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Biomedical subjects

J Brandon

Publications and source records attributed to J Brandon.

16 recordsLinked to original sources
PubMed2006

Compact multileaf collimator for conformal and intensity modulated fast neutron therapy: electromechanical design and validation.

The electromechanical properties of a 120-leaf, high-resolution, computer-controlled, fast neutron multileaf collimator (MLC) are presented. The MLC replaces an aging, manually operated multirod collimator. The MLC leaves project 5 mm in the isocentric plane perpendicular to the beam axis. A taper is included on the leaves matching beam divergence along one axis. The 5-mm leaf projection width is chosen to give high-resolution conformality across the entire field. The maximum field size provided is 30 x 30 cm2. To reduce the interleaf transmission a 0.254-mm blocking step is included. End-leaf steps totaling 0.762 mm are also provided allowing opposing leaves to close off within the primary radiation beam. The neutron MLC also includes individual 45 degrees and 60 degrees automated universal tungsten wedges. The automated high-resolution neutron collimation provides an increase in patient throughput capacity, enables a new modality, intensity modulated neutron therapy, and limits occupational radiation exposure by providing remote operation from a shielded console area.

Electronics, Medical↗
PubMed2004

Application of semiconductors for dosimetry of fast-neutron therapy beam.

Two types of ion implanted miniature p-i-n diodes were tested in a d(48.5) + Be fast-neutron beam produced in the Detroit superconducting cyclotron. The increase in forward voltage drop caused by neutron-induced damage was correlated with neutron dose measured in a water phantom. The neutron and gamma dose components were predetermined using twin detector (Tissue-equivalent ion chamber paired with miniature Geiger-Müller counter) method. The increase in the voltage drop for 1 mA injection current was monitored together with the cyclotron beam target current, thus the differential voltage drop could be defined precisely for given radiation dose. The average neutron sensitivities of tested diodes were 1.284 +/- 0.014 and 0.528 +/- 0.058 mV per cGy. The miniature detectors can be utilised in characterisation of small radiation fields and in the regions of high dose gradient as well as for in vivo dosimetry of the patients undergoing fast-neutron therapy.

Equipment Design↗
PubMed1998

Prospective evaluation of new and old criteria to discriminate between supraventricular and ventricular tachycardia in implantable defibrillators.

This study was designed to evaluate the ability to distinguish between supraventricular tachycardias (SVTs) and ventricular tachycardias (VTs) based on onset, stability, and width criteria in an implantable defibrillator. Inappropriate detection of atrial fibrillation and sinus tachycardia is a common problem in patients with implantable defibrillators. The onset, stability, and width criteria were studied in 17 patients who underwent implantation of a Medtronic 7218C implantable defibrillator by inducing sinus tachycardia and atrial fibrillation. Additional data on the width criteria was obtained by pacing at separate sites in both the left and right ventricle. Patients were studied at different times for up to 6 months to determine any changes in the criteria. The onset and stability criteria caused inappropriate detections in 36% and 12% of the episodes, respectively. The addition of the width criteria decreased the inappropriate detection using the onset and stability criteria to 5% and 2%, respectively. Pacing from the RV apex, RV outflow tract, and LV apex was appropriately detected as wide in 76%, 41%, and 94%, respectively. The width criteria changed over time in individual patients, but was stable by 6 months in all but one patient. No single criterion is satisfactory for distinguishing between SVT and VT in this patient population, but the combination of criteria seems to provide better discrimination. The width criteria can change dramatically over time and needs to be monitored carefully. Newer algorithms will need to be developed to allow better detection of supraventricular tachycardias.

Aged↗
PubMed1993

Reduced total complement haemolytic activity in schizophrenic patients.

Serum concentrations of the third and fourth components of the complement system and total complement haemolytic activity were measured in 167 psychiatric patients. Total complement haemolytic activity was decreased in chronic schizophrenic patients as compared to healthy controls and bipolar patients. The relatively diminished total haemolytic activity was not attributable to drug treatment. It is not clear if the reduced total haemolytic activity is an epiphenomenon or related to the involvement of an autoimmune process in the pathophysiology of schizophrenia.

Autoimmune Diseases↗
PubMed1992

Planning to keep your job.

Keeping your job and moving up the ladder require a strategy that not only sets goals for the institution's information systems, but also keeps your boss happy. Being seen as "doing what is right" for the hospital, meeting expectations and maintaining credibility are vital to staying off the "hit list."

Career Mobility↗
PubMed1992

Reengineering: more than meets the eye.

Changes too often leave us shaken, unsteady and unable to perform, yet hospital reengineering usually means major, lingering change. Systematic reengineering, properly implemented, can reduce the strain.

Computer Simulation↗
PubMed1991

Haloperidol and lithium carbonate treatment did not influence serum immunoglobulin levels in schizophrenic and affective patients.

Serum immunoglobulin levels were studied in 153 psychiatric patients (87 schizophrenic, 48 bipolar and 18 unipolar patients), and 35 healthy controls. Psychotropic treatments (haloperidol in the schizophrenic patients and lithium in the bipolar affective patients) did not alter serum immunoglobulin levels. Decreased mean IgM serum level was detected in the major affective patients (unipolar and bipolar) compared with normal controls. Nonspecific environmental, infectious, autoimmune and emotional factors that can play a role in the alterations obtained in psychiatric patients are discussed.

Adolescent↗
PubMed1991

Cold agglutinin autoantibodies in psychiatric patients: their relation to diagnosis and pharmacological treatment.

BACKGROUND AND METHOD: The purpose of this study was to compare titers of cold agglutinins in schizophrenic patients with those in patients with major affective disorders and in normal healthy subjects. One hundred sixty-six psychiatric patients and 37 healthy comparison subjects were included in the study. Ninety of the patients suffered from schizophrenia, 54 from bipolar disorder, and 22 from major depression. Venous blood samples were obtained from all subjects between 8:00 and 10:00 a.m. and were immediately tested for cold agglutinin titers. RESULTS: A high frequency (42.2%) of positive cold agglutinin titers was detected in the schizophrenic patients, compared with the bipolar (11.1%) and unipolar (9.0%) patients and the comparison group (8.1%). The investigators did not find any pharmacological effect on these results. CONCLUSIONS: The findings suggest that, at least in this group, positive cold agglutinin titers are associated with schizophrenia. However, this observation cannot provide direct evidence for the involvement of viral or autoimmune factors in schizophrenia.

Adult↗
PubMed1991

Reengineering the hospital: making change work for you.

Two of the industry's prominent management experts and authors explain that the Information Systems Department can take a leading role in reengineering the management infrastructure of a healthcare organization. Change is no longer the enemy of management if the infrastructure is set up to accommodate and promote change from within.

Cost Control↗
PubMed1985

Intestinal giardiasis: the importance of serial filming.

Intestinal giardiasis is a common enteric pathogen. Conventional diagnostic screening studies are only 50% accurate. Although radiologic abnormalities in the small intestine have been described, barium studies are often normal. Symptoms may be chronic and debilitating but are effectively treated with appropriate therapy. Three cases were encountered in which recognition of subtle radiographic abnormalities in the small intestine was responsible for proper diagnosis. These findings consisted of a progression from relatively normal jejunum on initial films to dilution, segmentation, and apparent increased fold thickness in the proximal small intestine on delayed films. When this pattern is identified, the radiologist may suggest the possibility of giardiasis and thus direct the referring physician to use definitive diagnostic procedures.

Barium Sulfate↗
PubMed1977

Runaway adolescents' perceptions of parents and self.

The purpose of the study was to investigate the relationship between runaway behavior in adolescence and an adolescent's self-concept and antecedent parental treatment. The Cornell Parent Behavior Questionnaire and the Adjective Check List were used to assess 47 runaways and a matched group of non-runaways. Analyses of the data indicated: (a) runaway adolescents report more punishment and less support from their parents; (b) runaway girls report the most and runaway boys the least degrees of parental control; (c) runaways hold a less favorable self-concept, specifically on the dimensions of anxiety, self-doubt, poor interpersonal relationships, and defensiveness; (d) runaways also manifest, as an aspect of the self, a readiness for counseling.

Adolescent↗
PubMed1974

Sea law.

Explore the source record for details and available documents.

Jurisprudence↗
PubMedDate not supplied

Effect of methylprednisolone on predicted myocardial infarction size in man.

Therapeutic manipulations designed to conserve myocardium in patients with acute myocardial infarction appear to improve prognosis. To assess the role of glucocorticoids given in pharmacologic dosage in the early treatment of patients with acute myocardial infarction, serial serum creatine phosphokinase (CPK) were obtained every 1-2 hours in 39 consecutive patients admitted with acute myocardial infarction. Determination of completed infarction size (ISc) was made using all available CPK values (range 70-160 hours). Predicted infarct size (ILp) was based on early data following the rise in CPK from baseline values: projected CPK values were obtained over a 160 hour period using a curve fitting procedure based upon nonlinear Gauss-Newton stepwise iterations. In 13 uncomplicated control patients ISp was 43.2 +/- 11.6 (mean +/- SE) CPK-gram-equivalents (CPK-q-eq), based on data from the first 7 hours following the rise in serum CPK, while ISc was 44.7 +/- 11.4 CPK-geq (r = .99, n = 13). In 7 additional control patients whose hospitals courses were complicated by clinical extension ISp was 71.8 +/- 18.0 CPK-g-eq while ISc was 118.6 +/- 31.0 CPK-g-eq (p less than .03). In 19 patients treated with 3 grams of methylprednisolone 7-14 hours following the rise in serum CPK from baseline, data from early CPK determinations (7 hours) indicated an ISp of 118.5 +/- 24.1 CPK-g-eq while total CPK data indicate an ISc of 89.6 +/- 13.2 CPK-g-Eq (p less than .04). The exponential clearance of CPK (kd) was approximated in the controls (kd = .00095 +/- .00007 min-1) and glucocorticoid treated patients (kd = .00099 +/- .00006 min-1) and found to be similar. Thus, administration of a pharmacologic dose of methylprednisolone 7-14 hours following rise in serum CPK from baseline in a group of patients with acute myocardial infarctions has resulted in salvage of myocardium.

Adult↗