enhancement of clinical outcome using obi and cone beam ct in radiotherapy

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