X-ray Physics: Research, Development and Education

The X-ray Physics unit at the Karolinska University Hospital is split across the Huddinge and Solna sites. We support diagnostic and interventional imaging with ionizing radiation in a large variety of clinics and ensure radiation safety. Teaching and research also play an important role in our activities. We are involved in the training and professional development of medical physicists as well as other healthcare professionals. Our research interests are diverse, but with a practical emphasis, demonstrating that in-house developments drive improvements in the quality of the clinical service.

About our activities

Teaching activities

Our team has a key role in teaching on the Medical Physics Master's Programme, run by Stockholm University. We have also organized short courses for the professional development of medical physicists in Sweden. Our staff members teach other healthcare professionals too, such as radiographers within their education at Södertörns Högskola and radiologists under their specialist programme. 

Research activities

Our research interests focus on dosimetry (of both patient and staff) and image quality, exploring what is possible in a modern healthcare environment. In this era of "big data", this means an increasing emphasis on informatics as well as the more traditional skills of radiation physicists and engineers.

Several of our staff members are registered for doctoral studies and we have links to a variety of academic institutions, including the Karolinska Institute (KI) and the Royal Institute of Technology (KTH) in Stockholm, as well as several others in Sweden and around the world. We also have strong relationships with vendors and healthcare companies, which aid our research and development activities.

For further details, please see a summary of our recent publications at the bottom of this page.


A phantom developed by the X-Ray Physics unit has been licensed by a well-known manufacturer (The Phantom Laboratory, Inc.) and is now available commercially. For the full story see here(öppnas i nytt fönster).


Head of X-ray Physics: Albert Sundvall
Research representative: Gavin Poludniowski, PhD

Recent publications

Below is a list of the X-ray Physics unit's publications from the last five years. The names of authors associated with the unit are highlighted with asterix (*) in the text.



Experimental assessment of a phosphor model for estimating the relative extrinsic efficiency in radioluminescent detectors

Jan Lindström*, Gudrun Alm Carlsson, Erik Wåhlin*, Åsa Carlsson Tedgren, Gavin Poludniowski*

Physica Medica, 2020-08-01, Volume 76, Pages 117-124, Copyright © 2020


Age-specific and Gender-Specific Radiation Risks in Paediatric Angiography and Interventional Cardiology: Conversion Coefficients and Risk Reference Values

Angeliki Karambatsakidou*, Kristoffer Steiner, Annette Fransson*, Gavin Poludniowski*

Br J Radiol. 2020 Jun;93(1110):20190869


Diagnosis of foreign body aspiration with ultralow-dose CT using a tin filter: a comparison study

Lena Gordon, Patrik Nowik*, Shahla Mobini Kesheh*, Marika Lidegran, Sandra Diaz

Emerg Radiol ​​​​2020 Aug; 27(4):399-404. Epub 2020 Mar 9.


The synthetic localizer radiograph – A new CT scan planning method

Patrik Nowik*, Gavin Poludniowski*, Anders Svensson, Robert Bujila*, Fabian Morsbach, Torkel B. Brismar

Physica Medica, Volume 61, May 2019, Pages 58-63


Calculating organ and effective doses in paediatric interventional cardiac radiology based on DICOM structured reports – Is detailed examination data critical to dose estimates?

 Angeliki Karambatsakidou*, Artur Omar*, Annette Fransson*, Gavin Poludniowski*.

Physica Medica 57 (2019) 17–24


A model for the emission of K and L x rays from an x-ray tube.

Omar A*, Andreo P, Poludniowski G.
Nuclear Instruments and Methods in Physics Research Section B 437, 36-47.


Performance of different theories for the angular distribution of bremsstrahlung produced by keV electrons incident upon a target.

Omar A*, Andreo P, Poludniowski G*.
Radiation Physics and Chemistry 148, 73-85.(öppnas i nytt fönster)

Radiation dose from X-ray examinations of impacted canines: cone beam CT vs two-dimensional imaging.

Kadesjö N*, Lynds R, Nilsson M, Shi XQ.
Dentomaxillofac Radiol. 2018;47(3):20170305(öppnas i nytt fönster).


Cone-beam computed tomography with ultra-low dose protocols for pre-implant radiographic assessment: An in vitro study.

Liljeholm R, Kadesjö N*, Benchimol D, Hellén-Halme K, Shi XQ.
Eur J Oral Implantol. 2017;10(3):351-359(öppnas i nytt fönster).

The dosimetric impact of including the patient table in CT dose estimates.

Nowik P*, Bujila R*, Kull L, Andersson J, Poludniowski G*.
Phys Med Biol. 2017;62(23):N538-N547(öppnas i nytt fönster).

Risk of Meningioma after CT of the Head.

Nordenskjöld AC, Bujila R*, Aspelin P, Flodmark O, Kaijser M.
Radiology. 2017;285(2):568-575(öppnas i nytt fönster).

Practical approaches to approximating MTF and NPS in CT with an example application to task-based observer studies.

Bujila R*, Fransson A*, Poludniowski G*.
Phys Med. 2017;33:16-25(öppnas i nytt fönster).

Evaluating the impact of scan settings on automatic tube current modulation in CT using a novel phantom.

Merzan D*, Nowik P*, Poludniowski G*, Bujila R*.
Br J Radiol. 2017;90(1069):20160308(öppnas i nytt fönster).

Assessment of the occupational eye lens dose for clinical staff in interventional radiology, cardiology and neuroradiology.

Omar A*, Kadesjö N*, Palmgren C*, Marteinsdottir M*, Segerdahl T, Fransson A*. 
J Radiol Prot. 2017;37(1):145-159(öppnas i nytt fönster).


Upper limits of the photon fluence rate on CT detectors: Case study on a commercial scanner.

Persson M, Bujila R*, Nowik P*, Andersson H, Kull L, Andersson J, Bornefalk H, Danielsson M.
Med Phys. 2016;43(7):4398(öppnas i nytt fönster).

A framework for organ dose estimation in x-ray angiography and interventional radiology based on dose-related data in DICOM structured reports.

Omar A*, Bujila R*, Fransson A*, Andreo P, Poludniowski G*.
Phys Med Biol. 2016;61(8):3063-83(öppnas i nytt fönster).

Skin dose, effective dose and related risk in transcatheter aortic valve implantation (TAVI) procedures: is the cancer risk acceptable for younger patients?

Karambatsakidou A*, Omar A*, Chehrazi B*, Rück A, Scherp Nilsson J* and Fransson A*. 
Radiat Prot Dosimetry. 2016;169(1-4):225-31(öppnas i nytt fönster).


Metal artefact reduction in CT imaging of hip prostheses—an evaluation of commercial techniques provided by four vendors.

Andersson KM, Nowik P*, Persliden J, Thunberg P, Norrman E. 
Br J Radiol. 2015;88(1052):20140473(öppnas i nytt fönster).

Technical Note: On the calculation of stopping-power ratio for stoichiometric calibration in proton therapy.

Ödén J, Zimmerman J, Bujila R*, Nowik P*, Poludniowski G*.
Med Phys. 2015;42(9):5252-7(öppnas i nytt fönster).

On the feasibility of utilizing active personal dosimeters worn on the chest to estimate occupational eye lens dose in x-ray angiography.

Omar A*, Marteinsdottir M*, Kadesjö N*, Fransson A*. 
J Radiol Prot. 2015;35(2):271-84(öppnas i nytt fönster).

Quality control of CT systems by automated monitoring of key performance indicators.

Nowik P*, Bujila R*, Poludniowski G* and Fransson A*. 
J Appl Clin Med Phys. 2015;16(4):254–265(öppnas i nytt fönster).

Evaluation of the effective dose of cone beam CT and multislice CT for temporomandibular joint examinations at optimized exposure levels.

Kadesjö N*, Benchimol D, Falahat B, Näsström K, Shi XQ.
Dentomaxillofac Radiol. 2015;44(8):20150041(öppnas i nytt fönster).

Effective radiation dose of a MSCT, two CBCT and one conventional radiography device in the ankle region.

Koivisto J, Kiljunen T, Kadesjö N*, Shi XQ, Wolff J.
J Foot Ankle Res. 2015 Mar 12;8:8(öppnas i nytt fönster).

Low tube voltage dual source computed tomography to reduce contrast media doses in adult abdomen examinations: A phantom study.

Thor D*, Brismar T and Fischer M. 
Med Phys. 2015;42(9):5100-9(öppnas i nytt fönster).


Monte Carlo investigation of backscatter factors for skin dose determination in interventional neuroradiology procedures.

Omar A*, Benmakhlouf H, Marteinsdottir M*, Bujila R*, Nowik P*, Andreo P. Proceedings Vol. 9033, Medical Imaging 2014: Physics of Medical Imaging; 90331T(öppnas i nytt fönster).