METHOD FOR ASSESSING A POSITION OF A PATIENT TO AN AUTOMATIC EXPOSURE CONTROL CHAMBER

Abstract

Method for assessing a position of a patient with respect to an automatic exposure control chamber, AEC chamber (11, 12), for a medical exam, wherein a patient is positioned between an X-ray source and the AEC chamber (11, 12); comprising the steps:—acquiring (S10) an X-ray image (32) of at least part of the patient, wherein the AEC chamber is configured for detecting a radiation dose of the X-ray source;—determining (S20), by the control unit, a position of the AEC chamber (11, 12) with respect to the patient from the acquired X-ray image (32);—determining (S30), by the control unit, an exam protocol performed on the patient dependent on the medical exam to be performed on the patient and determining, by the control unit, an ideal position of the AEC chamber (11, 12) with respect to the patient dependent on the exam protocol, wherein the ideal position relates to a position of the patient relative to the AEC chamber (11, 12), in which the detected radiation dose is reliable for the medical exam; and—determining (S40), by the control unit, a position deviation of the position of the AEC chamber from the ideal position of the AEC chambers; characterized in that determining, by the control unit, the position deviation comprises the steps:—segmenting at least an anatomical structure (21, 22) of the patient in the X-ray image (32) thereby determining at least one segmented anatomical structure (21, 22); and—determining the position deviation dependent on the at least one segmented anatomical structure (21, 22);—determining an overlap of the at least one segmented anatomical structure (21, 22) with the AEC chamber (11, 12); and—determining the position deviation dependent on the determined overlap.

Claims

1. A method for assessing a position of a patient with respect to an automatic exposure control (AEC) chamber for a medical exam, comprising: acquiring an X-ray image of at least part of a patient positioned between an X-ray source and the AEC, wherein the AEC chamber is configured to detect radiation dose that correlates to a radiation dose of the X-ray source; determining a position of the AEC chamber with respect to the patient from the acquired X-ray image; determining an exam protocol performed on the patient dependent on the medical exam to be performed on the patient, and determining an ideal position of the AEC chamber with respect to the patient dependent on the exam protocol, wherein the ideal position relates to a position of the patient relative to the AEC chamber, in which the detected radiation dose is reliable for the medical exam; and determining a position deviation of the position of the AEC chamber from the ideal position of the AEC chambers by: segmenting at least an anatomical structure of the patient in the X-ray image, thereby determining at least one segmented anatomical structure; determining the position deviation dependent on the at least one segmented anatomical structure; determining an overlap of the at least one segmented anatomical structure with the AEC chamber; and determining the position deviation dependent on the determined overlap.

2. The method according to claim 1, wherein the at least one anatomical structure of the patient in the X-ray image is segmented by a deep learning network.

3. The method according to claim 1, further comprising: determining deviation evaluation data, indicating the quantity of the deviation, by comparing the position of the AEC chamber with the ideal position of the AEC chamber; determining condition data, relating to additional conditions of the specific medical exam; and determining a root cause for the position deviation dependent on the deviation evaluation data and the condition data.

4. The method according to claim 3, wherein the condition data comprise a room, where the medical exam takes place, a time, when the medical exam takes place and/or an identification of an operator, who positions the patient with respect to the AEC chamber.

5. The method according to claim 3, wherein the root cause is determined using a statistical analysis of the deviation evaluation data of a plurality of medical exams.

6. The method according to claim 2, further comprising: displaying the root cause on a graphical user interface.

7. The method according to claim 2, further comprising: providing a database of a plurality of root causes associated with a plurality of condition data; and predicting a root cause depending on the condition data and the associated root causes before executing the medical exam.

8. The method according to claim 1, wherein the exam protocol is determined automatically dependent on the medical exam.

9. The method according to claim 4, comprising: providing the position deviation to the operator.

10. (canceled)

11. An X-ray system, comprising: an X-ray source configured to radiate a patient for a medical exam with X-ray radiation; an automatic exposure control (AEC) chamber, configured to detect a radiation dose that correlates to a radiation dose of the X-ray source; and at least one processor configured to perform a method for positioning the AEC for a medical exam, the method comprising: acquiring an X-ray image of at least part of the patient positioned between the X-ray source and the AEC; determining a position of the AEC chamber with respect to the patient from the acquired X-ray; determining an exam protocol performed on the patient dependent on the medical exam to be performed on the patient, and determining an ideal position of the AEC chamber with respect to the patient dependent on the exam protocol, wherein the ideal position relates to a position of the patient relative to the AEC chamber in which the detected radiation dose is reliable for the medical exam; and determining a position deviation of the position of the AEC chamber from the ideal position of the AEC chambers by: segmenting at least an anatomical structure of the patient in the X-ray image, thereby determining at least one segmented anatomical structure; determining the position deviation dependent on the at least one segmented anatomical structure; determining an overlap of the at least one segmented anatomical structure with the AEC chamber; and determining the position deviation dependent on the determined overlap.

12. (canceled)

13. (canceled)

14. A non-transitory computer-readable medium for storing executable instructions that, when executed, cause a method to be performed for assessing a position of a patient with respect to an automatic exposure control (AEC) chamber for a medical exam, the method comprising: acquiring an X-ray image of at least part of a patient positioned between an X-ray source and the AEC, wherein the AEC chamber is configured to detect a radiation dose that correlates to a radiation dose of the X-ray source; determining a position of the AEC chamber with respect to the patient from the acquired X-ray image; determining an exam protocol performed on the patient dependent on the medical exam to be performed on the patient, and determining an ideal position of the AEC chamber with respect to the patient dependent on the exam protocol, wherein the ideal position relates to a position of the patient relative to the AEC chamber in which the detected radiation dose is reliable for the medical exam; and determining a position deviation of the position of the AEC chamber from the ideal position of the AEC chambers by: segmenting at least an anatomical structure of the patient in the X-ray image, thereby determining at least one segmented anatomical structure; determining the position deviation dependent on the at least one segmented anatomical structure; determining an overlap of the at least one segmented anatomical structure with the AEC chamber; and determining the position deviation dependent on the determined overlap.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0061] FIG. 1a shows an X-ray image of a lung in front of an X-ray detector in an ideal position;

[0062] FIG. 1b shows another X-ray image of a lung in front of a X-ray detector in an unideal position; and

[0063] FIG. 2 shows a schematic diagram of a method for assessing a position of a patient to an automatic exposure control chamber, AEC chamber, for a medical exam.

DETAILED DESCRIPTION OF EMBODIMENTS

[0064] FIG. 1 shows a first X-ray image 31 of a left lung 21 and a right lung 22. The first X-ray image 31 is determined by a medical exam, wherein an exam protocol is followed. Radiological images may be flipped vertically. Depending on that, what is described herein as left lung 21 can in reality be the right lung of the patient and what is described herein as right lung 22 can in reality be the left lung of the patient. A patient is positioned between an X-ray source, configured for radiating the patient with X-ray radiation, and an X-ray detector. The X-ray detector is configured for detecting a radiation dose correlating to the X-ray radiation of the X-ray source. The X-ray detector comprises a plurality of AEC chambers, namely a first AEC chamber 11, a second AEC chamber 12, a third AEC chamber 13, a fourth AEC chamber 14 and a fifth AEC chamber 15.

[0065] In this case, the medical exam is to X-ray the lungs 21, 22. Thus, the first AEC chamber 11 and the second AEC chamber 12 are relevant for estimating the radiation dose, the patient has been exposed by the X-ray source during performing the x-ray scan of the lungs 21, 22. Thus, based on the radiation dose received by the first AEC chamber 11 and the second AEC chamber 12, the radiation dose the patient has been exposed to can be estimated. To be specific, the radiation dose detected by the AEC chambers 11, 12 is compared to a radiation dose that is expected to be detected by the AEC chambers 11, 12 depending on the specific medical exam that is performed on the patient. The radiation dose detected by the AEC chambers 11, 12 rather correlates to the radiation dose, the patient is exposed to. Consequently, the X-ray source stops the radiation, if a predetermined threshold for the detected radiation dose has been reached. As can be seen from FIG. 1, the patient is ideally positioned in such a way between the radiation source and the AEC chambers, that the first AEC chamber 11 and the second AEC chamber 12 are overlapping the left lung 21 and the right lung 22 respectively as much as possible. In this case, an overlap ratio of the left lung 21 and the right lung 22 with the first AEC chamber 11 and the second AEC chamber 12 is around 90%. Thus, the radiation dose that the first AEC chamber 11 and the second AEC chamber detect is a good indicator of how high the radiation dose is that the lungs 21, 22 are exposed to.

[0066] In contrast to the ideal position shown in FIG. 1, FIG. 2 shows a second X-ray image 32 of a left lung 21 and a right lung 22, wherein the patient did not stand in an ideal position between the x-ray source and the first AEC chamber 11 as well as the second AEC chamber 12. The position of the patient to the AEC chamber 11 and the AEC chamber 12 can be determined based on the geometry of the AEC chambers.

[0067] Additionally, the second x-ray image 32 is processed by a machine learning algorithm for semantic segmentation of the lungs 21, 22 in the second x-ray image 32. The machines learning algorithm is preferably executed by a deep neural network. Thus, in the second x-ray image 32, the left lung 21 and the right lung 22 can be determined by image recognition. Based on the segmented left lung 21 and the segmented right lung 22 an overlap with the first AEC chamber 11 and the second AEC chamber 12 can be determined. In this case, the overlap ratio between the first AEC chamber 11 and the left lung 21 is below 50%. A reason for such a low overlap can have a plurality of reasons. For example, the patient might be translationally shifted compared to the ideal position between the AEC chamber and the X-ray source. As another example, the whole system of AEC chambers and X-ray source might be miscalibrated. From the overlap ratio itself, in a first step, it can be determined, if the radiation dose detected by the AEC chambers 11, 12 is a reliable source for asserting the radiation dose the patient has been exposed to. Thus, the overlap ratio is compared with a predetermined threshold, which preferably is determined based on the type of medical exam that is performed. In this case, an overlap of under 80% leads to the assumption that the X-ray radiation detected by the AEC chambers was not reliable and that most likely the patient has been exposed to more X-ray radiation than needed. This result can be provided to the operator of the medical exam, for example by a display.

[0068] Additionally, from the shape and size of the lungs 21, 22 a root cause for the position deviation between the determined position and the ideal position can be determined. In this case, the left lung 21 is significantly smaller than usual on the left side. This can be the consequence of a translational shift of the patient between the AEC chamber and the X-ray source. Thus, the part of the left lung 21 that should overlap the first AEC chamber is covered by the scapula of the patient, blocking the X-ray radiation between the left lung 21 and the first AEC chamber 11.

[0069] In order to provide information about the insufficient overlap of the AEC chambers 11, 12 with the lungs 21, 22, the position of the patient, as determined from the X-ray image, is compared to the ideal position, as predetermined dependent on the performed medical exam. For an improved analysis, not only the single X-ray image 32 needs to be analyzed. Thus, for a plurality of medical exams, a position deviation of the AEC chambers 11, 12 to the ideal position of the AEC chambers 11, 12 is determined and each is associated with additional condition data. The condition data may comprise a room, where the medical exam takes place, a time, when the medical exam takes place and/or an identification of an operator, who positions the patient with respect to the AEC chambers 11, 12. For example, one specific operator has the tendencies to translationally shift the patient between the AEC chambers 11, 12 and the X-ray source to the left compared to the ideal position. This is determined by a statistical analysis of a plurality of position deviations associated with a plurality of condition data.

[0070] Thus, in an ideal case, a root cause can be predicted dependent on the condition data before executing the medical exam based on the statistical analysis. For example, for a certain operator, who has to identify himself before executing the medical exam, a common root cause for position deviation can be determined and displayed to the operator. For example, the operator is informed that he has the tendencies to translationally shift the patient slightly to the left. Thus, the operator can correct his usual mistake of dispositioning the patient and an overexposure of the patient with X-ray radiation can be prevented.

[0071] FIG. 2 shows a schematic diagram of a method for assessing a position of a patient to an AEC chamber 11, 12 for a medical exam wherein a patient is positioned between an X-ray source and the AEC chamber 11, 12. In a first step S10, an X-ray image 32 of at least part of the patient is acquired, wherein the AEC chamber is configured for detecting a radiation dose, which correlates to a radiation dose of the X-ray source. In a second step S20, a position of the AEC chamber 11, 12 is determined with respect to the patient from the acquired X-ray image 32. In a third step, an exam protocol performed on the patient dependent on the medical exam to be performed on the patient is determined and an ideal position of the AEC chamber 11, 12 is determined with respect to the patient dependent on the exam protocol, wherein the ideal position relates to a position of the patient relative to the AEC chamber 11, 12, in which the detected radiation dose is reliable for the medical exam. In a fourth step S40, a position deviation of the position of the AEC chamber from the ideal position of the AEC chambers is determined.

LIST OF REFERENCE SIGNS

[0072] 10 X-ray detector [0073] 11 first AEC chamber [0074] 12 second AEC chamber [0075] 13 third AEC chamber [0076] 14 fourth AEC chamber [0077] 15 fifth AEC chamber [0078] 21 left lung [0079] 22 right lung [0080] 31 first X-ray image [0081] 32 second X-ray image [0082] 40 scapula [0083] S10 acquiring an X-ray image [0084] S20 determining a position of the AEC chamber [0085] S30 determining an exam protocol [0086] S40 determining a position deviation