TABLE 3.
Comparison of mean and median failure downtimes by downtime category in all LINACS and in the multileaf collimators (MLCs)
| Category | Faults | Total downtime (hours) | Mean downtime (minutes) | Median downtime (minutes) | |
|---|---|---|---|---|---|
| LINAC | A | 102 | 1.51 (0.002%) | 1.65 ± 0.16 | 1 |
| B | 2088 | 798.61 (1.19%) | 22.95 ± 0.25 | 20 | |
| C | 1657 | 66052.43 (98.80%) | 2391.76 ± 522.70 | 165 | |
| MLC | A | 37 | 0.900 (0.01%) | 1.46 ± 0.27 | 1 |
| B | 733 | 297.43 (3.39%) | 24.35 ± 0.42 | 23 | |
| C | 438 | 8463.20 (96.60%) | 1159.34 ± 338.19 | 120 |
Note: A constitutes a downtime less than 5 min, B a downtime between 5 min and 1 h, and C downtimes are longer than an hour.