A new position recording system for the partial-body counter at KIT

Hegenbart, L.; Breustedt, B.

doi:10.1093/rpd/ncq416

Cited by 3 publications

(5 citation statements)

References 1 publication

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“…This is a topic that requires further study; and • The bias results obtained for the array are considerably smaller than the values for an individual detector. As already stated in previous studies, the accuracy of measurement depends on the positioning of the detectors relative to the phantom or the person counted (Hegenbart and Breustedt 2010). Ideally, the operator needs to reproduce the same detector position for the calibration measurements with the phantom and for each test person measurement, which is not always possible.…”

Section: Resultsmentioning

confidence: 99%

“…The density change of the lung due to inhaled air was assessed by the Institute of Radiation Research at the Karlsruhe Institute of Technology (Hegenbart and Breustedt 2010) in Germany. They obtained an increase in the counting efficiency of their detector array by 3% for a density change of 0.077 g cm −3 and a decrease of 6% in the counting efficiency for a density change of 0.177 g cm −3 .…”

Section: Introductionmentioning

confidence: 99%

“…For a density change ranging from 0.294 to 0.360 g cm −3 , the change in the detector counting efficiency was about ± 1%. Hegenbart and Breustedt (2010) concluded that for an awake sitting male adult, the expected influence on lung counting efficiency caused by density fluctuations is marginal and can be neglected.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Respiratory Motion on Lung Counting Efficiency Using a 4D NURBS-Based Cardio-Torso (NCAT) Phantom

Tremblay¹,

Kramer²,

Capello³

et al. 2014

Health Physics

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The Human Monitoring Laboratory (Canada) has looked at parameters (lung volume, lung deposition pattern, etc.) that can affect the counting efficiency of its lung counting system. The calibration of the system is performed using the Lawrence Livermore National Laboratory (LLNL) torso phantom; however, the effect of respiratory motion cannot be accounted for using these phantoms. When measuring an internal deposition in the lungs of a subject, respiration causes a change in the volume of the lungs and the thoracic cavity and introduces a variable distance between the lungs and the detectors. These changes may have an impact on the counting efficiency and may need to be considered during a measurement. In this study, the HML has simulated the respiration motion using a 4D non-uniform rational b-spline (NURBS)-based Cardiac-Torso (NCAT) phantom and determined the impact of that motion on the counting efficiency of their lung counting system during measurement. The respiratory motion was simulated by a 16 timeframe cycled 4D NURBS-based NCAT phantom developed at the Department of Biomedical Engineering and Radiology, University of North Carolina. The counting efficiency of the four germanium detectors comprising the HML lung counting system was obtained using MCNPX version 2.6E for photon energies between 17 and 1,000 keV. The amount of uncertainty due to the breathing motion was estimated by looking at the efficiency bias, which was highest at low photon energies as expected due to attenuation and geometry effects. Also, to reduce the influence of the detectors' positioning, an array was calculated by adding the individual detector tallies for a given energy and timeframe. For photon energies of 40 keV and higher, the array efficiency bias showed an underestimation of about 5%. If compared to other parameters already studied by the HML, this value demonstrates the insignificant impact of the breathing motion.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of Respiratory Motion on Lung Counting Efficiency Using a 4D NURBS-Based Cardio-Torso (NCAT) Phantom

Tremblay¹,

Kramer²,

Capello³

et al. 2014

Health Physics

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“…Marzocchi et al (2011) select optimal detector positions for a partial-body setup with a computational phantom in chair and stretcher position by calculating maximum photon flux around the source structure (figure 4.4), but do not specify any method or guidelines to reproduce these positions in general. Hegenbart and Breustedt (2011) use a position recording system for a rack of two phoswich detectors with sensors related to the mechanics of the rack to track position and orientation.…”

Section: Thyroidmentioning

confidence: 99%

“…Additional dimensions are measured with a laser range finder relative to the walls or the floor. A previous version of the system that is in operation for the phoswich system is described by Hegenbart and Breustedt (2011).…”

Section: Detector Positioningmentioning

confidence: 99%

Personalised Body Counter Calibration Using Anthropometric Parameters

Pölz

Breustedt

2015

Radiat Prot Dosimetry

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Zusammenfassung AbstractBody counting is a method for in vivo activity assessment applied to the monitoring of people with high risk of radionuclide incorporation. Energy-sensitive radiation detectors are arranged relative to the body to quantify radionuclide deposits in anatomical structures, such as lungs, liver and skeleton. This method depends on the specific detection system and is sensitive to the individual anatomy of the person. Accurate activity estimates, which are the basis for dose calculation, require extensive calibration procedures typically involving experimental measurements of anthropomorphic phantoms conforming to a reference person. Current calibration methods offer personalisation for lung and liver counting only with respect to body mass and height and do not specify uncertainties.This work revises and extends the currently applied personalisation methods using radiation transport simulation in combination with computational phantoms derived from medical imaging data. A framework was developed that allows computation of samples of calibration factors for various anatomies in standard measurement setups and anthropometric parameters quantifying anatomic properties. Those samples are applied to create statistical models to derive personalised calibration factors given specific values of anthropometric parameters measured on the person. This gives better estimates in activity assessment and, thereby, dose calculation while quantifying and reducing uncertainties.The framework was implemented in form of an abstract, modular data model, a software tool for modelling, simulation and evaluation of general body counting scenarios, and a statistical analysis method for correlating anthropometric parameters and calibration factors. This allows efficient and reproducible modelling for virtual measurement reconstruction as well as sensitivity analyses. The framework was applied to the calibration of the In Vivo Measurement Laboratory (IVM) at Karlsruhe Institute of Technology (KIT) comprising four freely arrangeable high-purity germanium detectors in lung, liver, knee and head measurement setups. Because of the interindividual anatomical variations in the applied phantoms and iv additional sensitivity analyses, it was possible to give estimates of the expected uncertainties and to reduce them through an algorithmically reproducible approach on calibration.

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Voxel2mcnp

Hegenbart

Pölz²,

Benzler³

et al. 2012

Health Physics

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Voxel2MCNP is a program that sets up radiation protection scenarios with voxel models and generates corresponding input files for the Monte Carlo code MCNPX. Its technology is based on object-oriented programming, and the development is platform-independent. It has a user-friendly graphical interface including a two- and three-dimensional viewer. A row of equipment models is implemented in the program. Various voxel model file formats are supported. Applications include calculation of counting efficiency of in vivo measurement scenarios and calculation of dose coefficients for internal and external radiation scenarios. Moreover, anthropometric parameters of voxel models, for instance chest wall thickness, can be determined. Voxel2MCNP offers several methods for voxel model manipulations including image registration techniques. The authors demonstrate the validity of the program results and provide references for previous successful implementations. The authors illustrate the reliability of calculated dose conversion factors and specific absorbed fractions. Voxel2MCNP is used on a regular basis to generate virtual radiation protection scenarios at Karlsruhe Institute of Technology while further improvements and developments are ongoing.

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A new position recording system for the partial-body counter at KIT

Cited by 3 publications

References 1 publication

Effect of Respiratory Motion on Lung Counting Efficiency Using a 4D NURBS-Based Cardio-Torso (NCAT) Phantom

Effect of Respiratory Motion on Lung Counting Efficiency Using a 4D NURBS-Based Cardio-Torso (NCAT) Phantom

Personalised Body Counter Calibration Using Anthropometric Parameters

Voxel2mcnp

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