Corso per l

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CT data Monte Carlo and DICOM standard
Barbara Caccia Stéphane Chauvie
Istituto Superiore di Sanità, Roma Santa Croce e
Carle Hospital, Cuneo

• Corso per lutilizzo del codice GEANT4 in campo
  medico
• Catania, 12-14 Ottobre 2009

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Radiotherapy Tretment planning
Medical accelerator
Patient
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Patient!
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Patient
For Geant4 patient is a detector materials
geometry
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(No Transcript)
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G4Material compound

• Compound composition by fraction of mass
• a 14.01g/mole
• G4Element elN
• new G4Element(name"Nitrogen",symbol"N",z
  7.,a)
• a 16.00g/mole
• G4Element elO
• new G4Element(name"Oxygen",symbol"O",z
  8.,a)
• density 1.290mg/cm3
• G4Material Air
• new G4Material(name"Air",density,ncomponents2
  )
• Air-gtAddElement(elN, 70.0perCent)
• Air-gtAddElement(elO, 30.0perCent)

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Example gas

• It may be necessary to specify temperature and
  pressure
• (dE/dx computation affected)
• G4double density 27.mg/cm3
• G4double temperature 325.kelvin
• G4double pressure 50.atmosphere
• G4Material CO2
• new G4Material(CarbonicGas", density,
  ncomponents2
• kStateGas, temperature,
  pressure)
• CO2-gtAddElement(C,natoms 1)
• CO2-gtAddElement(O,natoms 2)

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Define detector geometry

• Three conceptual layers
• G4VSolid -- shape, size
• G4LogicalVolume -- daughter physical volumes,
  material, sensitivity, user limits, etc.
• G4VPhysicalVolume -- position, rotation

G4VSolid
G4VPhysicalVolume
G4LogicalVolume
G4Material
G4Box
G4VisAttributes
G4PVPlacement
G4VSensitiveDetector
G4Tubs
G4PVParameterised
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Nothing could describe a single patient
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Parameterised Physical Volumes

• User written functions define
• the size of the solid (dimensions)
• Function ComputeDimensions()
• where it is positioned (transformation)
• Function ComputeTransformations()
• Optional
• the type of the solid
• Function ComputeSolid()
• the material
• Function ComputeMaterial()
• Limitations
• Applies to simple CSG solids only
• Daughter volumes allowed only for special cases
• Very powerful
• Consider parameterised volumes as leaf volumes

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G4PVParameterised

• G4PVParameterised(const G4String pName,
• G4LogicalVolume
  pCurrentLogical,
• G4LogicalVolume
  pMotherLogical,
• const EAxis pAxis,
• const G4int nReplicas,
• G4VPVParameterisation pParam)
• Replicates the volume nReplicas times using the
  parameterisation pParam, within the mother volume
• The positioning of the replicas is dominant along
  the specified Cartesian axis
• If kUndefined is specified as axis, 3D
  voxelisation for optimisation of the geometry is
  adopted
• Represents many touchable detector elements
  differing in their positioning and dimensions.
  Both are calculated by means of a
  G4VPVParameterisation object
• Alternative constructor using pointer to physical
  volume for the mother

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Dose calculation CT
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Hounsfield Units
Segnale su detettori TAC
?el ? NA Z/A
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Hounsfield Units
Spettro non monocromatico
We must determine mass density ? and elemental
composition wi
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Visualization

Material HU interval
Air -1000-950
Water/tissue -950125
ICRP cortical bone 125 2000
Steel 3095
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CQ uniformity
Valutazione della graduale variazione dei numeri
CT in un fantoccio omogeneo

• Confronto tra numero CT medio di una ROI al
  centro del fantoccio con quello delle ROI ai
  bordi del fantoccio

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CQ CT numbers
Inserti di differente materiale con numeri CT
variabili nel range di interesse
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CT numbers linearity
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INTEROPERABILITY CONNECTIVITY
Radiotherapy
Radiology
Nuclear medcine
SPECT
Medical Physics
HIS/RIS/PACS
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The DICOM Standard

• DICOM covers
• Communication protocols over networks
• File formats (on different types of media)
• Information Object Definitions (content)
• Services (functionality)
• Grayscale display
• Security
• Hanging protocols
• Structured reporting
• Etc.

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DICOM Functional Groupings
Image Related Workflow and Information Management
Image Related Information Transfer
Persistent Object Storage
Query Request
Retrieve Request
Persistent Object Storage
Print Management
Media Interchange
Print Images
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DICOM Transfer over Network Media
D I C O M . . . . . . . F I L E
. . . . . . . . . .
Data Set

Meta Data

Media Transfer
Group 2 ( Describes Data Set)
Patient Name Patient ID Rows Columns Bits Stored
Header
Image
Group 0 ( Describes Service C-Store)
Command
Network Transfer

Data Set

D I C O M . . . . . M E S S A G
E . . . . . . .
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DICOM Information Object Definitions
Information Entities
Modules
Attributes
Image Pixel Module
Patient Module
Patient Information
Row/Col Size Photometric Interpretation
General Study Module
Patient Study Module
Study Information
Series Information
General Series Module
Frame of Reference Module
General Equipment Module
Instance
(Image) Information
Image Plane Module
Image Pixel Module
Contrast/Bolus Module
General Image Module
Overlay Plane Module
VOI LUT Module
Image Module
SOP Common Module
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Network Addressing with DICOM
Handshake Requirements
Association / Negotiation
ID CT_AE1IP 10.3.253.8Port 104
ID WK_AE1IP 10.3.253.9Port 4006
CT Config File
Wkstn Config File
IP Addr AE Title Port
10.3.253.1 Fusion 104
10.3.253.9 WK_AE1 4006
IP Addr AE Title Port
10.3.253.1 Fusion 104
10.3.253.8 CT_AE1 104
Node Level Security
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Typical Network Flow
DICOM AE B
DICOM AE A
A-ASSOCIATE-RQ

A-ASSOCIATE-AC
or A-ASSOCIATE-RJ
DICOM Messages
A-RELEASE-RQ
A-RELEASE-RSP
or A-ABORT
Either AE
Only The AE Which Initiated The Association May
Release It However, Either May Initiate An A-ABORT