RADIATION ONCOLOGY

First Site Experience on Real-time Motion Synchronization on the Radixact® System

X. Allen Li, PhD, FAAPM

Medical College of Wisconsin

Accuray at ASTRO, Sept 16, 2019

DisclosureMCW receive research funding from Accuray Incorporated

DisclaimerThe views expressed in this presentation are those of the presenters and do not necessarily reflect the views or policies of Accuray Incorporated or its subsidiaries. No official endorsement by Accuray Incorporated or any of its subsidiaries of any vendor, products or services contained in this presentation is intended or should be inferred.

Organ motion during radiation therapy delivery is a major problem!

Motion in Pelvis

Prostate Motion Continuous drift

Transient Excursion

Excursion

Low Frequency

Techniques to Treat Mobile Tumors

Slide reproduced with permission

Techniques to Treat Mobile Tumors

Slide reproduced with permission

Techniques to Treat Mobile Tumors

Slide reproduced with permission

®

RADIATION ONCOLOGY

Synchrony® on Radixact®

Schnarr et al, Med Phys. 2018 45:1329

Image Credit: J. Smilowitz, UW Madison

kV Detector

kV Source

RADIATION ONCOLOGY

Synchrony® on Radixact®

Sequential kV x-rays radiography during helical delivery to detect lung targets or fiducials Dynamic jaws and fast binary MLC “re-

point” the beam to known position of the target with sub-mm accuracy

Schnarr et al, Med Phys. 2018 45:1329

RADIATION ONCOLOGY

Synchrony®• LED markers detected by camera for

respiration tracking• Tracking modalities

– Quasi-static: irregular motion + fiducial(s)

– Respiratory with fiducials: respiration motion + fiducial(s)

– Respiratory without fiducial: respiration motion + trackable target

• Plan type settings– Helical– Fixed/dynamic jaws– Jaw width: 1.0 cm, 2.5 cm

RADIATION ONCOLOGY

Synchrony® Clinical implementation @ F-MCW 6/14-16, 2019: Software upgrade (weekend) Radixact® Treatment Delivery System v2.0 (Console Software

V7.0) iDMS® Data Management System v3.0 Precision® TPS v3.0

6/21-6/23, 2019: Hardware installation (weekend) Camera system kV imaging system

6/24-7/12, 2019: Commissioning and QA (outside normal working hours)

7/24/2019: First patient treatment

RADIATION ONCOLOGY

Synchrony

RADIATION ONCOLOGY

Accuracy of Tracking LED Motion

RADIATION ONCOLOGY

DQA: Effect of Motion Tracking on 3D Dosimetry

Tracking mode Gamma Passing Rate (%)Irregular motion with fiducials 97.2Respiration motion with fiducials 99.5Respiration motion without fiducials 100.0gamma criteria: 3 mm 3% with 5% threshold

RADIATION ONCOLOGY

DQA: Effect of Motion Tracking on 3D Dosimetry

gamma criteria: 3 mm 3% with 5% threshold

Tracking respiration motion (±10 mm) without fiducials

ChecklistsSynchrony®

The First Case Treated with Synchrony®

45 year old male with stage IV colorectal cancer with pulmonary metastases in lung.

Max GTV diameter: 2.7cm

Respiration motion of 7 mm in superior-inferior direction

SBRT of 54 Gy in 3 fractions.

Two Plans:1) GTV from mid-position CT for motion correction plan2) ITV from 10-phase 4DCT for non-correction plan

ITV

GTV

Two Plans:1) PTVSync = GTV+5mm for motion correction plan2) PTV = ITV+5mm for non-correction plan

PTVSync

PTV

Motion Correction vs. Non-Correction plans

Motion correction enabled higher GTV dose

Motion Correction vs. Non-Correction PlansMotion correction plan

No correction plan

% Diff

PTV 18.3cc 26.3cc -30%Max Dose in GTV/ITV 69.7 66.6 +5%Lung V20 3.3% 3.5% -6%Lung V5 15.9% 17.9% -11%Mean lung dose 2.79Gy 3.13Gy -12%

The motion correction enabled a higher tumor dose with no cost to the normal tissue doses.

Pre-Tx DQA

Pre-Tx DQA

Pre-Tx DQA

Passing rate: 100%

Determining/Verifying Radiography Angles

Selecting appropriate tracking parameters

Observations From the First Patient Treatments

Proper tracking parameter setting Appropriate LED placement Delivery time with motion correction: 16 min (door to door)

PreciseART®

Dose Trending from PreciseART®

Motion correction plan No correction plan

Motion correction plan

No correction plan

% Diff

GTV=2.5cc ITV=4.0cc -60%Lung V20 2.3% 3.2% -28%Lung V5 14.3% 17.9% -20%

Mean lung dose

2.38Gy 3.00Gy -20%

Max Cord dose

12.8Gy 14.3Gy -12%

The motion correction reduced the dose to spinal cord

2nd case: Lung SBRT, 3x18Gy

Improving tumor targeting, reducing irradiation volume, increasing local control and decreasing toxicities

Allowing more SBRT, hypofractionation, ablative RT, improving lung SBRT

Transferring the success of SBRT for lung and liver to other tumor sites

Increasing radiation delivery efficiency Supporting value-based healthcare delivery models, which

economically reward treatment quality and efficiency to improve patient outcomes

Offering possibility to treat novel diseases

Impact of Motion Correction During Radiation Therapy

Strong partnershipDedicated team

AcknowledgementsF-MCW• Guangpei Chen, PhD• An Tai, PhD• Tim Keiper, PhD• Sara Lim, PhD• Elizbeth Gore, MD• Lisa Fisher• Allie Hren• Chris Schultz, MD

Technical Support from Accuray Jeremy Heil Dan Sidney Dan Lucas Michael Kissick Dylan Casey Brandon Frederick Andrea Cox Todd Weston

Funding Supports: Accuray Incorporated MCWCC Fotsch Foundation