A. van Aswegen

Anglo American (South Africa)

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M. G. Lötter

University of the Free State

Alexander Otto

Fraunhofer Institute for Electronic Nano Systems

C.P. Herbst

University of the Free State

P.C. Minnaar

University of the Free State

S. Richard Underwood

Royal Brompton Hospital

P. Hendrik Pretorius

University of Massachusetts Chan Medical School

P.H.T. Kleynhans

University of the Free State

Hanlie du Raan

University of the Free State

J.A. van Staden

University of the Free State

Chee Yee Loong

Whittington Hospital

Cooperative Institutions

University of the Free State

University of Pretoria

Columbia University

Royal Brompton Hospital

Emory University

University College London

Harvard University

Cornell University

Cedars-Sinai Medical Center

Imperial College London

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n Vergelyking van drie verskillende tegnieke die berekening van glomerulere filtrasiespoed

South African Medical Journal (1990)

C.P. Herbst Marilyn Dunn Annalie C. Viviers MC van Zyl A. van Aswegen

The clearance of inulin, creatinine and radioactive tracers from the blood may be used to measure glomerular filtration rate (GFR). These techniques, however, are usually invasive and time-consuming. Although the clearance of a radioactive tracer is usually applied in nuclear medicine for the determination of GFR, it is also possible to convert the concentration of the tracer in the kidneys to absolute GFR by means of a regression equation. As this new technique is much faster, we have compared it with the conventional technique. A good correlation was found with the standard radionuclide techniques (r = 0,91), but the reference method was underestimated on the average by 14 ml/min. The new regression equation derived in our clinic will ensure future accurate GFR measurements within 6 minutes.

TRACER

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Left ventricular function evaluation using radionuclide methods in the intensive coronary care unit.

Radiology (1986)

A. van Aswegen Alexander Otto C.P. Herbst JA Marx P.H.T. Kleynhans

We describe an adapted first-transit (FT) technique to perform left ventricular ejection fraction (LVEF) measurements on patients with Swan-Ganz catheters in the intensive cardiac care unit (ICCU). The radionuclide is introduced directly into the right pulmonary artery through the catheter. High-quality images of the left ventricle are obtained owing to minimal activity in the right ventricle and left lung. LVEF measurements obtained by FT compared well with measurements obtained from gated blood pool studies (r = 0.91) but gave consistently lower values. The adapted FT method improves LVEF determination and left-ventricular wall motion evaluation in the ICCU patient.

Ventricular Function

10.1148/radiology.158.1.2999868

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Accuracy of organ radioactivity quantification comparing the geometrical mean and channel ratio techniques

Journal of Nuclear Medicine (1994)

Hanlie Naudé M.G. Loetter A. van Aswegen

The accuracy of quantification of radioactivity in organs is determined by scatter and attenuation. The standard Geometrical mean Method is inaccurate since scatter correction is not performed. Accuracy can be improved by expressing the organ activity as a percentage of a reference source of the same size and at the same depth as the organ of interest. The Channel Ratio Method corrects for scatter but is according to Monte Carlo simulations dependent on depth of organ and on energy spectrum shift during rotation of the scintillation camera head. The purpose of this work was to compare the experimental accuracy of organ quantification by using the Geometrical Mean and Channel Ratio Methods. The influence of organ and reference source depths and sizes on accuracy was determined.

Accuracy and precision

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The relationship between administered radiopharmaceutical activity in myocardial perfusion scintigraphy and imaging outcome

European Journal of Nuclear Medicine and Molecular Imaging (2007)

Cleo Robinson A. van Aswegen Steven A. Julious T. O. NUNAN W. H. Thomson

Correction for attenuation

10.1007/s00259-007-0597-9

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Citations (21)

Acquisition and processing of cerebral blood flow data with a multichannel analyser and microcomputer.

PubMed (1974)

M. G. Lötter A. van Aswegen E.T. Altona P.C. Minnaar F.R. Erasmus

The method of the determination of cerebral blood flow in dogs with radio-isotopes to evaluate ethrane as a new anaesthetic agent is described, as well as the use of a multichannel analyser and the programmes developed for the analysis of data in a conversational mode. Preliminary results of the use of the computer programme are presented.

Analyser

Micro computer

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Effect of chopped light on the dissolution and leaching of chalcopyrite

Minerals Engineering (2020)

Frank K. Crundwell L.J. Bryson A. van Aswegen B.D.H. Knights

Photocurrent

Bornite

10.1016/j.mineng.2020.106703

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Citations (9)

Radiation doses to radiation workers at two academic hospitals

S Jansen A. van Aswegen M. G. Lötter

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Biodistribution and absorbed radiation dose estimates of 99mTc-labeled dimercaptopropionyl human serum albumin.

PubMed (1999)

A. van Aswegen J. Marais Graham J. Kemp Mirinda Nel J.A. van Staden

The use of 99mTc-labeled red blood cells (RBC) for the evaluation of left ventricular function using equilibrium-gated blood-pool imaging suffers from several problems and potential risks. In this study, we estimated the absorbed radiation dose of 99mTc-labeled dimercaptopropionyl human serum albumin (DMP-HSA) as a potential alternative to 99mTc-RBC.After the administration of 99mTc-DMP-HSA, whole-body imaging was performed up to 48 h after injection in five volunteers. The heart contents, liver and remainder of the body were used as source organs. Multicompartment modeling of the biodistribution was performed and absorbed radiation dose estimates for 99mTc-DMP-HSA were obtained using the Medical Internal Radiation Dose (MIRD) calculation.Residence times of 0.62 and 0.43 h were obtained for the heart contents and liver, respectively. Radiation dose estimates yielded an effective dose of 0.0055 mSv/MBq.99MTC-DMP-HSA yielded absorbed radiation doses comparable with those of 99mTc-RBC. Therefore, the radiation properties of 99mTc-DMP-HSA are such that it can be used for clinical diagnostic studies.

Biodistribution

Human serum albumin

Internal radiation

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Evaluation of an uncollimated printed paper transmission source used under scatter limiting conditions

Physica Medica (2010)

J.A. van Staden Hanlie du Raan M. G. Lötter C.P. Herbst A. van Aswegen

Collimated light

Radioactive source

Correction for attenuation