1. Dr. Malhar Patel DNB (Radiation Oncology)
4D-CBCT (Symmetry) – a useful tool to verify and treat traditional ITV without 4D-CT simulation in treatment of lung cancer.
Dr. Malhar Patel
DNB (Radiation Oncology)
4D-CBCT (Symmetry) – a useful tool to verify & treat traditional ITV without 4D-CT simulation in a treatment of lung cancer.

2. Introduction Image guidance EPID 4D-CBCT (Symmetry)
Challenges in modern radiotherapy.
What to do about it???
Image guidance
EPID
4D-CBCT (Symmetry)
Introduction

3. 6D Definition
Ling et al defined IGRT more broadly as ―the use of imaging for detection and Diagnosis, Delineation of target and organs at risk (OARs), Determining biological attributes, Dose distribution design, Dose delivery assurance, and Deciphering treatment response,‖ a so-called six-dimensional definition.

4. Lung Tumour Motion While Free Breathing
Artifact
PTV??

5. The Management of Respiratory Motion in Radiation Oncology
AAPM TG‐76 (Report 91)
SUPERIOR - INFERIOR
ANTERIOR – POSTERIOR
LEFT - RIGHT
0 – 18.5 mm
0 – 9.5 mm
0 – 10 mm
• Accounting for Respiratory Motion • Motion‐encompassing methods (Free Breathing) • Respiratory Gating Techniques • Breath‐hold Techniques • Forced shallow breathing ‐ abdominal compression • Real‐time tumor‐tracking
The Management of Respiratory Motion in Radiation Oncology
AAMP: American Association of Physicists in Medicine

6. CONCLUSIONS:
Systematic and random baseline variations constitute a substantial portion of the geometric variability present in the treatment of patients with lung cancer and require generous safety margins when relying on accurate setup/immobilization or bony anatomy-driven correction strategies.
The 4D-CBCT has the ability to accurately monitor tumor trajectory shape and baseline variations and drive image-guided correction strategies that allows safe margin reduction.
Int J Radiat Oncol Biol Phys. 2008 Feb 1;70(2): Epub 2007 Nov 26

7. Combination of Thermoplastic Mask and Vac Lock For Thorax Region.
Immobilization
Immobilization Device.
Combination of Thermoplastic Mask and Vac Lock For Thorax Region.

8. Patient preparation Instruct patient to breathe in 3 phase
You Have 4D CT SCAN??
Instruct patient to breathe in 3 phase
Normal Breathing
Deep Inspiration
Deep Expiration
Patient preparation.

9. CT Simulation Whole Thorax region 3 phase respiration CT
Slice thickness 3mm
Patient aligned to the fiducials & laser marks
IV contrast to enhance target & critical organs
DICOM images transferred through networking
Fiducial
CT Imaging

10. GTV: Gross Tumour Volume
CTV: Clinical Target Volume
ITV: Internal Target Volume
PTV: Planning Target Volume
ITV = CTV + IM (Internal Margin)
PTV = ITV + SM (Setup Margin)

11. Contouring
GTV
Contouring

12. XVI Imaging and 4D Symmetry
Pre-RT evaluation.
Daily XVI Imaging was done.
4D CBCT (Symmetry) First Day and repeated weekly.
XVI Imaging and 4D Symmetry

13. 4D (Symmetry) Pre RT Evaluation

14. 4D (Symmetry) After 20 #
4D (Symmetry) After 15 #

15. (Anterior-Posterior)
Results
The defined ITV margin is adequate to cover the moving target in free respiratory cycle.
30 4D-CBCT
130 XVI (CBCT)
Organ Motion
Longitudinal
(Superior-Inferior)
Vertical
(Anterior-Posterior)
Lateral
(Left Right)
4.9 mm
2.56 mm
1.89 mm
Results
SUPERIOR - INFERIOR
ANTERIOR – POSTERIOR
LEFT - RIGHT
0 – 18.5 mm
0 – 9.5 mm
0 – 10 mm
AAMP

16. Transitional Setup Error
Setup Errors
Transitional Setup Error
Lateral
Longitudinal
Vertical
Mean (cm)
0.1165
-0.187
standard deviation (SD)
Setup Errors for Transitional

17. Conclusion
Accuracy
Precision
Verification
Conclusion
FUTURE???

18. 12 February 2018
Thank you