Left Breast Deep Inspiration Breath Hold Treatment Based on 3D Surface Matching

Transcription

1 Left Breast Deep Inspiration Breath Hold Treatment Based on 3D Surface Matching X Tang, J Lian, S Chang, Z Xu, J Halle, E Jones, and L Marks Department of Radiation Oncology University of North Carolina Chapel Hill xiaoli_tang@med.unc.edu 1

2 Outline Respiratory gating at the DIBH mode Motivation External gating AlignRT Beam Hold a VisionRT gating software DIBH clinical flow in UNC At CT SIM Daily treatment 2

3 Deep inspiration Moves the heart inferior & posterior Displacing it from the left breast 3

4 Why gate breast patient? DIBH can maximize the distance between chest wall and heart to reduce cardiac toxicity 4 Breath hold DIBH CT Free breathing Regular CT

5 Heart DVH comparison 5

6 Literature review Toronto Sunnybrook regional cancer centre 5 patients: Decreased irradiated volume 6

7 Literature review (cont.) 5 patients: Achieved a mean absolute reduction of in heart volume 7

8 External gating External surrogate systems Varian RPM system track a block on abdomen Siemens Anzai system track abdomen amplitude VisionRT GateRT system track one point on breast surface Direct breast surface matching system VisionRT AlignRT Beam Hold system track breast surface 8

9 External surrogate systems Indirect tracking A block, a belt, or a point on a surface RPM Photos courtesy of P Keall, VisionRT Ltd., and Siemens Anzai 9 GateRT

10 AlignRT Beam Hold 3D imaging solution for patient setup and real time tracking during RT Non-invasive Does not require any markers Does not require additional radiation 10

11 VisionRT system in treatment room 11

12 3D surface rendering 12 CT skin rendering Real patient surface Patient surface

13 Surface matching algorithm Gating based on real-time deltas R stands for reference 3D image (either CT surface rendering or patient surface image) V stands for verification 3D image 13

14 Real time deltas Real time register V to R The following deltas have to meet the preset threshold in order to BEAM ON R V VRT VRT LONG LONG LAT LAT R V R V 2 2 VRTR VRTV LONGR LONGV LATR LATV 2 VRTR VRT V R LONG V LONG LATR LAT V 14

15 Surface matching based DIBH in UNC Started July 2010 first in the US Treated more than 30 patients 15 min slot for daily treatment 6 DIBH patients this week 15

16 AT CT SIM Obtain one set of regular CT Obtain one set of deep inspiration breath hold CT Tattoo patient the conventional way (free breathing) 16

17 Threshold selection 17

18 Patient setup Align patient based on tattoos Adjust couch position when patient holds her breath at DIBH mode to meet all AlignRT Beam Hold tolerance (threshold) On port film days, take films while patient holds her breath and all tolerances are met 18

19 Reference images Non-bolus days Bolus days 19 CT skin rendering Surface capture at DIBH

20 Real-time delta 20

21 Gated treatment Coach patient to hold her breath Audio coaching Video coaching Beam ON automatically when all tolerances met 21

22 Real-time delta example 22 BEAM ON BEAM OFF

23 Port film example with and without breath hold (BH) Port w/o BH DRR Port w/ BH 23

24 Port film example with bolus DRR Port with BH and bolus 24

25 Future clinical application Head and Neck Photos courtesy of CDR systems All other sites surface is better than 3 tattoos 25

26 Acknowledgment 26