Transcript Seminario Geant4 INFN

DICOM Network Roles
– Successful communication - products must play “opposite roles”
Receive images = Service Class Provider (SCP)
Send images = Service Class User (SCU)
Image Send
CT Image Storage
SOP Class (SCU)
CT Image Storage
SOP Class (SCP)
Network roles are defined for all DICOM
Functions
DICOM Conformance
Statement
– It is Required!
– It is a Public Document
– It Conveys a Product’s DICOM Functionality
– It is Based on DICOM Vocabulary
Abstract Syntaxes (SOP Classes),
Transfer Syntaxes, SCU/SCP…..
– It is Used to Compare Connectivity
– It is most Often on the Web @ Vendor Site
– It Does Not Address All of an Application’s Capabilities, but
should Address All of the Application’s DICOM ones
A Major Step Towards Interoperability
Language and … dictionary
128 bit inutili (non sempre)
DICM
“std” DICOM
(0008,0000) UL
(0008,0020) DA
(0008,0022) DA
(0008,0023) DA
(0008,0030) TM
(0008,0032) TM
(0008,0060) CS
(0008,0070) LO
(0008,0080) LO
(0008,1040) LO
(0008,1090) LO
(0010,0010) PN
(0010,0020) LO
(0010,0030) DA
(0010,0040) CS
(0018,0050) DS
(0018,0060) DS
(0018,0090) DS
(0018,1030) LO
(0018,1100) DS
(0018,1120) DS
(0018,1140) CS
(0018,1150) IS
(0018,1151) IS
(0018,5100) CS
(0028,0030) DS
424 # 4 IdentifyingGroupLength
[20070509] # 8 StudyDate
[20070509] # 8 AcquisitionDate
[20070509] # 8 ImageDate
[163853] # 6 StudyTime
[163933] # 6 AcquisitionTime
[CT] # 2 Modality
[Philips ] # 8 Manufacturer
[OSP S.CROCE CUNEO ] # 18 InstitutionName
[RADIOLOGIA] # 10 InstitutionalDepartmentName
[Brilliance 64 ] # 14 ManufacturerModelName
[TEST CTDI 16 CM HEAD^.] # 22 PatientName
[11111 ] # 6 PatientID
[20070509] # 8 PatientBirthDate
[O ] # 2 PatientSex
[0.5 ] # 6 SliceThickness
[120 ] # 4 KVP
[500 ] # 4 DataCollectionDiameter
[Encefalo Ax Testa ] # 22 ProtocolName
[500 ] # 4 ReconstructionDiameter
[0 ] # 2 GantryDetectorTilt
[CW] # 2 RotationDirection
[3000] # 4 ExposureTime
[30] # 2 XrayTubeCurrent
[HFS ] # 4 PatientPosition
[0.9765625\0.9765625 ] # 20 PixelSpacing
DICOM
Images dimension:
Ammettendo che ogni voxel occupi 32 byte qual è lo spazio RAM
necessario a simulare 40 cm di TAC di cui il seguente è parte
dell’header DICOM di un’immagine?
circa 170 MByte
circa 2 Mbyte
circa 670 Mbyte
Geant4-DICOM
interface
Developed by L. Archambault, L. Beaulieu, V.-H. Tremblay (Univ. Laval
and l'Hôtel-Dieu, Québec)
Donated to Geant4 for the common profit of the scientific community
– under the condition that further improvements and developments are made publicly
available to the community
Released with Geant4 5.2, June 2003 in an extended example
– by S. Guatelli mainly
T. Aso & A.Kimura Ashikaga Institute of Technology
Deeply revised in by Pedro Arce in 2007
– Small improvements by S. Chauvie
Geant4 examples/extended/medical/DICOM
From phantom to MC
Rows,columns(#):
PixelSpacing_X,Y(mm):
SliceTickness(mm):
SliceLocation(mm):
512
0.875
5.0
20.0
Header + DATA SETS
512
0.875
…cont…
1500
1000
y = 995,06x - 1000,1
2
R = 0,9981
CT number
500
0
0,0
0,5
1,0
1,5
2,0
-500
-1000
-1500
#######################################
# Density Range
Materials
#--------------------------------------------------#
g/cm3
#--------------------------------------------------# [ 0.100 , 0.351 ]
Lungs (inhale)
# [ 0.351 , 0.800 ]
Lungs (exhale)
# [ 0.919 , 0.979 ]
Adipose
# ] 0.979 , 1.004 ]
Breast
# ] 1.004 , 1.043 ]
Phantom
# ] 1.043 , 1.109 ]
Liver
# ] 1.109 , 1.113 ]
Muscle
# ] 1.113 , 1.400 ]
Trabecular Bone
# [ 1.496 , 1.654 ]
Dense Bone
#######################################
ICRU 46
relative electronic density
3-D
view
… and ends.
The structure
From DICOM image to Geant4 geometry
Reading image information
Transformation of pixel
data into densities
Association of densities to
a list of corresponding
materials
Defining the voxels
– Geant4 parameterised
volumes
– parameterisation function:
material
reverse engineering by S. Guatelli
Start reading DICOM files
Tranlsate TAGS with DICT
Read the header and create the tag
Implicit Endian Explicit VR, special cases
Implicit Endian Explicit VR, other cases
Implicit Endian Implicit VR
Create .g4dcm
Data.dat
CT2Density.dat
Write density
Splitting materials in density intervals: In the class DicomDetectorConstruction, it is
defined a density interval G4double densityDiff = 0.1;
Navigation….
:
The 1D optimisation . It will be very slow because each time a track exits a
voxel it has to loop to all other voxels to know which one it may enter
The 3D optimisation with G4SmartVoxel: a 3D grid is built, so that the
location of voxels is fast, but it requires a lot of memory
Using G4NestedParameterisation. The search is done hierarchically in X, Y
and Z. It is fast and does not require big memory
Using G4PhantomParameterisation/G4RegularNavigation: an special
algorithm to navigate in regular voxelised geometries (see GEANT4 doc).
This is the fastest way without any extra memory requirement (and it is the
default in this example). It includes an option (default) to skip frontiers
between voxels when they have the same material. When using this option
at each step the energy is all deposited in the last voxel; for properly
distribution of the dose (=energy/volume) the G4PSDoseDeposit_RegNav
scorer can be used
MC Dose calculation in Radiotherapy
How accurate is the dose
calculation ?
Description of
patients
Energy
deposition
Geometry
Physics
DICOM
Validation
studies
Grazie per l’attenzione!