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Chapter 1
Introduction
Throughout the decades Philips Cardio-Vascular X-Ray System 1 has gone through a lot of changes.
These changes mainly pertain to more functionality and more sophisticated internal techniques, like
newer techniques for X-ray generation and acquisition. Each of the components as well as the entire
system has evolved over the years. There is no end to the continuous improvement, and going with
that is the everlasting increasing complexity of these systems. All sorts of efforts have to be taken to
cope with this complexity, so that doctors and patients can still depend on them. In other words, the
systems have to be kept dependable. Dependability is a property that a successful system must have.
It can be decomposed into the more lower level attributes availability, integrity, maintainability,
reliability and safety [4]. The threats to a dependable operation come in the shape of faults, errors
and failures and will hinder correct service delivery more and more often. The reasons for this is
that managing the complexity has become a lot harder. Although the world of physical systems has
never been perfect and systems are breaking as a rule, the effort put in servicing them is growing.
One of these efforts is fault diagnosis. Fault diagnosis is the process of identifying the root cause(s)
of a failure. A good fault diagnosis process, and/or a better design accommodating fault diagnosis, is
essential for achieving high dependability. The sooner a broken component is identified, the sooner
appropriate recovery actions can be taken, and users can depend on the system.
This thesis discusses an alternative approach to fault diagnosis, aimed at one of the modalities
that Philips Medical Systems (PMS) develops and services, namely the Cardio-Vascular X-Ray
System. Philips Medical Systems is a company that develops and services state-of-the-art medical
systems. As most suppliers of embedded systems, it has to cope with the complexity crisis, caused
by the shift from hardware to software and an increased amount of third party components. In order
to preserve a desired level of safety and reliability, it is of prime concern that fault diagnosis
is done efficiently and effectively upon the systems. The costs and effort that we devote to manually
diagnosing the systems, and keeping them up and running in a safe way, are just no longer
acceptable.
The next section points out the role of a fault diagnosis process in a dependable operation,
presents the fault diagnosis practice at PMS of today, and shows the drawbacks of this approach.
Sections 1.2 and 1.3 introduce alternative automated approaches to fault diagnosis. Section 1.4
gives the problem statement. Finally, this introductional chapter concludes with an outline of this
thesis.
1 The meaning of all terms and acronyms that are printed italic are described in the Glossary of Terms, Appendix A.
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