LINAC Tolerances Flashcards
1
Q
Daily
X-ray output consistency (all energies)
A
3%
2
Q
Daily
Laser localization - 3D
A
2mm
3
Q
Daily
Laser localization - IMRT
A
1.5mm
4
Q
Daily
Laser localization - SRS/SBRT
A
1mm
5
Q
Daily
ODI at Iso - 3D
A
2mm
6
Q
Daily
ODI at Iso - IMRT
A
2mm
7
Q
Daily
ODI at Iso - SRS/SBRT
A
2mm
8
Q
Daily
Collimator size - 3D
A
2mm
9
Q
Daily
Collimator size - IMRT
A
2mm
10
Q
Daily
Collimator size - SRS/SBRT
A
1mm
11
Q
Daily
Door Interlock
A
Functional
12
Q
Daily
Door closing safety
A
Functional
13
Q
Daily
Audio/Visual
A
Functional
14
Q
Daily
Radiation area monitor
A
Functional
15
Q
Daily
Beam On indicator
A
Functional
16
Q
Monthly
X-ray output
A
2%
17
Q
Monthly
Typical dose rate output accuracy - IMRT and SRS/SBRT
A
2% at dose rate
18
Q
Monthly
Photon bean profile constancy
A
1%
19
Q
Monthly
Electron bean profile constancy
A
1%
20
Q
Monthly
Electron bean energy constancy
A
2% / 2mm
21
Q
Monthly
Light/radiation field
A
2mm or 1% on each side
22
Q
Monthly
Light/radiation field - asymmetric
A
1mm or 1% on each side
23
Q
Monthly
Gantry/collimator indicators
A
1 degree
24
Q
Monthly
Accessory trays
A
2mm
25
Monthly
| Jaw position indicators - symmetric
2mm
26
Monthly
| Jaw position indicators - asymmetric
1mm
27
Monthly
| Cross hair centering
1mm
28
Monthly
| Tx couch positioning - 3D & IMRT
2mm / 1 degree
29
Monthly
| Tx couch positioning - SRS/SBRT
1mm / 0.5 degree
30
Monthly
| Wedge placement accuracy
2mm
31
Monthly
| Compensator placement accuracy
1mm
32
Monthly
| Latching of wedges & blocking tray
Functional
33
Monthly
| Localization lasers - 3D
+- 2mm
34
Monthly
| Localization lasers -IMRT
+- 1mm
35
Monthly
| Localization lasers - SRS/SBRT
< +- 1mm
36
Monthly
| Beam output constancy
2%
37
Monthly
| Phase, amplitude beam control
Functional
38
Monthly
| In-room respiratory monitoring system
Functional
39
Monthly
| Gating Interlock
Functional
40
CT Simulator tolerances
Daily
CT Number accuracy
CT Number for water - 0 +- 5 HU
41
CT Simulator tolerances
Monthly:
CT Number accuracy
4 to 5 different materials - 0 +- 5HU
42
CT Simulator tolerances
Annually
CT Number accuracy
Electron density phantom - 0 +- 5 HU
43
Profile Tolerance
1% from Baseline
44
Calibration TG-51 Tolerance
1%
45
MLC Picket Fence Test Tolerance
Weekly
46
MLC Step/Shoot & Sliding Window
Annual
47
PDD/TMR Tolerance
1%
48
IGRT (KVCT and MVCT) iso check
Daily
49
IGRT (KVCT and MVCT) iso check tolerance
Daily:
| 2mm / 1mm (SRS)
50
Dynamic Wedge Output
Monthly
51
Profile Tolerance
1% from Baseline
52
Calibration TG-51 Tolerance
1%
53
MLC Picket Fence Test Tolerance
Weekly
54
MLC Step/Shoot & Sliding Window
Annual
55
PDD/TMR Tolerance
1%
56
IGRT (KVCT and MVCT) iso check
Daily
57
IGRT (KVCT and MVCT) iso check tolerance
2mm / 1mm (SRS)
58
Dynamic Wedge Output
Monthly
59
Annual:
| Temporal accuracy of phase/amplitude gating
100ms of expected
60
Annual Calibration of surrogate for respiratory phase/amplitude
100ms of expected
61
Annual
| Gating Interlock testing
Functional
62
Annual
| X-ray flatness change from baseline
1%
63
Annual
| X-ray symmetry change from baseline
+- 1%
64
Annual
| Electron flatness change from baseline
1%
65
Annual:
| Electron symmetry change from baseline
+- 1%
66
SRS arc rotation mode (range: .5-1.0 MU/deg)
MU set vs. delivered: 1MU or 2% (whichever is greater)
Gantry arc set vs. delivered: 1 degree or 2% (whichever is greater)
67
Annual
| Calibration TG-51
1% Annual
68
Annual
| Output Factors for Small Fields
< 2%
69
Annual
| PDD/TMR
1%
70
Annual
| TBI PDD X-ray
1%
71
Annual
| TSET: electron PDD
1mm
72
Annual
| TBI/TSET Output
2%
73
LINAC Wedge Tests
Daily: Functional
Monthly: Output
Annual: Profile
74
LINAC MLC Tests - Weekly
Picket Fence - visual inspection
75
LINAC MLC Tests - Monthly
Leaf Position Accuracy - 1mm for leaf positions of IMRT field for 4 cardinal gantry angles;
Travel speed - loss of leaf speed > 0.5 cm/s;
Leaf Setting vs Radiation Field - 2mm
76
LINAC MLC Tests - Weekly
Transmission - 0.5% from baseline;
Leaf Position Repeatability - +- 1mm;
MLC Spoke shot - < 1mm radius;
Rad-Light Coincidence - +-2mm;
Step & Shoot test - <0.35cm max error RMS, 95% of error counts<0.35 cm;
Moving Window test - <0.35cm max error RMS, 95% of error counts<0.35 cm
77
LINAC Annual Calibration - TG-51:
1. Frequency - Annual
2. Specified - In Water
3. Calibration Factor - NDw
4. Photons - Ion Chamber
5. Photon Measurement depth - 10cm
6 .Photon Calibration depth - Dmax
7. Electrons - Parallel Plate Ion Chamber
8. e' Measurement depth - d reference
9. e' Calibration depth - Dmax
10. Photon measurements use Pb foil - remove e' contamination
78
How often are Ion chambers calibrated?
every 2 years
