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[P052] Influence of X-ray field position on doses in organs and tissues for chest radiography
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Abstracts / Physica Medica 52 (2018) 99–187
respectively). Contrast to noise ratio has changed in ranges from 10% to 64% for Optima580 and from 4% to 68% for Optima540. Uniformity differed from 1,4 HU up to 11,2 HU for Optima580 and from 0,2 HU to 8,8 HU for Optima540. Noise assessed as a standard deviation differed in ranges from 4% up to 35% for Optima580 and from 8% up to 59% for Optima540. Conclusions. Phantom studies have helped to assessed variations in particular parameters depending on the position in scanned field of view. This is important to know the limitations of technology used in daily routine practice. https://doi.org/10.1016/j.ejmp.2018.06.374
[P052] Influence of X-ray field position on doses in organs and tissues for chest radiography Krystsina Makarevich, Victor Minenko, Siamion Kutsen, Kiryl Verenich * Institute for Nuclear Problems, Belarusian State University, Laboratory of Theoretical Physics and Simulation of Nuclear Processes, Minsk, Belarus ⇑ Corresponding author. Purpose. We studied how changing of the field position influences the absorbed doses in organs and tissues during chest radiography. Methods. The ICRP voxel phantoms were adopted for modelling of chest radiography in posterior-anterior projection. The parts of phantoms that lie inside the beam and scattered radiation region located at the distance of 15 cm from the field edge were taken. The TASMIP model was used for the spectrum of X-ray tube. The following parameters were taken into account: anode voltage, filtration, voltage ripple, the focus-to-detector distance and the field size. Monte-Carlo simulation of X-ray transport within the chosen parts of phantoms was used [1]. At the standard position the center of X-ray field lied 40 cm from the top of the male phantom and 36.8 cm from the top of the female phantom. 5% to 20% shifts of the field center were considered. Results. Changes in X-ray field position cause large differences in organ doses for organs that originally lied inside the beam or on the boundaries of the beam volume. After the field center shift by 20% up from the standard position the absorbed dose in adrenals of male decreases by a factor of 8.6. This effect is less than 20% for large organs and tissues such as lungs, muscle or skin. After the field center shift by 20% down the standard position the absorbed dose in female lungs decreases by 6%. Doses to organs of female are almost always larger than doses to the same organs of male. For standard field position the doses in female’s liver and lungs are 1.6 and 1.8 times higher than corresponding doses for male phantom. Conclusions. Shift of X-ray field position up and down from the standard value should be considered for dose optimization during chest radiography. Differences between male and female bodies should be taken into account for more accurate patient dose assessment.
References 1. Makarevich K, Minenko V, Verenich K and Kuten S. Using the Monte Carlo method for assessing the tissue and organ doses of patients in dental radiography. Physics of Particles and Nuclei Letters 2016; 13:406-415. https://doi.org/10.1016/j.ejmp.2018.06.375
[P053] Contrast-enhanced digital mammography on commercial systems: an optimization study Adriano Contillo *, Angelo Taibi Università Degli Studi DI Ferrara, Dipartimento DI Fisica e Scienze Della Terra, Ferrara, Italy ⇑ Corresponding author. Purpose. We introduce a novel algorithm for dual energy (DE) subtraction proposed in [1,2], based on an iterative procedure for taking into account the intrinsic polychromaticity of conventional X-ray tubes. The result is an improvement of background cancellation with respect to the currently available DE systems. The algorithm was applied to a set of DE radiographs of a dedicated anthropomorphic phantom embedding small agglomerates of contrast medium (iodine), acquired with a commercial mammography system. Methods. The employed anthropomorphic phantom, specifically designed for DE applications, is a polymethyl methacrylate (PMMA) box of parallelepipedal shape. It contains a large number of PMMA spheres of different diameters, embedded in paraffin wax. Moreover, it embeds a system of cavities that can be filled with iodine solutions of various concentrations. The phantom was imaged with X-ray beams of low energy (29 ± 2 kV) and high energy (47 ± 2 kV), generated by a commercial mammography unit with a tungsten anode and additional filtrations of rhodium (low energy) and copper (high energy). Results. We achieved an almost complete cancellation of the background texture, resulting in an enhanced visibility of the iodine details. Such result was achieved with lower exposures than the values typical of diagnostic practice. We noticed no significant dependence of the image quality on the particular choice of beam energies. Conclusions. The implementation of the novel subtraction algorithm on a commercial unit allowed an effective background cancellation with a reduced amount of delivered dose. Such result was largely independent of the imaging parameters, which is an indication of robustness of the algorithm. In conclusion, the proposed algorithm paves the way to an improvement of the diagnostic effectiveness of DE imaging.
References 1. Contillo A, Di Domenico G, Cardarelli P, Gambaccini M and Taibi A. A novel approach to background subtraction in contrastenhanced dual-energy digital mammography with commercially available mammography devices: Polychromaticity correction. Medical Physics 2015;42:6641-6650. 2. Contillo A, Di Domenico G, Cardarelli P, Gambaccini M and Taibi A. A novel approach to background subtraction in contrastenhanced dual-energy digital mammography with commercially available mammography devices: Noise minimization. Medical Physics 2016;43:3080-3089. https://doi.org/10.1016/j.ejmp.2018.06.376
[P054] Absorbed and effective doses from the intraoral dental Xray radiography ta Jurgita Laurikaitiene˙ a,*, Diana Adliene a, Marius Laurikaitis b, Ru ras Andrejaitis b Nedzinskiene˙ c, Artu a
Kaunas University of Technology, Faculty of Mathematics and Natural Sciences, Kaunas, Lithuania b Hospital of Oncology, the Hospital of Lithuanian University of Health Sciences Kauno Klinikos, Department of Radiotherapy, Kaunas, Lithuania
Abstracts / Physica Medica 52 (2018) 99–187
respectively). Contrast to noise ratio has changed in ranges from 10% to 64% for Optima580 and from 4% to 68% for Optima540. Uniformity differed from 1,4 HU up to 11,2 HU for Optima580 and from 0,2 HU to 8,8 HU for Optima540. Noise assessed as a standard deviation differed in ranges from 4% up to 35% for Optima580 and from 8% up to 59% for Optima540. Conclusions. Phantom studies have helped to assessed variations in particular parameters depending on the position in scanned field of view. This is important to know the limitations of technology used in daily routine practice. https://doi.org/10.1016/j.ejmp.2018.06.374
[P052] Influence of X-ray field position on doses in organs and tissues for chest radiography Krystsina Makarevich, Victor Minenko, Siamion Kutsen, Kiryl Verenich * Institute for Nuclear Problems, Belarusian State University, Laboratory of Theoretical Physics and Simulation of Nuclear Processes, Minsk, Belarus ⇑ Corresponding author. Purpose. We studied how changing of the field position influences the absorbed doses in organs and tissues during chest radiography. Methods. The ICRP voxel phantoms were adopted for modelling of chest radiography in posterior-anterior projection. The parts of phantoms that lie inside the beam and scattered radiation region located at the distance of 15 cm from the field edge were taken. The TASMIP model was used for the spectrum of X-ray tube. The following parameters were taken into account: anode voltage, filtration, voltage ripple, the focus-to-detector distance and the field size. Monte-Carlo simulation of X-ray transport within the chosen parts of phantoms was used [1]. At the standard position the center of X-ray field lied 40 cm from the top of the male phantom and 36.8 cm from the top of the female phantom. 5% to 20% shifts of the field center were considered. Results. Changes in X-ray field position cause large differences in organ doses for organs that originally lied inside the beam or on the boundaries of the beam volume. After the field center shift by 20% up from the standard position the absorbed dose in adrenals of male decreases by a factor of 8.6. This effect is less than 20% for large organs and tissues such as lungs, muscle or skin. After the field center shift by 20% down the standard position the absorbed dose in female lungs decreases by 6%. Doses to organs of female are almost always larger than doses to the same organs of male. For standard field position the doses in female’s liver and lungs are 1.6 and 1.8 times higher than corresponding doses for male phantom. Conclusions. Shift of X-ray field position up and down from the standard value should be considered for dose optimization during chest radiography. Differences between male and female bodies should be taken into account for more accurate patient dose assessment.
References 1. Makarevich K, Minenko V, Verenich K and Kuten S. Using the Monte Carlo method for assessing the tissue and organ doses of patients in dental radiography. Physics of Particles and Nuclei Letters 2016; 13:406-415. https://doi.org/10.1016/j.ejmp.2018.06.375
[P053] Contrast-enhanced digital mammography on commercial systems: an optimization study Adriano Contillo *, Angelo Taibi Università Degli Studi DI Ferrara, Dipartimento DI Fisica e Scienze Della Terra, Ferrara, Italy ⇑ Corresponding author. Purpose. We introduce a novel algorithm for dual energy (DE) subtraction proposed in [1,2], based on an iterative procedure for taking into account the intrinsic polychromaticity of conventional X-ray tubes. The result is an improvement of background cancellation with respect to the currently available DE systems. The algorithm was applied to a set of DE radiographs of a dedicated anthropomorphic phantom embedding small agglomerates of contrast medium (iodine), acquired with a commercial mammography system. Methods. The employed anthropomorphic phantom, specifically designed for DE applications, is a polymethyl methacrylate (PMMA) box of parallelepipedal shape. It contains a large number of PMMA spheres of different diameters, embedded in paraffin wax. Moreover, it embeds a system of cavities that can be filled with iodine solutions of various concentrations. The phantom was imaged with X-ray beams of low energy (29 ± 2 kV) and high energy (47 ± 2 kV), generated by a commercial mammography unit with a tungsten anode and additional filtrations of rhodium (low energy) and copper (high energy). Results. We achieved an almost complete cancellation of the background texture, resulting in an enhanced visibility of the iodine details. Such result was achieved with lower exposures than the values typical of diagnostic practice. We noticed no significant dependence of the image quality on the particular choice of beam energies. Conclusions. The implementation of the novel subtraction algorithm on a commercial unit allowed an effective background cancellation with a reduced amount of delivered dose. Such result was largely independent of the imaging parameters, which is an indication of robustness of the algorithm. In conclusion, the proposed algorithm paves the way to an improvement of the diagnostic effectiveness of DE imaging.
References 1. Contillo A, Di Domenico G, Cardarelli P, Gambaccini M and Taibi A. A novel approach to background subtraction in contrastenhanced dual-energy digital mammography with commercially available mammography devices: Polychromaticity correction. Medical Physics 2015;42:6641-6650. 2. Contillo A, Di Domenico G, Cardarelli P, Gambaccini M and Taibi A. A novel approach to background subtraction in contrastenhanced dual-energy digital mammography with commercially available mammography devices: Noise minimization. Medical Physics 2016;43:3080-3089. https://doi.org/10.1016/j.ejmp.2018.06.376
[P054] Absorbed and effective doses from the intraoral dental Xray radiography ta Jurgita Laurikaitiene˙ a,*, Diana Adliene a, Marius Laurikaitis b, Ru ras Andrejaitis b Nedzinskiene˙ c, Artu a
Kaunas University of Technology, Faculty of Mathematics and Natural Sciences, Kaunas, Lithuania b Hospital of Oncology, the Hospital of Lithuanian University of Health Sciences Kauno Klinikos, Department of Radiotherapy, Kaunas, Lithuania