Because of the difficulties in concluding whether a person has drowned or not, information that could be relevant for postmortal diagnosis of drowning was studied. With postmortal CT images lung volume, mean attenuation, anterior-posterior difference, lung density profile and amount of water within the lungs were investigated.The report also evaluates three examples of software that calculates lung volume from postmortal CT images: Siemens’ Syngo Pulmo CT, Siemens‘ Volume Evaluation and GE Medical Systems’ Volume Viewer. The method used at autopsy was also studied. The repeatability and validity were tested and sources of errors identified.Repeatability and validity for the three tested types of software were acceptable, while the method used at autopsy had to be improved. The study also showed that lung volume related to length, anterior-posterior difference and lung density profile seemed to vary between drowned and other deceased. These measures might conclude whether a person has drowned.
Contents
1 INTRODUCTION
1.1 FORMULATION OF THE PROBLEM
1.2 AIM OF THE THESIS
2 BACKGROUND
2.1 THE LUNGS
2.1.1 Anatomy and histology
2.1.2 Pulmonary ventilation
2.2 DEATH BY DROWNING
2.3 COMPUTED TOMOGRAPHY
2.3.1 Generation of X-rays and its interaction with the human body
2.3.2 Detection of X-rays
2.3.3 Artifacts
2.4 MEAN LUNG DENSITY
2.5 ANTERIOR-POSTERIOR DIFFERENCE
2.6 LUNG DENSITY PROFILE
2.7 AMOUNT OF WATER
3 METHODS AND MATERIAL
3.1 SEGMENTATION
3.1.1 Thresholding
3.1.2 Mathematical morphology
3.2 THE SOFTWARE
3.2.1 syngo Pulmo CT
3.2.2 Volume Evaluation
3.2.3 Volume Viewer
3.3 THE PHANTOMS
3.3.1 Milk carton
3.3.2 Bottle
3.3.3 Bottle with tubes
3.4 MATERIAL
3.5 DATA ACQUISITION
3.6 REPEATABILITY OF THE MEASUREMENTS
3.7 VALIDITY
3.8 DIFFERENCES BETWEEN DROWNED AND OTHER DECEASED
3.8.1 Lung volume
3.8.2 Mean lung density
3.8.3 Anterior-Posterior difference
3.8.4 Lung density profile
3.8.5 Amount of water
4 RESULTS
4.1 REPEATABILITY
4.2 VALIDITY
4.2.1 Validation against a known volume
4.2.2 Validation against autopsy volume
4.3 LUNG VOLUME
4.4 MEAN LUNG DENSITY
4.5 ANTERIOR-POSTERIOR DIFFERENCE
4.6 LUNG DENSITY PROFILE
4.7 AMOUNT OF WATER
5 DISCUSSION
5.1 THE SOFTWARE
5.1.1 Syngo Pulmo CT
5.1.2 Volume Evaluation
5.1.3 Volume Viewer
5.2 REPEATABILITY
5.3 VALIDITY
5.3.1 Validation against a known volume
5.3.2 Validation against autopsy volume
5.4 LUNG VOLUME
5.5 MEAN LUNG DENSITY
5.6 ANTERIOR-POSTERIOR DIFFERENCE
5.7 LUNG DENSITY PROFILE
5.8 AMOUNT OF WATER
5.9 CONCLUSIONS
5.10 FUTURE WORK
6 REFERENCES
Author: Sylvan, Elin
Source: Linköping University
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