UseCase on treatment planning at HIMAC

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Use-Case on treatment planning at HIMAC

• Koichi Murakami
• KEK
• 1st Workshop on the Italy-Japan Collaboration on
  Geant4 Medical Application
• 8/Mar./04, INFN Genova

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Introduction

• Our project was just started and we are not yet
  familiar with practical use-cases in medical
  application.
• It is important to collect practical use-cases
  and requirements for medical users.
• We had hearing for treatment planning system at
  HIMAC (NIRS) on last Dec.
• with a brief demonstration of the system.
• collecting use-cases and documentation
• picking up requirements from use-cases

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Basic Flow of Radiation Treatment

• Diagnosis
• Prescription according to the treatment protocol.
• Treatment planning (our scope)
• Discussion based on the results of treatment
  planning
• Treatment

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Input/Output of the system

• At first, we list up items taking part in the
  system.
• Diagnosis (input)
• Treatment protocol to be applied
• Image data (CT) of a patient
• DICOM format
• Specification of ROI (Region Of Interest)
• Identification of organs
• Specification of target (cancer) volume
• Parameters of treatment system
• beam energy, parameters of beam line (input)
• parameters of collimators (range shifter, MLC,
  Bolus) (i/o)
• Discussion based on the results of treatment
  planning (output)
• Dose distribution
• DVH (Dose Volume Histogram)

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Image Data (CT)

• DICOM format
• Dr. View is used as visualization tools.
• Resolution
• 512x512 pixels of 0.7mm2 in xy-plane
• 21cm x 15cm (at MLC in HIMAC)
• dz3/5 mm along z-direction, 30cm in total
• Correction
• position
• smoothing
• density (removal of artifact)
• Conversion from CT-value to density
• material is defined as water.

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Specification of ROI

• ROI (Region Of Interest)
• region for scoring DVH
• OAR (Organs At Risk)
• Tumor (Target) Volume
• GTV lt CTV lt PTV
• GTV (Gloss Tumor Volume)
• CTV (Clinical Target Volume)
• PTV (Planning Target Volume)
• TV PTV 6mm (HIMAC)
• Operation is carried out by doctors.
• Marking ROI for each sliced CT image by hand
• Automatic identification of organs is possible
  with commercial tools.

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Parameters of Treatment System

• Beam energy
• depending on the depth to tumor
• Parameters of magnets
• making laterally uniform beam area
• Wobbler magnet and scatterer thickness
• Ridge filter
• forming SOBP (Spread Out Bragg Peak)
• Range Shifter
• adjusting range
• Collimators
• Ring collimators
• MLC (multi leaf collimator)
• Bolus
• being sculpted for tumor depth
• Control protocols of hardware
• GPIB
• Original format

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Discussion for Treatment

• Treatment team has discussion based on the
  results of treatment planning.
• Dose Distribution
• Spatial resolution
• 2 times larger size of cells than CT image
  (1.4mmx1.4mm)
• same size along z-direction
• more fine resolution in other facilities
• DVH (Dose Volume Histogram)
• Integrated volume having dose more than given
  over ROI.
• DVH in TV vs. DVH in OAR (Organ At Risk)

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Documentation
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Documentation

• Making formatted documentation was just started
  for our situation.
• Digging out actors (list of actors)
• Breaking down to sub-systems (tentative)
• Glossary of terminology
• Description of use-cases

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Digging out Actors

• List of Actors
• Doctors
• MRT (Medical Radiation Technologists) as
  Operators/Planners
• This is our (japanese) situation. Situation can
  be different between countries.
• Other concerned participants
• Patients
• QA of system (design/study/evaluation)

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System Component

• Breaking down to sub-systems
• This is currently tentative.
• Modeling / Visualization
• Management of Geometry and Parameters
• Dose Calculation
• Analysis

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Scope of System Component (1)Modeling /
Visualization

• I/O of image data
• Interface with CT-system and image servers
• Visualization of image data
• Image processing in medical use
• automatic detection of organs
• editing CT-values
• modeling of human body
• production of DRR (Digitally Reconstructed
  Radiograph)
• (Graphical) user interface

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Scope of System Component (2)Management of
Geometry and Parameters

• I/O and management of geometry and parameters
• beam line parameters and (Geant4) geometry
• information of patients
• converted from CT images to a suitable for
  planning (e.g. Geant4 geometry)
• Calculation and management of parameters of
  instruments forming exposure area
• collimators/filters
• interface with CAD/CAM system
• (Graphical) user interface

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Scope of System Component (3)Dose Calculation /
Analysis

• Dose Calculation
• Dose calculation engine
• non-MC base code
• MC code (e.g. Geant4)
• Scoring (Tally) package
• Analysis
• Analysis (histogramming) package
• Interface with visualization of result
• (Graphical) user interface

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Description of Use-cases

• Items in each use-case
• Identifier
• Goals in Context
• Scope
• System / Sub-system / Component
• as Black Box / White Box
• Level
• Summary / User-goal / Function (according to
  abstraction level)
• Actors
• Pre-condition
• Guarantees
• Scenario
• Extensions
• branches for main scinario
• alternatives in cases of failure
• variations of what to do for main scenario
• Technology and Data Variation
• variations of how to do for main scenario
• Notes

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Documentation of Use-Case

• Weve made documentation for higher level of
  use-cases.
• 1 summary level of use-case and 4 user-goal level
  of use-cases for sub-systems
• Use-Case Planning radiation treatment
• Making treatment plan with treatment planning
  system.
• summary (top) level
• scope radiation treatment planning system
• sub-systems are used as black boxes.

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User-goal level of Use-Cases (1)

• Input of treatment information
• Scope Visualization / Modeling (White Box)
• Processing CT image of a patient and setting
  information of treatment
• Input of exposure condition
• Scope Management of geometry and parameters (WB)
• Setting exposure condition of the system
• beam line parameters
• exposed dose

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User-goal level Use-Cases (2)

• Calculation of parameters of instruments
• Scope Management of geometry and parameters (WB)
• Calculating parameters of instruments forming
  exposed area
• ridge filter
• range shifter
• bolus
• MLF (Multi Leaf Collimator)
• Calculation of Dose Distribution
• Scope Dose Calculation (WB)
• Calculating dose distribution in ROI under the
  given condition

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Future Direction

• Collecting Use-Cases for as many facility /
  system of treatment planning system as possible
• Documentation of Use-Cases
• Breaking down to well-defined sub-systems
• Finding components which can be shared between
  different system.
• Picking up requirements