4D-CBCT is latest software gadget in field of radiation oncology. It will calculate breathing movement during treatment of lung cancer and help in delineate the target better. This presentation will convince you that even if you do not have 4D-CT simulation, you can confidently use 4D-CBCT at optimal level.

1. 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)

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

3. 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.
6D Definition

4. Lung Tumour Motion While Free Breathing
Motion Artifact

5. AAMP: American Association of Physicists in Medicine
AAPM TG-76 (Report 91)
• 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
SUPERIOR - INFERIOR ANTERIOR – POSTERIOR LEFT - RIGHT
0 – 18.5 mm 0 – 9.5 mm 0 – 10 mm

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):590-8. Epub 2007 Nov 26

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

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

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
FiducialFiducial

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
GT
V

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

13. 4D (Symmetry) Pre RT Evaluation

14. 4D (Symmetry) After 20 #

15. 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
SUPERIOR - INFERIOR ANTERIOR – POSTERIOR LEFT - RIGHT
0 – 18.5 mm 0 – 9.5 mm 0 – 10 mm
AAMP

16. Setup Errors
Transitional Setup
Error
Lateral Longitudinal Vertical
Mean (cm) 0.1165 -0.1055 -0.187
standard deviation
(SD)
0.066447 0.324877 0.093529

17. Conclusion
• Accuracy
• Precision
• Verification
FUTURE???