Gail Haar

The Institute of Cancer Research, Joint Department of Physics, Faculty Member

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Papers by Gail Haar

Safety Issues for HIFU Transducer Design

AIP Conference Proceedings, 2005

Safe use of Doppler ultrasound during the 11 to 13+ 6‐week scan: is it possible?

Ultrasound has an excellent safety record. It has been used in obstetrics for five decades with n... more Ultrasound has an excellent safety record. It has been used in obstetrics for five decades with no proven harmful effects. In this issue of the Journal, two new studies address ultrasound safety. Pellicer et al.1 present a study indicating that Doppler ultrasound exposure of the ductus venosus of embryonic rats can lead to increased apoptotic activity in fetal liver tissue, while Heikkilä et al.2 present new data regarding ultrasound and handedness. Pellicer et al.1 used an ultrasound device at low intensity with exposure times from 3 s to 10 min. A linear relationship between apoptotic activity and pulsed Doppler scanning time was found: the longer the exposure time, the more liver cell damage was observed. Of course, it is difficult to extrapolate the results of this animal model to humans. There are also questions about whether it matters that apoptotic activity in the fetal liver is raised transiently, and there is some difficulty in explaining the mechanisms of damage (whether due to thermal or nonthermal effects). There are, however, two other recent animal studies which have demonstrated a relationship between length of exposure to Doppler ultrasound and potentially irreversible biological effects3,4. In many countries today, more than 70% of all pregnancies undergo nuchal translucency screening at 11 to 13 + 6 weeks. From an ultrasound safety perspective, this is not problematic as long as it is performed with low-intensity B-mode ultrasound by properly trained sonographers or sonologists. However, recent research has advocated Doppler measurement of the cardiac and infracardiac regions of the 11 to 13 + 6-week fetus5,6. Since Doppler usually generates higher intensity outputs than does B-mode ultrasound, the question of safety must be considered. Also in this issue of the Journal, there is a new ISUOG (International Society of Ultrasound in Obstetrics and Gynecology) statement on the use of Doppler ultrasound at 11 to 13 + 6 weeks7, and this Opinion discusses some of the issues raised.

Ultrasonic Biophysics

Hill/Physical Principles of Medical Ultrasonics, Second Edition, 2004

Do We Need to Restrict the Use of Doppler Ultrasound in the First Trimester of Pregnancy?

Ultrasound in Medicine & Biology, 2013

A Pilot Study Investigating the Potential of High-Intensity Focused Ultrasound to Treat Tumours Rapidly

AIP Conference Proceedings, 2007

The aim of this project was to investigate the possibility of rapid tumour destruction by a novel... more The aim of this project was to investigate the possibility of rapid tumour destruction by a novel method of treating the periphery of a tumour and inducing ischemia by impeding the blood supply. Ex vivo experiments were initially carried out in bovine liver to determine the optimum conditions for focal depth, gantry transducer speed circle diameter and intensity of the ultrasound beam. In vivo experiments were then performed in PGV rat livers implanted with a HSN fibrosarcoma cell line. The tumours were treated by novel technique of creating an annular lesion around the perimeter of the tumour. Macroscopic and microscopic examination of the lesion at post mortem was performed. In addition histological examination of the untreated tumour which was within the annular circle of treatment was examined. This showed evidence of karyolytic nuclei a week after treatment suggesting death by infarction within this area. There was also some evidence of endothelial damage in the blood vessels with fragmented nuclei visible in the lumen. The work presented here adds to our understanding of how high intensity focused ultrasound may be used to treat tumours in as faster and more efficient way. Further work in this area will facilitate the design of future therapeutic interventions in the medical and veterinary world.

Numerical Modelling of High Intensity Focused Ultrasound Phased Arrays by an Angular Spectrum Decomposition using Highly-Oscillatory Quadrature

AIP Conference Proceedings, 2007

The angular spectrum decomposition technique has been adapted to enable modelling of a ten-elemen... more The angular spectrum decomposition technique has been adapted to enable modelling of a ten-element focused array used in our laboratory. In order to solve the integral representation of our transducer array, we have applied a quadrature method which is both efficient and accurate for the evaluation of integrals which feature highly-oscillatory behaviour. This approach is not limited by a requirement for transducer variables (such as amplitude, frequency and phase) to remain constant. We present a comparison between experimental and theoretical results for a ten-element array transducer.

Preliminary Experience Using Extracorporeal High‐Intensity Focused Ultrasound For The Treatment Of Kidney And Liver Tumours

by Andrew Protheroe and Gail Haar

AIP Conference …, 2005

Preliminary Experience Using Extracorporeal High‐Intensity Focused Ultrasound For The Treatment O... more

Spatial Control of Microbubble‐Mediated Non‐Viral Gene Delivery Using Focused Ultrasound

by Nigel Bush and Gail Haar

AIP Conference …, 2007

Spatial Control of Microbubble‐Mediated Non‐Viral Gene Delivery Using Focused Ultrasound. [AIP Co... more

High Intensity Focused Ultrasound (HIFU) as a Salvage Treatment for Recurrent Prostate Cancer after Brachytherapy — a Feasibility Study

AIP Conference Proceedings, 2007

HIFU may be an effective salvage treatment for patients who develop local recurrence after perman... more HIFU may be an effective salvage treatment for patients who develop local recurrence after permanent low-dose brachytherapy. It has been suggested that the presence of seeds in the prostate may obstruct the HIFU beam or alter the heating characteristics of the prostate tissue. Acoustic field measurements were made using a membrane hydrophone and lesioning experiments were carried out in ex

A Study of Cavitation Activity in Ex vivo Tissue Exposed to High Intensity Focused Ultrasound

AIP Conference Proceedings, 2007

Cavitation is often avoided in Focused Ultrasound Surgery (FUS or HIFU) because it can render les... more Cavitation is often avoided in Focused Ultrasound Surgery (FUS or HIFU) because it can render lesion formation unpredictable. However, cavitation is known to enhance heating. Emissions used as indicators for cavitation activity in ex vivo tissue are not fully understood. This study investigates a wide range of simultaneous acoustic emissions and other potential indicators of cavitation activity. A high frequency (<=50MHz) data acquisition system is used to detect cavitation ex vivo. The passive cavitation detector (PCD) used is a broadband (0.1-10MHz) cavitation sensor. Its broadband nature allows simultaneous measurement of subharmonics, superharmonics and broadband emissions, all potential indicators of either inertial or both types of cavitation. The electrical impedance change of the transducer (1.69MHz, 15cm focal length, 1.79f-number), caused by backscattered ultrasound, has been monitored. Low frequency acoustic signals (<100kHz) have been recorded using a hydrophone (Reson TC4013, 1Hz-170kHz). The ultimate aim of this work is to investigate the possibility of detecting cavitation signals from HIFU during clinical treatments. Results of monitoring multiple cavitation signals during ex vivo HIFU exposure are presented. The relationship between impedance change and superharmonic emissions, indicating discrete acoustic emissions or scattering of ultrasound from bubbles, are discussed. Artefacts in B-mode ultrasound scans taken during HIFU exposures have been seen to correlate with impedance change and acoustic emissions. This is still under investigation. Cavitation thresholds in degassed water and ex vivo tissue have been investigated. This work paves the way for investigation of the enhancement of lesion formation from HIFU exposures by exploiting cavitation activity.

Biological Effects of Ultrasound. Clinics in Diagnostic Ultrasound 16

Int J Radiat Biol, 1985

Ultrasound in physiotherapy in the United Kingdom: Results of a questionnaire

Physiotherapy Theory and Practice, 1988

In 1985, questionnaires were distributed to physiotherapists in the UK, asking for informa-tion a... more

Standardization of ultrasound exposure reporting for bio-effects and safety studies

Ultrasound, Feb 1, 2010

Safety issues for HIFU transducer design

by Jean Chapelon, Gail Haar, G. Fleury, and Olivier Le Baron

In contrast with most ultrasound modalities for medical applications, (especially ultrasound imag... more In contrast with most ultrasound modalities for medical applications, (especially ultrasound imaging), High Intensity Focused Ultrasound (HIFU) involves technologies and procedures which may present risk to the patient. These risks, resulting from the high power levels required for effective therapy, should be taken into account at the earliest stages in the design of a system dedicated to HIFU treatment. An understanding of these risks must thus be shared amongst the many players in the field of therapy using high power ultrasound. Moreover, since the number of applications of HIFU has increased appreciably over recent years and the technology is ready to move from the research to the industrial level, it is worth now considering solutions that should be put in place to guarantee the safety of the patient during HIFU treatment. This paper reports thoughts on this, and identifies some risks to the patient that must be taken into consideration in the design of HIFU transducers, and p...

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Turning up the Power: High Intensity Focused Ultrasound (HIFU) for the Treatment of Cancer

Ultrasound, 2007

Cavitation Detection in Ex Vivo Bovine Liver Tissue Exposed to High Intensity Focued Ultrasound (Hifu)

2007 4th IEEE International Symposium on Biomedical Imaging: From Nano to Macro, 2007

A study of the feasibility of detecting broadband high frequency emissions (6-12 MHz) generated b... more A study of the feasibility of detecting broadband high frequency emissions (6-12 MHz) generated by acoustic cavitation activity during clinical high intensity focused ultrasound (HIFU) exposures are presented. The ability to monitor acoustic emissions, drive power fluctuations and audible (1-20 kHz) emissions is demonstrated in ex vivo tissue, and the utility of active cavitation detection (ACD) is shown. It is

Cavitation characteristics in High Intensity Focused Ultrasound lesions

The Journal of the Acoustical Society of America, 2014

A study of thermal dose-induced autophagy, apoptosis and necroptosis in colon cancer cells

International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group, Jan 14, 2015

The pleiotropic effects of heat on cancer cells have been well documented. The biological effects... more The pleiotropic effects of heat on cancer cells have been well documented. The biological effects seen depend on the temperature applied, and the heating duration. In this study we investigate the cytotoxic effects of heat on colon cancer cells and determine how different cell death processes such as autophagy, apoptosis and necroptosis play a role in cell response. The thermal dose concept was used to provide a parameter that will allow comparison of different thermal treatments. Two human colon cancer cell lines, HCT116 and HT29, were subjected to ablative temperatures using a polymerase chain reaction thermal cycler. Temperature was recorded using thermocouples. Cell viability was assessed using the MTT assay. Induction of apoptosis was estimated using an enzyme-linked immunosorbent assay that detects cleaved cytoplasmic nucleosomes. Protein regulation was determined using immunoblotting. The percentage of cells undergoing apoptosis and autophagy was determined with annexin V/pro...

BMUS Safety Committee

Ultrasound, 2007

Recent Advances and Techniques in Therapeutic Ultrasound

Ultrasound, 1987

Safety Issues for HIFU Transducer Design

AIP Conference Proceedings, 2005

Safe use of Doppler ultrasound during the 11 to 13+ 6‐week scan: is it possible?

Ultrasonic Biophysics

Hill/Physical Principles of Medical Ultrasonics, Second Edition, 2004

Do We Need to Restrict the Use of Doppler Ultrasound in the First Trimester of Pregnancy?

Ultrasound in Medicine & Biology, 2013

A Pilot Study Investigating the Potential of High-Intensity Focused Ultrasound to Treat Tumours Rapidly

AIP Conference Proceedings, 2007

Numerical Modelling of High Intensity Focused Ultrasound Phased Arrays by an Angular Spectrum Decomposition using Highly-Oscillatory Quadrature

AIP Conference Proceedings, 2007

Preliminary Experience Using Extracorporeal High‐Intensity Focused Ultrasound For The Treatment Of Kidney And Liver Tumours

by Andrew Protheroe and Gail Haar

AIP Conference …, 2005

Preliminary Experience Using Extracorporeal High‐Intensity Focused Ultrasound For The Treatment O... more

Spatial Control of Microbubble‐Mediated Non‐Viral Gene Delivery Using Focused Ultrasound

by Nigel Bush and Gail Haar

AIP Conference …, 2007

Spatial Control of Microbubble‐Mediated Non‐Viral Gene Delivery Using Focused Ultrasound. [AIP Co... more

High Intensity Focused Ultrasound (HIFU) as a Salvage Treatment for Recurrent Prostate Cancer after Brachytherapy — a Feasibility Study

AIP Conference Proceedings, 2007

A Study of Cavitation Activity in Ex vivo Tissue Exposed to High Intensity Focused Ultrasound

AIP Conference Proceedings, 2007

Biological Effects of Ultrasound. Clinics in Diagnostic Ultrasound 16

Int J Radiat Biol, 1985

Ultrasound in physiotherapy in the United Kingdom: Results of a questionnaire

Physiotherapy Theory and Practice, 1988

In 1985, questionnaires were distributed to physiotherapists in the UK, asking for informa-tion a... more

Standardization of ultrasound exposure reporting for bio-effects and safety studies

Ultrasound, Feb 1, 2010

Safety issues for HIFU transducer design

by Jean Chapelon, Gail Haar, G. Fleury, and Olivier Le Baron

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Turning up the Power: High Intensity Focused Ultrasound (HIFU) for the Treatment of Cancer

Ultrasound, 2007

Cavitation Detection in Ex Vivo Bovine Liver Tissue Exposed to High Intensity Focued Ultrasound (Hifu)

2007 4th IEEE International Symposium on Biomedical Imaging: From Nano to Macro, 2007

Cavitation characteristics in High Intensity Focused Ultrasound lesions

The Journal of the Acoustical Society of America, 2014

A study of thermal dose-induced autophagy, apoptosis and necroptosis in colon cancer cells

International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group, Jan 14, 2015

BMUS Safety Committee

Ultrasound, 2007

Recent Advances and Techniques in Therapeutic Ultrasound

Ultrasound, 1987

Gail Haar

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