Résumé
Objective To test the spatial resolution and average glandular dose (AGD) of full field digital mammography system to obtain high-resolution and contrast breast X-ray images with the lowest dose.Methods The M12 breast X-ray performance test phantom was placed on the breast support center position,then line-pair card was put on the M12 phantom and fixed groove,and exposure was carried out with auto exposure control,28 kV tube voltage and common anode filtration combination so as to detect the spatial resolution.Half-value layer (HVL) was measured by Fluke TNT12000 ray detection tools,2 mm-thickness plate and aluminum sheets with different thicknesses,and then AGD was calculated accordingly.Results The spatial resolutions were all higher than 7 lp/mm and proved to meet the quality standard,which had the vertical spatial resolution being 8 lp/mm,the maximum value of the lateral spatial resolution being 10 lp/mm and the minimum value being 8 lp/mm.AGD was lower than 2 mGy and then proved qualified which was limited within 0.60 and 0.61 mGy.Conclusion The test of spatial resolution and AGD of full digital mammography system can assess the performance and radiation dose,reflect the performance of equipment,ensure image quality and lower radiation dose.
Résumé
Objective To test the spatial resolution and average glandular dose (AGD) of full field digital mammography system to obtain high-resolution and contrast breast X-ray images with the lowest dose.Methods The M12 breast X-ray performance test phantom was placed on the breast support center position,then line-pair card was put on the M12 phantom and fixed groove,and exposure was carried out with auto exposure control,28 kV tube voltage and common anode filtration combination so as to detect the spatial resolution.Half-value layer (HVL) was measured by Fluke TNT12000 ray detection tools,2 mm-thickness plate and aluminum sheets with different thicknesses,and then AGD was calculated accordingly.Results The spatial resolutions were all higher than 7 lp/mm and proved to meet the quality standard,which had the vertical spatial resolution being 8 lp/mm,the maximum value of the lateral spatial resolution being 10 lp/mm and the minimum value being 8 lp/mm.AGD was lower than 2 mGy and then proved qualified which was limited within 0.60 and 0.61 mGy.Conclusion The test of spatial resolution and AGD of full digital mammography system can assess the performance and radiation dose,reflect the performance of equipment,ensure image quality and lower radiation dose.
Résumé
The purpose of this study is to comprehensively compare and evaluate the characteristics of image quality for digital mammography systems which use a direct and indirect conversion detector. Three key metrics of image quality were evaluated for the direct and indirect conversion detector, the modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE), which describe the resolution, noise, and signal to noise performance, respectively. DQE was calculated by using a edge phantom for MTF determination according to IEC 62220-1-2 regulation. The contrast to noise ratio (CNR) was evaluated according to guidelines offered by the Korean Institute for Accreditation of Medical Image (KIAMI). As a result, the higher MTF and DQE was measured with direct conversion detector compared to indirect conversion detector all over spatial frequency. When the average glandular dose (AGD) was the same, direct conversion detector showed higher CNR value. The direct conversion detector which has higher DQE value all over spatial frequency would provide the potential benefits for both improved image quality and lower patient dose in digital mammography system.