TH‐EF‐BRA‐08: Extending the Concept of Weighted CT Dose Index to Elliptical Phantoms of Various Aspect Ratios

doi:https://doi.org/10.1118/1.4926315

TH‐EF‐BRA‐08: Extending the Concept of Weighted CT Dose Index to Elliptical Phantoms of Various Aspect Ratios

A Markovich,Ashraf G. Morgan,F Dong,A Primak,X Li-2015-06-01-Medical Physics

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TL;DRAbstract

Purpose: Standard CT dosimetry phantoms are currently perfectly circular cylinders. Lately elliptical cylinders have been proposed as an alternative because they better represent the shapes of the human body and allow the evaluation of tube current modulation systems. The purpose of this study was to extend the concept of CTDIw to elliptical phantoms of various aspect ratios. Methods: Based on published adult and pediatric data, eight body aspect ratios were chosen from the full range between 1 (perfectly circular) and 1.72 (extremely elliptical). For each value, two elliptical cylinders were created digitally to represent adult and pediatric bodies. They had the same cross‐sectional areas as the standard 32‐cm and 16‐cm CTDI phantoms. For each digital phantom, CTDI₁₀₀ at central and peripheral locations were simulated for tube voltages between 70–140 kVp using a Monte Carlo program previously validated for a clinical CT system (SOMATOM Definition Flash, Siemens Healthcare). The simula

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Purpose: Standard CT dosimetry phantoms are currently perfectly circular cylinders. Lately elliptical cylinders have been proposed as an alternative because they better represent the shapes of the human body and allow the evaluation of tube current modulation systems. The purpose of this study was to extend the concept of CTDIw to elliptical phantoms of various aspect ratios. Methods: Based on published adult and pediatric data, eight body aspect ratios were chosen from the full range between 1 (perfectly circular) and 1.72 (extremely elliptical). For each value, two elliptical cylinders were created digitally to represent adult and pediatric bodies. They had the same cross‐sectional areas as the standard 32‐cm and 16‐cm CTDI phantoms. For each digital phantom, CTDI₁₀₀ at central and peripheral locations were simulated for tube voltages between 70–140 kVp using a Monte Carlo program previously validated for a clinical CT system (SOMATOM Definition Flash, Siemens Healthcare). The simula

Keywords

Imaging phantomDosimetryWeightingNuclear medicineMonte Carlo methodStandard deviationOpticsPhysics

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