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Chapter 2
State-of-the-Practice
Fault diagnosis at PMS
This chapter describes the current approach to fault diagnosis, that Philips nowadays applies on
their Cardio-Vascular X-Ray Systems. This description is given to show why a new approach could
improve the fault diagnosis process, and what items of the current fault diagnosis process could be
improved. The outline of this chapter is as follows. The first section introduces preliminaries. The
second section gives an overview of today’s means and procedures within PMS for doing fault diagnosis.
The third section provides a more concrete understanding of the current practice by applying
it on a real-life example. This real-life example is a subsystem of the Philips Cardio-Vascular X-Ray
System. The final section of this chapter shows why the current approach is suboptimal. It does by
introducing items that make a fault diagnosis technique good, and use them as criteria for estimating
the diagnostic performance of the current approach.
2.1 Preliminaries
This section introduces preliminaries. Section 2.1.1 introduces the system that is subject to diagnosis;
the Philips Cardio-Vascular X-Ray System. Section 2.1.2 introduces the real-life example that
is used in Section 2.3 to give a concrete example of today’s approach to fault diagnosis at PMS. This
example is also used in Chapter 3 and Chapter 4 to give concrete examples of alternative approaches
to fault diagnosis. Section 2.1.3 introduces terminology and concepts that are required to discuss
issues in the remainder of this thesis.
2.1.1 Philips Cardio-Vascular X-Ray System
The Cardio-Vascular (C/V) X-Ray System is one of the modalities developed and serviced by
Philips Medical Systems. The system is used to enable diagnosis and treatment of patients with
cardiac and vascular diseases. Figure 2.1 shows a picture of such a system. In short it works as
follows: the patient lies on the table. One or (in the picture) two stands are positioned around the
patient in order to capture images of the body. To enable the capturing, two devices have been assembled
on the far ends of the stands. The first, a collimator, is used to limit and aim the radiation
beam. The second, the so-called flat detector, is used to capture the X-rays. Then, the signals are
processed to digital output that can be shown on the monitors. The doctors use the shown information
to diagnose or operate a patient.
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