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

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

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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

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SLIDE 1
  • M. Saiful Huq – Transition from 2D to 3DCRT & IMRT

1 IAEA-CN-170/ 013

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

TECDOC-

  • 1588

1588

  • M. Saiful Huq, Ph.D., Professor and Director, Dept. of Radiation

Oncology University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania, USA huqs@upmc.edu

ICARO Vienna April 27-29 2009

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SLIDE 2

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

  • M. Saiful Huq – Transition from 2D to 3DCRT & IMRT

2 IAEA-CN-170/ 013

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SLIDE 3
  • M. Saiful Huq – Transition from 2D to 3DCRT & IMRT

3 IAEA-CN-170/ 013

Conventional radiation therapy Conventional radiation therapy

Shaped field defined from planar radiograph

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SLIDE 4

3D conformal radiation therapy 3D conformal radiation therapy

  • M. Saiful Huq – Transition from 2D to 3DCRT & IMRT

4 IAEA-CN-170/ 013

Full 3D CT dataset; ICRU 50,62 definition of target and OAR volumes

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SLIDE 5

IMRT IMRT

  • M. Saiful Huq – Transition from 2D to 3DCRT & IMRT

5 IAEA-CN-170/ 013

Full 3D CT dataset; ICRU 50,62 definition of target and OAR volumes; co-registration of PET and CT images

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SLIDE 6
  • M. Saiful Huq – Transition from 2D to 3DCRT & IMRT

6 IAEA-CN-170/ 013

IMRT IMRT (3DCRT) (3DCRT) planning and delivery planning and delivery process process

Positioning and immobilization Image acquisition Structure segmentation Treatment planning and evaluation File transfer and management Plan validation as necessary Treatment delivery and verification Position verification

Adapted from an illustration presented by Webb, 1996

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SLIDE 7

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

  • M. Saiful Huq – Transition from 2D to 3DCRT & IMRT

7 IAEA-CN-170/ 013

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SLIDE 8

IMRT IMRT -

  • advantages

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
  • M. Saiful Huq – Transition from 2D to 3DCRT & IMRT

8 IAEA-CN-170/ 013

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SLIDE 9

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

  • M. Saiful Huq – Transition from 2D to 3DCRT & IMRT

9 IAEA-CN-170/ 013

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SLIDE 10

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
  • M. Saiful Huq – Transition from 2D to 3DCRT & IMRT

10 IAEA-CN-170/ 013

See also: IAEA TECDOC 1588 AAPM Guidance document: Med Phys 30, 2089-2115 (2003)

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SLIDE 11

Clinical implementation of IMRT: Highlights Clinical implementation of IMRT: Highlights

  • Linac
  • MLC
  • OBI/CBCT
  • Gating
  • Shielding
  • Imaging
  • CT Sim

(MRI, PET/CT)

  • EPID, port films
  • 4D CT (optional)
  • TPS
  • Inverse planning
  • R&V
  • 2nd

check software

  • Immobilization
  • QA/Dosimetry
  • Chamber/diode array or

film/EPID dosimetry

  • MLC QA (film/EPID)
  • M. Saiful Huq – Transition from 2D to 3DCRT & IMRT

11 IAEA-CN-170/ 013

Equipment Equipment

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SLIDE 12

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
  • M. Saiful Huq – Transition from 2D to 3DCRT & IMRT

12 IAEA-CN-170/ 013

Clinical implementation of IMRT: Highlights Clinical implementation of IMRT: Highlights

See also: IAEA TECDOC 1588 AAPM Guidance document: Med Phys 30, 2089-2115 (2003)

Training Training

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SLIDE 13

Medical physicists

  • Understanding of optimization methods
  • Characteristics of IMRT dose distributions, plan QA
  • Beam modeling and delivery for IMRT
  • M. Saiful Huq – Transition from 2D to 3DCRT & IMRT

13 IAEA-CN-170/ 013

See also: IAEA TECDOC 1588 AAPM Guidance document: Med Phys 30, 2089-2115 (2003)

Clinical implementation of IMRT: Highlights Clinical implementation of IMRT: Highlights Training Training

In addition to the previous ones

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SLIDE 14

Medical oncologist

  • IMRT/SRS/SBRT

Radiologists

  • PET
  • M. Saiful Huq – Transition from 2D to 3DCRT & IMRT

14 IAEA-CN-170/ 013

Additional Staffing Additional Staffing

  • Increased time for planning and delineation
  • f target volume (Physician, planner)
  • Image guidance
  • Increased treatment time/delivery/QA

Clinical implementation of IMRT: Highlights Clinical implementation of IMRT: Highlights Training Training

TUMOUR STAGING TUMOUR STAGING WITH PET ( WITH PET (18

18F

F-

  • FDG)

FDG)

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SLIDE 15

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

15 IAEA-CN-170/ 013

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SLIDE 16

Modern radiotherapy is complex Modern radiotherapy is complex

  • M. Saiful Huq – Transition from 2D to 3DCRT & IMRT

16 IAEA-CN-170/ 013

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) !

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SLIDE 17

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
  • M. Saiful Huq – Transition from 2D to 3DCRT & IMRT

17 IAEA-CN-170/ 013

ROSIS database; ICRP Draft 2009

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SLIDE 18
  • M. Saiful Huq – Transition from 2D to 3DCRT & IMRT

18 IAEA-CN-170/ 013

Josef Novotny

Assessment of dose Assessment of dose

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SLIDE 19

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

  • M. Saiful Huq – Transition from 2D to 3DCRT & IMRT

19 IAEA-CN-170/ 013

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SLIDE 20
  • 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

  • M. Saiful Huq – Transition from 2D to 3DCRT & IMRT

20 IAEA-CN-170/ 013

Risk assessment Risk assessment

AAPM TG100: A new paradigm for QA in radiation therapy

  • New tools

Process tree FMEA Fault tree

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SLIDE 21

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
  • M. Saiful Huq – Transition from 2D to 3DCRT & IMRT

21 IAEA-CN-170/ 013

AAPM TG100: A new paradigm for QA in radiation therapy

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SLIDE 22
  • M. Saiful Huq – Transition from 2D to 3DCRT & IMRT

22 IAEA-CN-170/ 013

It is useful to report all accidents before consequences appear

Our job is not to prevent errors, but to keep the errors from injuring the patients. Lucian Leape It is impossible to make anything foolproof because fools are so ingenious. Artur Bloch, Murphy’s law

Courtesy: Josef Novotny