204-205 / 1345
Set I Registration (Nodal CTV/Bony matching)
Match to Pelvic lymph nodes CTV/Vessels
Set II Registration (Soft-tissue matching)- Surrogate organ
motion
Taking
Set I
shifts as a starting point,
matching is done for CTV
Primary (at mid-cervix and mid-uterus)
CBCT Matching Workflow
Set-up errors and organ motion
Systematic
(∑)
, Random
(σ)
error distribution and calculated safety
margin (Van herk’s Recipe)
Nodal region
Cervix
Uterus
Σ σ Margin
Σ
σ Margin
Σ
σ
Margin
X +
2.0 2.8
7.0
X +
2.1
3.0
7.3
X +
2.2
2.7
7.3
X -
2.7 3.3
8.9
X -
2.3
2.9
7.7
X -
2.3
2.7
7.6
Y +
3.0 4.1
10.3
Y +
2.3
4.0
8.5
Y +
2.7
4.8
10.2
Y -
1.9 3.5
7.2
Y +
1.8
3.1
6.7
Y -
3.0
4.3
10.4
Z +
2.4 3.5
8.5
Z +
2.7
3.9
9.5
Z +
6.6
6.2
20.9
Z -
2.9 3.6
9.8
Z -
2.3
3.8
8.5
Z -
4.0
3.8
12.6
Intra-fraction organ motion
Pre-treatment MR GTV (n=67)
Organ motion
(mm)
<45.6 cc (n=34)
>45.6 cc (n=33)
Cervix
Uterus
Cervix
Uterus
Translational
couch shifts
Mean
Shifts
(±SD)
Van
Herk’s
margin
Mean
Shifts
(±SD)
Van
Herk’s
margin
Mean
Shifts
(±SD)
Van
Herk’s
margin
Mean
Shifts
(±SD)
Van
Herk’s
margin
Left-lateral (X+)
2.8 (±1.3)
4.6 2.7 (±2.2)
6.9 4.3 (±2.4)
7.7 3.0 (±2.0)
6.2
Right-lateral (X-)
3.5 (±1.8)
5.8 3.9 (±2.2)
6.7 4.8 (±2.5)
7.9 4.4 (±2.3)
7.2
Anterior (Y+)
3.8 (±2.1)
6.8 5.6 (±2.6)
8.6 4.6 (±2.2)
7.5 5.9 (±2.7)
9.3
Posterior (Y-)
4.7 (±1.6)
5.9 6.5 (±3.2)
10.0 4.1 (±1.9)
6.0 6.8 (±2.7)
9.0
Superior (Z+)
4.7 (±3.5)
10.9 5.6 (±6.5)
19.1 4.3 (±1.7)
5.9 9.2 (±6.2)
19.0
Inferior (Z-)
4.0 (±2.3)
7.8 6.1 (±4.6)
13.5 4.3 (±2.3)
7.5 5.2 (±3.1)
9.6
No difference in organ motion irrespective of
pre-treatment tumor volume
or
mid-treatment tumor regression
Mid-treatment MR GTV regression (n=67)
<50% reduction (n=33)
>50% reduction (n=34)
Cervix
Uterus
Cervix
Uterus
Mean
Shifts
(±SD)
Van
Herk’s
margin
Mean
Shifts
(±SD)
Van
Herk’s
margin
Mean
Shifts
(±SD)
Van
Herk’s
margin
Mean
Shifts
(±SD)
Van
Herk’s
margin
3.5 (±2.3)
7.0 2.8 (±2.5)
7.7 3.5 (±1.9)
6.4 2.9 (±1.6)
5.3
4.1 (±2.0)
6.4 4.3 (±2.5)
6.4 4.2 (±2.5)
7.8 4.0 (±2.0)
6.3
4.2 (±2.5)
8.1 5.8 (±2.5)
8.3 4.2 (±1.8)
6.3 5.6 (±2.9)
9.6
4.7 (±1.9)
6.3 6.7 (±3.3)
6.3 4.2 (±1.6)
5.7 6.7 (±2.6)
8.4
4.9 (±3.2)
10.1 8.4 (±8.0)
23.1 4.1 (±2.3)
7.2 6.5 (±4.9)
15.2
3.7 (±2.5)
8.1 5.3 (±4.6)
8.1 4.6 (±2.0)
7.0 6.1 (±3.2)
10.2
TMH data (unpublished)