Application of 2D frameless angiography in planning

Gamma Knife radiosurgery for AVMs

A.V. Dalechina1, A.V. Golanov1,2, V.V. Kostjuchenko1

1Moscow Gamma Knife Center2Burdenko Neurosurgical Institute

Moscow Gamma Knife Center

Burdenko Neurosurgical Institute

No conflict of interest disclosure in presentation

3 main questions of this presentation

•How do we apply this method?

• Are we sure that this method is correct ?

•What is the advantage of using this method?

How do we apply this method?

2DSA

STANDARD WAY

2DSA

Draft manual adjustment

Autofusion and verification

CT

XA+

Contouring

any treatment planning

system, which supports import

DICOM / DICOM

RTSTRUCT

iPlan

GammaPlan

multiPlan

1. Contouring on one projection

2. Continue contouring on second projection

3. Volumes, contoured on the angiography are projected to the CT and volumes, contoured on the CT are projected to XA . Adjust contours using agreement between planes and observing different angio frames

4. Draw contours on the CT inside crossection of two XA projections

5. Observe back projection from the CT to XA

6. Finish. Export DICOM CT and RTSTRUCT data

Localization

ImageFusion

CT

XA+

Choose frameSynthetic marcsDefine in LGP

Math behind

Where

1.15

1.16

1.17

1.18

1.19

-5 -4 -3 -2 -1 0 1 2 3 4 5

Ox Oy Oz Ga Ka Ca Sdd R

Pattern Intensity measure function graphs in thevicinity of global solution. One unit correspondsto 0.4 mm or 0.4 degrees.

1. Pattern Intensity measure function

2. Simplex optimization method

Vary 8 parameters (6 position and rotation, one source-detector distance, and one distortion correction factor if necessary)

Are we sure that this method is correct ?

Accuracy

NovalisGamma Knife

Internal structures position determining with accuracy

~ 1mmMarcs on localization box

Synthetic marcs (red)

Verification60 patients with frame-based SRS3 independent usersiPlan RTImage 4.1

Results:

No significant difference in AVM volume. The mean difference between stereotactic coordinates:

AP: 0.6±0.5 mmLAT: 0.9±0.7 mmCC : 0.7±0.6 mm

“This frameless approach assures accurate target localization and can be used in a clinical setting”.

What is the advantage of using this method?

Clinic

• XNAV is routinely used at Burdenko Neurosurgical Institute during last 5 years after 2011

524 patients

• XNAV is routinely used at Moscow Gamma Knife Center during last 4 years after 2012

90 patients

75%

25%

Cyber KnifeXNav without XNav

36%

64%

Gamma KnifeXNav without XNav

2008 – 2012 y.

2012 – 2016 y.

2011 – 2016 y.

2009– 2011 y.

Wait time before treatment

0

1

2

3

4

5

6

7

8

9

10

aver

age

wai

ting

time,

hour

s

2008 2009 2010 2011 2012 2012 (after july) 2013 2014 2015

XNav

Conclusion

• Frameless approach assures accurate AVM localization

• Avoid discomfort and risks associated with additional invasive angiography

• In perspective 2D frameless angiography – powerful tool for effectively use of Gamma Knife Icon for AVM irradiation

Thank you for listening!