A computer-controlled dynamic phantom for respiratory-gated medical radiotherapy research

This paper describes the breathing phantom built to test a six-degree-of freedom sensing device designed for use in Respiratory-Gated Radiotherapy (RGRT). It is focussed on the construction of a test bed that was designed to address tumour motion issues while, at the same time, behaving in much the same way as the human tissues when irradiated. The phantom can produce respiratory movement in three dimensions. Shift differences between the motion axes can be introduced. The position error in the worst case scenario is not greater that 0.4 mm. Emphasis is made on the technical limitations of current sensing technologies, especially with regard to acceleration sensitivity. This study demonstrates that the sensitivity of accelerometers used to sense tumour motion should be 0.05 mG or less

Photon radiation testing of commercially available off-the-shelf microcontroller devices

The results of photon radiation testing of various microcontroller devices is described. This was testing was useful to select the microcontroller in a 6DOF MEMS-based INS. This systems is being developed for the in-vivo monitoring of tumour position during clinical radiotherapy treatments. This application requires a radiation-tolerant processor in order to perform appropriately in a radiotherapy environment. A phantom has been built to replicate the working conditions that the microcontroller devices are required to endure. Each time, a number of identical microcontroller devices have been exposed, in 5turn, to X-ray doses in excess of 50 Gy from a clinical radiotherapy LINAC

Multiphysical computation of the structural bending in a bottom-drive VCM

Purpose - This paper intends to lay a background knowledge towards the feasibility of developing a bottom-drive variable capacitance micromotor (VCM) using a surface micromachining process (SMP). The purpose of this paper is to determine the possibility of neglecting the bending of the rotor plates caused by the electrostatic normal forces when deploying a set of mechanical supports. Design/methodology/approach -A multiphysics simulation approach is considered in order to analyse the coupled electromechanical effects in a steady state and to evaluate if the proposed geometries are useful to reduce the bending of the plates. Findings -A surfaced micromachined bottom-drive VCM requires mechanical reinforcement in order to eliminate the risk of an electrical short circuit caused by the deformation in the rotor plates. The combination of an external supporting ring and anchored structural ribs on top of the rotor poles is sufficient to neglect the deformation in the poles of the rotor. Originality/value -An original analysis with the objective of setting a background in the development of a bottom-drive electrostatic micromotor using a SMP is presented

Tracking of internal organ motion with a six degree-of-freedom MEMS sensor: concept and simulation study.

This paper presents a wireless tracking system capable of measuring position and orientation about three orthogonal axes with a frequency bandwidth of 320 Hz. A real-time algorithm determines the six degree-of-freedom (6DOF) sensor posture, comprising the three components of dimensional position (heave, sway and surge) and the three components of rotational orientation (pitch, yaw and roll). An inertial algorithm has been simulated in software and tested in hardware. Techniques for sensor functionality and 3D manipulation are described within this paper. A miniaturized version of this sensor is thought to be ideal in applications requiring detection or tracking of tumour motion in radiation oncology

Multiphysical computation of the structural bending in a bottom-drive VCM

Purpose - This paper intends to lay a background knowledge towards the feasibility of developing a bottom-drive variable capacitance micromotor (VCM) using a surface micromachining process (SMP). The purpose of this paper is to determine the possibility of neglecting the bending of the rotor plates caused by the electrostatic normal forces when deploying a set of mechanical supports. Design/methodology/approach -A multiphysics simulation approach is considered in order to analyse the coupled electromechanical effects in a steady state and to evaluate if the proposed geometries are useful to reduce the bending of the plates. Findings -A surfaced micromachined bottom-drive VCM requires mechanical reinforcement in order to eliminate the risk of an electrical short circuit caused by the deformation in the rotor plates. The combination of an external supporting ring and anchored structural ribs on top of the rotor poles is sufficient to neglect the deformation in the poles of the rotor. Originality/value -An original analysis with the objective of setting a background in the development of a bottom-drive electrostatic micromotor using a SMP is presented

Stable Sliding PD Control for underwater gliders:Experimental results

In this paper we describe the mechanical and electronic design of KAY JUUL, an academic underwater glider, we also show the results from experimental tests developed in a pool. A Sliding PD Control scheme have been applied in the system, due to we don't know the parameters of the KAY JUUL yet, the control output variables were selected based on simulation results and theoretical analysis of the ROGUE, an academic glider developed by Princeton University. Satisfactory results were expected, have been achieved and are presented here

VLSI architecture of a Kalman filter optimized for real-time applications

This paper presents a parametrized VLSI architecture for an nstate Kalman filter implementation intended for real-time applications that typically require a sensing rate not far from 300 samples per second. The architecture has been optimized in silicon area and power consumption. This approach has been proved with a fabricated chip using a 0.5μm CMOS technology. The fabricated integrated circuit executes a two-state Kalman filter employing 70K transistors. For a performance of 50 filter iterations/second, the chip requires a clock frequency of 200 KHz where a negligible power consumption of 1.1mWis observed. This performance can be increased up to 176,991 iterations/second at a clock frequency of 20 MHz