Cause of Device-Related Incident
Device factors

Clinical Specialty or Hospital Department
Clinical/Biomedical Engineering; Facilities Engineering; Radiology / Ultrasound / Nuclear Med.

Device Factors
Device failure; Failure of accessory; Improper maintenance, testing, repair, or lack or failure of incoming inspection; Improper modification; Random component failure

Document Type
Hazard Reports

External Factors
*Not stated

Mechanism of Injury or Death
Mechanical (puncture, perforate, lacerate, break, cut, tear, nick, crush)

Support System Failures
*Not stated

Tampering and/or Sabotage
*Not stated

User Errors
*Not stated

UMDNS
Radiographic/Fluoroscopic Systems, Angiographic/Interventional [16-597]; Radiographic/Fluoroscopic Systems, Cardiovascular [17-192]; Radiographic/Fluoroscopic Systems, General-Purpose [16-885]; Radiographic/Fluoroscopic Systems Urological [16-212]; Radiographic/Fluoroscopic Units, Mobile [11-758]; Radiographic/Tomographic Systems, Linear [16-884]; Radiographic/Tomographic Systems, Multidirectional [16-556]; Radiographic Systems, Digital [18-430]; Radiographic Systems, Film [17-174]; Radiographic Units, Chest [10-822]; Radiographic Units, Dental [13-269]; Radiographic Units, Mammographic [12-425]; Radiographic Units, Mobile [13-272]; Radiographic Units, Pneumoencephalographic [16-555]; Radiographic Units, Podiatric [17-669]

Mechanical Malfunctions and Inadequate Maintenance of Radiologic Devices



Hazard [Health Devices Jan 1989;18(1):53-4]

This report was prepared in cooperation with Antti Servomaa, section chief at STUK, the Finnish Center for Radiation and Nuclear Safety.

ECRI continues to receive and review numerous reports of mechanical failures in radiologic equipment that either resulted in or had the potential to cause serious patient injury or death. In one instance, a cobalt therapy unit fell and killed a patient. After examining many other malfunctions that occur with radiologic equipment and assessing how these malfunctions are detected, we have concluded that mechanical components are not being properly inspected during routine inspection and preventive maintenance.

We also investigated information on malfunctions discovered in the Nordic countries (Finland, Norway, Sweden) compiled by STUK and reviewed incidents cited in ECRI’s Health Devices Alerts database (1976-present), as well as the FDA’s Device Experience Network (DEN) and Medical Device Reporting (MDR) databases (1984-present). Our investigation revealed that malfunctions of radiologic devices were discovered during acceptance testing, periodic inspections, and use. Malfunctions discovered during use were most likely to cause serious injury; however, it is also clear that when acceptance testing and periodic inspections are performed consistently and properly, failures during clinical use are reduced significantly. Malfunctions related to improper design or manufacturing errors (e.g., incorrect or improper radiation filtration) were usually identified during acceptance testing. Malfunctions discovered at this stage often result in manufacturer recalls, thereby benefiting other customers.

The most extensive data on periodic inspections of radiologic devices was available from the Nordic countries. Their experience shows that periodic inspections most often identify malfunctions related to patient radiation safety and image quality. Typical patient radiation safety failures are inaccurate technique indicators (e.g., kVp, mA), poor radiation beam collimation, poor automatic exposure control (AEC) performance, and poor image receptor performance. Because such malfunctions can result in increased patient radiation dose (if only through needed retakes), periodic inspections are essential. Data from the Nordic countries also showed that incorrect maintenance and user errors are responsible for about half of the patient injuries that result during use of radiologic devices, while device design accounts for the other half.

Table 1 presents data from Sweden, collected in 1984 and 1985, that illustrates these points. Compared with other devices, incorrect maintenance accounted for a higher percentage of the problems for radiologic devices.

Table 1. Medical Device Malfunctions (by Area)
Resulting in Serious Injury or Death

Equipment

Device Design

User Error

Incorrect Maintenance

Other

Total

Radiology

23 (47%)

8 (16%)

17 (35%)

1

49

Anesthesia/ Intensive Care

32 (35%)

32 (35%)

20 (22%)

8

92

Surgical

34 (51%)

17 (25%)

10 (15%)

6

67

Others

53 (54%)

24 (24%)

16 (16%)

5

98

Total

142 (46%)

81 (26%)

63 (21%)

20

306

From ECRI’s databases, we found that mechanical failures are responsible for about half of all radiologic device failures during use. This point is illustrated in Table 2.

Table 2. ECRI’s Database Analysis:
Types of Failures Listed by Radiologic Device

Device Type

M*

E*

R*

Total

Dental

24

1

24

49

Mammographic

15

3

15

33

Mobile

41

4

20

65

Fluoroscopic

17

1

17

35

Tomographic

1

4

8

13

General Purpose

4

1

8

13

Skeletal

1

1

Total

103

14

92

209

Percent

24

1

24

49

* M = Mechanical; E = Electrical; R = Radiation related.

These findings indicate that improper inspection and preventive maintenance often lead to mechanical failures during use, a fact that is confirmed by the problem reports received and investigations performed by ECRI. Typical mechanical failures include broken tube columns and counterweight cables and sheared bolts for support structures. In all instances, mechanical failures could have been prevented through proper periodic inspection of mechanical components followed by corrective maintenance. Potential mechanical malfunctions and their associated hazards are being overlooked.

In many hospitals, and in all of the cases we investigated, outside services perform inspections and preventive maintenance procedures; yet, mechanical malfunctions still occur. Therefore, hospitals must check that manufacturers and third parties perform sufficiently thorough mechanical inspections.

Recommendations

  1. Ensure that all mechanical components are examined during periodic inspections of radiologic devices and that worn or faulty parts are replaced immediately. Ensure that the manufacturer or third party performing the inspection or preventive maintenance procedure follows these recommendations.
  2. Check that the following points are covered during inspection:
    • Remove all equipment shrouds and covers and inspect all mechanical components for signs of wear (e.g., metal filings, frayed cables, loose fixtures, inadequate lubrication).
    • With heavy structures such as gamma cameras and cobalt therapy units, pay particular attention to the mechanical supports (including cables, counterweights, springs, fasteners, and drive mechanisms).
  3. Exercise all moving components and structures (including switches) while checking for signs of excessive wear or binding.
  4. Follow the manufacturer’s guidelines for overhauls, parts replacement, and lubrication. Such servicing should be performed by personnel trained or authorized by the equipment manufacturer.

UMDNS Terms

  • Radiographic/Fluoroscopic Systems, Angiographic/Interventional [16-597]
  • Radiographic/Fluoroscopic Systems, Cardiovascular [17-192]
  • Radiographic/Fluoroscopic Systems, General-Purpose [16-885]
  • Radiographic/Fluoroscopic Systems Urological [16-212]
  • Radiographic/Fluoroscopic Units, Mobile [11-758]
  • Radiographic/Tomographic Systems, Linear [16-884]
  • Radiographic/Tomographic Systems, Multidirectional [16-556]
  • Radiographic Systems, Digital [18-430]
  • Radiographic Systems, Film [17-174]
  • Radiographic Units, Chest [10-822]
  • Radiographic Units, Dental [13-269]
  • Radiographic Units, Mammographic [12-425]
  • >Radiographic Units, Mobile [13-272]
  • Radiographic Units, Pneumoencephalographic [16-555]
  • Radiographic Units, Podiatric [17-669]

Cause of Device-Related Incident

Device factors: Device failure; Failure of accessory; Improper maintenance, testing, repair, or lack or failure of incoming inspection; Improper modification; Random component failure

Mechanism of Injury or Death

Mechanical

 


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