Overview of Advanced Techniques in Radiation Therapy Jacob (Jake) Van Dyk Manager, Physics & Engineering, LRCP Professor, UWO University of Western Ontario
Acknowledgements Glenn Bauman Jerry Battista Slav Yartsev Jeff Chen Bryan Schaly Jeff Kempe Rashid Dar Curtis Woodford 1 1 1/6/2010
Outline Underlying hypothesis for modern technologies New technologies IMRT/IGRT/ART/4D/gating/SBRT Are people using them? Does it make a difference? Summary 2 2 1/6/2010
Hypothesis Better dose distributions yield better clinical outcomes! Normal Tissue Toxicity (NTCP) Tumour Control Probability (TCP) Basic strategy, reduce the treatment volume (i.e., irradiate a smaller volume of normal tissue ) allows dose escalation 3 3 1/6/2010
Recent Technologies to Reduce Treated Volumes Intensity-Modulated Radiation Therapy (IMRT) Image-Guided Radiation Therapy (IGRT) Adaptive Radiation Therapy (ART) 4D imaging/treatment Stereotactic Body Radiation Therapy (SBRT) Other issues not addressed Imaging for target volume delineation Biological modelling/optimization 4 4 1/6/2010
Intensity Modulated Radiation Therapy (IMRT) Sophisticated computer controlled radiation beam delivery to improve conformality of dose to tumour Usually multiple directions Vary intensities within each beam Usually uses inverse treatment planning Give dose-volume prescription/limitations Computer determines beam intensities 5 5 1/6/2010
Required Intensity Pattern 6 6 1/6/2010 Courtesy J Chen
MLC Leaf Sequencing 7 7 1/6/2010 Courtesy J Chen
Resulting Intensity Pattern 8 8 1/6/2010 Courtesy J Chen
Full IMRT Delivery Technique 9 9 1/6/2010 IMRT CWG, IJROBP, 51, 880, 2001
Methods of IMRT Delivery Fixed Beam IMRT Tomotherapy IMAT 10 10 1/6/2010
Image-Guided Radiation Therapy (IGRT) What can change from day to day? Set-up uncertainty Organ motion Tumor Shrinkage Expansion Deformation Microscopic spread (CTV) Location Normal tissue Shrinkage Expansion Deformation Location 11 11 1/6/2010
Daily Treatment Set-up Image-guided radiation therapy (IGRT) 12 12 1/6/2010 Meyer et al, Front RT & Oncol. 40:10; 2007
Methods of Set-up Guidance Laser set-up Electronic Portal Imaging MV CBCT Siemens In-room CT - Siemens kv Cone-beam CT - Elekta 13 13 1/6/2010 MV CT - TomoTherapy
LRCP Experience with IGRT using Helical Tomotherapy (HT) kvct study Contour structures CT-Sim Develop treatment plan TPS Delivery QA Patient setup Treatment HT at LRCP: Daily image guidance with intensity modulated delivery 14 14 1/6/2010 Registration Daily MVCT study Treatment Machine
MV-kV Registration Patient Shifts MVCT kvct MVCT kvct 15 15 1/6/2010
Detecting anatomic change or response to treatment (Stage III NSCLC) t 0 kv CT for plan 1 t 0 + 24 d kv CT for plan 2 t 0 + 60 d MV CT t 0 + 67 d kv CT for plan 3 16 16 1/6/2010
Image Guidance for Set-up and Organ Motion using Tomotherapy Reviewed data of >110 patients treated on HT Helps define frequency of imaging By anatomic site 17 17 1/6/2010
MVCT Set-up Corrections From September 2004 to April 2007 12 R = (x - x 0 ) 2 + (y - y 0 ) 2 + (z - z 0 ) 2 10 8 R (mm) 6 4 2 0 0 20 40 60 80 100 Patient identification SIB Brain H & N Spine Lung Breast Pelvis Brain Skull Chest Abdomen Average values (SD) for setup corrections of over 110 patients treated on LRCP unit 18 18 1/6/2010 Courtesy Slav Yartsev
Change in patient setup due to weight loss (medullary thyroid ca) Early consistency not a predictor of total treatment course 19 19 1/6/2010 Bauman et al, IJROBP 68: 632-641, 2007
GTV Regression from Daily MVCTs 250 200-1.6% /day Volume (cc) 150 100-5.1% /day -0.5% /day 50 0 0 10 20 30 40 50 60 Time (elapsed days) Data potentially useful for radiobiological modeling 20 20 1/6/2010 Woodford et al, IJROBP, 69: 1316-1322; 2007.
Dose Distributions Initial plan for 22 fractions Adapted plan for 8 fractions 21 21 1/6/2010 Woodford et al, IJROBP, 69: 1316-1322; 2007
Conclusions from NSCLC Study GTV changes difficult to predict based on patient or tumour characteristics 40% of these patients would benefit from adapted plans When to adapt For these patients adapt when there is 30% reduction in GTV within first 15-20 fractions Reduced mean lung dose (MLD) & V 20 Dependent on disease and stage 22 22 1/6/2010 Woodford et al, IJROBP, 69: 1316-1322; 2007
Intrafraction Tumour Motion 4D CT If it s moving, you can t hit it. If you can t hit it, you can t cure it! Jerry Battista 23 23 1/6/2010
Intrafraction Motion 24 Strategies to compensate for respiratory motion Internal Target Volume (ITV) definition with fluoroscopy 24 1/6/2010 Results in larger margin Breath hold techniques (voluntary or forced) Respiratory gating Tumor tracking 3-D CRT MLC follows tumour motion IMRT DMLC follows tumour motion 3-D CRT IMRT P. Keal et al.
Respiratory Gating System Real Time Position Management (RPM) system Varian Medical Systems Plastic box with infrared reflectors on chest Motion recorded by infrared camera Assume correlation between chest wall & tumour motion 25 25 1/6/2010
Robotic Radiosurgery - CyberKnife : Tumour Tracking and Image Guidance Real-time image guidance Automatically track, detect, and correct for intra-fraction target movements Non-coplanar treatment delivery Both isocentric and non-isocentric beams Unlimited reach throughout the body Routine delivery of 150 to 200 beams per fraction 26 26 1/6/2010
X-ray Sources IMAGING SYSTEM Linear Accelerator ROBOTIC DELIVERY SYSTEM TARGETING SOFTWARE Manipulator Image Detectors 27 27 1/6/2010 Courtesy Accuray, Inc
Up and Coming Technologies MR-guided RT Utrecht Edmonton ViewRay Linac MRI 28 28 1/6/2010 Courtesy of G Fallone Cross Cancer Inst Edmonton, AB
Dose Painting: Photons vs Protons 29 29 1/6/2010 Flynn et al. PMB 53: 4153-4167; 2008
Implementation? London Regional Cancer Program, Canada TomoTherapy: 1 st patient Sept 2004 IMRT: with inverse planning started April 2005 In 2008: ~30% patients IMRT; ~60% IMRT, with breast & H&N forward planned IMAT: Started 2002; 150 patients treated 4D CT: Started Nov 2005; 350 patients Gating: Started Dec 2004; 96 treated 30 30 1/6/2010
Implementation? UK Survey, 2007 IMRT used by 46% of centres IGRT used by 21% of centres Lack of implementation due to: Lack of staff Insufficient access to equipment Lack of time for complex planning Insufficient funding 31 31 1/6/2010 Jefferies et al. Clin Oncol 21:204-217; 2009
Implementation? TomoTherapy Annual Revenues ($ Millions) PubMed Search: Adaptive Radiation Therapy 35 $233 32 N u m b er o f p u b lic a tio n s 30 25 20 15 10 5 0 $204 24 $156 18 10 $76 4 $46 2 2 1 1 1 1 1 1 0 $12 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 Year 2003 2004 2005 2006 2007 2008 32 32 1/6/2010
Do advanced techniques make a difference? 2008 33 33 1/6/2010
IMRT Clinical Trials This review shows evidence of of reduced toxicity for various tumour sites by by use of of IMRT. The findings regarding local control and overall survival are generally inconclusive. Endpoint Trial Quality 34 34 1/6/2010 Veldeman et al. Lancet Oncol 9: 367-375; 2008
Summary New technologies are evolving rapidly Especially since early 2000s Major issue is target volume delineation New functional imaging modalities support improvements Reduction of normal tissue irradiation is allowing: Increase in prescribed doses Modified fractionation Implementation of new technologies is hampered by resources (staff, time, money) Knowledge of optimal dose prescription remains limited, especially for dose painting 35 35 1/6/2010