Background
Methods
Clinical linear accelerator
Monte Carlo simulation
Design of the energy degrader
10 × 10 cm2 cone | 15 × 15 cm2 cone | ||||||
---|---|---|---|---|---|---|---|
r
|
T
t
|
T
b
|
r
|
T
t
|
T
b
| ||
ED-Pa
| - | - | 1.0 | ED-Pa
| - | - | 1.0 |
ED-1 | 2 | 0.7 | 0.3 | ED-1 | 2 | 0.6 | 0.4 |
ED-2 | 2 | 0.6 | 0.4 | ED-2 | 3 | 0.6 | 0.4 |
ED-3 | 2 | 0.5 | 0.5 | ED-3 | 6 | ` | 0.4 |
ED-4
| 2 | 0.4 | 0.6 |
ED-4
| 4 | 0.3 | 0.7 |
ED-5 | 2 | 0.3 | 0.7 | ED-5 | 6 | 0.3 | 0.7 |
Measurement with ion-chamber
In-vivo dosimetry
Results
Head component modelling for source parameters
Monte Carlo simulations of the energy degraders
Relative central-axis depth-dose curve and cross-beam dose profiles
Nominal energy (MeV) | Surface dose (%) |
d
max (cm) |
R
90 (cm) |
R
80 (cm) |
R
50 (cm) |
R
p (cm) | E0 (MeV) |
X
con (%) |
---|---|---|---|---|---|---|---|---|
7 | 88.8 | 1.16 | 1.83 | 2.07 | 2.59 | 3.35 | 6.03 | 1.3 |
9 | 80.7 | 2.05 | 2.74 | 2.99 | 3.54 | 4.39 | 8.25 | 1.2 |
9 with bolus | 91.3 | 1.05 | 1.74 | 1.99 | 2.54 | 3.33 | 5.92 | - |
Nominal energy (MeV) | Surface dose (%) |
d
max (cm) |
R
90 (cm) |
R
80 (cm) |
R
50 (cm) |
R
p (cm) |
E
0 (MeV) |
X
con (%) |
---|---|---|---|---|---|---|---|---|
7 | 89.7 | 1.12 | 1.74 | 1.99 | 2.52 | 3.31 | 5.87 | 1.1 |
9 | 80.5 | 2.03 | 2.72 | 2.98 | 3.55 | 4.38 | 8.27 | 1.1 |
9 with bolus | 91.1 | 1.03 | 1.72 | 1.98 | 2.55 | 3.32 | 5.94 | - |
Output factors
Cone (cm2) | Output factor calculated | Output factor measured | Difference (%) |
---|---|---|---|
10 × 10 | 0.888 | 0.882 | 0.6 |
15 × 15 | 0.980 | 0.972 | 0.8 |
A/P ratio | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Energy | Cone size (cm2) | 0.75 | 1.00 | 1.25 | 1.50 | 1.75 | 2.00 | 2.25 | 2.50 | 3.00 | 3.75 |
7 MeV | 10 × 10 | 0.335 | 0.490 | 0.623 | 0.738 | 0.805 | 0.858 | 0.870 | 0.882 | - | - |
15 × 15 | - | - | - | - | - | 0.900 | 0.922 | 0.946 | 0.963 | 0.972 | |
9 MeV | 10 × 10 | 0.903 | 0.952 | 0.983 | 1.000 | 1.005 | 1.008 | 1.004 | 1.000 | - | - |
15 × 15 | - | - | - | - | - | 1.003 | 1.005 | 1.007 | 1.004 | 0.996 |
In-vivo dosimetry
OSLD number | SSD (cm) | Cone size (cm2) | Measure Dose (cGy) | |
---|---|---|---|---|
Patient 1 | 1 | 100 | 10 | 156 |
2 | 153 | |||
Patient 2 | 3 | 100 | 15 | 152 |
4 | 139 | |||
Patient 3 | 5 | 105 | 15 | 152 |
6 | 152 |