METHOD FOR OPERATING A TEMPERATURE CONTROL, APPARATUS FOR A MEDICAL EXAMINATION APPARATUS, A TEMPERATURE CONTROL APPARATUS, AND A MEDICAL EXAMINATION APPARATUS

Abstract

A method for operating a temperature control apparatus for a medical examination device, in particular a magnetic resonance apparatus, wherein the medical examination device causes a heat input into the body of a patient to be examined during an examination procedure, and wherein the temperature control apparatus has at least one temperature modifier designed for controlling the temperature of the patient, at least one item of heat information that describes the heat balance of the patient is determined, in order to determine a control parameter for controlling at least one ambient parameter that describes the at least one temperature modifier by taking into account at least one ambient condition on the body of the patient, and at least one examination parameter that describes the examination procedure as the input variables of a heat balance model.

Claims

1. A method for operating a temperature control apparatus for a medical examination apparatus, said medical examination apparatus executing an examination procedure on a patient that causes a heat input into the body of the patient, and said temperature control apparatus comprising at least one temperature modifier, said method comprising: providing a processor with an electronic representation of at least one ambient condition on the body of the patient, and at least one examination parameter that describes said examination procedure; in said processor, using said at least one ambient condition and said at least one examination parameter as inputs to a heat balance model from which a heat balance of the patient is determined as an output of the heat balance model; from said heat balance of the patient provided as the output of said heat balance model, determining, in said processor, a control parameter for said temperature modifier that controls at least one ambient parameter that is influenced by said temperature modifier; and providing said control parameter from said processor to said temperature modifier at a selected time relative to said examination procedure.

2. A method as claimed in claim 1 comprising determining said control parameter in said processor by evaluating a comfort criterion, provided to the processor, that describes thermal comfort of the patient.

3. A method as claimed in claim 2 comprising, in said processor, implementing a check based on said comfort criterion as to whether a balance of activities described by said heat balance model, heat loss by the patient, and heat production in the patient due to said heat input, is equalized so as to be within an equalization interval in a range around an exact equalization.

4. A method as claimed in claim 3 comprising providing an indication from said processor to an operator of said medical examination apparatus if said check indicates that said comfort criterion cannot be fulfilled by a change in said control parameter.

5. A method as claimed in claim 2 comprising using, as said comfort criterion, stabilization of a trunk temperature of the patient.

6. A method as claimed in claim 5 comprising providing an indication from said processor to an operator of said medical examination apparatus if said check indicates that said comfort criterion cannot be fulfilled by a change in said control parameter.

7. A method as claimed in claim 1 wherein said medical examination apparatus is a magnetic resonance scanner comprising a local radio-frequency (RF) coil, and comprising providing said processor with said examination parameter selected from the group consisting of a specific absorption rate of the patient during said examination procedure, thermal insulation relative to the patient provided by said local RF coil, and heat production by said local RF coil during said examination procedure.

8. A method as claimed in claim 1 comprising providing said processor with said ambient parameter selected from the group consisting of air temperature in said medical examination apparatus, humidity in said medical examination apparatus, air velocity in said medical examination apparatus, and radiation temperature within a patient receiving receptacle of said medical examination apparatus.

9. A method as claimed in claim 1 comprising providing said computer with at least one patient parameter that describes the patient, selected from the group consisting of metabolic activity of the patient and thermal insulation of the patient from an environment associated with said medical examination apparatus, and using at least one patient parameter in said processor as an additional input to said heat balance model.

10. A method as claimed in claim 1 comprising, in said processor, calculating a control parameter characteristic as a function of time in advance of said examination procedure.

11. A method as claimed in claim 10 comprising monitoring thermal comfort of the patient during said examination procedure, and updating said control parameter characteristic, upon occurrence of an updating criterion, using current input variables determined during said monitoring.

12. A method as claimed in claim 1 comprising determining said at least one control parameter at a time outside of said examination procedure.

13. A method as claimed in claim 1 comprising using a fan as said temperature modifier, said fan having a volume flow that is specified dependent on said at least one control parameter.

14. A method as claimed in claim 1 comprising using a pad that is in thermally conductive contact with the patient as said temperature modifier, said pad having a temperature that is specified dependent on said at least one control parameter.

15. A temperature control apparatus for a medical examination apparatus, said medical examination apparatus executing an examination procedure on a patient that causes a heat input into the body of the patient, said temperature control apparatus comprising: at least one temperature modifier; a processor provided with an electronic representation of at least one ambient condition on the body of the patient, and at least one examination parameter that describes said examination procedure; said processor being configured to use said at least one ambient condition and said at least one examination parameter as inputs to a heat balance model from which a heat balance of the patient is determined as an output of the heat balance model; said processor being configured to determine, from said heat balance of the patient provided as the output of said heat balance model, a control parameter for said temperature modifier that controls at least one ambient parameter that is influenced by said temperature modifier; and said processor being configured to provide said control parameter from said processor to said temperature modifier at a selected time relative to said examination procedure, and said temperature modifier then operating according to said control parameter.

16. A medical examination apparatus comprising: a medical examination scanner that executes an examination procedure on a patient that causes a heat input into the body of the patient; at least one temperature modifier; a processor provided with an electronic representation of at least one ambient condition on the body of the patient, and at least one examination parameter that describes said examination procedure; said processor being configured to use said at least one ambient condition and said at least one examination parameter as inputs to a heat balance model from which a heat balance of the patient is determined as an output of the heat balance model; said processor being configured to determine, from said heat balance of the patient provided as the output of said heat balance model, a control parameter for said temperature modifier that controls at least one ambient parameter that is influenced by said temperature modifier; and said processor being configured to provide said control parameter from said processor to said temperature modifier at a selected time relative to said examination procedure, and said temperature modifier then operating according to said control parameter.

17. A non-transitory, computer-readable data storage medium encoded with programming instructions, said storage medium being loaded into a computer that operates a temperature control apparatus for a medical examination apparatus, said medical examination apparatus executing an examination procedure on a patient that causes a heat input into the body of the patient, and said temperature control apparatus comprising at least one temperature modifier, said programming instructions causing said computer to: receive an electronic representation of at least one ambient condition on the body of the patient, and at least one examination parameter that describes said examination procedure; use said at least one ambient condition and said at least one examination parameter as inputs to a heat balance model from which a heat balance of the patient is determined as an output of the heat balance model; from said heat balance of the patient provided as the output of said heat balance model, determine a control parameter for said temperature modifier that controls at least one ambient parameter that is influenced by said temperature modifier; and provide said control parameter from said computer to said temperature modifier at a selected time relative to said examination procedure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1 shows an exemplary embodiment of an inventive medical examination device in which a patient is situated.

[0029] FIG. 2 is shows a flowchart of an exemplary embodiment of the inventive method.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] FIG. 1 shows an exemplary embodiment of a medical examination device in the form of a magnetic resonance scanner 1 in which a patient 2 is located. The medical examination scanner 1 has a basic field magnet 3, which surrounds a patient-receiving opening 4 having a patient couch 5, a local coil 6 that is arranged on the trunk of the patient 2, a control and evaluation computer 7, an input interface 8 and an output interface 9.

[0031] In addition, the medical examination scanner 1 has a temperature control apparatus 10 having a controller 11, and a temperature modifier in the form of a fan 12 directed toward the patient 2, and a pad-like temperature control facilitator 13 can be controlled by the controller 11. The pad-like temperature control facilitator is arranged between the patient 2 and the patient couch 5. In addition, the temperature control apparatus 10 has a sensor 14 (shown schematically), with which any one or more of the air temperature, humidity, air velocity, radiation temperature, vertical air temperature difference and radiation asymmetry inside the patient-receiving device 4 can be measured as ambient parameters, as well as the skin temperature as a body temperature, the cardiac frequency and the rate of perspiration of the patient 2 that describes the transpiration behavior as the patient parameter. The rate of perspiration and the skin temperature are approximated by a first-order low-pass filter. The controller 11 is connected, moreover, to the control and evaluation computer 7 and receives operator entries transmitted from the input interface 8 and send output information to the output interface 9 via the computer 7. In an alternative exemplary embodiment, the temperature control apparatus 10 has its own input interface and its own output interface.

[0032] The volume flow generated by the fan 12 can be changed as a function of a control parameter provided by the controller 11. The fan 12 can be put, by a further control parameter into an operating mode that warms the patient 2 and into an operating mode that cools a patient 2. The temperature of the temperature control apparatus 13 can likewise be changed to heat and cool the patient 2 by a control parameter of the controller 11.

[0033] FIG. 2 is a flowchart of an exemplary embodiment of a method for operating the temperature control apparatus 10 for the implementation of which method the controller 11 is designed, and which will be described below:

[0034] In a step S1 input variables are detected for a heat balance model that describes the heat balance of the patient 2. For this purpose the controller 11 receives the patient parameters and ambient parameters measured by the sensor 14. In addition, the controller 11 receives examination parameters from the control and evaluation computer 7 in the form of planning data of a planned examination procedure for the patient 2 by the medical examination device 1. These parameters describe a course as a function of time of a specific absorption rate and thermal insulation and heating of the patient 2 by the local coil 6 arranged on his trunk during the examination procedure. The controller 11 receives further patient parameters that describe the age, body mass, gender and clothing of the patient 2 by operating entries by operators of the medical examination scanner 1 in the operating terminal 8.

[0035] In a following step S2 an item of heat information that describes the heat balance of the patient 2 is determined by taking into account the examination parameters, ambient parameters and patient parameters.

[0036] These parameters are used here as input variables for a heat balance model that models the heat balance of the patient 2. This model describes the heat production inside the body of the patient 2 as a function of the specific absorption rate, heating due to the local coil 6 and a metabolic activity derived from the age, body mass and gender of the patient 2. In addition, the heat balance model describes the heat loss from the body of the patient 2 to his or her surroundings due to heat radiation, convection and heat conduction. For this purpose the model takes into account the ambient parameters and the thermal insulation of the patient 2 by the patient's clothing described by a patient parameter, and the thermal insulation of the patient 2 by the local coil 6 described by an examination parameter. Determination of the heat loss also includes the thermal insulation of the patient 2 by the pad-like temperature control facilitator 13.

[0037] The heat information describes the difference in heat production and heat loss by the patient 2 within the content of a balance of activities. Other clearances apart from a difference are also conceivable within the scope of further exemplary embodiments. In addition, a further item of heat information is determined which describes the thermal comfort of the patient 2 on an empirically determined scale, standardized using a comparison group, for which purpose the input variables are also used. The Predicted Mean Vote (PMV) to ISO 7730 is used as the scale.

[0038] In a step S3 fulfillment of a comfort criterion that describes the thermal comfort of the patient is checked in order to determine the control parameters. The comfort criterion is aimed at stabilizing the trunk temperature of the patient 2 and checks whether the balance of activities is equalized. This is deemed to be fulfilled if heat production and heat loss lie within a predeterminable equalization interval. The comfort criterion checks, moreover, from body function parameters available to the patient data the measured body temperature, cardiac frequency, transpiration behavior and sensitivity to drafts for adherence to specified limit values. It is likewise checked within the scope of the comfort criterion whether the vertical air temperature difference described as the ambient parameter, and the radiation asymmetry in the patient-receiving device 4 lie within specified limits.

[0039] In a step S4 it is checked whether the comfort criterion can be fulfilled by a change in the control parameters for the fan 12 and the temperature control apparatus 13.

[0040] If this is not the case, a warning signal is generated in step S5, and this is sent via the control and evaluation computer 7 to the output interface 9 for outputting an indication to the operator of the medical examination device 1. The operator can infer from this indication that, for example, by changing the clothing of the patient 2 or removing or placing a cover from/on the patient 2 they can establish his thermal comfort. The method is then begun again in step S1.

[0041] If, by contrast, the result of the check in step S4 is that the comfort criterion can be fulfilled, a control parameter characteristic as a function of time is determined in a step S6 for the fan 12 and the temperature control apparatus 13 in such a way that the comfort criterion is fulfilled.

[0042] In a subsequent step S7 the fan 12 and the temperature control apparatus 13 are controlled according to the control parameter characteristic as a function of time.

[0043] In a further step S8 variables for checking an updating criterion are detected, and these describe whether re-calculation of a control parameter characteristic as a function of time is necessary. For this purpose the criterion checks the patient parameters for adherence to specified further limit values. Furthermore, the updating criterion provides regular re-determination of the control parameter characteristic using a regular timing grid.

[0044] In a step S9 it is checked whether the updating criterion was fulfilled. If this is not the case the method continues in step S7, so the fan 12 and the temperature control apparatus 13 are continuously controlled according to the control parameter characteristic as a function of time, and the updating criterion is checked. If the updating criterion is not fulfilled, by contrast, the method begins again with step S1 to determine an updated control parameter characteristic.

[0045] In a further exemplary embodiment of the method, the steps described above and shown in FIG. 2 are carried out first of all before an examination procedure is begun by the medical examination device 1. The thermal comfort of the patient 2 can therefore be ensured as early as during planning of the examination procedure by way of control the fan 12 and the temperature control apparatus 13. First, predefined basic settings can be used for the input variables, in particular with respect to the air temperature, humidity, clothing and a mean specific absorption rate. In this regard, the fact that the thermal load is time-dependent due to the specific absorption rate is taken into account. In particular, the evaluation of the comfort criterion as early as before the beginning of the examination procedure enables a check as to whether thermal comfort is foreseeably given for the entire duration of the examination procedure. Since in the case of the medical examination device designed as a scanner 1, the complete examination procedure, having a number of examination sequences is pre-planned, the control parameter characteristic can also be planned accordingly. An interruption or termination of an ongoing examination procedure can be avoided by outputting the indication.

[0046] Once the examination procedure has begun, the method is carried out continuously, so the thermal comfort of the patient is optimally ensured for the entire duration of the examination procedure, in particular even in the case of an unplanned change in circumstances determined by the ambient parameters and patient parameters. The method is also continued after the end of the examination procedure. It can therefore be ensured that in the case of an unavoidable increase in trunk temperature the patient can be efficiently cooled in order to quickly restore thermal comfort.

[0047] Although modifications and changes may be suggested by those skilled in the art, it is the intention of the Applicant to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of the Applicant's contribution to the art.