectomy (LA) in childhood, we prospectively compared 14 LAs with 50 open appendectomies (OA) over 6 months in a single children's hospital. Antibiotic usage was at the discretion of the surgeon regardless of the procedure performed and was not different between groups. LA was performed under the direction of a single laparoscopy-trained surgeon and patient selection was based on parental consent. A three-puncture LA technique was used; children from this group were allowed to return to full activities as soon as they were comfortable. There were no significant differences between groups for severity of disease, age, weight, hospital cost, or complications. The types of complications that developed were comparable in both groups. The percent of complicated appendicitis (gangrene or perforation) was 32% in the OA group and 36% in the LA group. Patients in the LA group spent significantly fewer days in the hospital and returned to unrestricted activities (school, athletics, etc) faster than patients in the OA group. LA is approximately $1,000 more expensive than OA, the differences being easily explainable by the cost of the disposable supplies necessary for the procedure (laser fibers, trocars, etc), but because of the shorter hospital stay in the LA group the mean total cost for each group was comparable. These data suggest that although there appears to be no cost advantage, LA shortens the hospital stay and allows children to return to unrestricted activity sooner than OA. LA should be considered as a reasonable alternative to OA and may be the procedure of choice in the hands of pediatric surgeons experienced in laparoscopic techniques.

A correlation is suggested between the analyzing power ${\mathit{A}}_{\mathit{N}}$ of the inelastic np${\mathrm{\ensuremath{\pi}}}^{+}$ production channel and the elastic $^{3}$${\mathit{F}}_{3}$ nucleon-nucleon phase parameters. Results for ${\mathit{A}}_{\mathit{N}}$ are shown from a coupled channel isobar model, where the short-range interaction is parametrized as a boundary condition at 0.7 fm, dictated by the internal quark structure, and which differs from other models by an improved description of the $^{3}$${\mathit{F}}_{3}$ elastic phase parameters.

Lye ingestion in children continues to be a problem and may result in severe esophageal strictures. Esophageal dilatations to treat these strictures usually result in bacteremia. A case of 13-year-old boy who developed a brain abscess after multiple esophageal dilatations is presented and discussed and the literature on the subject is reviewed.

Neurenteric cysts are rare, with fewer than 30 cases noted in the literature. We report the case of a newborn infant with respiratory distress caused by a large neurenteric cyst that was identified by prenatal ultrasound. Treatment consisted of excision of the mass through a right posterolateral thoracotomy. The cyst adhered to the spine at the level of the first thoracic vertebra and communicated with the jejunum through a posterior diaphragmatic defect. Postoperative studies with magnetic resonance imaging (MRI) and computed tomography (CT) disclosed an anterior meningocele and tethering of the spinal column. This is the second reported case of a neurenteric cyst demonstrated by prenatal ultrasound. The presence of an intrathoracic cyst associated with spinal abnormalities is characteristic of this anomaly. With imaging techniques such as MRI and CT, we may detect residual intraspinal disease associated with neurenteric cysts.

Sixty-three patients with biopsy-proven Hirschsprung's disease were diagnosed at LeBonheur Children's Medical Center, Memphis, TN between 1955 and 1980. Fifty-eight of these patients had pull-through procedures performed by three similarly trained pediatric surgeons. The follow-up was 100 percent, averaging 8 years from initial diagnosis. Demographics, surgical procedures performed, and complications are reviewed. Significant findings are (1) anastomotic strictures occurred most frequently when the level of aganglionosis was at the sigmoid colon; (2) postoperative encopresis was most likely when the endorectal pull-through procedures were performed before the age of 10 months; and (3) with selective use of colostomies or enterostomies performed prior to the pull-through procedure, the incidence of enterocolitis was low, with 0% mortality. On the basis of these findings, we recommend that, when the most proximal level of aganglionosis is the sigmoid colon, it is important to critically inspect the angulation of mesenteric blood vessels and viability of the splenic flexure pull-through colon segment to prevent ischemia and therefore anastomotic strictures. The endorectal pull-through procedure should be delayed until after 10 months of age. Infants with Hirschsprung's disease should have a colostomy or enterostomy prior to a pull-through procedure. Patients diagnosed at 10 months of age or more, who have not had earlier bouts of enterocolitis, are not low percentile weight, and are without signs of severe obstruction, are candidates for pull-through without a prior fecal diversion procedure.