Level 3   Level 4  
  Parameters Numbers (%) Numbers (%)
Causes of incident Violation/skip procedure or policy 29 -59% 49 -45%
Incomplete knowledge/skill 8 -16% 2 -2%
Miscommunication 6 -12% 18 -17%
Manual misentry/operation error 4 -8% 39 -36%
Work environment 1 -2% 1 -1%
Incorrect supervision 1 -2% 0 -
Staff experiences ≥5 years 22 -45% 66 -61%
<5 years 27 -55% 43 -39%
Caused by RO 36 -74% 33 -30%
MP 0 - 39 -36%
RT 11 -22% 34 -31%
RO/MP 2 -4% 1 -1%
RT/MP 0 - 2 -2%
Detected by Weekly review session 31 -63% 8 -7%
RO 2 -4% 8 -7%
MP 0 - 19 -17%
RT 13 -27% 74 -68%
Nurse 1 -2% 0 -
MP/RT 2 -4% 0 -
Phase of occurrence CT-S 0 - 23 -21%
Treatment planning 36 -74% 55 -51%
Preparation 1 -2% 17 -16%
Position verification 1 -2% 6 -6%
Treatment delivery 10 -20% 1 -1%
On-treatment verification 1 -2% 7 -6%
Phase of detection Treatment planning 0 - 1 -1%
Preparation 1 -2% 41 -38%
Position verification 0 - 27 -25%
Treatment delivery 11 -22% 17 -16%
On-treatment verification 36 -74% 16 -15%
Other 1 -2% 7 -6%
Table 3: Characteristics of level 3 and level 4 incidents. Abbreviations: RO: Radiation Oncologist; MP: Medical Physicist; RT: Radiology Technologist; CT-S: Computed Tomography Simulation. Totals may not be 100% due to rounding.