Geant4에서 Dicom file의 이용

What is DICOM?

The standard for Digital Imaging and Communications in

Medicine.

Developed by the National Electrical Manufacturers

Association (NEMA) in conjunction with the American

College of Radiology (ACR).

Covers most image formats for all of medicine.

Specification for messaging and communication

between imaging machines.

DICOM File Format

A single DICOM file contains:

A header

information about the patient's name, the type of

scan, image dimensions, etc

Image data

in compressed (bitmap) or

uncompressed form (jpeg, gif…)

DICOM file header 구조

DICOM requires a 128-byte preamble

(usually set to zero).

'D', 'I', 'C', 'M' letters comes next.

The rest is the real header information in groups.

For example: group 0002hex is the file meta

information group.

DICOM file header 구조

ㅁㅁ

DICOM File Header

The meaning of some fields:

0002:0010 --> Reports the structure of the image data

0028:0002 --> Samples Per Pixel

0028:0004 --> Photometric Interpretation

0028:0100 --> Bits Allocated

...

Geant4의 DICOM 예제

geant4_9_6\examples\extended\medical\DICOM

Geant4의 DICOM 예제

DICOM file의 변환 문제점

dicomHandler에서 text file로 변환

Ascii hexa값의 실수 변환 문제.

Header 버퍼의 overflow(Siemens).

Header의 구조 차이(GE).

Data 저장의 차이(12, 16 bits).

Pixel padding value 문제.

Pixel to density 변환 문제.

Ascii hexa값의 실수 변환 문제

GetValue 메소드의 오류

생성자에서 버퍼크기 조절

Header 버퍼의 overflow(Siemens)

Header의 구조 차이(GE)

GE CTSim의 파일 구조

Header의 구조 차이(GE)

정상 파일의 구조

Data 저장의 차이(12, 16 bits)

12비트 처리

Data 저장의 차이(12, 16 bits)

16비트 처리

Pixel padding value 문제

Pixel Padding Value

Pixel Padding Value (0028,0120) is used to pad images

to rectangular format.

The native format of some images is not rectangular.

It is common for devices with this format to pad the

images to the rectangular format required by the DICOM

Standard with a specific pixel value that is not

contained in the native image. Further, when resampling,

such as after spatial registration, padding may need to

be used to fill previously non-existent pixels.

Pixel padding value 문제

Padding value and representation

Pixel to density 변환 문제

Pixel 값을 density로 변환

Pixel to density 변환 문제

HU값 확인

Pixel to density 변환 문제

Catphan

물질 할당

Density별 물질 할당(ICRU Report 46)

Pixel to density 변환 문제

CT의 pixel을 밀도와 물질로 변환

물질의 구성 성분

materials density (g/cm3) element composition

air 0.00129 N(0.7), O(0.3)

inhalation 0.217

H(0.103), C(0.105), N(0.031)

O(0.749), Na(0.002), P(0.002)

S(0.003), Cl(0.002), K(0.003)

exhalation 0.508

H(0.103), C(0.105), N(0.031)

O(0.749), Na(0.002), P(0.002)

S(0.003), Cl(0.002), K(0.003)

adipose 0.967

H(0.114), C(0.598), N(0.007)

O(0.278), Na(0.001), S(0.001)

Cl(0.001)

breast 0.990

H(0.109), C(0.506), N(0.023)

O(0.358), Na(0.001), P(0.001)

S(0.001), Cl(0.001)

water 1.000 H(0.112), O(0.888)

muscle 1.061

H(0.102), C(0.143), N(0.034)

O(0.710), Na(0.001), P(0.002)

S(0.003), Cl(0.001), K(0.004)

liver 1.071

H(0.102), C(0.139), N(0.030)

O(0.716), Na(0.002), P(0.003)

S(0.003), Cl(0.002), K(0.003)

trabecular bone 1.159

H(0.085), C(0.404), N(0.058)

O(0.367), Na(0.001), Mg(0.001)

P(0.034), S(0.002), Cl(0.002)

K(0.001), Ca(0.044), Fe(0.001)

dense bone 1.575

H(0.056), C(0.235), N(0.050)

O(0.434), Na(0.001), Mg(0.001)

P(0.072), S(0.003), Cl(0.001)

K(0.001), Ca(0.146)

예제에 실제 CT를 사용

Medical_Linac에 적용

Medical_Linac에 적용

감사 합니다