IGRT – Just a Buzz

Transcription

IGRT – Just a Buzz

IGRT – Just a Buzz-Word ?
5th Langendorff – Symposium, 26‐27 April, Freiburg Fridtjof Nüsslin
Klinik für Strahlentherapie
und Radiologische Onkologie
Klinik und Poliklinik für Strahlentherapie und Radiologische Onkologie
Scope
• Introduction
•
History & Definition of IGRT
• Rationale of IGRT
•
•
Quality of Treatment Delivery
Reduction of Treatment Toxicity
• Technologies
•
EPID, CBCT, MR-Linac
• Critiques
•
•
•
•
Clinical relevance
Radiation Risk Assessment
Costs: investment versus outcome
Global view: impact on cancer care
• Conclusion
Introduction
History and Definition of IGRT
The more than 10 year history of IGRT
a
c
Canada Post
Corporation (1988)
Cobalt Therapy, 1951,
Johns , Cunningham, Holloway
b
a) 60Co treatment head, (b) a small 120kV diagnostic X‐ray unit, (c) an image intensifier coupled to a vidicon camera, and (d) a counterweight, that also acts as a protection shield. Ionisation chambers are built‐in the counterweight, allowing transit dosimetry. Dr. H. Lokkerbol, NKI in the Netherlands, implemented clinically in 1961.
A (short) history of image‐guided radiotherapy, Verellen et al, RTO 86 (2008)
Imaging in Clinical Oncology
Localisation/ Treatment Planning
Diagnosis
Treatment Delivery
Treatment Response,
Follow‐up
Portal Film
Ultrasound
Convent. X‐ray
CT
MR, fMR, MRS
PET‐CT, MR‐PET
Radioisotopes/
SPECT, PET
Image
Guided
Radiotherapy
EPID
Helical
CBCT
IGRT:
imaging in the treatment room prior or
during treatment delivery
• to allow for proper adjustment
based on acquired images,
• to decrease PTV to CTV margin
“I can´t hit what I can´t see,
I can´t cure what I can´t hit“
Harold Johns 1915-1998
For a long time RT Technology Development was
following the inverse Path:
Guidance by intuition instead imaging
Rationale of IGRT
• Quality of treatment delivery
– To deliver the treatment as prescribed
– To measure the radiotherapy delivery performance
• Biological relevant dose optimization
– Reduction of toxicity
– Dose escalation approach
– Hypofractionation
– Adaption of treatment (multi‐modality therapy)
IGRT: Quality of Treatment Delivery
• To deliver the treatment as prescribed
•
•
•
•
•
Reducing geometric uncertainties
Eliminating systematic errors
Verifying / correcting patient set-up & beam positioning
Intra-fraction motion management (4D-Image acquisition,
gating, tracking)
Adapting margins and treatment plan during the course of
treatment
• To measure the radiotherapy delivery performance
•
•
•
•
Analysis of image data
Exit dose evaluation
Model based dose calculation algorithms
TCP & NTCP assessment
Patient positioning - set up errors
& CBCT frequency
none
First five days
daily
CBCT – cone beam CT
ML – medio‐lateral (L‐R) Image guidance in lung cancer radiotherapy
Higgins et al 2011
IGRT: Reduction of Treatment Toxicity
• To reduce the PTV margin around the CTV
• To allow for high conformal treatment techniques with
steep dose gradients (3D-CRT, SRT, IMRT, pRT)
• To prevent exceeding critical organ dose threshold
Clinical Impact ‐ Examples:
50% reduction in genitourinary toxicity and improved biochemical control in high‐risk patients when applying IGRT. Zelefsky et al, 3.5 cm
PTV Ø 4 cm
IROBP 84 (2012)
22.5 cm3
V 33.5 cm3
• Superiority of IG‐CRT (equivalent to BRT and Reducing the margin from 10 mm Surgery) over standard RT of prostate ca. to 5 mm saves 50% of the PTV Kupelian et al. IROBP 58 (2004)
(CTV diameter 3cm)
•
At 24 months, no significant differences were seen between randomised groups in non‐xerostomia late toxicities, locoregional
control, or overall survival.
47 patients were assigned to each treatment arm. Median follow‐up was 44∙0 months (IQR 30∙0–59∙7). At 12 months xerostomia side‐
effects were reported in 73 of 82 alive patients; grade 2 or worse xerostomia at 12 months was significantly lower in the IMRT group than in the conventional radiotherapy group.
Technologies
EPID, CBCT, MR-Linac,
Innovations
IGRT Solutions: Radiographic imaging
• Planar Systems (Portal film
• Digital Systems (EPID)
• kV‐/ MV‐Systems (CBCT, Helical)
• Ultrasound
• new horizons
MRI-guided RT
ELEKTA/PHILIPS: The MRI‐linac Rotating gantry with 3 Cobalt‐60 teletherapy heads and 3 combines a 1.5 T MRI scanner and a MLCs. Split‐magnet MRI system for volumetric and multi‐ 6 MV linear accelerator. planar soft‐tissue imaging. (VIEWRAY)
Cross Cancer Institute, Edmonton, B.G.Fallone (2012)
The Cross Cancer Institute is investigating two linac‐MR designs: a longitudinal configuration (left) and a transverse configuration (right). The team is installing both configurations to confirm the dosimetric differences between the two. Image courtesy of the Cross Cancer Institute. 6 MV Linac 0.6T & SC‐MRI
Innovative Solution from SALK:
Robotic Positioning & Imaging System
PAIR = Patient Alignment Imaging Ring PAIR = treatment unit + positioning/imaging unit
Some critical remarks ….
Yes, IGRT is more than just a buzz
word, but …….
Risk ‐ Benefit
Quality Assurance
Health Care Costs
Global Perspective
Technology Obsession
IGRT – what is the real benefit?
• How translates improving treatment deliver quality into
better outcome?
• Outcome assessment by clinical trials;
•
•
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Short term: set-up uncertainties & reduction of motion
artifacts
Appropriate time pattern
Influence of tumor site and IGRT method
• Conventional fractionation and PTV concept adequate?
• Re-visiting the conventional target volume concept
(GTV-CTV-ITV-PTV): IGTV or PTVIG (C.Ling,2006)
• IGRT&IMRT: Re-visiting 2Gy-fractionation RT, hypo- or
single fraction RT
D95% GTV
Fractionation
D95% PTV
Does IGRT ensure target
dose coverage of head and
neck IMRT patients?
(P.Graff et al., RTO 2012)
Comparisons of MVCBCT‐generated dosimetric data (patient 1 as an example). Dosimetric index variations (DVH data); top: GTV; center: hPTV; bottom: spinal cord.
Fractionation
D95% Spine
Fractionation
Conclusion:
The dosimetric impact of anatomic
changes during RT is of lesser
importance than the effects of IGRT repositioning.
IGRT in Brachytherapy (Interventional RT)
„Brachytherapy well acknowledged for all its inherent physical & biological advantages, carrying the paradigm of basic physical superiority to external beam photon radiotherapy: High tumour dose with normal tissue sparing at the same time“ R.Pötter, RTO 2009
Technological Progress
Advanced imaging, computer, application & delivery
technology
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•
•
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Transrectal ultrasonography (Holm et al, 1983)
Imaging before, during and after BT (CT, MRI)
Image based on-line treatment planning
Afterloading developments
Cost efficiency
Radiation dose associated with
radiological IGRT techniques
Orthogonal kV-imaging:
Helical kV-CT
Helical MV-CT
kV-CBCT
MV-CBCT
< 1 mGy
10-15 mGy/Scan
10-20 mGy
10-30 mGy
80-100 mGy
Additional radiation exposure of PTV may be neglected, however, peripheral dose has to be considered (depending on the acquisition protocol).
SSK Empfehlungen, 2010
Data Handling & Storage
Typical responses to IGRT data storage requirements:
•
•
•
•
„that is a lot more than we are used to“
„where do I put this data?
„how can one move large data volumes to where it is needed?
„what is it going to cost?“
Problems:
• Storage Requirement
• Archive
• Communication
• Workflow
• Hardware Infrastructure
• Staff, Maintenance
Rough Estimate:
Facility treating
2000 pts with 30 fx & daily
IGRT require 1TB/y
SJ Swerdloff (2007)
Total costs of Cancer Care
• Cancer Care Costs per total health costs (2004‐2010)
– Europe: 4.1% (NL) to 7% (S)
– USA: 5%
– Japan: 9.3%
• Rate of increase in health care spending (USA):
– 5% of GDP in 1965 to 20% in 2020 • Cost of imaging for cancer: 5.1% to 10.3% /year during 1999‐2006 in USA
05.06.2013
Fusszeile
23 Commission, 2011
The Lancet Oncology
BCSoMD Medical Equipment Results: Radiotherapy Availability
30%of cancers could be prevented
Approximately 70% of cancer deaths occur in low‐ and middle‐
income countries
36% of the world do not have at least 1 Radiotherapy unit per 2 million population, 81% of them from low and lower‐middle income countries
Adapted from WHO, 2012
Future
• Smarter Systems
• Software tools for image analysis
• Balanced Technology Development
• Outcome Assessment (clinical trials)
• Cost efficiency
Conclusion
• The new frontier is individualized medicine, IGRT which aims to tailor the treatment to the patient is the response of radiotherapy to this approach.
• IGRT is expected to provide a more successful, less toxic and more cost‐effective treatment.
• IGRT challenges for clinical evaluation and technical innovation
Thank you

IGRT – Just a Buzz

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