Studies of the cavitational effects of clinical ultrasound by sonoluminescence: 1. Correlation of sonoluminescence with the standing wave pattern in an acoustic field produced by a therapeutic unit

A Therasonic 1030 (Electro-Medical Supplies) therapeutic ultrasound generator operating at 1 MHz continuous wave was used to insonate aerated water at two temperatures, 22 C and 37 C. Using various acoustically reflecting materials, sound fields were set up with different standing wave components. Measurements of the acoustic pressure variations on the axis of the sound fields were made using a needle hydrophone and the results were compared with photographs of the spatial distributions of the image intensified sonoluminescent light output. The near field region was used, thereby simulating the clinical situation.Sustained sonoluminescence was observed for nominal intensities of 3 W cm-2, and acoustic reflections of greater than 40%. Under these conditions, if sonoluminescence did not appear spontaneously it could always be induced by rotating the transducer. Whenever bands of maximum light output formed they correlated closely with the pressure antinodes in the standing wave pattern. Very little light was produced by travelling wave fields

Studies of the cavitational effects of clinical ultrasound by sonoluminescence: 4. The effect of therapeutic ultrasound on cells in monolayer culture in a standing wave field

In previous work the phenomenon of sonoluminescence (SL) has been used to find the conditions in which transient cavitation during exposure to ultrasound is likely to be maximum. This paper reports the effect of therapeutic ultrasound on growth of mouse tumour cells in monolayer culture when the cells are insonated either at a pressure antinode or at a pressure node in a standing wave ultrasound field that is known to produce strong bands of SL at the pressure antinodes. Reduced cell numbers 72 h after insonation were recorded when the cells were insonated at an antinode but not when they were at a node. The possibility that this effect might be an artefact of the experimental system, and further experiments that could elucidate the nature of the damage, are discusse

Studies of the cavitational effects of clinical ultrasound by sonoluminescence: 5. Search for sonoluminescence in vivo in the human cheek

In a previous experiment, sonoluminescence was observed in aerated water, especially at the pressure anti nodes in the standing-wave field of a physiotherapeutic ultrasound device (Therasonic 1030). Mammalian cells in vitro showed growth inhibition when placed at the pressure antinodes but not at adjacent pressure nodes. In the light of these results, we looked for sonoluminescence in vivo when a similar standing-wave field was set up. To detect luminescence, a light guide was held against the inner surface of the human cheek. This would channel any luminescence photons to a cooled, red sensitive photomultiplier which would quantify the light. Direct insonation of the cheek produced no detectable luminescence. Similarly when a water bag was placed against the outer surface of the cheek, and the latter was insonated through the bag, no luminescence was detected. Sonoluminescence from the water bag was, however, detected when the bag was placed against the inner surface of the cheek, showing that absorption of sound by the cheek tissue was not preventing cavitation. Further analysis showed that if cavitation had been occurring in the cheek without detection using the system employed, then the resulting sonoluminescence would have to be at most 0.025 times as intense as that produced by an equivalent volume of aerated wate

Studies of the cavitational effects of clinical ultrasound by sonoluminescence: 2. Thresholds for sonoluminescence from a therapeutic ultrasound beam and the effect of temperature and duty cycle

Sonoluminescence, produced when a therapeutic ultrasound generator operating at 1 MHz was used to insonate a tank of water, was detected using a photomultiplier tube and analysed using pulse height analysis. Spectra of the number of counts per second were obtained for the complete range of observed pulse heights, under exposure conditions similar to those used in clinical practice. Water containing different concentrations of dissolved gases and an agar solution were investigated during the course of the experiments. Measurements were made to establish a threshold for sonoluminescence and the total sonoluminescent light output from tap water insonated with continuous wave ultrasound at 1 W cm-2 was estimated. The density of free radicals produced under these conditions was also estimated. The effects of temperature and duty cycle were investigated.Sonoluminescence increased with temperature over the range 22-45 ºC and pulsed regimens produced more sonoluminescence than continuous wave ultrasound over a significant part of the pulse height spectrum

Studies of the cavitational effects of clinical ultrasound by sonoluminescence: 3. Cavitation from pulses a few microseconds in length

Sonoluminescence can readily be seen when aerated water is insonated with continuous wave therapeutic ultrasound at room temperature but is not easily observed when short pulses of diagnostic ultrasound are used. In this work an ultrasound generator, operating in the region of 1 MHz and capable of producing pulses of different length and repetition rate, was used for insonation. The pulse repetition rate of the ultrasound was fixed at 1 kHz since this is characteristic of diagnostic machines, and a series of thresholds for sonoluminescence as obtained for two transducers, one therapeutic and one diagnostic, as the number of cycles in each pulse was varied. Sonoluminescence was observed for pulses of a few cycles, but the ultrasound intensity threshold for onset increased sharply with decreasing pulse length. Under all conditions tested, sonoluminescence was more readily sustained than initiated. At about 20 cycles per pulse, peak negative pressures of about 400 kPa initiated sonoluminescence. These conditions are well within the range of some regimens for Doppler ultrasound and not far removed from the diagnostic situation

The role of the biomedical physicist in the education of the healthcare professions: An EFOMP project

The role of the biomedical physicist in the education of the healthcare professions has not yet been studied in a systematic manner. This article presents the first results of an EFOMP project aimed at researching and developing this important component of the role of the biomedical physicist. A background to the study expands on the reasons that led to the need for the project. This is followed by an extensive review of the published literature regarding the role. This focuses mainly on the teaching contributions within programmes for physicians, diagnostic radiographers, radiation therapists, and the postgraduate medical specializations of radiology, radiotherapy, interventional radiology and cardiology. Finally a summary list of the specific research objectives that need to be immediately addressed is presented. These are the carrying out of a Europe-wide position audit for the role, the construction of a strategic role development model and the design of a curriculum development model suitable for modern healthcare professional education. © 2008 Associazione Italiana di Fisica Medica

A comprehensive SWOT audit of the role of the biomedical physicist in the education of healthcare professionals in Europe

Although biomedical physicists provide educational services to the healthcare professions in the majority of universities in Europe, their precise role with respect to the education of the healthcare professions has not been studied systematically. To address this issue we are conducting a research project to produce a strategic development model for the role using the well-established SWOT (Strengths, Weaknesses, Opportunities, Threats) methodology. SWOT based strategic planning is a two-step process: one first carries out a SWOT position audit and then uses the identified SWOT themes to construct the strategic development model. This paper reports the results of a SWOT audit for the role of the biomedical physicist in the education of the healthcare professions in Europe. Internal Strengths and Weaknesses of the role were identified through a qualitative survey of biomedical physics departments and biomedical physics curricula delivered to healthcare professionals across Europe. External environmental Opportunities and Threats were identified through a systematic survey of the healthcare, healthcare professional education and higher education literature and categorized under standard PEST (Political, Economic, Social-Psychological, Technological-Scientific) categories. The paper includes an appendix of terminology. Defined terms are marked with an asterisk in the text. © 2009 Associazione Italiana di Fisica Medica