Dosimetry of small electron fields shaped by lead

Electron radiotherapy fields are commonly used to treat superficial cancers. Field shaping can be achieved by placing lead on the patient surface to minimise the dose to surrounding areas. However, significant dosimetry changes under high density material edges for electron fields have been reported in the literature. This project evaluated the dosimetry of small dimension electron fields shaped with lead placed on the surface. Comparisons were made between circular lead cutouts placed on the skin and low melting point alloy cutouts placed in an applicator. Depth doses, profiles and output factors were measured using a diode detector in a water phantom. Film was also used to determine surface dose delivered when the lead cutouts were placed on the surface. Minimal differences were observed between the different setups for the depth dose curves, although significant differences were seen in the penumbra and the surface doses. The penumbra is smaller for the lead cutouts placed on the surface, however, significant dose increases at the edge of the field were observed for larger fields and energies; this may result in undesirable clinical effects.

Family preservation and family support programs: child maltreatment outcomes across client risk levels and program types

OBJECTIVES

This study evaluated client-level outcomes among an entire statewide group of Family Preservation and Family Support (FPFS) programs funded under PL 103-66.

METHOD

A total of 1,601 clients (primarily low income, moderate to high risk with no current involvement in the child protection system) were assessed and followed over time for future child maltreatment events reported to Child Protective Services. The study compared program completers with program dropouts, compared recipients of more lengthy full-service programs with recipients of one-time services, and examined the effects of program duration, intensity, service site (center-based vs. home based) and service model/content. Effects were modeled using survival analysis and variable-exposure Poisson hierarchical models, controlling for initial client risk levels and removing failure events because of surveillance bias. Changes in lifestyle, economic and risk factors were also examined.

RESULTS

A total of 198 (12.2%) participants had at least one defined failure event over a median follow-up period of 1.6 years. Controlling for risk and receipt of outside services, program completers did not differ from program dropouts or from recipients of one-time services, and there was no relationship between program intensity or duration and outcomes. Program types designed to help families meet basic concrete needs and programs using mentoring approaches were found to be more effective than parenting and child development oriented programming, and center-based services were found to be more effective than home-based services, especially among higher risk parents.

CONCLUSIONS

The findings did not support the effectiveness of these services in preventing future maltreatment cases, and raised questions about a number of common family support assumptions regarding the superiority of home-visiting based and parent training services. A number of possible reasons for this are explored.

Photon buildup in orthovoltage X-ray beams

Orthovoltage x-ray beams exhibit the characteristic of depth dose buildup which is not well described in the literature. The principal reason for this phenomenon is the increase in dose deposited due to electrons set in motion by secondary (Compton) scattered photons within the phantom, as depth is increased until longitudinal equilibrium is reached. This happens within a few millimetres of the surface and has been demonstrated both experimentally and by Monte Carlo methods. The Monte Carlo technique also enabled description of a second order primary dose buildup effect (due to longitudinal electronic disequilibrium) that would be impossible to detect with conventional detectors due to the short range of the electrons. The magnitude of buildup was observed to alter with various combinations of beam parameters. Variations will also occur with detectors used to measure buildup. It is recommended that radiation oncology departments assess this effect in the context of their clinical data in current use to ensure that there are not doses higher than prescribed being applied a few millimetres below the skin surface, especially if data was collected with a thin windowed, parallel plate ionisation chamber and/or that coarse steps for depth dose data collection were used along the beam central axis.

An independent check method of radiotherapy computer plan derived monitor units

With the increasing complexity of radiotherapy computer treatment planning systems (CTPS), verification of the treatments is an important component of a quality assurance program. The radiation dose delivered to a patient is based on treatment machine monitor units (MUs) that are calculated either using data tables or within the CTPS. An independent method for checking radiotherapy MU calculations is proposed. This method involves calculating the dose at a point (usually ICRU reference point) using the derived MUs and independently measured treatment data and comparing to the dose at the same point as predicted by the CTPS. A program was developed using Microsoft Excel to assist in performing this check. The program contains the beam data and various correction factors and calculates the dose after input of the treatment setup parameters. This independent method is used to check all radiotherapy treatment fields at Liverpool Hospital and has found a number of significant errors in the planning process and in the CTPS calculations.

The culture of morning report: ethnography of a clinical teaching conference

We studied the structure, process, and subjective meaning of "morning report," a time-honored, medical teaching conference attended by faculty, house officers, and students at a pediatric teaching hospital. Methods included participant observation, focused interviews, and content analyses. Results showed substantial variation by rank in behavior, perception, and participation based on a highly structured division of labor. The most frequent suggestion for improving morning report was to shorten it. Data indicate that morning report, at least at our study site, is out of step with current learner-centered models, seems perfunctory, and may be costly in the current climate of decreased revenues and downsizing. The persistence of morning report, despite these liabilities, attests to its significance as a cultural event.

Adolescence as a culture-bound syndrome

In keeping with an expanded definition of culture-bound syndromes, this paper argues that adolescence in American society has been 'medicalized' into a full-blown symptom complex or pathologic condition. Culture-bound syndromes in highly differentiated societies such as the U.S., may be taxonomically sorted by distinctive cultural identity system domains of age, gender, family, vocation and ethnicity.

A sexually transmitted diseases curriculum in adolescent medicine

We conducted a needs assessment and developed and evaluated a model curriculum on sexually transmitted diseases (STDs) for house officers on an adolescent medicine rotation. Residents thought it important for physicians to acquire skill in treating STDs during residency (mean rating, 4.4 on a five-point scale) and were willing to provide medical care for adolescents likely to have an STD (mean rating, 4.4). Knowledge was measured before and after presentation of both of the two curriculum levels. There were significant increases in knowledge after each level, with a mean increase of 4.4 (of 50 possible) points for level 1 and a mean increase of 1.8 (of 38 possible) points for level 2. This improved knowledge about STDs should reflect increased competence and enhanced willingness to treat STDs in adolescents.

General anesthesia during percutaneous transluminary coronary angioplasty for acute myocardial infarction: results of a randomized controlled clinical trial

Acutely ill patients with myocardial infarction may require immediate cardiac catheterization and coronary angioplasty to achieve myocardial reperfusion. To determine the feasibility of using general anesthesia under these circumstances, a randomized clinical trial was performed. Of 50 patients, 25 received anesthesia and 25 receive intravenous sedation. There were transient increases in heart rate and blood pressure after tracheal intubation in the anesthetized patients, followed by significant and sustained decreases below baseline values once steady state anesthesia was attained. Arterial oxygenation was significantly improved in anesthetized patients. There were no serious complications due to anesthesia, but the small sample size limited the power of the study to detect differences in morbidity or mortality. Patients strongly preferred anesthesia. These results show that general anesthesia is feasible in patients undergoing interventional cardiac catheterization during acute myocardial infarction, when pain, anxiety or agitation do not respond adequately to conventional measures.

Myocardial tolerance to total ischemia in the dog anesthetized with halothane or isoflurane

Myocardial tolerance to total ischemia was compared in animals anesthetized with halothane or isoflurane by measuring the time required for development of cardiac rigor in the absence of coronary circulation or wall stress. Sixteen dogs, eight in each group, were anesthetized with equally potent inspired concentrations of either halothane (2 MAC) or isoflurane (2 MAC), intubated, and ventilated. Thirty minutes later, the heart was rapidly excised. A left ventricular slab was prepared and maintained at 37 degrees C. A portion of each slab was placed in a compressibility gauge that detects rigor onset by an abrupt increase in resistance to tissue deformation. Subendocardial tissue pressure was continuously measured in a second slab using needle-tipped Millar pressure transducers. A third slab was used for intermittent tissue sampling and HPLC assay of high-energy nucleotide levels. There were no differences in pre-ischemic heart rate, mean arterial pressure, glucose, lactate, PO2, PCO2, pH, plasma epinephrine, or norepinephrine levels between the two groups. The onset of rigor as measured by the compressibility gauge was delayed in the halothane group (68 +/- 7.2 vs. 60 +/- 5.0 min; P less than .05). Tissue ATP and ADP levels declined throughout the period of ischemia, with a trend towards preservation in the halothane group. The data show that myocardial tolerance to total normothermic ischemia is improved in animals anesthetized with halothane compared to isoflurane, independent of the effects on hemodynamics or collateral coronary circulation.

Anesthetic implications for the management of patients with acute myocardial infarction: a matched cohort study of patients undergoing emergency myocardial revascularization

Emergency coronary artery bypass grafting (CABG) is advocated as a treatment of acute myocardial infarction (AMI). To attempt to define anesthetic management problems in this patient group, a retrospective study was conducted comparing the perioperative courses of 23 patients undergoing emergency CABG during AMI with 23 elective patients, individually matched for gender, operating surgeon, ejection fraction, and aortic crossclamp time. The 23 AMI patients were anesthetized 5.98 +/- 3.0 (range 1.5 to 11.0) hours after the onset of chest pain. Anesthetic agents were similar for both groups. Induction of anesthesia was well tolerated by AMI patients. Tolerance of cardioplegic arrest was impaired in the AMI group as evidenced by the sharp increase in frequency of inotropic support required to discontinue bypass in the AMI group compared to elective patients (12/23 v 3/23; P less than .005). Fifteen AMI patients who received preoperative streptokinase had greater postoperative bleeding. Three AMI patients died postoperatively. The number of patients requiring prolonged postoperative ventilation and extended ICU care was higher in the AMI group. It is concluded that patients undergoing emergency CABG during AMI represent a greater risk than elective patients. They have a higher incidence of myocardial dysfunction following cardioplegic arrest during bypass. Those who receive preoperative thrombolytic therapy exhibit greater bleeding tendencies.

Physicians' values and experience during adolescence. Their effect on adolescent health care

The values and experience of physicians as adolescents can effect their care of adolescent patients. Eighty residents were studied using extensive personal data gathered from a structured interview, a questionnaire of perceived clinical skills, and a videotape with a simulated patient. A "values" and "risk-taking during adolescence" score was constructed and related to the resident's perceived skills for and attitudes about adolescent health care. Residents with higher values scores (more conservative) were more likely to be pediatric than internal medicine residents and less likely to prescribe birth control pills to an adolescent. Residents with higher risk-taking scores considered themselves more skilled in dealing with substance abuse and sexually transmitted diseases and in recognizing psychologic problems. Values or risk-taking scores were not related to the resident's perceived skill in areas such as evaluating hypertension or performing Tanner staging. These data suggest that certain values and experiences may be influential in the physician's ability and approach to dealing with certain issues related to adolescent health care.

Sister-sister incest as a manifestation of multigenerational sexual abuse

Incestuous child sexual abuse has received increasing attention recently, but relatively little attention has focused on the multigenerational dimensions of this problem. The case presented places incest into a multigenerational context and demonstrates how quickly family relationships may become eroticized in an uncommon form: between sisters.

How shall we see them? Perspectives for research with disabled organizations

This paper analyzes the experiences of two social scientists who participated as consultants in a long-term (4 years) film production project sponsored by an organization of disabled persons. The expectations of the investigators (both able bodied) at the beginning of the project are summarized, particularly with regard to social organization within the disabled community. The analysis contrasts these expectations with the reality of the project experience, focusing on the pertinence of appropriate variables for understanding the structure and behavior of disabled groups. A concluding section suggests implications for other investigators involved on a cooperative basis with disabled groups in applied research.

Mutagenesis by mutator gene mutH1 in continuous cultures of Escherichia coli

Mutability as a function of growth rate was examined in bacterial strains containing mutator gene mutH1. The rate of mutation to bacteriophage T5 resistance was found to be proportional to rate of growth in glucose-limited chemostat cultures. This finding supports the hypothesis that the mutator mutH1 gene product increases the error frequency during deoxyribonucleic acid replication.

Effect of dark repair on ultraviolet sensitivity of bacteriophage-infected bacteria

Feiner, R. R. (Columbia University, New York, N.Y.), and R. F. Hill. Effect of dark repair on ultraviolet sensitivity of bacteriophage-infected bacteria. J. Bacteriol. 91:1239-1247. 1966.-Changes in ultraviolet (UV) sensitivity of phage-host complexes during phage development have been studied for the following systems: T1 and Escherichia coli B, T1 and E. coli K-12S, lambda and E. coli K-12S. Complexes were formed with bacterial strains differing in ability to dark-repair UV damage to deoxyribonucleic acid and, after irradiation, were plated on bacteria differing similarly. In the first half of the latent period, the resistance of complexes formed with nonrepairing bacteria increased considerably; with T1 and E. coli B hcr(-), in 4 min the resistance became the same as that of complexes formed with repairing bacteria. The repair ability of plating bacteria affected survival curves only upon irradiation in the second half of the latent period after mature phages were present in the initial complex. Use of nonrepairing bacteria both for initial infection and for plating of late complexes resulted in a series of survival curves showing for all three systems the same pattern of change originally reported for T2-E. coli B complexes. Thus, a hitherto unexplained difference between radiation survival curves for T-even and T-odd phages seems due to repair of T-odd phages by the host.