BACKGROUND OF THE INVENTION
The subject matter described herein relates generally to imaging
detectors, such as computed tomography (CT) detectors, and more particularly, to a
fault tolerant cooling system for CT detectors.
CT detectors may include a detector rail having a plurality of
detector components positioned thereon. The detector components also may include a
collimator having openings formed therein to direct x-rays emitted from a subject to a
scintillator. The collimator separates the x-rays along the scintillator. The x-rays are
then converted to light waves with a plurality of photodiodes positioned behind the
scintillator. An analog-to-digital converter converts the analog light waves to digital
signals that are then used to generate an image of the subject.
In operation, the detector components may generate a considerable
amount of heat which may affect the operation of the CT detector. For example, the
heat may cause the detector components to shift on the detector rail. As such, the
openings of the collimator may become misaligned with openings in the scintillator,
leading to scatter or noise in the image generated by the CT imaging system.
Additionally, some detector components are sensitive to changes in temperature. For
example, the photodiodes may overheat or become damaged if exposed to large
changes in temperature or cause image artifact due to increased electronic noise due
to leakage current from photodiode and/or A/D device. This may be particularly
problematic given that large amounts of heat may be generated by the analog-todigital
converter which is positioned adjacent to the photodiodes.
Accordingly, at least some known imaging systems include a
cooling system to cool the CT detector. The cooling system may include, for
example, fans, heat sinks, temperature sensors, or the like. In operation, the
temperature sensors provide an indication of the various operational temperatures at
certain points within the cooling system. However, when a single temperature sensor
fails, at least one known imaging system is shut down, A technician may then be
contacted to repair the failed temperature sensor. As a result, a single failed
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temperature sensor may cause the imaging system to be taken out of operation for an
extended period of time until the technician can repair and/or replace the failed
temperature sensor.
SUMMARY OF THE INVENTION
In one embodiment, a liquid cooled thermal control system for a
computed tomography (CT) detector is provided. The control system includes a
plurality of temperature sensors and a control mode selector module coupled to the
plurality of temperature sensors. The control mode selector module is programmed to
receive an input from the plurality of temperature sensors, identify the inputs as either
valid inputs or invalid inputs, and determine an operational mode of the liquid cooled
thermal control system based on the identified inputs.
In another embodiment, a computed tomography (CT) imaging
system is provided. The CT imaging system includes a detector rail, an x-ray detector
positioned on the detector rail, the x-ray detector including a plurality of detector
components, at least some of the detector components configured to detect x-rays, and
a cooling system providing cooling fluid to at least one of the x-ray detector or the
detector rail. The cooling system includes a plurality of temperature sensors and a
control mode selector module coupled to the plurality of temperature sensors. The
control mode selector module is programmed to receive an input from the plurality of
temperature sensors, identify the inputs as either valid inputs or invalid inputs, and
determine an operational mode of the cooling system on the identified inputs.
In a further embodiment, a method of controlling an operation of a
computed tomography (CT) detector cooling system is provided. The method
includes receiving a plurality of temperature sensor inputs from a plurality of
temperature sensors at a control mode selector module, identifying the inputs as either
valid inputs or invalid inputs, and determining an operational mode of the cooling
system based on the identified inputs.
BRIEF DESCRIPTION OF THE DRAWINGS
3
Figure 1 is a schematic diagram of an exemplary cooling system
that may be utilized to provide cooling for a detector in accordance with various
embodiments.
Figure 2 illustrates a detailed block diagram of the cooling system
shown in Figure 1.
Figure 3 is a block diagram of an exemplary fault-tolerant control
system that may be formed in accordance with various embodiments.
Figure 4 is a logic flow chart of an exemplary method of
controlling the operation of the cooling system shown in Figure 1.
[0012] Figure 5 is a table of the logic flow chart shown in Figure 4.
Figure 6 is another logic flow chart of an exemplary method of
controlling the operation of the cooling system shown in Figure 1.
Figure 7 is a table of the logic flow chart shown in Figure 6.
Figure 8 is a graph of an operation of a control mode selector
module in accordance with various embodiments.
Figure 9 is another graph of the operation of the control mode
selector module in accordance with various embodiments.
Figure 10 is a graph illustrating a cooling performance of the
control mode selector module in accordance with various embodiments.
Figure 11 is another graph illustrating a cooling performance of the
control mode selector module in accordance with various embodiments.
Figure 12 is a pictorial drawing of a computed tomography (CT)
imaging system constructed in accordance with various embodiments.
Figure 13 is a schematic block diagram of the CT imaging system
of Figure 12.
DETAILED DESCRIPTION OF THE INVENTION
4
The foregoing summary, as well as the following detailed
description of certain embodiments, will be better understood when read in
conjunction with the appended drawings. To the extent that the figures illustrate
diagrams of the functional blocks of various embodiments, the functional blocks are
not necessarily indicative of the division between hardware circuitry. Thus, for
example, one or more of the functional blocks (e.g., processors, controllers, circuits or
memories) may be implemented in a single piece of hardware or multiple pieces of
hardware. It should be understood that the various embodiments are not limited to the
arrangements and instrumentality shown in the drawings.
As used herein, an element or step recited in the singular and
proceeded with the word "a" or "an" should be understood as not excluding plural of
said elements or steps, unless such exclusion is explicitly stated. Furthermore,
references to "one embodiment" are not intended to be interpreted as excluding the
existence of additional embodiments that also incorporate the recited features.
Moreover, unless explicitly stated to the contrary, embodiments "comprising" or
"having" an element or a plurality of elements having a particular property may
include additional such elements not having that property.
Although various embodiments are described with respect to a
computed tomography (CT) detector, it should be noted that the detector control
system described herein may be modified for use with other detectors or systems. For
example, a fault-tolerant detector control system may be utilized with a Positron
Emission Tomography (PET) system, a Single Photon Emission Computed
Tomography (SPECT) system, a Magnetic Resonance Imaging (MR!) system, and/or
an X-ray system, among others.
Figure 1 is a schematic diagram of an exemplary cooling system
100 that may be utilized to provide cooling for a detector illustrated as a CT detector
102. The cooling system 100 is in thermal communication with a plurality of detector
rails 104 of the CT detector 102. In particular, cooling channels 106 of the cooling
system 100 are in thermal communication with the detector rails 104. In various
embodiments, the cooling channels 106 include a cool channel 108 and a hot channel
110. In one embodiment, the cooling channels 106 may extend through the detector
rails 104. Optionally, a cold plate (not shown) may be coupled to the detector rails
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104 and the cooling channels 106 may extend through the cold plate. In another
embodiment, the cooling channels 106 may be configured to extend both through the
detector rails 104 and the cold plate. The cooling channels 106 have cooling fluid
flowing therethrough, which may be any suitable cooling fluid (e.g. liquid or gas).
In various embodiments, the cooling system 100 includes an
accumulator 120 and a pump 122 that are positioned downstream from the cooling
channels 106. In operation, the accumulator 120 receives cooling fluid from the
cooling channels 106. The amount of cooling fluid received in the accumulator 120
may depend on a pressure of the cooling fluid within the cooling system 100, as
described below. The pump 122 is positioned downstream of the accumulator 120 to
control a flow of the cooling fluid thorough the cooling system 100. The pump 122
may be a single speed pump or a variable speed pump.
In operation, the pump 122 discharges the cooling fluid
downstream to a heat exchanger 124. The heat exchanger 124 may be any suitable
heat exchanger, for example, an air-to-liquid heat exchanger or a liquid-to-liquid heat
exchanger. In the illustrated embodiment, the heat exchanger 124 is an air-to-liquid
heat exchanger having a fan 126. The cooling fluid flows from the heat exchanger
124 downstream to an inline heater 128. The inline heater 128 may be an electric
heater, a gas heater, or any other suitable heater. The inline heater 128 discharges the
cooling fluid downstream to the cooling channels 106.
During operation, the cooling channels 106 receive the cooling
fluid from the inline heater 128. The cooling fluid is provided at a predetermined
temperature that is configured to maintain a temperature of the detector rails 104.
More specifically, the cooling fluid in the cool channels 108 cools the detector rails
104 by receiving heat from the detector rails 104 through at least one of thermal
conduction or convection. The heated cooling fluid then flows through the hot
channels 110 downstream to the accumulator 120. The accumulator 120 stores a
portion of the cooling fluid based on a pressure within the cooling system 100. For
example, when the cooling system 100 is operating at a higher pressure, the
accumulator 120 may store more cooling fluid than when the cooling system 100 is
operating at a lower pressure. The accumulator 120 stores the cooling fluid to
maintain a substantially constant operating pressure of the cooling system 100. The
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accumulator 120 accounts for expansion of the cooling fluid at high pressures and
may be utilized to pressurize the pump 122, thereby, preventing cavitation within the
pump 122.
The pump 122 receives cooling fluid from the accumulator 120.
The pump 122 may be a variable speed pump that is controlled to adjust an amount of
cooling fluid discharged to the heat exchanger 124. By controlling a speed of the
pump 122, a temperature of the cooling fluid may be controlled. For example,
increasing a speed of the pump 122 increases the liquid flow rate as the cooling fluid
travels through the heat exchanger 124, which increases the cooling rate. Conversely,
decreasing a speed of the pump 122 decreases the liquid flow rate as the cooling fluid
flows through the heat exchanger 124, which decreases the cooling rate. In one
embodiment, the pump 122 discharges the cooling fluid to the heat exchanger 124 at a
flowrate that is configured to achieve the predetermined temperature of the cooling
fluid.
In the illustrated embodiment, the heat exchanger 124 receives the
cooling fluid from the pump 122. The heat exchanger 124 reduces the temperature of
the cooling fluid to a temperature that is below the predetermined temperature. The
fan 126 of the heat exchanger 124 may be controlled to adjust the temperature of the
cooling fluid. For example, the fan 126 may be operated at a higher speed to reduce
the temperature of the cooling fluid. Conversely, the fan 126 may be operated at a
lower speed to increase the temperature of the cooling fluid. More specifically, under
non-fault conditions, the fan 126 is used to control heat exchanger outlet liquid
temperature to the predetermined heat exchanger outlet liquid temperature. Under
non-fault condition, the inline heater 128 is used to control the inline heater outlet
liquid temperature to the predetermined inline heater outlet liquid temperature. The
power supplied to the inline heater 128 may be controlled to adjust the temperature of
the cooling fluid. By adjusting the power supplied to the inline heater 128, the heat
produced by the inline heater 128 is adjusted. For example, the inline heater 128 may
be operated at a higher power to increase the temperature of the cooling fluid.
Conversely, the inline heater 128 may be operated at a lower power to reduce the
temperature of the cooling fluid. The inline heater 128 discharges the cooling fluid
7
into the cool channels 106 at the predetermined temperature to maintain a temperature
of the detector rails 104.
Accordingly, in various embodiments, the cooling system 100 is
utilized to maintain a temperature of the detector rails 104 at a steady-state
temperature. Moreover, the cooling system 100 facilitates reducing or preventing
changes in the temperature of the detector rails 104. The cooling system 100 may
adjust several parameters to control the temperature of the cooling fluid. For
example, any one of a speed of the pump 122, a speed of the fan 126, or a power of
the inline heater 128 may be adjusted to achieve the predetermined temperature of the
cooling fluid.
Figure 2 illustrates a detailed block diagram of the cooling system
100 shown in Figure 1. As described above, the cooling system 100 includes the
accumulator 120, the pump 122, the heat exchanger 124, the fan 126, and the inline
heater 128. The cooling system 100 also includes a plurality of temperature sensors
that are disposed at various positions in the cooling system 100. In various
embodiments, the cooling system includes a first air temperature sensor 150 and a
second air temperature sensor 152. In the exemplary embodiment, the first and
second air temperature sensors 150 and 152 are disposed proximate to the fan 126 and
are configured to output an electrical signal that indicates a temperature of the air
entering the heat exchanger 124, i.e. the ambient air temperature. In various
embodiments, the temperature sensors 150 and 152 therefore are redundant
temperature sensors which each indicate the ambient air temperature.
The cooling system 100 also includes a third temperature sensor
154 and a fourth temperature sensor 156. In the exemplary embodiment, the third and
fourth temperature sensors 154 and 156 are disposed proximate to an inlet of the heat
exchanger 124 and are configured to output an electrical signal that indicates a
temperature of the cooling fluid entering the heat exchanger 124. In various
embodiments, the temperature sensors 154 and 156 therefore are redundant
temperature sensors which each indicate the temperature of the cooling fluid entering
the heat exchanger 124.
8
The cooling system 100 also includes a fifth temperature sensor
158 and a sixth temperature sensor 160. In the exemplary embodiment, the fifth and
sixth temperature sensors 158 and 160 are disposed proximate to an outlet of the heat
exchanger 124 and are configured to output an electrical signal that indicates a
temperature of the cooling fluid being discharged from the heat exchanger 124 and
thus the temperature of the cooling fluid entering the inline heater 128. In various
embodiments, the temperature sensors 158 and 160 therefore are redundant
temperature sensors which each indicate the temperature of the cooling fluid being
discharged from the heat exchanger 124.
The cooling system 100 also includes a seventh temperature sensor
162. In the exemplary embodiment, the seventh temperature sensor 162 is disposed
proximate to an outlet of the inline heater 128 and is configured to output an electrical
signal that indicates a temperature of the cooling fluid being discharged from the
inline heater 128. In various embodiments, the cooling system 100 may also include
an eighth temperature sensor (not shown) that also indicates a temperature of the
cooling fluid being discharged from the inline heater 128. It should be realized that
the temperature sensors shown in Figure 2 are exemplary, and that the cooling system
100 may include additional temperature sensors not shown in Figure 2. For example,
the cooling system 100 may include additional temperature sensors that are installed
in other positions on the cooling system 100.
The cooling system 100 includes a fan speed controller 170. In
operation, the fan speed controller 170 is configured to control the operation of the
fan 126. More specifically, the fan speed controller 170 is configured to transmit a
signal 172 to the fan 126 that either increases, decreases, or maintains the operational
speed of the fan 126. The cooling system 100 also includes a heater controller 174.
In operation, the heater controller 174 is configured to control the operation of the
inline heater 128. More specifically, the heater controller 174 is configured to
transmit a signal 176 to the inline heater 128 that either increases, decreases, or
maintains the operational temperature of the fluid being discharged from the inline
heater 128.
Figure 3 is a block diagram of an exemplary fault-tolerant control
system 200 that may be utilized to control the operation of a cooling system, such as
9
for example, the cooling system 100 shown in Figures 1 and 2. In various
embodiments, the control system 200 includes an analog-to-digital (A/D) converter
202. In operation, the A/D converter 202 receives analog data from the sensors
detectors 150-162 and converts the analog signals to digital signals for subsequent
processing. In various embodiments, the digital signals output from the A/D
converter 202 are input to a control mode selector module 204. In operation, the
control mode selector module 204 is configured to receive digital inputs from the A/D
converter 202 and then select and implement a control mode based on the received
digital signals. The control mode selector module 202 may be implemented as a piece
of hardware, such as a processor 206. Optionally, the control mode selector module
204 may be implemented as a set of instructions that are installed on the processor
206. The set of instructions may be stand alone programs, may be incorporated as
subroutines in an operating system installed on the processor 206, may be functions
that are installed in a software package on the processor 206, or may be a combination
of software and hardware. It should be understood that the various embodiments are
not limited to the arrangements and instrumentality shown in the drawings.
In operation, the control mode selector module 204 is configured to
perform various methods described herein. Accordingly, the control mode selector
module 204 may operate the cooling system in various operational modes or
configurations based on the inputs received from the sensors 150-162. For example,
in various embodiments, the control mode selector module 204 is configured to
control a temperature of the cooling fluid entering the detector 102 using all of the
sensors 150-162, a portion of the sensors 150-162, or only one of the sensors 150-162.
Accordingly, the control mode selector module 204 enables the cooling system to
remain operational when a single sensor has failed or multiple sensors have failed. In
various embodiments, the control mode selector module 204 is configured to maintain
the operational availability of the cooling system 100 using a plurality of valid sensors
or only a single valid temperature sensor by changing the control scheme of the
cooling system 100 while maintaining the temperature control for the detector 102.
For example, in various embodiments, the control mode selector
module 204 is configured to detect sensor failures. More specifically, the control
mode selector module 204 is configured to identify whether the sensors 150-162 are
10
"valid" or "invalid". The term "invalid" as used herein refers to a sensor that is
outputting a signal that is not representative of the actual temperature at the point
where the sensor is located. In contrast, the term "valid" as used herein refers to a
sensor that is outputting a signal that is representative of the actual temperature at the
point where the sensor is located. For example, if the actual temperature of the air
inlet to heat exchanger 124 is 80 degrees and the temperature sensor 150 is outputting
a signal that indicates the air temperature is 30 degrees, the control mode selector
module 204 is configured to identify the temperature sensor 150 as an "invalid"
temperature sensor. In contrast, if the actual temperature of the air inlet to heat
exchanger 124 is 80 degrees and the temperature sensor 150 is outputting a signal that
indicates the air temperature is 78 degrees, the control mode selector module 204 is
configured to identify the temperature sensor 150 as a "valid" temperature sensor.
Thus a sensor may be considered valid when the output form the sensor falls within a
predetermined range of values.
In various embodiments, the control mode selector module 204
may identify a sensor as "invalid" or "valid" based on comparing the output from the
sensor to the outputs from other sensors and a priori information. For example, both
temperature sensors 150 and 152 are used to provide a temperature of the air input to
the heat exchanger 124. Accordingly, if the temperature sensor 150 is outputting 80
degrees and the temperature sensor 152 is outputting 20 degrees, the control mode
selector module 204 may indicate that the temperature sensor 150 is "valid" and the
temperature sensor 152 is "invalid". Moreover, to identify "invalid" and "valid"
temperature sensors, the control mode selector module 204 may compare the outputs
from other temperature sensors to each other or use a priori scales or tables of
expected temperature values to identify "valid" and "invalid" temperature sensors.
In various embodiments, the control mode selector module 204 is
also configured to average the temperature values output from various sensors
together to generate an average temperature value at some locations. For example, as
discussed above, the sensors 150 and 152 are each configured to output a signal that
indicates the temperature of air entering the heat exchanger 124. Thus, the
temperature sensor 152 is redundant to the temperature sensor 150. Accordingly, in
the exemplary embodiment, the control mode selector module 204 is configured to
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initially identify whether the temperature sensors 150 and 152 are invalid or valid and
then use this information to generate an average air temperature reading Tairavg 250.
For example, assume that both temperature sensors 150 and 152
are determined to be "valid" temperature sensors. Moreover, assume that temperature
sensor 150 is outputting a signal indicating a temperature of 78 degrees and the
temperature sensor 152 is outputting a signal indicating a temperature of 82 degrees.
In the exemplary embodiment, the control mode selector module 204 generates a
Tairavg 250 having a value of 80 degrees. In one embodiment, if the control mode
selector module 204 determines that the temperature sensor 150 is invalid and the
temperature sensor 152 is valid, the control mode selector module 204 is configured
to set the Tairavg 250 output equal to the temperature sensor 152 output, i.e. 82 degrees.
In another embodiment, if the control mode selector module 204 determines that the
temperature sensor 152 is invalid and the temperature sensor 150 is valid, the control
mode selector module 204 is configured to set the Tairavg 250 output equal to the
temperature sensor 150 output, i.e. 78 degrees. In a further embodiment, if the control
mode selector module 204 determines that the temperature sensors 150 and 152 are
each invalid, the control mode selector module 204 is configured to identify Tairavg
250 as invalid information. The use of the invalid information is described in more
detail below.
The control mode selector module 204 is also configured to
average the values output from the sensors 154 and 156. For example, as discussed
above, the sensors 154 and 156 are each configured to output a signal that indicates
the temperature of the cooling fluid entering the heat exchanger 124. Thus, the
temperature sensor 154 is redundant to the temperature sensor 156. Accordingly, and
as described above with respect to the temperature sensors 150 and 152, the control
mode selector module 204 initially identifies whether the temperature sensors 154 and
156 are valid or invalid and then uses this information to generate an average air
temperature reading Thxk-avg 252.
Accordingly, if the temperature sensors 154 and 156 are each valid,
Thxin-avg 252 is an average value of the outputs from both temperatures sensors 154
and 156. If temperature sensor 154 is invalid, Thxin-avg 252 is set equal to temperature
sensor 156. If temperature sensor 156 is invalid, Thxin-avg 252 is set equal to
12
temperature sensor 154. Moreover, if both temperature sensors 154 and 156 are
invalid, the control mode selector module 204 is configured to identify Thxin-avg 252 as
invalid information.
The control mode selector module 204 is also configured to
average the values output from the sensors 158 and 160. For example, as discussed
above, the sensors 158 and 160 are each configured to output a signal that indicates
the temperature of the cooling fluid being discharged from the heat exchanger 124.
Thus, the temperature sensor 158 is redundant to the temperature sensor 160.
Accordingly, and as described above with respect to temperature sensors 150 and 152,
the control mode selector module 204 initially identifies whether the temperature
sensors 158 and 160 are invalid or valid and then uses this information to generate an
average temperature reading Thxout-avg 254.
Accordingly, if the temperature sensors 158 and 160 are each valid,
Thxout-avg 254 is an average value of the outputs from both temperatures sensors 158
and 160. If temperature sensor 158 is invalid, Thxout-avg 254 is set equal to the
temperature sensor 160. If temperature sensor 160 is invalid, Thxout-avg 254 is set equal
to the temperature sensor 158. Moreover, if both temperature sensors 158 and 160 are
invalid, the control mode selector module 204 is configured to identify Thxout-avg 254
as invalid information.
In the exemplary embodiment, the cooling system 100 includes
only a single sensor, sensor 162 that indicates a temperature of the fluid being
discharged from the inline heater 128. Accordingly, in the exemplary embodiment,
the selector module 204 is also configured to generate a signal Thbout-avg 256 that is set
equal to the output from temperature sensor 162 assuming that the temperature sensor
162 is determined to be valid. If the temperature sensor 162 is invalid, the control
mode selector module 204 is configured to identify Thbout-avg 256 as invalid
information.
In various embodiments, the control mode selector module 204 is
also configured to generate an initial temperature difference (ITD) signal 258 that
indicates a temperature difference between the average air temperature entering the
heat exchanger 124 (Tajr-avg 250) and the temperature of the cooling fluid entering the
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heat exchanger 124 (Thxin-avg 252). In the exemplary embodiment, ITD 258 = Thxin-avg
252 - Tair-avg 250. The control mode selector module 204 therefore generates various
temperature values that are indicative of the temperature of the air and/or cooling
fluid at various points in the cooling system 100. Although the exemplary
embodiment, is described with respect to temperatures Tair-avg 250, Thxin-avg 252, Thxoutavg
254, Thbout-avg 256, and ITD 258, it should be realized that other combinations or
temperature sensors may be utilized and that the temperatures Tair-avg 250, Thxin-avg
252, Thxout-avg 254, Thbout-avg 256, and ITD 258 are exemplary only. Accordingly, in
the exemplary embodiment, the control mode selector module 204 is configured to
identify each of the sensors 150-162 as either "valid" or "invalid" and generate the
signals Tak-avg 250, Thxin-avg 252, Thxout-avg 254, Thbout-avg 256, and ITD 258 as described
above.
In various embodiments, at least a portion of the outputs from the
sensors 150-162 are utilized by the fault-tolerant control system 200 to maintain the
operational temperature of the cooling fluid and thus maintain a temperature of the
detector rails 104 at the steady-state temperature. More specifically, the control mode
selector module 204 is configured to utilize the sensor inputs 150-162, and the valid
and invalid information derived for each of the sensor inputs 150-162 to select and
implement an operational control mode based on the signals. In operation, the control
mode selector module 204 is configured to generate a signal 270 to control the
operation of the fan controller 170. The control mode selector module 204 is also
configured to generate a signal 272 to control the operation of the heater controller
174.
Figure 4 is a logic flowchart 300 illustrating an exemplary
embodiment of a method to control the operation of the fan controller 170, and thus
the operation of the fan 126. In various embodiments, the logic flowchart 300 may be
implemented as a set of instructions that are installed on the control mode selector
module 204. Figure 5 is an exemplary table 302 illustrating the different operational
modes that may be selected by the control mode selector module 204 based on the
received inputs. In various embodiments, the control mode selector module 204 is
configured to utilize a first subset of the sensors 150-162 to control the operation of
the fan 126. In various embodiments, the first subset includes Thxin-avg 252, Thxout-avg
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254,
Thbout-avg 256, and Tair-avg 250. As shown in Figures 4 and 5, the label A in the
flow chart 300 is the Thxin-avg 252, the label B is the Thxout-avg 254, the label C is the
Thbout-avg 256, and the label D is the Tair-avg 250. Optionally, label A may also be the
ITD 258. Moreover, in the table 302, the label 0 in the columns for the various
sensors indicates that the sensor information is valid. For example, as shown in Table
302, the Tak-avg 250 value of "0" indicates that at least one of the air sensors 150 or
152 is generating valid information, etc. Moreover, the label " 1 " indicates that neither
of the air sensors 150 or 152 is generating valid information, thus the average air
sensor output Tair-avg 250 is invalid information.
In operation, at 310, the inputs A, B, C, and D are received. At
312, the control mode selector module 204 determines if either the inputs A, B, and D
are valid. In one embodiment, if the inputs A, B, and D are valid inputs, the control
mode selector module 204 is configured to operate the fan controller 170 in Mode 1.
In Mode 1, the control mode selector module 204 is configured to generate a signal,
such as the signal 270, shown in Figure 3 that is used to control the cooling fluid
temperature output from the heat exchanger 124. In various embodiments, and as
shown in the table of Figure 5, the signal 270 is a gain scheduled signal that is
calculated based on a difference in the cooling fluid temperature and the air
temperature at the heat exchanger 124. At 312, if control mode selector module 204
determines that any of the inputs A, B, and D are invalid, the method proceeds to 314.
At 314, the control mode selector module 204 is configured to
determine if the input A or the input D are valid inputs. In one embodiment, if either
the input A or the input D is a valid input, the control mode selector module 204 is
configured to operate the fan controller 170 in Mode 2. In Mode 2, the control mode
selector module 204 is configured to generate a signal, such as the signal 270, shown
in Figure 3 that is used to control the cooling fluid temperature output from the heat
exchanger 124. In various embodiments, and as shown in the table of Figure 5, the
signal 272 is not a gain scheduled signal, but rather is a baseline signal that is
generated based on the difference in the cooling fluid temperature and the air
temperature at the heat exchanger 124. At 314, if the control mode selector module
204 determines that neither of the inputs A or D is valid, the method proceeds to 316.
15
At 316, the control mode selector module 204 is configured to
determine if the input B is invalid and the input C is valid. In one embodiment, if the
input B is invalid and the input C is valid, the control mode selector module 204 is
configured to operate the fan controller 170 in Mode 3. In Mode 3, the control mode
selector module 204 is configured to generate a signal, such as the signal 270, shown
in Figure 3 that is used to control the cooling fluid temperature output from the heat
exchanger 124. In various embodiments, and as shown in the table of Figure 5, the
signal 270 is based on the heater outlet liquid temperature Thbout-avg 256. More
specifically, the Thbout-avg 256 signal is used to regulate the operation of the fan
controller 170 to maintain the temperature of the cooling fluid at the predetermined
temperature. At 316, if control mode selector module 204 determines that neither of
the B is valid or C is invalid, the method proceeds to 318.
At 318, the control mode selector module 204 is configured to
determine if the input A is valid and the inputs B and C are invalid. In one
embodiment, if the input A is valid and the inputs B and C are invalid, the control
mode selector module 204 is configured to operate the fan controller 170 in Mode 4.
In Mode 4, the control mode selector module 204 is configured to generate a signal,
such as the signal 270, shown in Figure 3 that is used to control the cooling fluid
temperature output from the heat exchanger 124. In various embodiments, and as
shown in the table of Figure 5, the signal 270 is based on the heat exchanger inlet
liquid temperature Thxin-avg 252 because the heat exchanger outlet temperature ThxoutaVg
254 and the inline heater temperature Thbout-avg 256 are not available or are invalid.
More specifically, the Thxin-avg 252 signal is used to regulate the operation of the fan
controller 170 to maintain the temperature of the cooling fluid at the predetermined
temperature. At 318, if control mode selector module 204 determines that the input A
is invalid and the inputs B and C are valid, the method proceeds to 320.
At 320, the control mode selector module 204 is configured to
determine if the inputs A, B, and C are invalid. In one embodiment, if the inputs A,
B, and C are invalid, the control mode selector module 204 is configured to operate
the fan controller 170 in Mode 5. In Mode 5, also referred to herein as the Equipment
protection mode, the control mode selector module 204 is configured to generate a
signal, such as the signal 270, shown in Figure 3 that is used to control the cooling
16
fluid temperature output from the heat exchanger 124. In various embodiments, and
as shown in the table of Figure 5, the signal 270 is configured to set the operational
speed of the fan 126 to for example 75% of the rated fan speed or whatever is
applicable to keep the acoustic noise acceptable for system. Moreover, the control
mode selector module 204 is configured to send the signal 272 to the heater controller
174 to shut down the inline heater 128. Thus, when the temperatures cannot be
determined for the heat exchanger inlet or outlet cooling fluid temperature and the
inline heater outlet temperature are not available, the control mode selector module
204 operates the cooling system in the equipment protection mode as described
above. At 320, if the control mode selector module 204 determines that any of the
inputs A, B, or C are valid, the method proceeds to 322, wherein the operation of the
cooling system 100 is maintained in its present mode of operation, and a technician is
contacted to evaluate the operation of the cooling system 100. At 324, the program
ends.
Figure 6 is a logic flowchart 350 illustrating an exemplary
embodiment of a method to control the operation of the heater controller 174, and
thus the operation of the inline heater 128. The logic flowchart 350 may be
implemented as a set of instructions that are installed on the control mode selector
module 204. Figure 7 is an exemplary table 352 illustrating the different operational
modes that may be selected by the control mode selector module 204 based on the
received inputs. In various embodiments, the control mode selector module 204 is
configured to utilize a second subset of the sensors 150-162 to control the operation of
the inline heater 128. In various embodiments, the second subset includes Thxin-avg
252, Thxout-avg 254, and Thbout-avg 256. In the exemplary embodiment, and as shown in
Figures 6 and 7, the label A in the flow chart 350 is the inline heater output
temperature Thbout-avg 256, the label B is the heat exchanger output temperature Thxoutavg
254, and the label C is the heat exchanger input temperature Thxin-avg 252.
Moreover, in the table 352, the label 0 in the columns for the various sensors indicates
that the sensor information is valid. For example, as shown in Table 352, the Thxin-avg
252 value of "0" indicates that at least one of the temperature sensors 154 or 156 is
generating valid information, etc. Moreover, the label " 1 " indicates that neither of the
temperature sensors 154 or 156 is generating valid information, thus the average heat
exchanger inlet temperature Thxin-avg 252 is invalid information.
17
Referring again to Figure 6, at 360, the inputs A, B, and C are
received. At 362, the control mode selector module 204 determines if the input A is
valid. In one embodiment, if the input A is valid, the control mode selector module
204 is configured to operate the heater 174 in Mode 1. In Mode 1, also referred to
herein as the baseline mode, the control mode selector module 204 is configured to
generate a signal, such as the signal 272, shown in Figure 3 that is used to control the
operation of the inline heater 128 and thus control the temperature of the cooling fluid
being discharged from the inline heater 128. In various embodiments, when the inline
heater output temperature signal Thbout-avg 256 is valid, the inline heater 128 is adjusted
based on the temperature of the cooling fluid output from the inline heater 128, i.e. the
Thbout-avg 256 is used to adjust the inline heater 128. At 362, if the control mode
selector module 204 determines that the input A is invalid, the method proceeds to
364.
At 364, the control mode selector module 204 is configured to
determine if the input A is invalid and the input B is valid. In one embodiment, if the
input A is invalid and the input B is valid, the control mode selector module 204 is
configured to operate the heater 128 in Mode 2. In Mode 2, the control mode selector
module 204 is configured to generate a signal, such as the signal 272, shown in Figure
3 that is used to control the operation of the inline heater 128 and thus control the
temperature of the cooling fluid being discharged from the inline heater 128. In
various embodiments, when the inline heater output temperature signal Thbout-avg 256
is invalid and the heat exchanger outlet temperature Thxout-avg 254 is available, the
inline heater 128 is adjusted based on the temperature of the cooling fluid output from
the heat exchanger 124, i.e. the Thxout-avg 254 signal is used to adjust the inline heater
128. At 364, if control mode selector module 204 determines that the input A is
invalid and the input B is invalid, the method proceeds to 366.
At 366, the control mode selector module 204 is configured to
determine if the inputs A and B are invalid and the input C is valid. In one
embodiment, if the inputs A and B are invalid and the input C is valid, the control
mode selector module 204 is configured to operate the heater 128 in Mode 3. In
Mode 3, the control mode selector module 204 is configured to generate a signal, such
as the signal 272, shown in Figure 3 that is used to control the operation of the inline
18
heater 128 and thus control the temperature of the cooling fluid being discharged from
the inline heater 128. In various embodiments, when the inline heater output
temperature signals Thx0ut-avg 254 and Thbom-avg 256 is invalid and the heat exchanger
inlet temperature Thxk-avg 252 is available, the inline heater 128 is adjusted based on
the temperature of the cooling fluid input to the heat exchanger 124, i.e. the Thxk-avg
252 signal is used to adjust the inline heater 128.
At 368, the control mode selector module 204 determines if the
inputs A, B, and C are invalid. In one embodiment, if the inputs A, B, and C are
invalid, the control mode selector module 204 is configured to operate the inline
heater in Mode 4. In Mode 4, also referred to herein as the equipment protection
mode, the control mode selector module 204 is configured to generate a signal, such
as the signal 172, shown in Figure 3 that is used to control the cooling fluid
temperature output from the heat exchanger 124. In various embodiments, and as
shown in the table of Figure 5, the signal 172 is configured to set the operational
speed of the fan 126 to 75% of the rated fan speed (or appropriate default speed to
keep acoustic noise within requirements). Moreover, the control mode selector
module 204 is also configured to send the signal 272 to the heater controller 174 to
shut down the inline heater 128. Thus, when the temperatures can not be determined
for the heat exchanger inlet, the heat exchanger outlet, or the inline heater outlet, the
control mode selector module 204 operates the cooling system in the equipment
protection mode as described above. At 370, if control mode selector module 204
determines that any of the inputs A, B, or C are indeterminate, the operation of the
cooling system 100 is maintained in its present mode of operation, and a technician is
contacted to evaluate the operation of the cooling system 100. At 364, the program
ends.
Figure 8 is a graph 400 representative of the performance of the
control mode selector module 204. The x-axis 402 illustrates time in seconds and the
y-axis 404 illustrates the various fan modes that may be selected by the control mode
selector module 204. As shown in the graph 400, the line 406 illustrates the various
modes of operation that be utilized to operate the fan 126 as shown in the flowchart of
Figure 4. In operation, the control mode selector module 204 substantially
continuously monitors the operator of the sensors 150-162 to determine whether the
19
sensors are valid or invalid. As shown in Figure 8, the control mode selector module
is able to shift the operational mode of the cooling system 100 in a short period of
time after a sensor is identified as invalid.
Figure 9 is another graph 410 representative of the operation of the
inline heater 128. The x-axis 412 illustrates time in seconds and the y-axis 414
illustrates the various inline heater modes that may be selected by the control mode
selector module 204. As shown in the graph 410, the line 416 illustrates the various
modes of operation that be utilized to operate the inline heater 128 as shown in the
flowchart of Figure 6. As shown in Figure 9, the control mode selector module is able
to shift the operational mode of the cooling system 100 in a short period of time after
a sensor is identified as invalid.
Figure 10 is a graph 420 that illustrates the cooling performance of
the control mode selector module 204 wherein an x-axis 422 is time and a y-axis is an
outlet temperature of the cooling fluid being discharged from the heat exchanger 124
in degrees Celsius. Moreover, a value 426 represents a baseline temperature, or a
predetermined temperature, at which the user desires to maintain the cooling fluid. A
line 428 is a temperature at which the cooling fluid is maintained without the use of
the control mode selector module 204 described above. A line 430 is an actual
temperature at which the cooling fluid is maintained utilizing the control mode
selector module 204 as described above. As shown in Figure 10, the line 428
fluctuates from the baseline temperature 426 when the control mode selector module
204 is not utilized. However, when the control mode selector module 204 is utilized,
the actual temperature, shown by the line 430, is maintained substantially equal to the
desired temperature shown by the line 426.
Figure 11 is a graph 440 that illustrates the cooling performance of
the control mode selector module 204 wherein an x-axis 442 is time and a y-axis is a
frame temperature of the detector shown in Figure 1 in degrees Celsius. Moreover, a
line 446 is a baseline temperature, or a predetermined temperature, at which the user
desires to maintain the frame temperature. A line 448 is a temperature at which the
cooling fluid is maintained without the use of the control mode selector module 204
described above. A line 450 is an actual temperature at which the cooling fluid is
maintained utilizing the control mode selector module 204 described above. As
20
shown in Figure 11, the line 448 fluctuates from the baseline temperature 446 when
the control mode selector module 204 is not utilized. However, when the control
mode selector module 204 is utilized, the actual temperature, shown by the line 450 is
maintained substantially equal to the desired temperature shown by the line 446.
Described herein is an exemplary control mode selector module
that is configured to receive inputs from a plurality of temperature sensors monitoring
a detector cooling system. The control mode selector module is programmed to
automatically determine whether the temperature sensors are generating valid or
invalid information. The control mode selector module is further programmed to
automatically configure the cooling system in various operational modes based on the
validity or invalidity of the information received from the temperature sensors.
A technical effect of various embodiments described herein is to
provide a control scheme that provides fault tolerant control for any temperature
sensor failure. The fault tolerant control is configured to maintain the cooling system
availability using only a single operational temperature sensor. More specifically, the
control scheme operates in various operational modes depending on the availability
and location of the temperature sensors. As one or more temperature sensors fail, the
control scheme enables the cooling system to remain operational until only a single
operational temperature sensor is indicated to be a valid temperature sensor. The
control scheme, in various embodiments, utilizes gain scheduling to vary the fan
speed using a Proportional-Integral-Derivative (PID) control scheme when all the
sensors are available. As the sensors fail the control mode is changed to achieve the
required temperature control. Therefore, using multiple temperature sensors provide
redundancy and enables the cooling system to be reconfigured to different operational
modes based on the validity or invalidity of the various temperature sensors.
The various methods and the control mode selector module may be
implemented in an exemplary imaging system. For example, Figure 12 is a pictorial
view of a multi-modality imaging system that is formed in accordance with various
embodiments. Figure 13 is a block schematic diagram of a portion of the multimodality
imaging system shown in Figure 12. Although various embodiments are
described in the context of an exemplary dual modality imaging system that includes
a CT imaging system and a positron emission tomography (PET) imaging system, it
21
should be understood that other imaging systems capable of performing the functions
described herein are contemplated as being used.
Referring to Figures 12 and 13, a multi-slice scanning imaging
system, for example, a CT imaging system 500 is shown as including a plurality of
the detectors 502 and in which the various embodiments may be implemented. The
system 500 may be used with the liquid cooled thermal control systems described
above. The CT imaging system 500 includes a gantry 504, which includes an x-ray
source 506 (also referred to as an x-ray source 506 herein) that projects a beam of xrays
508 toward a detector array 510 on the opposite side of the gantry 504. A
cooling system, for example, the cooling system 100 described above, is in thermal
contact with the detector array 510. The detector array 510 is formed by a plurality of
detector rows (not shown) including a plurality of the detectors 502 that together
sense the projected x-rays that pass through an object, such as a medical patient 512
between the array 510 and the source 506. Each detector 502 produces an electrical
signal that represents the intensity of an impinging x-ray beam and hence can be used
to estimate the attenuation of the beam as the beam passes through the patient 512.
During a scan to acquire x-ray projection data, the gantry 504 and the components
mounted therein rotate about a center of rotation 514. Figure 13 shows only a single
row of detectors 502 (i.e., a detector row). However, the multi-slice detector array
510 includes a plurality of parallel detector rows of detectors 502 such that projection
data corresponding to a plurality of quasi-parallel or parallel slices can be acquired
simultaneously during a scan.
Rotation of components on the gantry 504 and the operation of the
x-ray source 506 are controlled by a control mechanism 516 of the CT imaging
system 500. The control mechanism 516 includes an x-ray controller 518 that
provides power and timing signals to the x-ray source 506 and a gantry motor
controller 520 that controls the rotational speed and position of components on the
gantry 504. A data acquisition system (DAS) 522 in the control mechanism 516
samples analog data from the detectors 502 and converts the data to digital signals for
subsequent processing. An image reconstructor 524 receives sampled and digitized xray
data from the DAS 522 and performs high-speed image reconstruction. The
reconstructed image is applied as an input to a computer 526 that stores the image in a
22
storage device 528. The image reconstructor 524 can be specialized hardware or
computer programs executing on the computer 526. In various embodiments, the
computer 526 may include the control mode selector module 204 described above.
The computer 526 also receives commands and scanning
parameters from an operator via a console 530 that has a keyboard and/or other user
input and/or marking devices, such as a mouse, trackball, or light pen. An associated
display 532, examples of which include a cathode ray tube (CRT) display, liquid
crystal display (LCD), or plasma display, allows the operator to observe the
reconstructed image and other data from the computer 526. The display 532 may
include a user pointing device, such as a pressure-sensitive input screen. The operator
supplied commands and parameters are used by the computer 526 to provide control
signals and information to the DAS 522, x-ray controller 518, and gantry motor
controller 520. In addition, the computer 526 operates a table motor controller 534
that controls a motorized table 536 to position the patient 512 in the gantry 504. For
example, the table 536 moves portions of the patient 512 through a gantry opening
538.
Various embodiments provide a thermal control system that may
be mounted to and receive heat from detector rails and/or cold plates to receive heat
from the detector components. The thermal control system has a controlled
temperature (e.g. substantially constant temperatures) cooling fluid circulating
therethrough to maintain the detector rails at a substantially constant predetermined
temperature, for example, in response to one or more temperature sensor failures. The
cooling fluid temperature is controlled in various embodiments using a heat
exchanger, a fan directing air through the heat exchanger, an inline heater, and a
pump that act as actuators for temperature control. A fan speed of the fan may be
controlled using a control module based the cooling fluid temperature desired and
actually measured. The inline heater power also may be modulated to control the
cooling fluid temperature supplied to the detector rails. A pump speed also may be
controlled to achieve a required cooling fluid flow rate through the thermal control
system. At least one technical effect of some embodiments is maintaining a
substantially constant detector electronics temperature.
23
Various embodiments described herein provide a tangible and nontransitory
machine-readable medium or media having instructions recorded thereon
for a processor or computer to operate an imaging apparatus to perform an
embodiment of a method described herein. The medium or media may be any type of
CD-ROM, DVD, floppy disk, hard disk, optical disk, flash RAM drive, or other type
of computer-readable medium or a combination thereof.
The various embodiments and/or components, for example, the
modules, or components and controllers therein, also may be implemented as part of
one or more computers or processors. The computer or processor may include a
computing device, an input device, a display unit and an interface, for example, for
accessing the Internet. The computer or processor may include a microprocessor.
The microprocessor may be connected to a communication bus. The computer or
processor may also include a memory. The memory may include Random Access
Memory (RAM) and Read Only Memory (ROM). The computer or processor further
may include a storage device, which may be a hard disk drive or a removable storage
drive such as a floppy disk drive, optical disk drive, and the like. The storage device
may also be other similar means for loading computer programs or other instructions
into the computer or processor.
As used herein, the term "computer" or "module" may include any
processor-based or microprocessor-based system including systems using
microcontrollers, reduced instruction set computers (RISC), application specific
integrated circuits (ASICs), logic circuits, and any other circuit or processor capable
of executing the functions described herein. The above examples are exemplary only,
and are thus not intended to limit in any way the definition and/or meaning of the term
"computer".
The computer or processor executes a set of instructions that are
stored in one or more storage elements, in order to process input data. The storage
elements may also store data or other information as desired or needed. The storage
element may be in the form of an information source or a physical memory element
within a processing machine.
24
The set of instructions may include various commands that instruct
the computer or processor as a processing machine to perform specific operations
such as the methods and processes of the various embodiments of the subject matter
described herein. The set of instructions may be in the form of a software program.
The software may be in various forms such as system software or application
software. Further, the software may be in the form of a collection of separate
programs or modules, a program module within a larger program or a portion of a
program module. The software also may include modular programming in the form
of object-oriented programming. The processing of input data by the processing
machine may be in response to user commands, or in response to results of previous
processing, or in response to a request made by another processing machine.
As used herein, the terms "software" and "firmware" are
interchangeable, and include any computer program stored in memory for execution
by a computer, including RAM memory, ROM memory, EPROM memory, EEPROM
memory, and non-volatile RAM (NVRAM) memory. The above memory types are
exemplary only, and are thus not limiting as to the types of memory usable for storage
of a computer program.
It is to be understood that the above description is intended to be
illustrative, and not restrictive. For example, the above-described embodiments
(and/or aspects thereof) may be used in combination with each other. In addition,
many modifications may be made to adapt a particular situation or material to the
teachings of the various embodiments of the described subject matter without
departing from their scope. While the dimensions and types of materials described
herein are intended to define the parameters of the various embodiments of the
invention, the embodiments are by no means limiting and are exemplary
embodiments. Many other embodiments will be apparent to one of ordinary skill in
the art upon reviewing the above description. The scope of the various embodiments
of the inventive subject matter should, therefore, be determined with reference to the
appended claims, along with the full scope of equivalents to which such claims are
entitled. In the appended claims, the terms "including" and "in which" are used as the
plain-English equivalents of the respective terms "comprising" and "wherein."
Moreover, in the following claims, the terms "first," "second," and "third," etc. are
25
used merely as labels, and are not intended to impose numerical requirements on their
objects. Further, the limitations of the following claims are not written in means-plusfunction
format and are not intended to be interpreted based on 35 U.S.C. § 112, sixth
paragraph, unless and until such claim limitations expressly use the phrase "means
for" followed by a statement of function void of further structure.
This written description uses examples to disclose the various
embodiments of the invention, including the best mode, and also to enable one of
ordinary skill in the art to practice the various embodiments of the invention,
including making and using any devices or systems and performing any incorporated
methods. The patentable scope of the various embodiments of the invention is
defined by the claims, and may include other examples that occur to those skilled in
the art. Such other examples are intended to be within the scope of the claims if the
examples have structural elements that do not differ from the literal language of the
claims, or if the examples include equivalent structural elements with insubstantial
differences from the literal languages of the claims.
26

We Claim:
1. A liquid cooled thermal control system for an imaging detector
comprising:
a plurality of temperature sensors; and
a control mode selector module coupled to the plurality of temperature
sensors, the control mode selector module being programmed to:
receive an input from the plurality of temperature sensors;
identify the inputs as either valid inputs or invalid inputs; and
determine an operational mode of the hquid cooled thermal control system
based on the identified inputs.
2. The liquid cooled thermal control system of Claim 1, wherein the
control mode selector module is further programmed to:
select a first subset of the temperature sensors from the plurality of
temperature sensors;
identify the inputs from the first subset of temperature sensors as either valid
inputs or invalid inputs; and
determine an operational mode of an inline heater based on the identified
subset of inputs.
3. The liquid cooled thermal control system of Claim 2, wherein the
control mode selector module is further programmed to:
select a second different subset of temperature sensors from the plurality of
temperature sensors;
identify the inputs from the second different subset of temperature sensors as
either valid inputs or invalid inputs; and
determine an operational mode of a fan based on the identified subset of
inputs.
27
4. The liquid cooled thermal control system of Claim 1, wherein the
control mode selector module is further programmed to:
receive an input from a first temperature sensor;
automatically operate the hquid cooled thermal control system in a first
operational mode when the input from the first temperature sensor is valid; and
automatically operate the liquid cooled thermal control system in a second
different operational mode when the input from the first temperature sensor is invalid.
5. The liquid cooled thermal control system of Claim 1, wherein the
control mode selector module is further programmed to:
automatically operate the liquid cooled thermal control system in a first
operational mode based on a valid input received from a first temperature sensor;
automatically operate the liquid cooled thermal control system in a first
operational mode based on a invalid input received from a first temperature sensor
and a valid input received from a second temperature sensor.
6. The liquid cooled thermal confrol system of Claim 1, wherein the
temperature control comprises a fan and an inline heater, said control mode selector
module is further programmed to:
automatically control the operation of the fan using a first subset of the
plurality of temperature sensors; and
automatically control the operation of the inline heater using a different
second subset of the plurality of temperature sensors.
7. The liquid cooled fliermal control system of Claim 1, wherein the
mode selector module is further programmed to:
automatically control the operation of a fan using a heat exchanger inlet air
temperature, a heat exchanger inlet cooling fluid temperature, a heat exchanger
discharge cooling fluid temperature, and an inline heater discharge temperature; and
28
automatically control the operation of an inline heater using the heat
exchanger inlet cooling fluid temperature, the heat exchanger discharge cooling fluid
temperature, and the inline heater discharge temperature.
8. The liquid cooled thermal control system of Claim 1, wherein the
mode selector module is further programmed to operate at least one of a fan or an
inline heater in a protection mode when each of the inputs are invalid inputs.
9. The liquid cooled thermal control system of Claim 8, wherein to
operate the fan or the inline heater in the equipment protection mode, the mode
selector module is further programmed to:
de-energize an inline heater; and
operate a fan at approximately seventy-five percent of the fan's rated
operational speed.
10. A computed tomography (CT) imaging system comprising:
a detector rail;
an x-ray detector positioned on the detector rail, the x-ray detector including a
plurality of detector components, at least some of the detector components configured
to detect x-rays;
a cooling system providing cooling fluid to at least one of the x-ray detector or
the detector rail, the cooling system comprising
a plurality of temperature sensors; and
a control mode selector module coupled to the plxirality of temperature
sensors, the control mode selector module being programmed to
receive an input from the plurality of temperature sensors;
identify the inputs as either valid inputs or invalid inputs; and
determine an operational mode of the cooling system on the identified
inputs.
29
11. The CT imaging system of Claim 11, wherein the control mode
selector module is further programmed to:
select a &st subset of the temperature sensors from the plurality of
temperature sensors;
identify the inputs from the first subset of temperature sensors as either valid
inputs or invalid inputs; and
determine an operational mode of an inline heater based on the identified
subset of inputs.
12. The CT imaging system of Claim 11, wherein the control mode
selector module is further programmed to:
select a second different subset of temperature sensors from the plurality of
temperature sensors;
identify the inputs from the second different subset of temperature sensors as
either valid inputs or invalid inputs; and
determine an operational mode of a fan based on the identified subset of
inputs.
13. The CT imaging system of Claim 11, wherein the control mode
selector module is further programmed to:
recieve an input from a first temperature sensor;
automatically operate the liquid cooled thermal confrol system in a first
operational mode when the input from the first temperature sensor is valid; and
automatically operate the Uquid cooled thermal control system in a second
different operational mode when the input from the first temperature sensor is invalid.
14. The CT imaging system of Claim 11, wherein the control mode
selector module is fiuther programmed to:
30
automatically operate the liquid cooled thermal control system in a first
operational mode based on a valid input received fi:om a first temperature sensor;
automatically operate the liquid cooled thermal control system in a first
operational mode based on a invalid input received fi-om a first temperature sensor
and a valid input received fi:om a second temperature sensor.
15. The CT imaging system of Claim 11, wherein the control mode
selector module is fiuther programmed to:
automatically control the operation of the fan using a first subset of the
plurality of temperature sensors; and
automatically control the operation of the inline heater using a different
second subset of the plurality of temperature sensors.
16 The CT imaging system of Claim 11, wherein the control mode
selector module is fiuther programmed to operate at least one of a fan or an inline
heater in a equipment protection mode when each of the inputs are invahd inputs.
17. The CT imaging system of Claim 16, wherein to operate the fan or the
inline heater in the equipment protection mode, the mode selector module is further
programmed to:
de-energize an inline heater; and
operate a fan at approximately seventy-five percent of the fan's rated
operational speed or appropriately under acoustic noise level.
18. A method of controlling an operation of a computed tomography (CT)
detector cooling system comprising:
receiving a plurality of temperature sensor inputs fi-om a plurality of
temperature sensors at a control mode selector module;
identifying the inputs as either vahd inputs or invalid inputs; and
determining an operational mode of the cooling system based on the identified
inputs.
31
19. The method of Claim 18, further comprising:
selecting a first subset of temperature sensors from a plurality of temperature
sensors;
identifying the inputs from the first subset of temperature sensors as either
vaUd inputs or invalid inputs; and
determining an operational mode of an inline heater based on the identified
subset of inputs.
20. The method of Claim 19, further comprising:
selecting a second different subset of temperature sensors from the plurality of
temperature sensors;
identifying the inputs from the second different subset of temperature sensors
as either valid inputs or invalid inputs; and
determining an operational mode of a fan based on the identified subset of
inputs.