IPEM-translation最新文献

Background

Objective

Design and participants

Findings

Conclusion

The work described was undertaken to develop a means to estimate the delivered power over the exposed body surface of a neonate receiving phototherapy. Previous work of the group had involved the use of discrete photodiodes distributed over a newborn manikin surface. It was considered that improved accuracy of sensing over curved surfaces would be provided with the use of flexible solar cell elements. A group of products based on amorphous silicon was identified as potentially suitable and a range of its properties investigated. These included the wavelength sensitivity, the relative sensitivity of similar elements and the cosine response of elements. It was identified that with selection of elements of matched sensitivity, specific element types were appropriate for intended use. A total of 44 discrete solar cell elements of three separate sizes was used to cover the previously used manikin surface and a dedicated interface circuit was designed and constructed. A handheld calibrated spectroradiometer provided a means to relate incident irradiance values within specific wavelength bands to corresponding optical power over the manikin surface. Initial use of the system is described together with future potential developments in relation to clinical applications and testing standards for neonatal phototherapy devices.

Nuclear medicine healthcare workers are exposed to the risk of radioactive needlestick injury. To quantify the severity of this risk, the activity deposited into the skin and the injury depth have been experimentally measured for input into skin dosimetry program VARSKIN+. Agar test objects were pierced by hand with a needle containing Tc-99m Hydroxymethylene Diphosphonate (HMDP). The deposited activity was measured by contamination monitor and converted into deposited volume. Injury depth was measured with a ruler by piercing the test objects with visible dye.

The median volume deposited into test objects without gloves was 100 ± 50 nl (standard error) (interquartile range (IQR): 50–320 nl). Through one glove, this was reduced to 50 ± 20 nl (IQR: 30 - 140 nl), however, the difference was not significant (p > 0.1). The volume deposited through two gloves was highly variable due to the increased force required to puncture. The median injury depth was 4.0 ± 0.4 mm (standard error).

Decontamination efficacy was investigated by rinsing alone, with hand soap and by application of decontamination agent RadiacWash. All decontamination methods were found to significantly decrease the activity deposited (p < 0.001). Test objects rinsed for 60 s had a mean reduction of 42 % ± 6 % (95 % confidence interval). There was no significant difference observed between decontamination methods. This may be due to differences in absorption time between the sample groups.

Skin dose estimates have been calculated in VARSKIN+ using the results of the experiment. For injuries without gloves, involving 1011 MBq/ml of Tc-99m HMDP, a skin dose of 11 ± 5 mSv (propagated standard error) was calculated. Immediate decontamination under running water is recommended to reduce the dose. Further research is encouraged to investigate the protection offered by gloves.

The development of a flow/pressure measurement system in association with Bronkhorst High-Tech B.V. incorporating a Coriolis flow transducer, provided an opportunity to observe the flow/pressure dynamics of syringe drivers. A model of flow/pressure performance of syringe drivers was established where key variable factors included the compliance of the connected system and the associated line resistance. It was identified that the flow/pressure dynamics observed with the flow measurement system incorporating the Coriolis transducer matched that of the model. In this consideration the dominant compliance contribution related to that of the syringe. The model operates by considering the notional volume change in the residual fluid volume in the syringe with inflow from stepper motor action and outflow in the interval between sequential pulses. While many of the observations in the literature of syringe driver function are qualitative, the model allows a more precise prediction of associated device performance.

A photoplethysmogram (PPG) is an optically-derived signal that records the variation in blood volume within the microvasculature. Certain cardiovascular diseases (CVDs) are symptomatic of damaged blood vessels and problems in blood flow, including hypertension. While software implementations for heart rate and blood pressure estimation exist, point-of-care systems demand hardware-based implementations for real-time estimations to be useful for CVD detection. In this study, digital field programmable gate array (FPGA) based systems are developed for heart rate and blood pressure estimation from PPG signals by means of linear regression. In addition to the blood pressure estimation system, we present a prototype hypertension level detection system that achieves 92.42% accuracy while consuming 0.364 W of power. The Mean Absolute Error (MAE) $\pm$ Standard Deviation (SD) for heart rate estimation is 3.17 ± 2.79 beat per minute. The corresponding results for systolic and diastolic blood-pressure estimation are 4.75 ± 2.78 and 3.34 ± 2.60, respectively. The prototype can be further extended to wearable devices and medical equipment in the future.

Quantitative MR (qMR) has offered direct access to in-vivo biology and physiology for over three decades, yet it has failed to translate into the clinic. Why is this? The development of suitable phantoms is a key stage in the evolution of qMR, and here a systematic categorisation is proposed. Currently there is much attention paid to creating simple head phantoms containing materials with metrologically traceable values of MR quantities. However these are usually unrealistic; many of the disrupting phenomena present in clinical imaging are absent. Good performance with a simple traceable phantom is a necessary but not sufficient requirement for the establishment of good in-vivo measurement performance. There is therefore a premium on developing realistic phantoms. A proposal made for a more realistic body phantom that includes RF B₁ imperfections. It consists of lossy annuli placed around a standard head phantom. Other confounding phenomena could be identified, possibly built into an appropriate annulus around a simple head phantom, to form realistic phantoms; these would enable validation of qMR methods and translation to the clinic. The concept is probably applicable to other quantitative diagnostic imaging modalities.

Clinical translation of 7 tesla (T) MRI of the brain promises high image quality and potentially improved clinical diagnosis for patients compared to current standard lower field-strength MRI at 1.5 and 3T.

Here we describe how physics principles underlying ultra-high field (UHF) strength MRI affect 7T image quality, and how these can be exploited to translate 7T brain imaging into clinical practice. UHF MRI profits from higher inherent signal-to-noise ratio (SNR) and a resultant increase in achievable spatial resolution or acceleration factors; increase in sensitivity to magnetic susceptibility differences and a higher amplitude of the Blood Oxygen Level Dependent (BOLD) signal; increase in longitudinal relaxation time; and increased frequency dispersion and spectral resolution in MR spectroscopy.

Examples are presented of different brain pathologies, which are better illustrated on 7T compared to lower field strength by applying sequences and imaging techniques that exploit these intrinsic strengths of 7T MRI. This includes imaging of various vascular pathologies, epilepsy and brain tumours.