CASE STUDY-PROFESSIONAL SOFTWARE PRACTICE

Case Study- Professional Software Practice

Case Study-Healthcare Equipment

Case Background

Jane works as a project manager for a company that produces medical equipment. She has worked for several years on software that will run in a suite of intensive care equipment. The software monitors heartbeat, breathing rate and so on and records these in a log. More importantly it also triggers an alarm when the patient's condition becomes unstable or critical. The software has been developed over a long period but is particularly error-prone. It now appears to be functioning correctly but, from looking at the amount of testing that has been carried out and the number of errors that were uncovered, Jane estimates that the software still contains a significant number of faults.

When she reports this to her manager at the end of the testing cycle she is informed that no more testing is to be carried out and that the equipment will soon be on the market as an upgrade to the company's existing intensive care equipment.

When Jane protests about this and points out that errors could have fatal consequences she is informed that the decision has been taken and that it is no longer her responsibility. Nevertheless she is extremely worried about the possibility of errors occurring when the machines are in service and wonders whether she should do more to prevent this.

Introduction

Many national and international organizations have been involved for some time already in the definition and methods for the assessment of the quality of medical ultrasound equipment. Examples are the American Institute of Ultrasound in Medicine (AIUM, 1974), the American Association of Physicists in Medicine (AAPM) ( Carson and Zagzebski, 1977) and the International Electrotechnical Committee ( Hill, 1977). These efforts have not led to internationally accepted quality standards yet. One of the reasons is the ongoing rapid evolution of equipment features and performance. Another reason might be the ambiguity of these committees in defining a clear end point: should it be a technical standard, or a quality assessment from the user's point of view. Another limitation of the methods involved in quality standards so far is the involvement of subjective assessments in case of image quality. This limitation also holds for a recent AAPM report ( Goodsitt et al., 1998), although it has evidently been based on the end point of quality of use, i.e. imaging performance and for the paper by Dudley et al. (2001).

In this paper, the approach is followed that rather than “subjective” assessment, the performance measurements are carried out on echographic images which are digitally acquired in a computer. This allows for adequate calibrations and for more “objective” assessments of performance. A similar approach is followed in this paper for the assessment of Doppler flow velocity (cf. Hoskins et al., 1994).

A recent technical development of medical ultrasound equipment is “second harmonic imaging”. This feature is used to image the information related to the double of the transmitted frequency which is caused by finite amplitude effects (“tissue harmonic imaging”), or ...