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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 1Master‘s Program in Medical Physics
Chair in Computer Assisted Clinical MedicineFaculty of Medicine Mannheim University of HeidelbergTheodor-Kutzer-Ufer 1-3D-68167 Mannheim, GermanyLothar.Schad@MedMa.Uni-Heidelberg.dewww.ma.uni-heidelberg.de/inst/cbtm/ckm/
Physics of Imaging Systems
Basic Principles of Computer Tomography (CT) III
Prof. Dr. Lothar Schad
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 2
Applications
Applications
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 3
- high black/white contrast
Bones and Lung
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 4
130 kV, 150 mA, 0.8 s5 mm, Pitch 1.5, 50% overlap
Superior Vena Cava Thrombosis
- Siemens Emotion
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 5
4 - phase spiral studyexcellent enhancement
• precontrast
• arterial
• portal-venous
• delayed phase
• 8 mm, Pitch 1.5
• 130 kV, 120 mA, 1.5 s
• 120 ml / flow rate 3 ml/s
Liver Hemangioma Study
- Siemens Esprit
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 6
Siemens Emotion: sagittal reformat Siemens Volume Access: VRT
Ankle Joint: 1 mm Spiral CT
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 7
• low dose of 100 mAs
• 2 x 1.5 mm collimation
• 2 mm slice width
• 99 s spiral duration
• 2 mm, Pitch 2
• low dose ( 90 mA)
Siemens Emotion / Emotion Duo
Spine
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 8
2 x 1 mm, 60 mAs
1.25 mm axial slice
Siemens Emotion Duo
Pediatrics Head
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 9
• life size filming
• semi-automatic
evaluation for the
jaws and teeth
• presurgical planning
for implants
Dental CT: Clinical Option
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 10Brain: Cerebral Infarction I
CT MRI
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 11Brain: Cerebral Infarction II
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 12
measurement of bone mineral density (BMD) for: • early detection• diagnosis• follow-up of osteoporosis
management of: • metabolic bone diseases • fractures in aging patients
Osteoporosis: Bone Density Evaluation
- CT accuracy of 10% is required due to individual variation of about 30%- but CT reproducibility of better than 2% is necessary in follow-up studies !
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 13
assessment of pulmonarystructure & function
emphysema cystic fibrosis
clinical evaluation of newtherapeutic approaches
lung volume reductionsurgery (LVRS)pharmaceutical treatment
research & therapy in respiratory care (ICU)
Pulmonary CT: Lung Density Evaluation
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 14
source: Aurich and Beck. Institut für Informatik der Heinrich-Heine-Universität Düsseldorf, http://www.eccet.de/sample/colon.html#top
Virtual Coloscopy
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 15
CT Angiography
CT Angiography
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 16
1 mm, Pitch 2Siemens Emotion
2 x 0.5 mm, Pitch 3Siemens Volume Zoom
Cerebral Arteries
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 17
2 x 1 mm, Pitch 3, 1.25 mm SW 130 kV, 100 mA, 0.8 s, 2 mm, Pitch 2
Siemens Emotion / Emotion Duo
Carotids
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 18
130 kV, 143 mAs, 0.8 s, 2 x 1.5 mm, Pitch 4Siemens Emotion Duo
35 cm
Abdominal Aortic Stent Follow-up
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 19Kidney CTA
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 20Lung CTA
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 21
CT Contrast Agent
CT Contrast Agent
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 22Contrast Study Challenges
HU
time (s)
single slice: 40 s
multislice: 5 s
- catching the bolus at the right moment
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 23
pre-monitoringreference scan start injection
monitoring scans spiral scan
CARE Bolus - Automatic Bolus Tracking
patient individual start of the spiral scan
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 24Perfusion CT: ROI Evaluation
1 2
time – density curve
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 25
40 s
5 s
Perfusion CT: Time – to – Peak Map
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 26
perfusion (CBF) time - to - peaknative CT
Early Stroke Diagnosis
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 27Perfusion CT: Follow-up I
62 years old women, 0.7 h after beginning of symptoms, hemiparesis left
40 sec
5 sec
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 28Perfusion CT: Follow-up II
66 years old women, 1.2 h after beginning of symptoms, hemiparesis right
40 s
5 s
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 29Perfusion CT: Follow-up III
68 years old women, 2 h and 1 day after beginning of symptoms, hemiparesis left
0. day(2.0 h)
0. day2 h
1. day19 h
5 sec
40 sec
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 30
CT Cardio Imaging
CT Cardio Imaging
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 31
prospective triggeringsequence scans in a single heart phase
- quantification of coronary calcification- motion free images of thorax- imaging of large pulmonary vessels
retrospective gatingspiral acquisition and ECG-recording parallelreconstruction of imaging data at different heart phases possiblenot sensitive to cardiac arrhythmia since retrospective fitting of imaging data to the ECG-curve
high resolution coronary CTA imaging of bypass-transplants quantification of coronary calcification at high reproducibility
Cardio CT
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 32Cardio CT: Retrospective Gating I
ECG
time
z
zr
proj
ectio
n an
gle
θ
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 33Cardio CT: Retrospective Gating II
= 165 msrotation time2
temp. resolution =
- single source CT: temporal resolution of maximum 165 ms
courtesy: Siemens Medical Solution, Erlangen
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 34Cardio CT: Retrospective Gating III
- single source CT: technical challenge with high heart rates
courtesy: Siemens Medical Solution, Erlangen
60 bpm 100 bpm
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 35
source: Blobel et al. Fortschr Röntgenstr 2003
(a) 1 segment (half-scanreconstruction > 200 ms)
(b) 4 segments(c) 2 segments(d) 3 segments
Cardio CT: Multi – Segment Reconstruction
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 36Cardio CT: Retrospective Gating IV
- single source CT: multi-segment reconstruction
courtesy: Siemens Medical Solution, Erlangen
1 2
coronary arteries change position =limited image quality
(2 segment recon)varies between = 83 and 165 mstemp. resolution =
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 37
heart beat = 70 b/min heart beat = 85 b/min heart beat = 100 - 110 b/min
Cardio CT: 3D Reconstruction
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 38
3D reconstruction of heart and coronary vessels using four-slice multi-slice CT. Note the stent in the proximal part of the left anterior descending artery
cardiac vessel analysis of the stentedsegment in the same patient (Courtesy of Central Bank Medical Center, Moscow)
source: ECR Newsletter 4/2002
Cardio CT: Stent
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 39
source: Kalender. Computertomographie, Publicis MCD Verlag 2000
Cardio CT: Coronal Angiography
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 40Cardio CT: Heart Function (Pig)
- retrospective ECG gating
~ 70 ms
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 41
Dual Source CT
Dual Source CT
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 42
design of using multiple X-ray tubes with corresponding detectors
has been proposed in the early years of CT to reduce scan time and increase temporal resolution
(adapted according to Boyd, 1981).
Dual Source CT: Principle I
source: Kalender. Computertomographie, Publicis MCD Verlag 2000
X-ray fan
stationary detector ring
X-ray sourcealternative: rotating
detector ring
field-of-view
tube 2
tube 1
gantry window
detector 1
dete
ctor
2
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 43
0.33 seconds rotation
Dual Source CT: Principle II- dual source CT: two X-ray sources and two detectors at the same time
courtesy: Siemens Medical Solution, Erlangen
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 44
large aneurysm of ascending aorta
triple rule-out examination with artifact-free visualization of right
and left coronary arteries and aortic arch
pulmonary embolism (arrow)
pulmonary embolism
(arrow)
source: www.siemens.com/medical © 04.2007
Dual Source CT: Results I
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 45
= 83 msrotation time4
temp. resolution =
Dual Source CT: Temporal Resolution
courtesy: Siemens Medical Solution, Erlangen
- dual source CT: heart rate independent temporal resolution of 83 ms
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 46
60 bpm 100 bpm
courtesy: Siemens Medical Solution, Erlangen
Dual Source CT: Retrospective Gating - dual source CT: reliable imaging of all heart rates
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 47
single source CT dual source CTsingle source CT +
multi segment recon.
courtesy: University Medical Center Grosshadern, Munich
Dual Source CT: Results II- dual source CT: patient with varying heart rate between 86 bpm and 122 bpm
heart rate independent temporal resolution of 83 ms
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 48
- heart rate independent - temporal resolution: 83 ms- spatial resolution: 0.33 mm- 5 s for 103 mm- rotation: 0.33 sec- 120 kV, 400 mAs/rotation- heart rate: 73 bpm
courtesy: Erasmus MC, University Medical Center Rotterdam, The Netherlands
Dual Source CT: Results III- dual source CT: precise RCA and LAD in stent visualization with reduced
blooming and without motion artifacts
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 49
- heart rate independent - temporal resolution: 83 ms- spatial resolution: 0.33 mm- 6 s for 138 mm- rotation: 0.33 sec- 120 kV, 400 mAs/rotation- heart rate: 90 bpm
courtesy: Nagoya City University Hospital, Nagoya, Japan
Dual Source CT: Results IV- dual source CT: despite high heart rate of 90 bmp, motion free visualization
of the coronary arteries
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 50
- heart rate independent - temporal resolution: 83 ms- spatial resolution: 0.33 mm- 6 s for 125 mm- rotation: 0.33 sec- 120 kV, 380 mAs/rotation- heart rate: 122 bpm
courtesy: University Hospital of Munich – Grosshadern, Munich
Dual Source CT: Results V- dual source CT: despite high heart rate of 122 bmp, motion free visualization
of even small coronary arteries
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 51
- heart rate independent - temporal resolution: 83 ms- spatial resolution: 0.33 mm- 17 s for 270 mm- rotation: 0.33 sec- 120 kV, 300 mAs/rotation- heart rate: 64 - 89 bpm
courtesy: University Hospital of Munich – Grosshadern, Munich
Dual Source CT: Results VI- dual source CT: quick and accurate rule out of myocardial infarction, pulmonary
embolism, and aortic dissection
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 52
courtesy: University Hospital of Munich – Grosshadern, Munich
Dual Source CT: Results VII- dual source CT: fast visualization of the complete human anatomy in only
42 s with 0.33 mm isotropic resolution
- spatial resolution: 0.33 mm- 42 s for 1889 mm- rotation: 0.5 sec- 120 kV, 120 mAs/rotation- 1889 mm scan range
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 53
courtesy: University Hospital of Munich – Grosshadern, Munich
Dual Source CT: Results VIII- dual source CT: excellent visualization of the complete peripheral artery tree
showing an occlusion of the left iliac artery
- spatial resolution: 0.33 mm- 31 s for 1389 mm- rotation: 0.5 sec- 120 kV, 200 mAs/rotation- 1389 mm scan range
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 54
courtesy: University Hospital of Munich – Grosshadern, Munich
Dual Source CT: Results IX
thanks to
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 55
Micro CT
Micro CT
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 56
- pre-clinical in vitro CT imaging
- setup of a μ-CT scanner withfixed micro-focus X-ray tube and areadetector while rotating object
principle of μ-CT scanner
photo of in vitro μ-CT scannerexperimental setup
(IMP Erlangen)
source: Kalender. Computertomographie, Publicis MCD Verlag 2000
Micro CT: Setup I
rotating objectX-ray tube
detector
rotating axisX-raytube detector
rotating object
cone beam
variable zooming
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 57
imaging of two tungsten wires with 10 µm thickness
3D imaging of bone biopsy osteporosis
3D imaging of a vessel stent for quality control
source: Kalender. Computertomographie, Publicis MCD Verlag 2000
Micro CT: Resolution
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 58
source: Kalender. Computertomographie, Publicis MCD Verlag 2000
- pre-clinical in vitro CT imaging
- setup of a μ-CT scanner withrotating micro-focus X-ray tube andarea detector while fixed object
principle of μ-CT scanner
photo of in vitro μ-CT scanner(TomoScope 30s, VAMP
GmbH, Erlangen)
Micro CT: Setup II
mouse couch
detector
rotatinggantry
X-ray tube
detector
mouse couch
rotating gantry
X-ray tube
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 59
whole body scan with about 80 µm resolution
Micro CT: Results I
source: Kalender. Computertomographie, Publicis MCD Verlag 2000
RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 60
ALARA - principle = „As Low As Reasonably Achievable“
Comparison: CT and μ-CT
source: Kalender. Computertomographie, Publicis MCD Verlag 2000
focus size
x-ray tube power
spatial resolution
scan time
detector
field-of-view
dose
in vitro μ-CT in vivo CT
flat panel detector flat panel detector
not relevant according to ALARA
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RUPRECHT-KARLS-UNIVERSITY HEIDELBERG
Computer Assisted Clinical MedicineProf. Dr. Lothar Schad
12/9/2008 | Page 61Micro CT: Results II