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Dr Suman Das MD, FUICC (USA)
Consultant Radiation and Clinical Oncologist Queens NRI Hospital Vizag
Introduction
Queens NRI Hospital Dept. of Oncology
CBCT work flow (In our institute)
View the case
CBCT was first adapted for potential clinical use in 1982 at the Mayo Clinic Biodynamics Research Laboratory.1
Initial interest focused primarily on applications in angiography
Exploration of CBCT technologies for use in radiation therapy guidance began in 1992.
Integration of the first CBCT imaging system into the gantry of a linear accelerator in 1999.
http://www.ajnr.org/content/30/7/1285.long#ref-4
With CBCT, a full CT scan of the patient on the treatment couch is obtained immediately before radiation delivery
with the CT scan taken and reconstructed in less than 2 minutes.
The CT scan can then be automatically registered to the CT taken earlier for treatment planning to facilitate precise repositioning of the patient to the treatment machine isocenter.
AIM Higher doses to PTV and lower doses to normal tissue.
With the resulting steep dose gradients, motion management becomes an even more critical part of the process.
Movements During Radiation Therapy
Interfractional motion Change in patient position between treatment session. Patient setup changes Patient anatomy changes (tumor shrinking, organ fill status)
Intrafractional motion
Change in patient position during a treatment session. Breathing Gas passing Uncooperative patient
Role of CBCT
Reduce interfractional motion
Patient position adjustment
No-go condition identification
Assesses 3D patient status
Tumor evaluation
Adaptive planning
CBCT imaging components
KV source and kV imaging panel at 90º to treatment line used for three imaging modes: planar, fluoro, CBCT mounted on arms that are motorized to varying degrees.
CBCT is 3D aligned with reference image / planning CT
various tools: contours, ROIs, color overlay shifts necessary to align image sets correspond to couch shifts
correct patient setup translations and/or rotations CBCT -data preparation
Queens NRI Hospital Vizag Clinac IX Liniear accelerator with OBI
HDR Brachytherapy : Gammamed Plus
CT based Planning
Eclipse 10 with CT/MRI/PET registrations
1062 patients treated
Every month 70 new patients registered for radiation
Daily work load Avg 90 Patients
CBCT workflow Queens NRI Hospital
28yr female
C/O Hemoptysis for 3 month
Dyspnea for 15days
4/4/13: X Ray Chest: Homogenously opaque Lt Hemithorax with elevated lt hemidiaphragm and shift of mediastinum to lt s/o collapse or fibrosis of left lung.
4/4/13: CT Chest: 3.5 x 2.4cm sized hypoattenuating area seen towards left main bronchus completely obstructing the left main bronchus.
11/4/13: PET CT : Well defined homogenously enhancing hypodense soft tissue encasing and completely occluding the left main bronchus. Complete atelectasis of ;left lung lesion extending to right side causing narrowing rt main bronchus. 6.7cm x 3.0cmx5cm.
30/4/13: HPE: Adenoid cystic carcinoma of Bronchus.
PET CT fusion and volume deliniation
Radiation Planning phase 1
Ca Cervix Rapid Arc
Ca Prostate
Ca Tongue