Telemetric Sensor Research Articles

SU-FF-T-242: Evaluation of Implantable MOSFET Dosimeters for Conventional and Intraoperative Radiation Therapy

Purpose: To test the applicability and reliability of the manufacturer's calibration of implantable MOSFET dosimeters for use under differing clinical conditions. These include conventional radiation therapy and intraoperative radiation therapy, where the need for sterilizable, wireless telemetric sensors may make these detectors the best candidates for in vivo dosimetry. Method and Materials: The implantable dosimeters were manufactured and factory calibrated by Sicel Technologies, Inc. We tested these dosimeters for conventional radiotherapy beams, where the detectors were placed in a phantom and exposed to 20 treatment fractions with daily doses of 1, 2, or 4 Gy. We also tested the detectors for use in HDR-IORT, where the detectors were placed in a constant-temperature (37°C) water phantom and irradiated with an HDR Ir-192 source with single treatment fractions of 10, 12.5, or 15 Gy. Results: Under calibration conditions with conventional radiotherapy beams, we found the dose measured by the detectors using the manufacturer's calibration to be within ± 3% of the delivered dose, with a standard deviation of 2%. Preliminary results support the robustness of the calibration for conventional radiotherapy beams with both higher and lower daily doses, with an increase in error as the daily dose deviates from the calibrated dose. When an HDR Ir-192 source was used, the measured dose showed a linear deviation from the delivered dose due to differences in energy, dose rate, and total dose per fraction. These results suggest the need for additional correction factors when these detectors are used for HDR-IORT and most likely also for IOERT. Conclusion: We have verified the manufacturer's calibration of these dosimeters for conventional radiotherapy. With additional correction, these dosimeters appear to be an ideal choice for IORT. Conflict of Interest: ASB has a sponsored research agreement with Sicel Technologies, Inc.

Carbohydrate Ingestion During Exhaustive High-intensity Intermittent Shuttle Running In The Heat

Under certain conditions exercise capacity has been shown to improve with the ingestion of a suitable carbohydrate-electrolyte solution (CES). However, in hot environmental temperatures the fatigue process is often a consequence of dehydration and an accelerated rate of heat gain rather than carbohydrate availability; under these circumstances the volume of fluid ingested is considered more important than the carbohydrate intake. Exercise capacity may be reduced during prolonged intermittent exercise in 30°C when a CES is ingested compared with an energy-free flavoured water (FW) (Morris et al., J Sport Sci, 2003, 21:371–381). Purpose This study examines deep body temperature, energy expenditure and endurance capacity during the Loughborough Intermittent Shuttle Test (LIST) in the heat, when ingesting a 6.4% CES compared with a FW. Methods Nine male games players performed the LIST to volitional fatigue on two separate occasions at an ambient temperature of 30.4 ± 0.7 °C (mean ± SD) and relative humidity of 35.3 ± 2.5 %. Subjects ingested 6.5 ml·kg−1 body mass of test drink before exercise and 3.5 ml·kg−1 body mass during each 3 min rest period separating exercise blocks. Intestinal temperature was continuously monitored using an ingested telemetric sensor and expired air samples were collected at regular intervals during the protocol. Results No differences were detected in exercise capacity between trials: subjects ran for 86.9 (±19.9) min and 94.1 (± 28.2) min in the CES and FW trials respectively (P=0.26). Similarly no differences were apparent in intestinal temperature at the point of fatigue: CES 39.50 ± 0.50 °C; FW 39.47 ± 0.40 °C (P=0.26). Cumulative sprint time was faster when subjects ingested the CES (P=0.04) and a difference was also apparent in the total energy expenditures of 3.7 ± 0.2 MJ in the CES trial and 3.4 ± 0.4 MJ in the FW trial (P=0.02). The rate of carbohydrate oxidation was higher in the CES trail (202 ± 22 g·h−1) compared with the FW (168 ± 25 g·h−1)(P=0.04). Conclusion It appears that the ingestion of a 6.4% CES enabled subjects to perform at higher energy expenditures during the self-selected sprint phase of the exercise protocol. This increase in performance may be due to the greater availability and oxidation of carbohydrate. The increased exogenous supply of energy when ingesting the CES did not result in an increase in exercise capacity as previously reported. The deep body temperatures recorded at the point of fatigue suggest that subjects may have failed to continue exercise due to the attainment of a capacity-limiting state of hyperthermia rather than insufficient carbohydrate availability.

Carbohydrate Ingestion During Exhaustive High-intensity Intermittent Shuttle Running In The Heat

Under certain conditions exercise capacity has been shown to improve with the ingestion of a suitable carbohydrate-electrolyte solution (CES). However, in hot environmental temperatures the fatigue process is often a consequence of dehydration and an accelerated rate of heat gain rather than carbohydrate availability; under these circumstances the volume of fluid ingested is considered more important than the carbohydrate intake. Exercise capacity may be reduced during prolonged intermittent exercise in 30°C when a CES is ingested compared with an energy-free flavoured water (FW) (Morris et al., J Sport Sci, 2003, 21:371–381). Purpose This study examines deep body temperature, energy expenditure and endurance capacity during the Loughborough Intermittent Shuttle Test (LIST) in the heat, when ingesting a 6.4% CES compared with a FW. Methods Nine male games players performed the LIST to volitional fatigue on two separate occasions at an ambient temperature of 30.4 ± 0.7 °C (mean ± SD) and relative humidity of 35.3 ± 2.5 %. Subjects ingested 6.5 ml·kg−1 body mass of test drink before exercise and 3.5 ml·kg−1 body mass during each 3 min rest period separating exercise blocks. Intestinal temperature was continuously monitored using an ingested telemetric sensor and expired air samples were collected at regular intervals during the protocol. Results No differences were detected in exercise capacity between trials: subjects ran for 86.9 (±19.9) min and 94.1 (± 28.2) min in the CES and FW trials respectively (P=0.26). Similarly no differences were apparent in intestinal temperature at the point of fatigue: CES 39.50 ± 0.50 °C; FW 39.47 ± 0.40 °C (P=0.26). Cumulative sprint time was faster when subjects ingested the CES (P=0.04) and a difference was also apparent in the total energy expenditures of 3.7 ± 0.2 MJ in the CES trial and 3.4 ± 0.4 MJ in the FW trial (P=0.02). The rate of carbohydrate oxidation was higher in the CES trail (202 ± 22 g·h−1) compared with the FW (168 ± 25 g·h−1)(P=0.04). Conclusion It appears that the ingestion of a 6.4% CES enabled subjects to perform at higher energy expenditures during the self-selected sprint phase of the exercise protocol. This increase in performance may be due to the greater availability and oxidation of carbohydrate. The increased exogenous supply of energy when ingesting the CES did not result in an increase in exercise capacity as previously reported. The deep body temperatures recorded at the point of fatigue suggest that subjects may have failed to continue exercise due to the attainment of a capacity-limiting state of hyperthermia rather than insufficient carbohydrate availability.

The mobile robot localization problem treated as a constraint satisfaction problem

The problem considered here is mobile robot localization. We emphasize particularly the localization imprecision estimation. To this aim, the imprecise measurements given by a telemetric sensor and two odometers mounted on the mobile robot are modelled by intervals and are fused by constraint propagation on intervals. Indeed, the localization problem from dead reckoning and exteroceptive data can be modelled as a constraint satisfaction problem (CSP). So, at the end of the localization process, we get a 3-D subpaving which is supposed to contain the robot's position in a guaranteed way. The localization imprecision is naturally managed by our method.

Innovation requirements for telemetric sensor systems in medicine: results of a survey in Germany

Although first telemetric microsystems have been marketed for medical applications, the entry into the healthcare market represents a considerable challenge for many companies working in the field of microsystems technology. The Institute of Healthcare Industries (IHCI) at the Steinbeis University Berlin has conducted a study among experts in medicine, technology, and industry. The goal of the study was to investigate on innovation requirements and the market for telemetric microsystems in medicine. This article reviews selected results of the “Study on market and innovation requirements for telemetric microsystems in medicine”. It was performed in context with the project IMEX (Implantable and Extracorporeal modular microsystem platform), funded by the German ministry of science and research.

Telemetric surface acoustic wave sensor for humidity

Abstract. Surface acoustic wave sensors consist of a piezoelectric substrate with metal interdigital transducers (IDT) on top. The acoustic waves are generated on the surface of the substrate by a radio wave, as it is well known in band pass filters. The devices can be used as wireless telemetric sensors for temperature and humidity, transmitting the sensed signal as a shift of the sensor’s resonance frequency.

Continuous amperometric monitoring of subcutaneous oxygen in rabbit by telemetry

The primary objective was to develop a telemetric oxygen sensor designed for implantation in subcutaneous tissue. In the sensor, the platinum indicating electrode was covered with polythene to retard oxygen entry and avoid interference. Given the potential for large indicating electrodes to deplete oxygen in vivo, some sensors were made with very small indicating electrodes. Sensors were tested in the anesthetized rabbit at various oxygen concentrations. Animals were studied 1 and 5 days after implementation. The sensor could detect changes in oxygen in vivo. Measurements were similar at 1 and 5 days and sensors with different sized electrodes yielded similar results. This telemetric implantable amperometric sensor can detect variations in tissue oxygenation and may have applications in cardiopulmonary physiology, continuous glucose monitoring and other related fields.

Medical aspects of active implants in the eye

Due to progress in miniaturizing complex electronic systems the development of intraocular sensors and stimulators is feasible. The Retina Implant will restore vision in patients with progressive retinal degenerations by means of electrical stimulation of retinal neurons, e.g. in Retinitis pigmentosa. After severe destructions of the anterior segment with intact retina, e.g. after explosion trauma an intraocular display will restore vision. In glaucoma patients the implantation of a telemetric pressure sensor will help to optimise the management of each individual patient. Pressure profiles under everyday conditions will become available. These active implants will open new perspectives in treatment and diagnostics in ophthalmology.

Rise in background current over time in a subcutaneous glucose sensor in the rabbit: relevance to calibration and accuracy

In order to calibrate a continuous glucose monitor, accurate determination of the background current ( I 0) is necessary, in part because I 0 could change over time. We compared two methods of I 0 measurement: (1), extrapolation of sensor output data (as afunction of glucose leve) th the intercept at zero glucose and (2) direct measurement of the output of a blank anode with no enzyme coat. We implanted telemetric sensors subcutaneously in rabbits and measured their outputs during tri-level glucose clamps once per week for 5 weeks. The two methods yielded similar results. I 0 rose substantially over time and this increase reached significance during week 3 by the direct method but not until week 5 by the extrapolation method. Using the direct method, I 0 rose from 3.41 (0.60–8.48 nanoamperes (nA), median and range) during week 1 to 13.42 (9.1–14.3) during week 5. Using the extrapolation method, I 0 rose from 0.57 (0–16.7) during week 1 to 15.3 (12.2–21.6) during week 5. We conclude that I 0 can rise over time. If this rise went undetected and was assumed to be stable, a one-point calibration procedure would overestimate glycemia in the hypoglycemic range, i.e. fail to appreciate the severity of hypoglycemia. It is recommended that during validation of a chronic glucose sensor, I 0 be measured sequentially over time.

First clinical results with a telemetrie shunt-integrated ICP-sensor

The telemetric shunt-integrated sensors available up to now do not deliver negative CSF pressure values. Therefore, a new sensor was designed which is incorporated into the shunt line proximally to the valve. The monitor calculates the pressure values in relation to the atmospheric pressure obtained by a built-in barometer. The sensor covers a pressure range of —100 cmH20 to 200 cmH20 with a resolution of ±7 cmH20. First follow-up experiences are reported with seven patients over 14-17 months. Depending on the patient's body position telemetrically measured CSF-pressures varied between —20 cmH20 in erect and 15 cmH20 in supine position. In a patient with intermittent shunt dysfunction and stiff ventricular walls telemetrically measured CSF values corresponded earlier and were more sensitive with the clinical symptomatology than with the CT scan. So far, recognizable advantages of the telesensor are an improved assessment of shunt dysfunction and marginal CSF pressure increases, with practicability and simplicity of measurements in outpatients and a reduction of expensive CT or MRI controls. [Neurol Res 1999; 21: 117-120]

A new ventriculoperitoneal shunt with a telemetric intracranial pressure sensor: clinical experience in 94 patients with hydrocephalus.

We have developed a telemetric intracranial pressure sensor (OSAKA telesensor; Nagano Keiki Seisakusyo Co. Ltd., Tokyo, Japan) and investigated the clinical usefulness of new ventriculoperitoneal shunting with an OSAKA telesensor, an on-off valve, and a programmable valve. The OSAKA telesensor was applied in 94 patients at Osaka Medical College between March 1986 and December 1995. Postoperative management, postoperative course, postural change of intracranial pressure (ICP), and zero drift of the OSAKA telesensor were investigated. ICP was measured easily in all patients with no inconvenience. The setting of the programmable valve was adjusted postoperatively 38 times in 25 patients. Postoperative ICP in the upright position was -14.9 +/- 4.5 mm Hg, and the difference in ICP between the supine and the upright position was about 20 mm Hg. The slope of the decrease in ICP with continuous postural changes from the supine to the upright position was steep until about 30 to 45 degrees but became incrementally less or even rose slightly about this angle. The initial slope was steeper when the shunt was open than when the shunt was closed; it was also steeper postoperatively than preoperatively. This initial slope, therefore, may indicate the intracranial compliance. Seven cases of shunt malfunction were diagnosed correctly by ICP measurements. Zero drift of the OSAKA telesensor was easily corrected by comparing the ICP reading from the telesensor with the puncture pressure in the on-off valve. The OSAKA telesensor is very useful in the postoperative care and pathophysiological evaluation of patients with hydrocephalus.

A New Ventriculoperitoneal Shunt with a Telemetric Intracranial Pressure Sensor: Clinical Experience in 94 Patients with Hydrocephalus

A New Ventriculoperitoneal Shunt with a Telemetric Intracranial Pressure Sensor: Clinical Experience in 94 Patients with Hydrocephalus

All-fiber absolute temperature sensor using an unbalanced high-birefringence Sagnac loop

We demonstrate a highly sensitive temperature sensor based on a stress-induced high-birefringence-fiber Sagnac loop that uses a Nd-doped-fiber amplified spontaneous emission source. Relative temperature sensing is done in the spectral domain by shifts of a resonant wavelength lambda(r) and absolute temperature sensing by changes in separation between resonances Dlambda . The measured relative change of these parameters with temperature in the range 15-110 degrees C, is (1/lambda(r))(deltalambda(r)/deltaT) = -(1/Dlambda)(deltaDlambda/delta T) approximately (1/Dn)(delta Dn/deltaT)(-0.94 +/- 0.02) x 10(-3)/K, with measured fiber birefringence Dn = 8 x 10(-4) . This gives a wavelength-shift sensitivity of -1.00 nm/K at 1.065 microm and a resonance separation sensitivity of 0.006 nm/K for Dlambda = 6.8 nm . This telemetric point sensor has a loop length of 80 m, an operational bandwidth of more than 50 nm, and a temperature accuracy of better than 1 degrees C.

Telemetric sensors by microwave interferometry

Abstract This paper presents some possibilities offered by a specific microwave sensor called an I-Q demodulator or complex correlator. It is shown that this narrow-band complex correlator is able to provide information about the velocity profile and the position of a monochromatic transmitter which is inside a predefined area; this situation is qualified as cooperative configuration. Nevertheless, this complex correlator can also be used in the situation where only reflected signals are considered — non cooperative configuration — such as in anticollision and level measurement processes. Such sensors can naturally be used in many industrial application fields like robotics, tank gauging and berthing aid. Therefore, to answer industrial requirements, we show in this paper that the necessary compromise between good performance and low cost can be reached.

Intracranial pressure monitoring using a programmable pressure valve and a telemetric intracranial pressure sensor in a case of slit ventricle syndrome after multiple shunt revisions

A case of hydrocephalus showing slit ventricle syndrome after multiple shunt revisions was treated with a programmable pressure valve, and intracranial pressure was monitored with a telemetric sensor. High pressure setting produced positive and normal values of intracranial pressure in this patient. We report our experiences.

The relationship between ventricular fluid pressure and body position in normal subjects and subjects with shunts

Using a chronically implanted telemetric pressure sensor, we have determined the quantitative relationship between changes in body position and ventricular fluid pressure in normal subjects and subjects with shunts. The method allows accurate, reliable measurement of negative as well as positive pressures. We describe the derangement of postural intraventricular pressure regulation caused by placement of a shunt, as well as the influence of various shunt systems and the antisiphon device on this problem. Ventriculoatrial, ventriculoperitoneal, and ventriculopleural shunts all caused similar severely abnormal postural intracranial pressure relationships. The antisiphon device was generally effective in restoring normal pressures in patients in the upright position. We discuss the implications of our findings for understanding the mechanisms of postural intracranial pressure regulation in patients without hydrocephalus.

The Relationship between Ventricular Fluid Pressure and Body Position in Normal Subjects and Subjects with Shunts: A Telemetric Study

Abstract Using a chronically implanted telemetric pressure sensor, we have determined the quantitative relationship between changes in body position and ventricular fluid pressure in normal subjects and subjects with shunts. The method allows accurate, reliable measurement of negative as well as positive pressures. We describe the derangement of postural intraventricular pressure regulation caused by placement of a shunt, as well as the influence of various shunt systems and the antisiphon device on this problem. Ventriculoatrial, ventriculoperitoneal, and ventriculopleural shunts all caused similar severely abnormal postural intracranial pressure relationships. The antisiphon device was generally effective in restoring normal pressures in patients in the upright position. We discuss the implications of our findings for understanding the mechanisms of postural intracranial pressure regulation in patients without hydrocephalus.

Position, velocity profile measurement of a moving body by microwave interferometry

A telemetric sensor that uses microwave interferometry to determine the velocity profile of a moving body following a known linear trajectory is proposed. By a slight modification of the design, it is possible to determine both the velocity profile and the distance to the trajectory. The principle of the method and the preliminary experiments carried out in the laboratory before extending the process to full-sized outdoor applications are described. The experimental results confirm the feasibility of the concept.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Evaluation of a telemetric temperature sensor for deep hyperthermia application

Evaluation of a telemetric temperature sensor for deep hyperthermia application

Ten-year follow-up on the performance of a telemetric intracranial pressure sensor

Ten-year follow-up on the performance of a telemetric intracranial pressure sensor