Scientific instrument for a controlled choice of optimal photon energy in intra-oral radiography

Basic performance parameters are defined and analysed in order to optimise physical image quality in relation to the energy imparted to the patient in dental radiology. Air cavities were embedded in well-defined multimaterial, hard tissue phantoms to represent various objects in dento-maxillo-facial...

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Bibliographic Details
Published in:	Radiation protection dosimetry Vol. 80; no. 1; p. 321
Main Authors:	Helmrot, Ebba, Sandborg, Michael, Eckerdal, Olle, Alm Carlsson, Gudrun
Format:	Journal Article
Language:	English
Published:	1998
Subjects:	MEDICIN MEDICINE
Online Access:	Get full text
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Summary:	Basic performance parameters are defined and analysed in order to optimise physical image quality in relation to the energy imparted to the patient in dental radiology. Air cavities were embedded in well-defined multimaterial, hard tissue phantoms to represent various objects in dento-maxillo-facial examinations. Basic performance parameters were: object contrast (C), energy imparted (_) to the patient, signal-to-noise ration (SNR), C 2 /_ (film) and (SNR) 2 /_ (digital imaging system) as functions of HVL (half-value layer), used to describe the photon energy spectrum. For the film receptor, the performance index C 2 /_ is maximum (optimal) at HVL values of 1.5-1.7 mm Al in the simulated Incisive, Premolar and Molar examinations. Other imaging tasks (examinations), not simulated here, may require other optimal HVL. For the digital imaging system (Digora) the performance index (SNR) 2 /_, theoretically calculated, indicates that a lower value of HVL is optimal than with film as receptor. However, due to the limited number of bits (8 bits) in the analogue to digital converter (ADC) contrast resolution is degraded and calls for use of higher photon energies (HVL). Customised optimisations with proper concern for patient category, type of examination, diagnostic task is the ultimate goal of this work. The conclusions stated above give some general advice on the appropriate choice of photon energy spectrum (HVL). In particular situations, it may be necessary to use more dose demanding kV settings (lower HVL) in order to get sufficient image quality for the diagnostic task.
ISSN:	1742-3406 0144-8420