Real-time model for adaptive radiation therapy a biomechanical approach using a lego mindstorms
1. Gabriele GUIDI
Medical Physicist
Medical Physics Dpt, University Hospital “Policlinico”, MO
N Maffei, C Vecchi, G Baldazzi
Physics Dpt, University of Bologna
G M Mistretta, A Ciarmatori, T Costi
Medical Physics Dpt, University Hospital “Policlinico”, Modena
2. Disclosures
No conflicts of interest to disclose
Co-Funding:
• Italian Ministry of Health (MoH2010, GR-2010-2318757)
Dose warping methods for IGRT and Adaptive RT: dose accumulation based on
organ motion and anatomical variations of the patients during radiation
therapy treatments
• Tecnologie Avanzate S.r.l. (Italy): Co-Partner of MoH2010, GR-2010-2318757
NO CONFLICTS OF INTEREST TO DISCLOSE
3. Adaptive Radiation Therapy (ART) is a state-of-the-art approach that uses a feedback process to
account for patient-specific anatomic and/or biological changes, thus, delivering highly
individualized radiation therapy for cancer patients.
Needs for Clinical Practice:
1. Image Guided System
2. Fast Re-Contouring
3. Fast Re-calculation
4. Tools for Real-Time QA or Simulation
5. Predictive Tools for Biomechanical Approach
[Malone 2014] Malone C, Rock L, Skourou C, Efficacy evaluation of
retrospectively applying the Varian normal breathing predictive filter for
volume definition and artifact reduction in 4D CT lung patients, Journal of
Applied Clinical Medical Physics, vol 15, num 3.
What is Available?
1. Daily Setup Images (e.g. MVCT/kVCT)
2. Automatic PTV/OARs contouring
3. DIR and/or Warping methods
4. Hybrid deformable algorithms
5. Dose Accumulation algorithm
6. Workflow automation (Scripting, GPU, Cluster, iCloud)
7. Tracking/Robotic Systems (e.g.VisionRT, CyberKnife, ExaPot, X-Ray)
8. Predictive analysis
1. Neural Networks
2. Bayesian Network validation
ADAPTIVE RADIATION THERAPY
4. Tracking
WHAT IS THE PROBLEM?
BREATHING
MOTION
Approximate localization of
TUMOR & OAR
With 4DCT and/or
Gating System
Breathing Phase
Reconstruction
With Standard CT
(Mean Object
Positions)
Correlation between
External & Internal
Motion ??
5. 4DCT Breathing Motion
Contour GTV
Spatial-time
position
4D function
correlate to BPM
Simulate irregular BREATHING +
GTV spatial positions phases
Vision RT
Aim:
BIOMECHANICAL APPROACH
6. InfraRed /UltraSound
SENSOR
8 RIBs with 4 angular speed
Prototype “LINAC”
2 TUMOR with 4 DOF
EV3 BRICK:
Linux wireless CPU,
LabVIEW programmable
30 cm
24 cm
[Jeong 2011] Jeong H S, Han Y, Kum O et al., Development And
Evaluation of a Phantom for Multi-purpose Dosimetry in IMRT,
Nuclear Engineering And Technology, Vol.43 No.4 , 2011.
REAL-TIME ROBOT
7. Freedom offered by building bricks
Low-cost/home-made solution
Pediatric scale
Plastic materials avoid artifacts
Complete versatility with LabVIEW dedicated software
[Cruz-Martín 2012] Cruz-Martín A, Fernández-Madrigal J A,
Galindo C et al., A LEGO Mindstorms NXT approach for teaching
at Data Acquisition, Control Systems Engineering and Real-Time
Systems undergraduate courses, Computers & Education 59
(2012) 974–988.
ADVANTAGES FROM LEGO APPROACH
Human 4D simulation reproducible
9. Quasar phantom, interfaced
with VisionRT software,
reproduces BPM
Through sensors, the ROBOT
emulates in real-time patient’s
breathing motion
BREATHING REAL-TIME SIMULATION
4D Breathing Simulation
Tracking Tumor Simulation
10. (12 BPM)
[Castillo 2014] Castillo S J, Castillo R, Balter P, et al., Assessment of a
quantitative metric for 4D CT artifact evaluation by observer consensus,
Journal of Applied Clinical Medical Physics, vol 15, num 3.
PRELIMINARY RESULTS
11. PROTOTYPE TARGET MOTION SIMULATION vs. 4DCT ACQUISITION
We can move and reproduce the 4D motion using surrogate signals
… 4D Motion QA (Quality Assurance) and biomechanical analysis is feasible
12. Organ motion and deformation can lead divergence of treatments compared to the initial
constraints
Standard CT “freeze” images of Tumor and OAR
An anthropomorphic phantom can simulate the human physiology to follow and predict
changes in morpho-dosimetry using external surrogate
4DCT allows to follow dynamics parameters of breathing (spatial time localization)
CONCLUSIONS
LEGO MINDSTOMRS can help to prototype idea and make some experimental with low cost
13. Adaptive Radiation Therapy for LUNG disease requires adequate representation of the
anatomical ROI for a correct calculation of the amount of dose delivered
A correlation between internal organ motion and the breathing sinogram is fundamental
Creation of real models in conjunction with predictive analysis could increase accuracy of
treatments and ensuring that dose distributions are aligned with therapeutic targets
Internal – External correlation can be investigated using surrogate and anthropomorphic
phantom (…or using LEGO solutions)
TAKE HOME MESSAGE
14. GR-2010-2318757 - G.Guidi
- 2010 Ricerca Finalizzata e Giovani Ricercatori -
Ministero della Salute
“That’s too much!!!”
(Praha 2009 : Tomotherapy Meeting)
THANK YOU FOR YOUR ATTENTION
ACKNOWLEDGE