Gynae BT_Lucknow_2018

TMH data (unpublished)

Set-up errors and organ motion

Systematic (∑) , Random (σ) error distribution and calculated safety margin (Van herk’s Recipe)

CBCT Matching Workflow

Nodal region

Cervix

Uterus

Set I Registration (Nodal CTV/Bony matching) Match to Pelvic lymph nodes CTV/Vessels

Σ σ Margin

Σ

σ Margin

Σ

σ

Margin

2.0 2.8

7.0

2.1

3.0

7.3

2.2

2.7

7.3

X +

X +

X +

2.7 3.3

8.9

2.3

2.9

7.7

2.3

2.7

7.6

X -

X -

X -

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)

3.0 4.1

10.3

2.3

4.0

8.5

2.7

4.8

10.2

Y +

Y +

Y +

1.9 3.5

7.2

1.8

3.1

6.7

3.0

4.3

10.4

Y -

Y +

Y -

2.4 3.5

8.5

2.7

3.9

9.5

6.6

6.2

20.9

Z +

Z +

Z +

2.9 3.6

9.8

2.3

3.8

8.5

4.0

3.8

12.6

Z -

Z -

Z -

Intra-fraction organ motion

Mid-treatment MR GTV regression (n=67)

Pre-treatment MR GTV (n=67)

<50% reduction (n=33)

>50% reduction (n=34)

Organ motion (mm) Translational couch shifts

<45.6 cc (n=34)

>45.6 cc (n=33)

Cervix

Uterus

Cervix

Uterus

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

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) 4.1 (±2.0) 4.2 (±2.5) 4.7 (±1.9) 4.9 (±3.2) 3.7 (±2.5)

7.0 2.8 (±2.5) 6.4 4.3 (±2.5) 8.1 5.8 (±2.5) 6.3 6.7 (±3.3) 10.1 8.4 (±8.0) 8.1 5.3 (±4.6)

7.7 3.5 (±1.9) 6.4 4.2 (±2.5) 8.3 4.2 (±1.8) 6.3 4.2 (±1.6) 23.1 4.1 (±2.3) 8.1 4.6 (±2.0)

6.4 2.9 (±1.6) 7.8 4.0 (±2.0) 6.3 5.6 (±2.9) 5.7 6.7 (±2.6) 7.2 6.5 (±4.9) 7.0 6.1 (±3.2)

5.3 6.3 9.6 8.4

Left-lateral (X+) Right-lateral (X-)

2.8 (±1.3) 3.5 (±1.8) 3.8 (±2.1) 4.7 (±1.6) 4.7 (±3.5) 4.0 (±2.3)

4.6 2.7 (±2.2) 5.8 3.9 (±2.2) 6.8 5.6 (±2.6) 5.9 6.5 (±3.2) 10.9 5.6 (±6.5) 7.8 6.1 (±4.6)

6.9 4.3 (±2.4) 6.7 4.8 (±2.5) 8.6 4.6 (±2.2) 10.0 4.1 (±1.9) 19.1 4.3 (±1.7) 13.5 4.3 (±2.3)

7.7 3.0 (±2.0) 7.9 4.4 (±2.3) 7.5 5.9 (±2.7) 6.0 6.8 (±2.7) 5.9 9.2 (±6.2) 7.5 5.2 (±3.1)

6.2 7.2 9.3 9.0

Anterior (Y+) Posterior (Y-) Superior (Z+) Inferior (Z-)

15.2 10.2

19.0

9.6 No difference in organ motion irrespective of pre-treatment tumor volume or mid-treatment tumor regression