Acoustic images of gel dosimetry phantoms

AbstractThis work presents Vibro-acoustography (VA) as a tool to visualize absorbed dose in a polymer gel dosimetry phantom. VA relies on the mechanical excitation introduced by the acoustic radiation force of focused modulated ultrasound in a small region of the object. A hydrophone or microphone is used to measure the sound emitted from the object in response to the excitation, and by using the amplitude or phase of this signal, an image of the object can be generated. To study the phenomena of dose distribution in a gel dosimetry phantom, continuous wave (CW), tone burst and multi-frequency VA were used to image this phantom. The phantom was designed using ‘MAGIC’ gel polymer with addition of glass microspheres at 2% w/w having an average diameter range between 40–75 μm. The gel was irradiated using conventional 10 MeV X-rays from a linear accelerator. The field size in the surface of the phantom was 1.0×1.0 cm2 and a source-surface distance (SSD) of 100 cm. The irradiated volume corresponds to an approximately 8.0 cm3, where a dose of 50 gray was delivered to the gel. Polymer gel dosimeters are sensitive to radiation-induced chemical changes that occur in the irradiated polymer. VA images of the gel dosimeter showed the irradiate area. It is concluded that VA imaging has potential to visualize dose distribution in a polymer gel dosimeter

Obese elderly women exhibit low postural stability: a novel three-dimensional evaluation system

OBJECTIVE: The aim of this study was to evaluate the multisegmental static postural balance of active eutrophic and obese elderly women using a three-dimensional system under different sensory conditions. METHODS: A cross-sectional study was conducted on 31 elderly women (16 eutrophic and 15 obese) aged 65 to 75 years. The following anthropometric measurements were obtained: weight, height, waist and hip circumference, and handgrip strength. The physical activity level was evaluated using the International Physical Activity Questionnaire. Body composition was measured using the deuterium oxide dilution technique. The Polhemus (R) Patriot (three-dimensional) equipment was used to measure the parameters of postural balance along the anteroposterior and laterolateral axes. The data acquisition involved one trial of 60 s to test the limit of stability and four trials of 90 s each under the following conditions: (1) eyes open, stable surface; (2) eyes closed, stable surface; (3) eyes open, unstable surface; and (4) eyes closed, unstable surface. RESULTS: For the limit of stability, significant differences were observed in the maximum anteroposterior and laterolateral displacement (p<0.01) and in the parameter maximum anteroposterior displacement in the eyes closed stable surface condition (p<0.01) and maximum anteroposterior and laterolateral displacement in the eyes open unstable surface (p<0.01 and p = 0.03) and eyes closed unstable surface (p<0.01 and p<0.01) conditions. CONCLUSIONS: Obese elderly women exhibited a lower stability limit (lower sway area) compared with eutrophic women, leaving them more vulnerable to falls

Prototype of a low-cost 3D breast ultrasound imaging system

This work describes a setup of the new acquisition system for 3D ultrasound images (i.e. B-mode) for breast tomography. Since premature and precise breast lesions diagnoses turn out in treatment more efficient and save lives, we are looking for a more precise, less painful exams and dose reduction for the patient. Therefore, a low cost scanner mechanism was built aiming to accommodate breasts under water while patient is laid down on a bed in which a robotic arm guides the ultrasound probe to acquire 2D images. Then 3D image is reconstructed using the 2D images due to render the mammary volume searching for lesions. The low cost scanner was built using a regular ultrasound machine, linear probe and major controls made by an Arduino Uno. We compared the acquired phantom images with gold standard images for mammary tissues diagnostics, i.e. Computerized Tomography and Magnetic Resonance Images. This study was evaluated using a paraffin-gel and mineral oil control phantom. Results show that the provided module is convicting enough to be used in local hospital as the next step of this study

3D Ultrasound Breast Automated Acquisition System

Normally mammary evaluation is performed by mammography scans. This method is efficient in diagnoses early tumors stages, and must be annually repeated by women, usually, by the age of 40. However it has its disadvantages such as dose deposition in patients – recent studies have shown the potential cancer induction by mammography scans – besides the uncomfortable of breast compression. Also the ultrasonography is a common technique applied in clinical routines. Advances in ultrasound have improved image quality and its capability of perception changes in mechanical tissue properties. With ultrasound, it’s possible to generate different images modalities (B-mode, Doppler and elastography). One of its limitations is the free-hand acquisition which difficults reproducibility. In this project, we present a protocol for automatic breast imaging by ultrasound, using a robotic arm, capable of generating volumetric tridimensional mammary images // Normalmente a avaliação mamária é realizada por mamografia. Tal metodologia é eficaz no diagnóstico precoce de células tumorais, e deve ser repetido anualmente por mulheres, geralmente, a partir dos 40 anos de idade. Porém ela também apresenta por desvantagens a deposição de doses no paciente – estudos recentes avaliam o potencial de risco de câncer de mama induzido por mamografia –, além de desconforto na compressão das mesmas. A ultrassonografia também é uma técnica comumente utilizada nos exames de rotina. Os avanços ultrassônicos têm melhorado circunstancialmente a qualidade da imagem e a capacidade de identificar alterações nas estruturas mecânicas dos tecidos. Com o ultrassom, é possível gerar diferentes modalidades de imagens (modo-B, Doppler e elastográfico). Uma de suas limitações é a obtenção à mão livre que dificulta a reprodutibilidade. Nesse projeto, apresentamos um protocolo para imageamento automático ultrassônico mamário, usando um braço robótico, capaz de gerar um volume tridimensional da mama