Bajram Zeqiri FREng is an NPL Fellow in Ultrasound and Head of Science for Medical and Marine Physics within the Medical, Marine and Nuclear Department at NPL. He is an internationally recognised leader in the field of ultrasound metrology, specifically supporting its medical and industrial applications. He has been an NPL Fellow since 2008 and his contributions to the technical field have been underpinned by a passion for innovation, as evidenced through a string of patents related to ultrasound metrology. He works closely with industry, forming strong partnerships with national and international companies, seeing this as a mechanism for accelerating the impact of NPL's work. He was appointed Visiting Professor in the University College London Department of Medical Physics and Biomedical Engineering from 1 September 2019.
NPL’s activity in the ultrasound area has been important in establishing measurement standardisation that today underpins the safe and effective application of medical ultrasound globally. Bajram's research activities include: leading the development of standards for characterising the essential properties of physiotherapy ultrasound equipment; measurement and calibration standards for ultrasonic hydrophones and power measurement, as well as the establishment of reference facilities for determining the acoustic properties of tissue-like materials. One area of particular interest has been the development and characterisation of unique acoustic materials for applications covering the frequency range 10 kHz to 30 MHz some of which are now provided to the user community under Licence.
Bajram has an established track record for innovation related to ultrasound metrology and is the named inventor on six patents. These include the NPL Cavitation Sensor, a device which detects the high-frequency acoustic emissions generated by bubbles undergoing acoustic cavitation. In 2003, a paper describing the Cavitation Sensor won the IEEE Ultrasonics, Ferroelectrics and Frequency Control (UFFC) Outstanding Paper Award and, in 2009, the NPL Cavimeter was awarded the Ultrasonic Industry Association (UIA) Best Product Award for a device employing ultrasonic energy. Bajram has also pioneered the application of the pyroelectric effect within thin membranes of the piezopolymer polyvinylidene fluoride as a robust, solid-state, technique for ultrasound power measurement. A current research topic of interest addresses the application of these pyroelectric detectors to phase-insensitive Ultrasound Computed Tomography (UCT), supporting quantitative attenuation imaging of soft-tissue materials, for potential application in the breast disease diagnosis.
For over 25 years, Bajram has represented the UK on the key standardisation committee, IEC TC87: Ultrasonics through membership of Working Groups 6 (Focused transducers), 8 (Ultrasonic field measurement) and Working Group 3 (High Power Transducers), for which he was Convenor. He was a member of BSI Technical Committee EPL/87, the mirror committee of the International Electrotechnical Committee Technical Committee TC87. Other responsibilities of note: contribution to REF2014 as an invited member of Sub-Panel 13B: Electronic and Electrical Engineering, Metallurgy and Materials; Chaired the Strategic Planning Working Group of the CIPM Consultative Committee for Acoustics, Ultrasound and Vibration (CCAUV); membership of the UK Institute of Acoustics Research Coordination Committee and the Institute of Sound and Vibration Research (University of Southampton) Advisory Committee; membership of the Institute of Physics in Medicine and Biology (IPEMB) Special Interest Group on Ultrasound and Non-ionising Radiation and twice Convened the EURAMET Sub-committee on Ultrasound and Underwater Acoustics. Through invitation, Bajram contributed to a Working Group convened by the UK Health Protection Agency, whose task was to draft an Advisory Report on the Health Effects of Ultrasound and Infrasound, particularly relating to the public exposure. Since 2018, he has been a member of the Technical Programme Committee contributing to organising IEEE International Ultrasonics Symposia, the major technical meeting in the area.
In September 2021, Bajram was elected a Fellow of the Royal Academy of Engineering. In December 2021, he was awarded the Institute of Physics James Joule Medal and Prize for distinguished contributions to the development of acoustic measurement techniques and sensors; in particular, underpinning the provision of international standards enabling the safe clinical application of medical ultrasound.
He has published 130+ articles, over 80 of which are peer-reviewed journal articles.
Selected recent publications
- Bakaric, M, Fromme, P, Hurrell, A, Rajagopal, S, Miloro, P, Zeqiri, B, Cox, BT and Treeby, BE. Measurement of the temperature dependent output of lead zirconate transducers. Ultrasonics, 114,10.1016/j.ultras.2021.106378, 2021.
- Zeqiri, B, Wang, L, Miloro, M, Robinson, SP. A radiation force balance target material for applications below 0.5 MHz. Ultrasound Med. Biol., 46(9), 2520-2529, 2020.
- McGarry, CK, Grattan, LJ, Ivory, AM, Leek, F, Liney, LJ, Yang Liu, Miloro, P, Rai, R, Robinson, AP, Shi, AJ, Zeqiri, B and Clark, CH. Tissue mimicking materials for imaging and therapy phantoms: a review. Phys. Med. Biol., 25(23), doi: 10.1088/1361-6560/abbd17, 2020.
- Baker C, Sarno S, Eckersley RJ and Zeqiri, B. Pulse Pileup Correction of Signals from a Pyroelectric Sensor for Phase-Insensitive Ultrasound Computed Tomography (piUCT). IEEE Transactions on Instrumentation and Measurement, PP(99), 1-12, 2018.
- Baesso, RM, Costa-Felix, RPB, Miloro, P and Zeqiri, B. Ultrasonic parameter measurement as a means of assessing the quality of biodiesel production, Fuel, 241, 155-163, 2019.
- Memoli, G, Baxter, KO, Jones, HG, Mingard, KP and Zeqiri, B. Acoustofluidic measurements on polymer-coated microbubbles: Primary and secondary Bjerknes forces, Micromachines, 9, 8, Article number 404, 2018.
- Sarno, D, Hodnett, M, Wang, L and Zeqiri B. An objective comparison of commercially-available cavitation cleaners, Ultrasonics Sonochemistry, 34, 354-364, 2017.
- Fonseca, M, Zeqiri, B, Beard, PC et al. Characterisation of a phantom for multiwavelength quantitative photoacoustic imaging, Physics in Medicine and Biology, 61, 13, 4950-4973, 2016.
- Koukoulas, T, Robinson, SP, Rajagopal at al. A comparison between heterodyne and homodyne interferometry to realise the SI unit of acoustic pressure in water. Metrologia, 53, 2, 891-898, 2016.
- Rajagopal, S, Fury, C and Zeqiri, B at al. Report on BIPM/CIPM Key Comparison CCAUV.U-K4: Absolute calibration of Medical Hydrophones in the frequency range 0.5 MHz to 20 MHz Final Report. Metrologia, 53S, Article Number 09004, 2016.
- Fonseca, M, Saratoon, T, Zeqiri, B, Beard P and Cox, B. Sensitivity of quantitative photoacoustic tomography in version schemes to experimental uncertainty. Photons plus ultrasound imaging and sensing. Book series: Proceedings of SPIE meeting, San Francisco, California, Volume 9708, Article number: 97084X, 2016.
- Wang, L, Memoli, G, Hodnett, M, Butterworth, I, Sarno, D and Zeqiri, B. Towards a reference cavitating vessel Part III – Design and acoustic pressure characterisation of a multi-frequency sonoreactor. Metrologia, 52, 4, 575-594, 2015.
- Zeqiri, B, Cook, A, Retat, L, Civale, L and ter Haar, G. On measurement of the acoustic nonlinearity parameter using the finite amplitude insertion substitution (FAIS) technique. Metrologia, 52, 2, 406-422, 2015.
- Bornmann, P, Hemsel, T, Sextro, W, Memoli, G, Hodnett, M and Zeqiri, B. Cavitation detection by a self-sensing ultrasound transducer. TM-Tecsniches Messen, 82, 2, 73-84, 2015.
- Fonseca, M, Zeqiri, B, Beard, P and Cox, B. Characterisation of a PVCP based tissue-mimicking phantom for quantitative photoacoustic imaging. Opto-acoustic methods and applications in biophotonics II Book series: Proceedings of SPIE, Volume 9539, Article number: 953911, 2015.
- Rajagopal, S, Sadhoo, N and Zeqiri, B. Reference characterisation of sound speed and attenuation of the IEC agar-based tissue-mimicking material up to a frequency of 60 MHz, Ultrasound in Medicine and Biology, 41, 1, 317-333, 2015.
- Kenwright, DA, Sadhoo, N, Rajagopal, S and Zeqiri, B. Acoustic assessment of a konjac-carrageenan tissue-mimicking material at 5 - 60 MHz. Ultrasound in Medicine and Biology, 40, 12, 2895-2902, 2014.
- Rajagopal, S, Zeqiri, B and Gelat, PN. Calibration of miniature medical ultrasonic hydrophones for frequencies in the range 100 to 500 kHz using an ultrasonically absorbing waveguide. IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 61, 5, 765-778, 2014.
- Koukoulas, T, Rajagopal, S, Robinson, SP, Moss, B, Zeqiri, B and Theobald, PD. Primary ultrasonic interferometer photodiode characterisation using frequency modulated laser wavefront radiation. Metrologia, 50, 6, 572-579, 2013.
- Zeqiri, B, Baker, C, Alosa, G, Wells, PNT and Hai-Dong Liang. Quantitative ultrasonic computed tomography using phase-sensitive pyroelectric detectors. Physics in Medicine and Biology, 58, 15, 5237- 5268, 2013.©