Patent Application
20050086948
This invention relates generally to medical devices. In particular, this invention relates to X-ray detectors with cooling capabilities.
Imaging electronics found inside X-ray detectors generate thermal energy that must be removed in order to maintain a temperature within an operating range at an X-ray panel. Further, the X-ray panel must be kept on during some procedures that require continuous real-time imaging. The constant operation of the X-ray panel results in an equally continuous requirement for removal of the thermal energy.
Approaches for the removal of thermal energy are further constrained by the environment in which X-ray detectors operate. X-ray detectors are often constrained environmentally and dimensionally. Environmentally, the X-ray detectors are often used in sterile environments, such as an operating room and enclosed in a plastic sterile bag or other sealed enclosure when in operation. The sterile environment also affects the ability to use forced air-cooling in the X-ray detector. Further, the plastic sterile bag or other enclosures often insolates the X-ray detector and results in an increase of thermal energy. Dimensionally, the X-ray detector is part of an X-ray unit that often has to be compact and mobile. Such size requirements require the X-ray detectors to be designed with more constrained airflow and less efficient convection cooling.
In the past, thermal energy transfer in X-ray detectors has been accomplished by a temperature conditioner that circulates liquid coolant through a cold plate attached to the X-ray detector. However, this approach increases the size of the X-ray unit and creates additional issues of corrosion and material incompatibility. Further, the liquids used in cooling systems are often regulated by legal agencies such as the Environmental Protection Agency (EPA), thereby limiting their usefulness in some instances.
Therefore, a need exists for cooling X-ray detectors within a sterile environment and constrained area.
Methods and apparatus consistent with the present invention provide temperature regulation for an X-ray detector even when constrained by a sterile environment and within a confined space. The X-ray detector solution is implemented using solid-state devices. As a result, a less expensive temperature regulator allows thermal control over cooling and heating of the X-ray panel within the X-ray detector in order to maintain the temperature within an acceptable thermal range.
In one implementation, two thermally conductive surfaces form an upper and lower surface above and below a number of thermo-electronic devices. The thermo-electronic devices create a thermal gradient when electrical power is applied. When one of the thermally conductive surfaces is connected to an X-ray detector, the other acts as a heat dissipater. Thus, thermal control is achieved by a controller that monitors the temperature in the X-ray detector and adjust the current and voltage polarity in the thermo-electronic devices
Other apparatus, methods, features and advantages of the present invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims.
The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. In the figures, like reference numerals designate corresponding parts throughout the different views.
The invention may be better understood with reference to the following figures. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principals of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views.
While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.
In
When current is applied from the battery 120 to the thermoelectric temperature device 100, a path is created from the battery 120 through the electrode 114, the p-type doped semiconductor material 110, the conductive element 106, the n-type doped semiconductor material 108, electrode 112, and back to the battery 120. A hot junction and cold junction are created by the electrical current flowing through the thermoelectric temperature device 100.
The cold junction occurs at the conductive element 106 and cools the body 102. Heat is pumped to the hot junction, the other conductive element 116, from the cold junction at a rate proportional to the current passing through the electrodes 112 and 114. More precisely, the thermal energy at the thermal conductor 106 is absorbed by electrons as they pass from the low energy level in the p-type doped semiconductor material 110, to a higher energy level in the n-type semiconductor material 108. Upon reversing the current's direction through the electrodes 112 and 114, the hot junction and cold junctions reverse. Therefore, the thermo-electric device 100 may operate in one of two modes (cooling or heating) depending on the direction of the supplied current. The thermo-electric device 100 is shown connected to a battery supplying the current. In alternate embodiments, other type of current generating devices may be used such as a generator, alternator, and solar cells.
Turning to
The heat pipe 214 is in thermal contact with the cold plate 204, while the heat dissipating plate 212 is in thermal contact with the heat pipe 216. The heat pipes 214 and 216 are similarly in contact with each other. Thermal energy generated by the X-ray panel 208 within the X-ray detector is dissipated by the heat dissipating plate 212 and transferred to the cold plate 204 by the heat pipes 214 and 216. The cold plate 204 and heat pipe 216 are thermally isolated from contacting the other electronics 222 by thermal insulation 218 and 220 in order to transfer thermal energy from the X-ray panel 208 through the heat pipes and not through the other electronics 222. The thermal insulation 210, 218, and 220 may be made from an epoxy based insulation material, for example. The heat pipes 214 and 216 may be made out of thermal conducting material identical to the cold plate 204. In other embodiments, the heat pipes may also be made from thermal conducting ceramic material.
The thermo-electric device 100 allows thermal energy to be transferred from the X-ray panel 208 within the X-ray detector without placing possible harmful and corrosive liquids in the X-ray unit. The thermo-electric device 100 also allows a compact X-ray unit to be designed and deployed without increasing risk of infection to patients. Further, the thermo-electric device may be attached directly to the X-ray panel 208 and adjusted to maintain the temperature in the X-ray detector within a predetermined operating range.
A temperature conditioner 3 to 15 meters away from the X-ray detector may be used in conjunction with the thermoelectric device 100 in order to achieve the desired goal of temperature control of the X-ray detector. Examples of a temperature conditioner include a chiller or a heat exchanger. The thermal connection between the X-ray panel 208 in the X-ray detector and the thermoelectrical device may be accomplished with a heat pipe or any other highly conductive material. Further, the X-ray panel may be substantially isolated from the rest of the cooling system allowing additional control of the temperature at the X-ray panel 208 within the X-ray detector.
In
Turning to
The controller 402 may reverse the voltage generated by the power supply 408 and received by the thermoelectric device 406. In one embodiment, the controller 402 activates a switch 410, such as a relay, to reverse the voltage. In an alternate embodiment, a solid-state device may be used to switch the voltage and switch the thermo-electric device from a cooling mode to a heating mode. The controller 402 may be located within the X-ray detector or may be located external to the X-ray detector.
In
If heating is desired, then the voltage is adjusted by reversing the voltage received at the positive and negative inputs of the thermoelectric device 406 (Step 512). The default configuration is with the voltage polarity configured so the thermoelectric device 406 cools the X-ray detector. The amount of cooling is controlled by adjusting the current through the thermoelectric device 406 (Step 514). More current yields increased cooling. If cooling is desired and the voltage is in the default configuration, then the current is adjusted to either decrease or increase cooling (514). If cooling is required and the voltage is configured for heating, then the voltage is reversed. In an alternate embodiment, a fix current is supplied to the thermo-electric device 406.
The process is shown as stopping in
The foregoing description of an implementation of the invention has been presented for purposes of illustration and description. It is not exhaustive and does not limit the invention to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practicing of the invention. For example, the described implementation includes software but the present invention may be implemented as a combination of hardware and software or in hardware alone. Note also that the implementation may vary between systems. The invention may be implemented with both object-oriented and non-object-oriented programming systems. The claims and their equivalents define the scope of the invention.
