liu.seSearch for publications in DiVA
Change search
ReferencesLink to record
Permanent link

Direct link
A search for optimal x‐ray spectra in iodine contrast media mammography
Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.
Linköping University, Department of Medicine and Health Sciences, Radiation Physics . Linköping University, Faculty of Health Sciences.ORCID iD: 0000-0003-3352-8330
Joint Department of Physics, The Royal Marsden NHS Trust, London, UK.
Department of Medical Biophysics, University of Toronto, Sunnybrook and Women's College Health Sciences Centre, Ontario, Canada.
Show others and affiliations
2005 (English)In: Physics in medicine and biology, ISSN 0031-9155 (print), 1361-6560 (online), Vol. 50, no 13, 3143-3152 p.Article in journal (Refereed) Published
Abstract [en]

The aim of this work was to search for the optimal x-ray tube voltage and anode–filter combination in digital iodine contrast media mammography. In the optimization, two entities were of interest: the average glandular dose, AGD, and the signal-to-noise ratio, SNR, for detection of diluted iodine contrast medium. The optimum is defined as the technique maximizing the figure of merit, SNR2/AGD. A Monte Carlo computer program was used which simulates the transport of photons from the x-ray tube through the compression plate, breast, breast support plate, anti-scatter grid and image detector. It computes the AGD and the SNR of an iodine detail inside the compressed breast. The breast thickness was varied between 2 and 8 cm with 10–90% glandularity. The tube voltage was varied between 20 and 55 kV for each anode material (Rh, Mo and W) in combination with either 25 µm Rh or 0.05–0.5 mm Cu added filtration. The x-ray spectra were calculated with MCNP4C (Monte Carlo N-Particle Transport Code System, version 4C). A CsI scintillator was used as the image detector. The results for Rh/0.3mmCu, Mo/0.3mmCu and W/0.3mmCu were similar. For all breast thicknesses, a maximum in the figure of merit was found at approximately 45 kV for the Rh/Cu, Mo/Cu and W/Cu combinations. The corresponding results for the Rh/Rh combination gave a figure of merit that was typically lower and more slowly varying with tube voltage. For a 4 cm breast at 45 kV, the SNR2/AGD was 3.5 times higher for the Rh/0.3mmCu combination compared with the Rh/Rh combination. The difference is even larger for thicker breasts. The SNR2/AGD increases slowly with increasing Cu-filter thickness. We conclude that tube voltages between 41 and 55 kV and added Cu-filtration will result in significant dose advantage in digital iodine contrast media mammography compared to using the Rh/Rh anode/filter combination at 25–32 kV.

Place, publisher, year, edition, pages
2005. Vol. 50, no 13, 3143-3152 p.
National Category
Medical and Health Sciences
URN: urn:nbn:se:liu:diva-13217DOI: 10.1088/0031-9155/50/13/012OAI: diva2:18070
Available from: 2008-04-28 Created: 2008-04-28 Last updated: 2015-03-20
In thesis
1. Quantifying image quality in diagnostic radiology using simulation of the imaging system and model observers
Open this publication in new window or tab >>Quantifying image quality in diagnostic radiology using simulation of the imaging system and model observers
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Accurate measures of both clinical image quality and patient radiation risk are needed for successful optimisation of medical imaging with ionising radiation. Optimisation in diagnostic radiology means finding the image acquisition technique that maximises the perceived information content and minimises the radiation risk or keeps it at a reasonably low level. The assessment of image quality depends on the diagnostic task and may in addition to system and quantum noise also be hampered by overlying projected anatomy.

The main objective of this thesis is to develop methods for assessment of image quality in simulations of projection radiography. In this thesis, image quality is quantified by modelling the whole x‐ray imaging system including the x‐ray tube, patient, anti‐scatter device, image detector and the observer. This is accomplished by using Monte Carlo (MC) simulation methods that allow simultaneous estimates of measures of image quality and patient dose. Measures of image quality include the signal‐to‐noise‐ratio, SNR, of pathologic lesions and radiation risk is estimated by using organ doses to calculate the effective dose. Based on high‐resolution anthropomorphic phantoms, synthetic radiographs were calculated and used for assessing image quality with model‐observers (Laguerre‐Gauss (LG) Hotelling observer) that mimic real, human observers. Breast and particularly chest imaging were selected as study cases as these are particularly challenging for the radiologists.

In chest imaging the optimal tube voltage in detecting lung lesions was investigated in terms of their SNR and the contrast of the lesions relative to the ribs. It was found that the choice of tube voltage depends on whether SNR of the lesion or the interfering projected anatomy (i.e. the ribs) is most important for detection. The Laguerre‐Gauss (LG) Hotelling observer is influenced by the projected anatomical background and includes this into its figure‐of‐merit, SNRhot,LG. The LG‐observer was found to be a better model of the radiologist than the ideal observer that only includes the quantum noise in its analysis. The measures of image quality derived from our model are found to correlate relatively well with the radiologist’s assessment of image quality. Therefore MC simulations can be a valuable and an efficient tool in the search for dose‐efficient imaging systems and image acquisition schemes.

Place, publisher, year, edition, pages
Institutionen för medicin och hälsa, 2008
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1050
radiology, radiation physics, image quality, optimisation, effective dose, chest radiography
National Category
Radiology, Nuclear Medicine and Medical Imaging
urn:nbn:se:liu:diva-11662 (URN)978‐91‐7393‐952‐2 (ISBN)
Public defence
2008-05-09, Eken, Campus US, Linköpings universitet, Linköping, 09:00 (English)
Available from: 2008-04-28 Created: 2008-04-28 Last updated: 2015-03-20

Open Access in DiVA

No full text

Other links

Publisher's full textLink to Ph.D. thesis

Search in DiVA

By author/editor
Ullman, GustafSandborg, MichaelAlm Carlsson, Gudrun
By organisation
Radiation Physics Faculty of Health Sciences
Medical and Health Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 50 hits
ReferencesLink to record
Permanent link

Direct link