Implementing 3D conformal radiotherapy and IMRT Implementing 3D - PowerPoint PPT Presentation

ICARO Vienna April 27-29 2009 Implementing 3D conformal radiotherapy and IMRT Implementing 3D conformal radiotherapy and IMRT in clinical practice: Recommendations of IAEA- - in clinical practice: Recommendations of IAEA TECDOC- -1588 1588 TECDOC M. Saiful Huq, Ph.D., Professor and Director, Dept. of Radiation Oncology University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania, USA huqs@upmc.edu M. Saiful Huq – Transition from 2D to 3DCRT & IMRT 1 IAEA-CN-170/ 013

Goal of radiation therapy Goal of radiation therapy • Conformity of dose distribution to a 3D target volume at the same time minimizing the dose to an acceptable level to the surrounding healthy structures • Achieve local (or regional) control with limited risk of normal tissue complications 2 M. Saiful Huq – Transition from 2D to 3DCRT & IMRT IAEA-CN-170/ 013

Conventional radiation therapy Conventional radiation therapy Shaped field defined from planar radiograph M. Saiful Huq – Transition from 2D to 3DCRT & IMRT IAEA-CN-170/ 013 3

3D conformal radiation therapy 3D conformal radiation therapy Full 3D CT dataset; ICRU 50,62 definition of target and OAR volumes 4 M. Saiful Huq – Transition from 2D to 3DCRT & IMRT IAEA-CN-170/ 013

IMRT IMRT Full 3D CT dataset; ICRU 50,62 definition of target and OAR volumes; co-registration of PET and CT images 5 M. Saiful Huq – Transition from 2D to 3DCRT & IMRT IAEA-CN-170/ 013

Positioning and IMRT (3DCRT) (3DCRT) IMRT immobilization planning and delivery planning and delivery process process Image acquisition File transfer and management Structure segmentation Position verification Treatment planning and evaluation Plan validation as necessary Treatment delivery and verification Adapted from an illustration presented by Webb, 1996 M. Saiful Huq – Transition from 2D to 3DCRT & IMRT IAEA-CN-170/ 013 6

IMRT IMRT Requires knowledge and understanding of • patient immobilization/organ motion • volumetric imaging • 3D heterogeneous dose calculations • large-scale optimization • dynamic beam delivery of non-uniform beam fluences 7 M. Saiful Huq – Transition from 2D to 3DCRT & IMRT IAEA-CN-170/ 013

IMRT - - advantages IMRT advantages • Highly conformal, even concave dose distributions • Large dose gradient near the perimeter of both the target volume and healthy structures � Potentially allows for AHARA [as high (dose) as reasonably achievable] � Decreased dose to normal tissue • Improvement of therapeutic ratio 8 M. Saiful Huq – Transition from 2D to 3DCRT & IMRT IAEA-CN-170/ 013

However… … However • Increased conformity of IMRT may lead to “geographical miss of the tumor” due to inadequate target delineation, organ motion, patient positioning inaccuracies • A larger margin may lead to unacceptable high dose to adjacent normal critical structures 9 M. Saiful Huq – Transition from 2D to 3DCRT & IMRT IAEA-CN-170/ 013

Clinical implementation of IMRT Clinical implementation of IMRT • Equipment and space requirements • Staff training and patient education • Time and personnel requirements including their responsibilities • Changes in treatment planning & delivery practices • QA of equipment and individual patient treatments • Changes in scheduling & overall integration See also: IAEA TECDOC 1588 AAPM Guidance document: Med Phys 30, 2089-2115 (2003) 10 M. Saiful Huq – Transition from 2D to 3DCRT & IMRT IAEA-CN-170/ 013

Clinical implementation of IMRT: Highlights Clinical implementation of IMRT: Highlights Equipment Equipment • • Linac TPS • • MLC Inverse planning • • OBI/CBCT R&V • • Gating 2 nd check software • • Shielding Immobilization • • Imaging QA/Dosimetry • • CT Sim (MRI, PET/CT) Chamber/diode array or • film/EPID dosimetry EPID, port films • • MLC QA (film/EPID) 4D CT (optional) M. Saiful Huq – Transition from 2D to 3DCRT & IMRT IAEA-CN-170/ 013 11

Clinical implementation of IMRT: Highlights Clinical implementation of IMRT: Highlights Training Training Physicians • Cross-sectional anatomy • Inverse planning concepts, dose constraints • Margins, effects of organ motion • DVH based planning and analysis • Plan evaluation-dose conformality/heterogeneity • Dose prescription • Limitations of IMRT See also: IAEA TECDOC 1588 AAPM Guidance document: Med Phys 30, 2089-2115 (2003) M. Saiful Huq – Transition from 2D to 3DCRT & IMRT IAEA-CN-170/ 013 12

Clinical implementation of IMRT: Highlights Clinical implementation of IMRT: Highlights Training Training In addition to the previous ones Medical physicists • Understanding of optimization methods • Characteristics of IMRT dose distributions, plan QA • Beam modeling and delivery for IMRT See also: IAEA TECDOC 1588 AAPM Guidance document: Med Phys 30, 2089-2115 (2003) M. Saiful Huq – Transition from 2D to 3DCRT & IMRT IAEA-CN-170/ 013 13

Clinical implementation of IMRT: Highlights Clinical implementation of IMRT: Highlights Training Training Medical oncologist Radiologists • • IMRT/SRS/SBRT PET Additional Staffing Additional Staffing TUMOUR STAGING TUMOUR STAGING WITH PET ( 18 18 F F- -FDG) FDG) WITH PET ( • Increased time for planning and delineation of target volume (Physician, planner) • Image guidance • Increased treatment time/delivery/QA M. Saiful Huq – Transition from 2D to 3DCRT & IMRT IAEA-CN-170/ 013 14

Self questions to be asked!! Self questions to be asked!! • What can be achieved with IMRT? • What specific dose goals should be given to specific treatment sites? • What are the dose/dose-volume tolerances of organs at risk? � How is this affected by fractionation? • How are achievable results affected by margins- immobilization, localization, treatment delivery method, TPS and dose calculation method? M. Saiful Huq – Transition from 2D to 3DCRT & IMRT IAEA-CN-170/ 013 15

Modern radiotherapy is complex Modern radiotherapy is complex Hardware breaks, software always has bugs, and people Hardware breaks, software always has bugs, and people make mistakes! make mistakes! Every clinic is susceptible to these kinds of errors Every clinic is susceptible to these kinds of errors (i.e., BIG ones) ! (i.e., BIG ones) ! 16 M. Saiful Huq – Transition from 2D to 3DCRT & IMRT IAEA-CN-170/ 013

Reported accidental exposures with new Reported accidental exposures with new technologies technologies • Keeping equipment in calibration is essential • Few events resulted from machine errors � Micro-multileaf collimator � VARiS IMRT/MLC • However, each had a strong human failure • The vast majority of events begin with a staff error ROSIS database; ICRP Draft 2009 17 M. Saiful Huq – Transition from 2D to 3DCRT & IMRT IAEA-CN-170/ 013

Assessment of dose Assessment of dose Josef Novotny 18 IAEA-CN-170/ 013 M. Saiful Huq – Transition from 2D to 3DCRT & IMRT

ICRP draft 2009 ICRP draft 2009 Risk-informed and cost-effective approaches for prioritizing tests and checks by means of prospective methods of risk assessment, to be performed in cooperation with manufacturers 19 M. Saiful Huq – Transition from 2D to 3DCRT & IMRT IAEA-CN-170/ 013

Risk assessment Risk assessment • What is Risk? � A term which frequently embodies � probability of an event occurring and � severity should such an event occur • Need to quantitate probability and severity • New tools � Process tree � FMEA � Fault tree AAPM TG100: A new paradigm for QA in radiation therapy 20 IAEA-CN-170/ 013 M. Saiful Huq – Transition from 2D to 3DCRT & IMRT

Conclusions Conclusions • Human factors � Training � Miscommunication within and between departments • Lack of attention by people performing task • Lack of consistent procedural guidelines • People as well as linacs, need to be “commissioned” • Lack of comprehensive QA, QC & QM programs AAPM TG100: A new paradigm for QA in radiation therapy 21 M. Saiful Huq – Transition from 2D to 3DCRT & IMRT IAEA-CN-170/ 013

Our job is not to prevent errors, but to keep the errors from injuring the patients. Lucian Leape It is useful to report all accidents It is impossible to make before consequences anything foolproof appear because fools are so ingenious. Artur Bloch, Murphy’s law Courtesy: Josef Novotny M. Saiful Huq – Transition from 2D to 3DCRT & IMRT 22 IAEA-CN-170/ 013