The effect of extent of local resection on patterns of disease progression in malignant pleural mesothelioma

Background We sought to determine whether or not there are differences in disease progression after radical or nonradical (debulking) surgical procedures for malignant pleural mesothelioma. Methods Over a 49-month period, 132 patients with malignant pleural mesothelioma underwent surgery. Fifty-three underwent extrapleural pneumonectomy and 79 underwent nonradical procedures. Time to evidence of clinical disease progression was recorded, as was the site(s) of that disease. Results One-hundred nineteen patients were evaluable, of which 59% (22 radical; 48 nonradical) had disease progression. Overall 30-day mortality was 8.5% (7.5% radical; 9% nonradical). The median time to overall disease progression was considerably longer after extrapleural pneumonectomy than debulking surgery (319 days vs 197 days, p = 0.019), as was the time to local disease progression (631 days vs 218 days, p = 0.0018). There was no preponderance of earlier stage disease in the radical surgery group. There was a trend toward prolonged survival in those undergoing radical surgery, but no significant difference between the groups (497 days vs 324 days, p = 0.079). In those who had extrapleural pneumonectomy, time-to-disease progression significantly decreased with N2 disease compared with N0/1 involvement (197 days vs 358 days, p = 0.02). Conclusions Extrapleural pneumonectomy may be preferable to debulking surgery in malignant pleural mesothelioma to delay disease progression and give greater control of local disease. Involvement of N2 nodes is associated with accelerated disease progression and is therefore a contraindication to extrapleural pneumonectomy. © 2004 by The Society of Thoracic Surgeons.

Non-alcoholic fatty liver disease : can ultrasound assist in early diagnosis of prediabetes and delay progression to type2 diabetes mellitus

Non Alcoholic Fatty Liver Disease (NAFLD) is a condition that is frequently seen but seldom investigated. Until recently, NAFLD was considered benign, self-limiting and unworthy of further investigation. This opinion is based on retrospective studies with relatively small numbers and scant follow-up of histology data. (1) The prevalence for adults, in the USA is, 30%, and NAFLD is recognized as a common and increasing form of liver disease in the paediatric population (1). Australian data, from New South Wales, suggests the prevalence of NAFLD in “healthy” 15 year olds as being 10%.(2) Non-alcoholic fatty liver disease is a condition where fat progressively invades the liver parenchyma. The degree of infiltration ranges from simple steatosis (fat only) to steatohepatitis (fat and inflammation) steatohepatitis plus fibrosis (fat, inflammation and fibrosis) to cirrhosis (replacement of liver texture by scarred, fibrotic and non functioning tissue).Non-alcoholic fatty liver is diagnosed by exclusion rather than inclusion. None of the currently available diagnostic techniques -liver biopsy, liver function tests (LFT) or Imaging; ultrasound, Computerised tomography (CT) or Magnetic Resonance Imaging (MRI) are specific for non-alcoholic fatty liver. An association exists between NAFLD, Non Alcoholic Steatosis Hepatitis (NASH) and irreversible liver damage, cirrhosis and hepatoma. However, a more pervasive aspect of NAFLD is the association with Metabolic Syndrome. This Syndrome is categorised by increased insulin resistance (IR) and NAFLD is thought to be the hepatic representation. Those with NAFLD have an increased risk of death (3) and it is an independent predictor of atherosclerosis and cardiovascular disease (1). Liver biopsy is considered the gold standard for diagnosis, (4), and grading and staging, of non-alcoholic fatty liver disease. Fatty-liver is diagnosed when there is macrovesicular steatosis with displacement of the nucleus to the edge of the cell and at least 5% of the hepatocytes are seen to contain fat (4).Steatosis represents fat accumulation in liver tissue without inflammation. However, it is only called non-alcoholic fatty liver disease when alcohol - >20gms-30gms per day (5), has been excluded from the diet. Both non-alcoholic and alcoholic fatty liver are identical on histology. (4).LFT’s are indicative, not diagnostic. They indicate that a condition may be present but they are unable to diagnosis what the condition is. When a patient presents with raised fasting blood glucose, low HDL (high density lipoprotein), and elevated fasting triacylglycerols they are likely to have NAFLD. (6) Of the imaging techniques MRI is the least variable and the most reproducible. With CT scanning liver fat content can be semi quantitatively estimated. With increasing hepatic steatosis, liver attenuation values decrease by 1.6 Hounsfield units for every milligram of triglyceride deposited per gram of liver tissue (7). Ultrasound permits early detection of fatty liver, often in the preclinical stages before symptoms are present and serum alterations occur. Earlier, accurate reporting of this condition will allow appropriate intervention resulting in better patient health outcomes. References 1. Chalasami N. Does fat alone cause significant liver disease: It remains unclear whether simple steatosis is truly benign. American Gastroenterological Association Perspectives, February/March 2008 www.gastro.org/wmspage.cfm?parm1=5097 Viewed 20th October, 2008 2. Booth, M. George, J.Denney-Wilson, E: The population prevalence of adverse concentrations with adiposity of liver tests among Australian adolescents. Journal of Paediatrics and Child Health.2008 November 3. Catalano, D, Trovato, GM, Martines, GF, Randazzo, M, Tonzuso, A. Bright liver, body composition and insulin resistance changes with nutritional intervention: a follow-up study .Liver Int.2008; February 1280-9 4. Choudhury, J, Sanysl, A. Clinical aspects of Fatty Liver Disease. Semin in Liver Dis. 2004:24 (4):349-62 5. Dionysus Study Group. Drinking factors as cofactors of risk for alcohol induced liver change. Gut. 1997; 41 845-50 6. Preiss, D, Sattar, N. Non-alcoholic fatty liver disease: an overview of prevalence, diagnosis, pathogenesis and treatment considerations. Clin Sci.2008; 115 141-50 7. American Gastroenterological Association. Technical review on nonalcoholic fatty liver disease. Gastroenterology.2002; 123: 1705-25

The “Iranian ART Revolution”: infertility, assisted reproductive technology, and third-party donation in the Islamic Republic of Iran

Infertility is a social onus for women in Iran, who are expected to produce children early within marriage. With its estimated 1.5 million infertile couples, Iran is the only Muslim country in which assisted reproductive technologies (ARTs) using donor gametes and embryos have been legitimized by religious authorities and passed into law. Th is has placed Iran, a Shia-dominant country, in a unique position vis-à-vis the Sunni Islamic world, where all forms of gamete donation are strictly prohibited. In this article, we first examine the “Iranian ART revolution” that has allowed donor technologies to be admitted as a form of assisted reproduction. Then we examine the response of Iranian women to their infertility and the profound social pressures they face. We argue that the experience of infertility and its treatment are mediated by women’s socioeconomic position within Iranian society. Many women lack economic access to in vitro fertilization (IVF) technologies and fear the moral consequences of gamete donation. Thus, the benefits of the Iranian ART revolution are mixed: although many Iranian women have been able to overcome their infertility through ARTs, not all women’s lives are improved by these technologies.

Computed tomography analysis of sagittal plane parameters in adolescent idiopathic scoliosis treated by video assisted thoracoscopic spinal fusion and instrumentation

One of the primary treatment goals of adolescent idiopathic scoliosis (AIS) surgery is to achieve maximum coronal plane correction while maintaining coronal balance. However maintaining or restoring sagittal plane spinal curvature has become increasingly important in maintaining the long-term health of the spine. Patients with AIS are characterised by pre-operative thoracic hypokyphosis, and it is generally agreed that operative treatment of thoracic idiopathic scoliosis should aim to restore thoracic kyphosis to normal values while maintaining lumbar lordosis and good overall sagittal balance. The aim of this study was to evaluate CT sagittal plane parameters, with particular emphasis on thoracolumbar junctional alignment, in patients with AIS who underwent Video Assisted Thoracoscopic Spinal Fusion and Instrumentation (VATS). This study concluded that video-assisted thoracoscopic spinal fusion and instrumentation reliably increases thoracic kyphosis while preserving junctional alignment and lumbar lordosis in thoracic AIS.

Impaired drivers : The need to yoke treatment and sanctions

Objective: To understand the levels of substance abuse and dependence among impaired drivers by comparing the differences in patients in substance abuse treatment programs with and without a past-year DUI arrest based on their primary problem substance at admission (alcohol, cocaine, cannabis, or methamphetamine). Method: Records on 345,067 admissions to Texas treatment programs between 2005 and 2008 have been analyzed for differences in demographic characteristics, levels of severity, and mental health problems at admission, treatment completion, and 90-day follow-up. Methods will include t-tests,??, and multivariate logistic regression. Results: The analysis found that DUI arrestees with a primary problem with alcohol were less impaired than non-DUI alcohol patients, had fewer mental health problems, and were more likely to complete treatment. DUI arrestees with a primary problem with cannabis were more impaired than non-DUI cannabis patients and there was no difference in treatment completion. DUI arrestees with a primary problem with cocaine were less impaired and more likely to complete treatment than other cocaine patients, and there was little difference in levels of mental health problems. DUI arrestees with a primary problem with methamphetamine were more similar to methamphetamine non-arrestees, with no difference in mental health problems and treatment completion. Conclusions: This study provides evidence of the extent of abuse and dependence among DUI arrestees and their need for treatment for their alcohol and drug problems in order to decrease recidivism. Treatment patients with past-year DUI arrests had good treatment outcomes but closer supervision during 90 day follow-up after treatment can lead to even better long-term outcomes, including reduced recidivism. Information will be provided on the latest treatment methodologies, including medication assisted therapies and screening and brief interventions, and ways impaired driving programs and substance dependence programs can be integrated to benefit the driver and society.

The role of assisted self-help in services for alcohol-related disorders

Potentially harmful substance use is common, but many affected people do not receive treatment. Brief face-to-face treatments show impact, as do strategies to assist self-help remotely, by using bibliotherapies, computers or mobile phones. Remotely delivered treatments offer more sustained and multifaceted support than brief interventions, and they show a substantial cost advantage as users increase in number. They may also build skills, confidence and treatment fidelity in providers who use them in sessions. Engagement and retention remain challenges, but electronic treatments show promise in engaging younger populations. Recruitment may be assisted by integration with community campaigns or brief opportunistic interventions. However, routine use of assisted self-help by standard services faces significant challenges. Strategies to optimize adoption are discussed. ----- ----- Research Highlights: ► Many people with risky or problematic drinking do not currently receive treatment. ► Assisted self-help has a significant impact and can be delivered at low cost. ► Maximal effects from assisted self-help require engagement of potential users. ► Marketing campaigns and integration into existing service models may assist.

Ureaplasma parvum and ureaplasma urealyticum detected in semen after washing prior to assisted reproductive technology procedures

Objective: This study investigated: (i) the prevalence of ureaplasmas in semen and washed semen and (ii) the effect of ureaplasmas on semen andrology parameters. Design: Prospective study. Setting: IVF unit -private hospital, Brisbane, Australia. Patient(s): Three hundred and forty three men participating in an assisted reproductive technology (ART) treatment cycle. Intervention(s): Semen and washed semen tested by culture, PCR assays and indirect immunofluorescent antibody assays. Statistical differences were determined by a t-test, Wilcoxon or Pearson’s Chi- square test where appropriate. Main Outcome Measure(s): The prevalence of ureaplasmas in semen and washed semen and the effect of these microorganisms on semen andrology parameters. Result(s): Ureaplasmas were detected in 73/343 (22%) semen samples and 29/343 (8.5%) washed semen samples. Ureaplasmas adherent to the surface of spermatozoa were demonstrated by indirect immunofluorescent antibody testing. U. parvum serovar 6 (36.6%) and U. urealyticum (30%) were the most prevalent isolates in washed semen. A comparison of the semen andrology parameters of washed semen ureaplasma positive and negative groups demonstrated a lower proportion of non-motile sperm in the washed semen ureaplasma positive group. Conclusion(s): Ureaplasmas are not always removed from semen by a standard ART washing procedure and can remain adherent to the surface of spermatozoa.

Regulating assisted reproductive technologies in Victoria : the impact of changing policy concerning the accessibility of in vitro fertilisation for preimplantation tissue-typing

On 1 January 2010, the Assisted Reproductive Treatment Act 2008 (Vic) came into force. The legislation was the outcome of a detailed review and consultation process undertaken by the Victorian Law Reform Commission. Arguably, the change to the regulatory framework represents a significant shift in policy compared to previous regulatory approaches on this topic in Victoria. This article considers the impact of the new legislation on eligibility for reproductive treatments, focusing on the accessibility of such services for the purpose of creating a “saviour sibling”. It also highlights the impact of the Victorian regulatory body’s decision to abolish its regulatory policies on preimplantation genetic diagnosis and preimplantation tissue-typing, concluding that the regulatory approach in relation to these latter issues is similar to other Australian jurisdictions where such practices are not addressed by a statutory framework.

Infertility in Australia circa 1980 : an historical population perspective on the uptake of fertility treatment by Australian women born in 1946-51

Objective: To estimate the prevalence of lifetime infertility in Australian women born in 1946-51 and examine their uptake of treatment. Methods: Participants in the Australian Longitudinal Study on Women's Health born in 1946-51 (n=13,715) completed up to four mailed surveys from 1996 to 2004. The odds of infertility were estimated using logistic regression with adjustment for socio-demographic and reproductive factors. Results: Among participants, 92.1% had been pregnant. For women who had been pregnant (n=12738): 56.5% had at least one birth but no pregnancy loss (miscarriage and/or termination); 39.9% experienced both birth and loss; and 3.6% had a loss only. The lifetime prevalence of infertility was 11.0%. Among women who reported infertility (n=1511), 41.7% used treatment. Women had higher odds of infertility when they had reproductive histories of losses only (OR range 9.0-43.5) or had never been pregnant (OR=15.7, 95%CI 11.8-20.8); and higher odds for treatment: losses only (OR range 2.5-9.8); or never pregnant (1.96, 1.28-3.00). Women who delayed their first birth until aged 30+ years had higher odds of treatment (OR range 3.2-4.3). Conclusions: About one in ten women experienced infertility and almost half used some form of treatment, especially those attempting pregnancy after 1980. Older first time mothers had an increased uptake of treatment as assisted reproductive technologies (ART) developed. Implications: This study provided evidence of the early uptake of treatment prior to 1979 when the national register of invasive ART was developed and later uptake prior to 1998 when data on non-invasive ART were first collected.

Birth outcomes after spontaneous or assisted conception among infertile Australian women aged 28 to 36 years: A prospective, population-based study

Objective To examine the extent to which the odds of birth, pregnancy, or adverse birth outcomes are higher among women aged 28 to 36 years who use fertility treatment compared with untreated women. Design Prospective, population-based. Setting Not applicable. Patient(s) Participants in the ALSWH born in 1973 to 1978 who reported on their infertility and use of in vitro fertilization (IVF) or ovulation induction (OI). Intervention(s) Postal survey questionnaires administered as part of ALSWH. Main Outcome Measure(s) Among women treated with IVF or OI and untreated women, the odds of birth outcomes estimated by use of adjusted logistic regression modeling. Result(s) Among 7,280 women, 18.6% (n = 1,376) reported infertility. Half (53.0%) of the treated women gave birth compared with 43.8% of untreated women. Women with prior parity were less likely to use IVF compared with nulliparous women. Women using IVF or OI, respectively, were more likely to have given birth after treatment or be pregnant compared with untreated women. Women using IVF or OI were as likely to have ectopic pregnancies, stillbirths, or premature or low birthweight babies as untreated women. Conclusion(s) More than 40% of women aged 28–36 years reporting a history of infertility can achieve births without using treatment, indicating they are subfertile rather than infertile.

How should Australia regulate voluntary euthanasia and assisted suicide?

The purpose of this paper is to provide a basis from which to start an informed and rational dialogue in Australia about voluntary euthanasia (VE) and assisted suicide (AS). It does this by seeking to chart the broad landscape of issues that can be raised as relevant to how this conduct should be regulated by the law. It is not our purpose to persuade. Rather, we have attempted to address the issues as neutrally as possible and to canvass both sides of the argument in an even-handed manner. We hope that this exercise places the reader in a position to consider the question posed by this paper: How should Australia regulate voluntary euthanasia and assisted suicide? In line with the approach taken in the paper, this question does not take sides in the debate. It simply asks how VE and AS should be regulated, acknowledging that both prohibition and legalisation of such conduct involve regulation. We begin by considering the wider legal framework that governs end of life decision-making. Decisions to withhold or withdraw life-sustaining treatment that result in a person’s death can be lawful. This could be because, for example, a competent adult refuses such treatment. Alternatively, stopping or not providing treatment can be lawful when it is no longer in a person’s best interests to receive it. The law also recognises that appropriate palliative care should not attract criminal responsibility. By contrast, VE and AS are unlawful in Australia and could lead to prosecution for crimes such as murder, manslaughter or aiding and abetting suicide. But this is not to say that such conduct does not occur in practice. Indeed, there is a body of evidence that VE and AS occur in Australia, despite them being unlawful. There have been repeated efforts to change the law in this country, mainly by the minor political parties. However, apart from a brief period when VE and AS was lawful in the Northern Territory, these attempts to reform the law have been unsuccessful. The position is different in a small but increasing number of jurisdictions overseas where such conduct is lawful. The most well known is the Netherlands but there are also statutory regimes that regulate VE and/or AS in Belgium and Luxembourg in Europe, and Oregon and Washington in the United States. A feature of these legislative models is that they incorporate review or oversight processes that enable the collection of data about how the law is being used. As a result, there is a significant body of evidence that is available for consideration to assess the operation of the law in these jurisdictions and some of this is considered briefly here. Assisting a suicide, if done for selfless motives, is also legal in Switzerland, and this has resulted in what has been referred to as ‘euthanasia tourism’. This model is also considered. The paper also identifies the major arguments in favour of, and against, legalisation of VE and AS. Arguments often advanced in favour of law reform include respect for autonomy, that public opinion favours reform, and that the current law is incoherent and discriminatory. Key arguments against legalising VE and AS point to the sanctity of life, concerns about the adequacy and effectiveness of safeguards, and a ‘slippery slope’ that will allow euthanasia to occur for minors or for adults where it is not voluntary. We have also attempted to step beyond these well trodden and often rehearsed cases ‘for and against’. To this end, we have identified some ethical values that might span both sides of the debate and perhaps be the subject of wider consensus. We then outline a framework for considering the issue of how Australia should regulate VE and AS. We begin by asking whether such conduct should be criminal acts (as they presently are). If VE and AS should continue to attract criminal responsibility, the next step is to enquire whether the law should punish such conduct more or less than is presently the case, or whether the law should stay the same. If a change is favoured as to how the criminal law punishes VE and AS, options considered include sentencing reform, creating context-specific offences or developing prosecutorial guidelines for how the criminal justice system deals with these issues. If VE and AS should not be criminal acts, then questions arise as to how and when they should be permitted and regulated. Possible elements of any reform model include: ensuring decision-making is competent and voluntary; ascertaining a person’s eligibility to utilise the regime, for example, whether it depends on him or her having a terminal illness or experiencing pain and suffering; and setting out processes for how any decision must be made and evidenced. Options to bring about decriminalisation include challenging the validity of laws that make VE and AS unlawful, recognising a defence to criminal prosecution, or creating a statutory framework to regulate the practice. We conclude the paper where we started: with a call for rational and informed consideration of a difficult and sensitive issue. How should Australia regulate voluntary euthanasia and assisted suicide?

The right to choose an assisted death : time for legislation?

The legal framework that operates at the end of life in Australia needs to be reformed. • Voluntary euthanasia and assisted suicide are currently unlawful. • Both activities nevertheless occur not infrequently in Australia, in part because palliative care cannot relieve physical and psychological pain and suffering in all cases. • In this respect, the law is deficient. The law is also unfair because it doesn’t treat people equally. Some people can be helped to die on their own terms as a result of their knowledge and/or connections while some are able to hasten their death by the refusal of life-sustaining treatment. But others do not have access to the means for their life to end. • A very substantial majority of Australians have repeatedly expressed in public opinion polls their desire for law reform on these matters. Many are concerned at what they see is happening to their loved ones as they reach the end of their lives, and want the confidence that when their time comes they will be able to exercise choice in relation to assisted dying. • The most consistent reason advanced not to change the law is the need to protect the vulnerable. There is a concern that if the law allows voluntary euthanasia and assisted suicide for some people, it will be expanded and abused, including pressures being placed on highly dependent people and those with disabilities to agree to euthanasia. • But there is now a large body of experience in a number of international jurisdictions following the legalisation of voluntary euthanasia and/or assisted suicide. This shows that appropriate safeguards can be implemented to protect vulnerable people and prevent the abuse that opponents of assisted dying have feared. It reveals that assisted dying meets a real need among a small minority of people at the end of their lives. It also provides reassurance to people with terminal and incurable disease that they will not be left to suffer the indignities and discomfort of a nasty death. • Australia is an increasingly secular society. Strong opposition to assisted death by religious groups that is based on their belief in divine sanctity of all human life is not a justification for denying choice for those who do not share that belief. • It is now time for Australian legislators to respond to this concern and this experience by legislating to enhance the quality of death for those Australians who seek assisted dying.

Factors associated with suboptimal adherence to antiretroviral therapy in Viet Nam: A cross-sectional study using audio computer-assisted self-interview (ACASI)

Background: Optimal adherence to antiretroviral therapy (ART) is necessary for people living with HIV/AIDS (PLHIV). There have been relatively few systematic analyses of factors that promote or inhibit adherence to antiretroviral therapy among PLHIV in Asia. This study assessed ART adherence and examined factors associated with suboptimal adherence in northern Viet Nam. Methods: Data from 615 PLHIV on ART in two urban and three rural outpatient clinics were collected by medical record extraction and from patient interviews using audio computer-assisted self-interview (ACASI). Results: The prevalence of suboptimal adherence was estimated to be 24.9% via a visual analogue scale (VAS) of past-month dose-missing and 29.1% using a modified Adult AIDS Clinical Trial Group scale for on-time dose-taking in the past 4 days. Factors significantly associated with the more conservative VAS score were: depression (p < 0.001), side-effect experiences (p < 0.001), heavy alcohol use (p = 0.001), chance health locus of control (p = 0.003), low perceived quality of information from care providers (p = 0.04) and low social connectedness (p = 0.03). Illicit drug use alone was not significantly associated with suboptimal adherence, but interacted with heavy alcohol use to reduce adherence (p < 0.001). Conclusions: This is the largest survey of ART adherence yet reported from Asia and the first in a developing country to use the ACASI method in this context. The evidence strongly indicates that ART services in Viet Nam should include screening and treatment for depression, linkage with alcohol and/or drug dependence treatment, and counselling to address the belief that chance or luck determines health outcomes.

Lost in translation, found in translation : A case study of working psychodynamically in an interpreter-assisted setting

Effective use of psychotherapeutic treatment in interpreter-assisted settings is well established; however, there has been little discussion of the use of psychodynamically-informed treatments in such settings. The literature suggests that therapy facilitated by interpreters is not conducive to psychodynamic approaches due to the presence of a third person, the perceived lack of intimacy, and the difficulties of working with translated material. However, transference, countertransference and other unconscious communications and responses necessarily occur in every therapeutic setting, including triadic therapy using interpreters. This paper describes a short-term (12 session) psychodynamically-oriented intervention with a 52-year old Cantonese-speaking man suffering from depression. A female, Chinese-born interpreter assisted in every session. The integral role of supervision in supporting a containing relationship between the therapist and the patient and the difficult emotional responses experienced by the interpreter is highlighted. The paper attempts to trace some of the unconscious communications that occurred during the therapy and demonstrates the feasibility of working psychodynamically in an interpreter-assisted setting.

Improving ultrasound excitation systems using a flexible power supply with adjustable voltage and frequency to drive piezoelectric transducers

The ability of a piezoelectric transducer in energy conversion is rapidly expanding in several applications. Some of the industrial applications for which a high power ultrasound transducer can be used are surface cleaning, water treatment, plastic welding and food sterilization. Also, a high power ultrasound transducer plays a great role in biomedical applications such as diagnostic and therapeutic applications. An ultrasound transducer is usually applied to convert electrical energy to mechanical energy and vice versa. In some high power ultrasound system, ultrasound transducers are applied as a transmitter, as a receiver or both. As a transmitter, it converts electrical energy to mechanical energy while a receiver converts mechanical energy to electrical energy as a sensor for control system. Once a piezoelectric transducer is excited by electrical signal, piezoelectric material starts to vibrate and generates ultrasound waves. A portion of the ultrasound waves which passes through the medium will be sensed by the receiver and converted to electrical energy. To drive an ultrasound transducer, an excitation signal should be properly designed otherwise undesired signal (low quality) can deteriorate the performance of the transducer (energy conversion) and increase power consumption in the system. For instance, some portion of generated power may be delivered in unwanted frequency which is not acceptable for some applications especially for biomedical applications. To achieve better performance of the transducer, along with the quality of the excitation signal, the characteristics of the high power ultrasound transducer should be taken into consideration as well. In this regard, several simulation and experimental tests are carried out in this research to model high power ultrasound transducers and systems. During these experiments, high power ultrasound transducers are excited by several excitation signals with different amplitudes and frequencies, using a network analyser, a signal generator, a high power amplifier and a multilevel converter. Also, to analyse the behaviour of the ultrasound system, the voltage ratio of the system is measured in different tests. The voltage across transmitter is measured as an input voltage then divided by the output voltage which is measured across receiver. The results of the transducer characteristics and the ultrasound system behaviour are discussed in chapter 4 and 5 of this thesis. Each piezoelectric transducer has several resonance frequencies in which its impedance has lower magnitude as compared to non-resonance frequencies. Among these resonance frequencies, just at one of those frequencies, the magnitude of the impedance is minimum. This resonance frequency is known as the main resonance frequency of the transducer. To attain higher efficiency and deliver more power to the ultrasound system, the transducer is usually excited at the main resonance frequency. Therefore, it is important to find out this frequency and other resonance frequencies. Hereof, a frequency detection method is proposed in this research which is discussed in chapter 2. An extended electrical model of the ultrasound transducer with multiple resonance frequencies consists of several RLC legs in parallel with a capacitor. Each RLC leg represents one of the resonance frequencies of the ultrasound transducer. At resonance frequency the inductor reactance and capacitor reactance cancel out each other and the resistor of this leg represents power conversion of the system at that frequency. This concept is shown in simulation and test results presented in chapter 4. To excite a high power ultrasound transducer, a high power signal is required. Multilevel converters are usually applied to generate a high power signal but the drawback of this signal is low quality in comparison with a sinusoidal signal. In some applications like ultrasound, it is extensively important to generate a high quality signal. Several control and modulation techniques are introduced in different papers to control the output voltage of the multilevel converters. One of those techniques is harmonic elimination technique. In this technique, switching angles are chosen in such way to reduce harmonic contents in the output side. It is undeniable that increasing the number of the switching angles results in more harmonic reduction. But to have more switching angles, more output voltage levels are required which increase the number of components and cost of the converter. To improve the quality of the output voltage signal with no more components, a new harmonic elimination technique is proposed in this research. Based on this new technique, more variables (DC voltage levels and switching angles) are chosen to eliminate more low order harmonics compared to conventional harmonic elimination techniques. In conventional harmonic elimination method, DC voltage levels are same and only switching angles are calculated to eliminate harmonics. Therefore, the number of eliminated harmonic is limited by the number of switching cycles. In the proposed modulation technique, the switching angles and the DC voltage levels are calculated off-line to eliminate more harmonics. Therefore, the DC voltage levels are not equal and should be regulated. To achieve this aim, a DC/DC converter is applied to adjust the DC link voltages with several capacitors. The effect of the new harmonic elimination technique on the output quality of several single phase multilevel converters is explained in chapter 3 and 6 of this thesis. According to the electrical model of high power ultrasound transducer, this device can be modelled as parallel combinations of RLC legs with a main capacitor. The impedance diagram of the transducer in frequency domain shows it has capacitive characteristics in almost all frequencies. Therefore, using a voltage source converter to drive a high power ultrasound transducer can create significant leakage current through the transducer. It happens due to significant voltage stress (dv/dt) across the transducer. To remedy this problem, LC filters are applied in some applications. For some applications such as ultrasound, using a LC filter can deteriorate the performance of the transducer by changing its characteristics and displacing the resonance frequency of the transducer. For such a case a current source converter could be a suitable choice to overcome this problem. In this regard, a current source converter is implemented and applied to excite the high power ultrasound transducer. To control the output current and voltage, a hysteresis control and unipolar modulation are used respectively. The results of this test are explained in chapter 7.