TY  - JOUR
A1  - Baumann, Marcus
A1  - Goeyens, L.
A1  - Tréguer, P.
A1  - Baeyens, W.
T1  - The leading role of ammonium in the nitrogen uptake regime of Southern Ocean marginal ice zones / Goeyens, L. ; Tréguer, P. ; Baumann, M.E.M. ; Baeyens, W. ; Dehairs, F.
JF  - Journal of Marine Systems. 6 (1995), H. 4
Y1  - 1995
SN  - 0924-7963
SP  - 345
EP  - 361
ER  - 
TY  - JOUR
A1  - Weckesser, Martin
A1  - Grießmeier, Martin
A1  - Schmidt, Daniela
A1  - Sonnenberg, Frank
A1  - Ziemons, Karl
A1  - Kemna, Lars
A1  - Holschbach, Marcus
A1  - Langen, Karl-J.
A1  - Müller-Gärtner, Hans-W.
T1  - Iodine-123 α-methyl tyrosine single-photon emission tomography of cerebral gliomas: standardised evaluation of tumour uptake and extent
JF  - European Journal of Nuclear Medicine
N2  - Single-photon emission tomography (SPET) with the amino acid analogue l-3-[123I]iodo-α-methyl tyrosine (IMT) is helpful in the diagnosis and monitoring of cerebral gliomas. Radiolabelled amino acids seem to reflect tumour infiltration more specifically than conventional methods like magnetic resonance imaging and computed tomography. Automatic tumour delineation based on maximal tumour uptake may cause an overestimation of mean tumour uptake and an underestimation of tumour extension in tumours with circumscribed peaks. The aim of this study was to develop a program for tumour delineation and calculation of mean tumour uptake which takes into account the mean background activity and is thus optimised to the problem of tumour definition in IMT SPET. Using the frequency distribution of pixel intensities of the tomograms a program was developed which automatically detects a reference brain region and draws an isocontour region around the tumour taking into account mean brain radioactivity. Tumour area and tumour/brain ratios were calculated. A three-compartment phantom was simulated to test the program. The program was applied to IMT SPET studies of 20 patients with cerebral gliomas and was compared to the results of manual analysis by three different investigators. Activity ratios and chamber extension of the phantom were correctly calculated by the automatic analysis. A method based on image maxima alone failed to determine chamber extension correctly. Manual region of interest analysis in patient studies resulted in a mean inter-observer standard deviation of 8.7%±6.1% (range 2.7%–25.0%). The mean value of the results of the manual analysis showed a significant correlation to the results of the automatic analysis (r = 0.91, P<0.0001 for the uptake ratio; r = 0.87, P<0.0001 for the tumour area). We conclude that the algorithm proposed simplifies the calculation of uptake ratios and may be used for observer-independent evaluation of IMT SPET studies. Three-dimensional tumour recognition and transfer to co-registered morphological images based on this program may be useful for the planning of surgical and radiation treatment.
Y1  - 1998
SN  - 1619-7089
VL  - 25
IS  - 2
SP  - 150
EP  - 156
ER  - 
TY  - CHAP
A1  - Marcus, W.
A1  - Meliß, Michael
A1  - Späte, F.
T1  - Street lighting and advertising with photovoltaics
T2  - Harmony with nature : : proceedings / ISES Solar World Congress, Budapest 1993. International Solar Energy Society, Hungarian Section (H-ISES); Hungarian Solar Energy Society (HSES). Vol. 3: Photovoltaics
Y1  - 1993
SP  - 509
EP  - 514
PB  - Hungarian Energy Society
CY  - Budapest
ER  - 
TY  - CHAP
A1  - Knott, Thomas C.
A1  - Sofronia, Raluca E.
A1  - Gerressen, Marcus
A1  - Law, Yuen
A1  - Davidescu, Arjana
A1  - Savii, George G.
A1  - Gatzweiler, Karl-Heinz
A1  - Staat, Manfred
A1  - Kuhlen, Torsten W.
T1  - Preliminary bone sawing model for a virtual reality-based training simulator of bilateral sagittal split osteotomy
T2  - Biomedical simulation : 6th International Symposium, ISBMS 2014, Strasbourg, France, October 16-17, 2014 : proceedings (Lecture notes in computer science : vol. 8789)
N2  - Successful bone sawing requires a high level of skill and experience, which could be gained by the use of Virtual Reality-based simulators. A key aspect of these medical simulators is realistic force feedback. The aim of this paper is to model the bone sawing process in order to develop a valid training simulator for the bilateral sagittal split osteotomy, the most often applied corrective surgery in case of a malposition of the mandible. Bone samples from a human cadaveric mandible were tested using a designed experimental system. Image processing and statistical analysis were used for the selection of four models for the bone sawing process. The results revealed a polynomial dependency between the material removal rate and the applied force. Differences between the three segments of the osteotomy line and between the cortical and cancellous bone were highlighted.
KW  - Bone sawing
KW  - virtual reality
KW  - training simulator
Y1  - 2014
SN  - 978-3-319-12057-7 (Online)
SN  - 978-3-319-12056-0 (Print)
U6  - http://dx.doi.org/10.1007/978-3-319-12057-7_1
SP  - 1
EP  - 10
PB  - Springer
CY  - Cham
ER  -