TH-A-BRC-03: AAPM TG218: Measurement Methods and Tolerance Levels for Patient-Specific IMRT Verification QA

2016 ◽  
Vol 43 (6Part43) ◽  
pp. 3852-3853 ◽  
Author(s):  
M. Miften
Keyword(s):  
Measurement Methods ◽  
Patient Specific ◽  
Imrt Verification

Determination of a Pressure Drop in the Arteriovenous Fistula With Fluid Structure Interaction Simulations and In Vitro Methods

2017 ◽  
Author(s):  
Daniel Jodko ◽  
Tomasz Palczynski ◽  
Piotr Reorowicz ◽  
Kacper Miazga ◽  
Damian Obidowski ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Blood Vessel ◽  
Arteriovenous Fistula ◽  
In Vitro Model ◽  
Experimental Methods ◽  
Measurement Methods ◽  
Patient Specific ◽  
Vessel Walls ◽  
Vitro Model

A pressure drop and its oscillations occurring in the arteriovenous fistula due to sudden changes in the velocity vector direction or the transitional or turbulent flow, related to its complicated geometry, can exert a significant impact on the blood vessel wall behaviour. On the other hand, the pressure drop cannot be precisely measured in vivo with non-invasive measurement methods. The aim of this study is to assess the pressure drop with numerical and experimental methods in the patient-specific fistula model taking into account a pulsating nature of the flow and the elasticity of blood vessel walls. An additional target is to find a correlation between these two methods. FSI and in vitro simulations of the blood flow were performed for a patient-specific model of the fistula. Basic geometrical data of the correctly functioning mature fistula were obtained with angio-computed tomography. Those data were applied to develop a spatial CAD model of the fistula, which allowed for creating a virtual model for computer simulations and an analogous in vitro model made with rapid prototyping techniques. The material used to build the in vitro model is characterised by mechanical properties similar to the arterial tissue. A non-stationary computer simulation was carried out with an ANSYS software package, keeping as many flow similarities to the experiments carried out on the test stand as possible, and where the blood mimicking fluid was a water solution of glycerine. During the experiments, the static pressure was measured downstream and upstream of the anastomosis with precise pressure transducers. The pressure drop was determined with the numerical and experimental methods, which take into account the elasticity of blood vessels. This is a novel approach, since most of similar studies were conducted on the assumption of rigid blood vessel walls. The obtained results show that the pressure drop within the fistula is not so high as reported in the literature, which is correlated with the precision of measurement methods and the fact that a large portion of the fluid energy is accumulated by the elastic walls.

Quantitative analysis of patient-specific dosimetric IMRT verification

2004 ◽  
Vol 50 (1) ◽  
pp. 103-119 ◽  
Author(s):  
G J Budgell ◽  
B A Perrin ◽  
J H L Mott ◽  
J Fairfoul ◽  
R I Mackay
Keyword(s):  
Quantitative Analysis ◽  
Patient Specific ◽  
Imrt Verification

A critical comparison of selected implicit measurement methods.

2018 ◽  
Vol 11 (4) ◽  
pp. 249-266 ◽  
Author(s):  
Judith Znanewitz ◽  
Lisa Braun ◽  
David Hensel ◽  
Claudia Fantapié Altobelli ◽  
Fabian Hattke
Keyword(s):  
Measurement Methods ◽  
Critical Comparison ◽  
Implicit Measurement

Evaluation of a computerized cardiovascular simulation system using patient-specific data

2013 ◽  
Vol 61 (S 01) ◽  
Author(s):  
M Kaur ◽  
N Sprunk ◽  
U Schreiber ◽  
R Lange ◽  
J Weipert ◽  
...  
Keyword(s):  
Simulation System ◽  
Patient Specific ◽  
Specific Data ◽  
Cardiovascular Simulation

Effect of CT-based attenuation correction on uptake ratios in skeletal SPECT

2007 ◽  
Vol 46 (01) ◽  
pp. 38-42 ◽  
Author(s):  
V. Schulz ◽  
I. Nickel ◽  
A. Nömayr ◽  
A. H. Vija ◽  
C. Hocke ◽  
...  
Keyword(s):  
Vertebral Body ◽  
Facet Joint ◽  
One Dimension ◽  
Patient Specific ◽  
Data Sets ◽  
Facet Joints ◽  
Lumbar Vertebral Body ◽  
Ct System ◽  
Ct Data ◽  
Attenuation Corrected

SummaryThe aim of this study was to determine the clinical relevance of compensating SPECT data for patient specific attenuation by the use of CT data simultaneously acquired with SPECT/CT when analyzing the skeletal uptake of polyphosphonates (DPD). Furthermore, the influence of misregistration between SPECT and CT data on uptake ratios was investigated. Methods: Thirty-six data sets from bone SPECTs performed on a hybrid SPECT/CT system were retrospectively analyzed. Using regions of interest (ROIs), raw counts were determined in the fifth lumbar vertebral body, its facet joints, both anterior iliacal spinae, and of the whole transversal slice. ROI measurements were performed in uncorrected (NAC) and attenuation-corrected (AC) images. Furthermore, the ROI measurements were also performed in AC scans in which SPECT and CT images had been misaligned by 1 cm in one dimension beforehand (ACX, ACY, ACZ). Results: After AC, DPD uptake ratios differed significantly from the NAC values in all regions studied ranging from 32% for the left facet joint to 39% for the vertebral body. AC using misaligned pairs of patient data sets led to a significant change of whole-slice uptake ratios whose differences ranged from 3,5 to 25%. For ACX, the average left-to-right ratio of the facet joints was by 8% and for the superior iliacal spines by 31% lower than the values determined for the matched images (p <0.05). Conclusions: AC significantly affects DPD uptake ratios. Furthermore, misalignment between SPECT and CT may introduce significant errors in quantification, potentially also affecting leftto- right ratios. Therefore, at clinical evaluation of attenuation- corrected scans special attention should be given to possible misalignments between SPECT and CT.

Knowledge-Based Decision Support for Diagnosis and Therapy: On the Multiple Usability of Patient Data

1989 ◽  
Vol 28 (02) ◽  
pp. 69-77 ◽  
Author(s):  
R. Haux
Keyword(s):  
Expert Systems ◽  
Statistical Data ◽  
Patient Data ◽  
Attribute Selection ◽  
Patient Specific ◽  
Statistical Data Analysis ◽  
Inference Mechanism ◽  
Diagnosis And Therapy ◽  
Knowledge Based ◽  
Clinical Registries

Abstract:Expert systems in medicine are frequently restricted to assisting the physician to derive a patient-specific diagnosis and therapy proposal. In many cases, however, there is a clinical need to use these patient data for other purposes as well. The intention of this paper is to show how and to what extent patient data in expert systems can additionally be used to create clinical registries and for statistical data analysis. At first, the pitfalls of goal-oriented mechanisms for the multiple usability of data are shown by means of an example. Then a data acquisition and inference mechanism is proposed, which includes a procedure for controlling selection bias, the so-called knowledge-based attribute selection. The functional view and the architectural view of expert systems suitable for the multiple usability of patient data is outlined in general and then by means of an application example. Finally, the ideas presented are discussed and compared with related approaches.

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