SU-E-T-25: Real Time Simulator for Designing Electron Dual Scattering Foil Systems

PURPOSE

To create a user friendly, accurate, real time computer simulator to facilitate the design of dual foil scattering systems for electron beams on radiotherapy accelerators. The simulator should allow for a relatively quick, initial design that can be refined and verified with subsequent Monte Carlo (MC) calculations and measurements.

METHODS

The simulator consists of an analytical algorithm for calculating electron fluence and a graphical user interface (GUI) C++ program. The algorithm predicts electron fluence using Fermi-Eyges multiple Coulomb scattering theory with a refined Moliere formalism for scattering powers. The simulator also estimates central-axis x-ray dose contamination from the dual foil system. Once the geometry of the beamline is specified, the simulator allows the user to continuously vary primary scattering foil material and thickness, secondary scattering foil material and Gaussian shape (thickness and sigma), and beam energy. The beam profile and x-ray contamination are displayed in real time.

RESULTS

The simulator was tuned by comparison of off-axis electron fluence profiles with those calculated using EGSnrc MC. Over the energy range 7-20 MeV and using present foils on the Elekta radiotherapy accelerator, the simulator profiles agreed to within 2% of MC profiles from within 20 cm of the central axis. The x-ray contamination predictions matched measured data to within 0.6%. The calculation time was approximately 100 ms using a single processor, which allows for real-time variation of foil parameters using sliding bars.

CONCLUSIONS

A real time dual scattering foil system simulator has been developed. The tool has been useful in a project to redesign an electron dual scattering foil system for one of our radiotherapy accelerators. The simulator has also been useful as an instructional tool for our medical physics graduate students.

An analysis of listening skills of healthcare students in Nigeria

BACKGROUND

Listening is a primary communication skill essential for human learning and reported to be positively correlated with school achievement. It enables the healthcare professional to explore fully the ideas and concerns of the patient during a healthcare encounter. It is especially needed by healthcare students and professionals in light of the study showing that the typical physician will interrupt a patient after about 18-23 seconds.

OBJECTIVE

The objective of this study was to measure the listening skills of the undergraduate health sciences students in a Nigerian setting and to attempt to explain different levels of individual listening skills.

METHODS

Selected undergraduate students in medicine, dentistry, nursing and physiotherapy who volunteered to complete a self-administered questionnaire were studied. The questionnaire contained seventeen items, ranked on a 5-point Likert scale on the various habits people adopt when listening to others and the students' three most recent academic test scores.

RESULTS

The mean (SD) score for the seventeen items was 2.72 (1.14) out of 5. Seven items had mean scores greater than 3.00, eight items had mean scores between 2.00 and 3.00, and two items had mean less than 2.00. The students had a minimum score of 27 and a maximum score of 67 compared with a possible 17 and 85. The mean (SD) score for the listening scale by the students was 46.87 (7.33). Eighty percent of the respondents had good listening skills. There were no statistically significant associations between the listening skills scores of the students and several possible explanatory variables - age, gender, course being studied and test scores.

CONCLUSION

The findings indicate that neither males nor females are the better listeners. It showed impressively high levels of listening skills among the respondents. There was the absence of explanatory variables which were significant in explaining differences between individual listening skill scores.

Analysis of the perception of institutional culture for health sector reform in Nigeria

Purpose

The purpose of this paper is to analyse the perception of institutional culture in four hospitals in Nigeria and its influence on the implementation of the health sector reform programme in the country.

Design/methodology/approach

A cross‐sectional study of 507 healthcare professionals and managers using a self‐administered questionnaire was carried our.

Findings

The overall perception of institutional culture was above average at 56.4 per cent. The perceptions of the two dimensions of institutional culture were: leadership 59.3 per cent and character 54.0 per cent. Two out of the 11 statements on institutional culture had levels of perception that were lower than 50 per cent. These were: “staff morale and job satisfaction are high at all levels, and regularly evaluated by the institution” (41.6 per cent) and “information is shared openly in the institution” (44.3 per cent).

Originality/value

There is a need to strengthen the character dimension of the institutional culture of Nigerian hospitals, especially staff morale and job satisfaction as well as the sharing of information in the hospitals.

Preparation and Characterization of Mn0.4Ni x Zn0.6−x Fe2O4 Soft Spinel Ferrites for Low and High Frequency Applications by Citrate Precursor Method

In the present study, preparation and characterization of Mn-Ni-Zn soft ferrites with chemical formula Mn0.4Ni x Zn0.6−x Fe2O4, where x = 0.0, 0.2 and 0.4, by citrate precursor method has been reported. Microstructural properties studied with the help of X-ray diffraction and scanning electron microscopy show that the samples have almost uniform sized crystallites and have single phase spinel structure. The properties like initial permeability, permeability loss, dielectric constant, dielectric loss are studied as a function of frequency. The d.c. resistivity of the samples is also studied. Variation of d.c. resistivity with composition, x, of the ferrite sample shows that pure zinc ferrite has more resistivity than that of nickel substituted zinc ferrite. The dispersion in the magnetic and electrical properties has been discussed by using various mechanisms, models and theories.