X-ray image intake quality monitoring

Abstract

The quality of a chest X-ray depends on the inspiration state of the patient being imaged. If the patient's lungs are not significantly inflated during the chest X-ray, tissue from surrounding organs can obscure the image and the lung parenchyma is not effectively shown. Therefore, it is up to the medical professional to ensure that the patient is in the proper posture and inspiration state at the point of image exposure. But this can be difficult for patients with chronic conditions. Therefore, this application discusses a means of assessing the inspiration state using the position of the ribs and diaphragm line in the X-ray image. Thus, an accurate estimate of the inspiration state can be automatically reported to the medical professional before the patient leaves the examination room, allowing a retake of the X-ray if necessary.

Description

TECHNICAL FIELD

[0001] The present invention relates to X-ray image inhalation quality monitoring, and in particular to an apparatus for X-ray image inhalation quality monitoring, a method for X-ray image inhalation quality monitoring, an X-ray imaging system, a computer program element and a computer readable medium. BACKGROUND

[0002] Chest X-ray screening is an important procedure for the detection and monitoring of early stage lung abnormalities and diseases in the lungs of a patient. A medical person such as a physician or radiologist detects abnormalities directly from the X-ray image. It is the task of the medical imaging professional to evaluate the image quality directly after acquisition. The image is checked to have sufficient quality before the patient leaves the examination room. If the chest X-ray image does not have sufficient quality, a new image should be taken before the patient leaves the examination room. The image quality depends on the skill of the system operator, ensuring that a predefined standard operating procedure is followed. In particular, factors related to the patient positioning with respect to the detector require the cooperation of the patient. US 2004 / 0161141 discusses a method for inferring an orientation of a radiographic image from a digital representation of the image. However, such a system can be further improved. SUMMARY

[0003] Therefore, it can be desirable to provide techniques for enhanced X-ray image inhalation quality monitoring. The object of the present invention is solved by the subject matter of the independent claims, wherein further embodiments are incorporated in the dependent claims. It should be noted that aspects of the following description of the method according to the present invention also apply to the apparatus, the X-ray imaging system, the computer program element and the computer readable medium according to the present invention.

[0004] According to a first aspect of the present invention, a method for X-ray image inhalation quality monitoring is provided, comprising the following steps:

[0005] a) receiving an X-ray image of a region of interest of a patient;

[0006] b) generating a diaphragm line representing a path of a diaphragm in the X-ray image, and generating a rib line representing a path of a rib in the X-ray image;

[0007] c) detecting the diaphragm line, and detecting the rib line;

[0008] d) evaluating the X-ray image for a presence of a crossing condition between (i) the diaphragm line and (ii) the rib line, wherein the crossing condition of the diaphragm line and the rib line is defined according to a crossing condition rule; and

[0009] e) comparing the presence of the intersection condition between the rib line and the diaphragm line with a predetermined X-ray image inspiration quality monitoring rule which assigns an image inspiration state in accordance with an intersection condition rule to produce an X-ray image inspiration quality measure.

[0010] Thus, the method has the effect of improving the success rate of medical imaging and simplifying the evaluation process. An algorithm analyzes the chest X-ray image and uses the presence (or absence) of a rib-diaphragm intersection as an indication of a high-quality image that has been taken or not. Furthermore, there is also the benefit that the rejection of low-quality images becomes less dependent on variations or biases in the technical level of different system operators. Furthermore, the automatic quantification of the patient's breathing state can be integrated into the automatic radiological interpretation and reporting process. For example, a consolidating region in the image (e.g. caused by a condition such as tuberculosis) can require the radiograph to be taken in an alternative inspiration state that can be detected. Misinterpretation of such an image can be avoided and a report of the presence of a contagious tuberculosis process in the lung can be generated.

[0011] In an embodiment of the method according to the application, the first rib line has a first intersection condition rule and the second rib line has a second intersection condition rule which is different from the first rule. The first rule and the second rule are used to determine the intersection condition. Thus, it is possible to define the intersection condition which takes into account different anatomical characteristics of different ribs, so that very accurate inspiration quality monitoring rules can be defined.

[0012] In another embodiment of the method according to the application, step b) further comprises a step bl):

[0013] bl) dividing the X-ray image into a right lung field portion and a left lung field portion; and

[0014] wherein in step c) the steps of detecting the diaphragm line and the rib line are performed in the left lung field portion, the right lung field portion or both; and

[0015] wherein steps d) and e) are repeated to enable a left lung X-ray image inspiration quality measure and / or a right lung X-ray image inspiration quality measure to be calculated.

[0016] Thus, it is possible to collect useful inspiration quality data separately for the right lung or the left lung.

[0017] In another embodiment of the method according to the application, steps b2), el) and e2) are provided, comprising:

[0018] b2) identifying a consolidating region in the left lung field or the right lung field of the X-ray image; and

[0019] el) providing a right lung X-ray image inspiration quality measure as the X-ray image inspiration quality measure if a consolidating region is identified in the left lung field; or

[0020] e2) if a consolidation area is identified in the right lung field, providing a left lung X-ray image inhalation quality measure as the X-ray image inhalation quality measure.

[0021] Thus, lung portions which are not suitable for lung image quality assessment can be excluded.

[0022] According to a second aspect of the present application, a device for X-ray image inhalation quality monitoring is provided. The device comprises a processing unit. The processing unit is configured to receive an X-ray image of a region of interest of a patient, to generate a diaphragm line representing a path of a diaphragm in the X-ray image, to generate a rib line representing a path of a rib in the X-ray image, to detect the diaphragm line and to detect the rib line, to assess the X-ray image for a presence of a crossing condition between (i) the diaphragm line and (ii) the rib line. The crossing condition of the diaphragm line and the rib line is defined according to a crossing condition rule, and wherein the processor is configured to compare the presence of the crossing condition between the rib line and the diaphragm line to a predetermined X-ray image inhalation quality monitoring rule which specifies an image inhalation state in dependence on the crossing condition rule, and to produce an X-ray image inhalation quality measure. Thus, a device is provided which has similar advantages as the first aspect discussed above.

[0023] In an embodiment of the device according to the present application, the first rib line has a first crossing condition rule and the second rib line has a second crossing condition rule which is different from the first rule, and wherein the first rule and the second rule are used for determining the crossing condition. Thus, it is possible to define a crossing condition which takes into account different anatomical properties of different ribs.

[0024] In another embodiment of the device according to the present application, the processing unit is further configured to divide the X-ray image into a right lung field portion and a left lung field portion, to detect the diaphragm line and the rib line in the left lung field portion, the right lung field portion or both, and to repeat the detection to enable calculation of a left lung X-ray image inhalation quality measure and / or a right lung X-ray image inhalation quality measure. Thus, it is possible to collect useful inhalation quality data separately for the right lung or the left lung.

[0025] In another embodiment of the device according to the present application, the processing unit is further configured to identify a consolidation area in the left lung field or the right lung field of the X-ray image, and wherein the processing unit is configured to provide a right lung X-ray image inhalation quality measure as the X-ray image inhalation quality measure if a consolidation area is identified in the left lung field, or to provide a left lung X-ray image inhalation quality measure as the X-ray image inhalation quality measure if a consolidation area is identified in the right lung field. Thus, lung portions which are not suitable for lung image quality assessment can be excluded.

[0026] In a further embodiment of the apparatus according to the application, the processing unit is further configured to detect a clavicle line representing a path of a clavicle in the X-ray image, to generate a clavicle division line representing a line dividing the clavicle line in the X-ray image, and to evaluate the X-ray image with respect to a presence of a clavicle crossing condition of the clavicle division line with the diaphragm line, wherein the crossing condition rule is defined as an intersection point of the clavicle division line with the diaphragm line. Thereby, a crossing condition rule can be provided which is related to more bones in the patient’s anatomy, thereby enabling an improvement of the measurement accuracy.

[0027] In a further embodiment of the apparatus according to the application, the predetermined X-ray image inhalation quality monitoring rule is outputting a positive X-ray image inhalation quality measure when a posterior portion of the tenth rib line fulfills a crossing condition rule defining an intersection of the tenth rib line with the diaphragm line. Thereby, a standard inhalation quality evaluation parameter is provided.

[0028] A further embodiment of the apparatus according to the application further comprises an output unit. The output unit is configured to display the X-ray image inhalation quality measure. Thereby, the inhalation quality measure can be displayed to a medical professional.

[0029] In a further embodiment of the apparatus according to the application, the processing unit is further configured to receive imaging guideline configuration information comprising rib count configuration information, and to compare a number of further rib lines positioned in the lung field with the rib count configuration information to produce a guideline inhalation status comparison. The output unit is further configured to display the guideline inhalation status comparison. Thereby, in this way, the apparatus uses standard information from regulatory bodies and automatically applies this information to the X-ray image when taking the X-ray image.

[0030] According to a third aspect of the present application, an X-ray imaging system is provided.

[0031] The X-ray imaging system comprises an X-ray image acquisition device having an X-ray source and an X-ray detector, and the apparatus as previously described.

[0032] The X-ray image acquisition device is configured to acquire X-ray image data of a region of interest of a patient and to provide the X-ray imaging data to the apparatus.

[0033] Thereby, an X-ray imaging system is provided which has the capability to provide a user with a lung image quality assessment.

[0034] According to a fourth aspect of the present application, a computer program element for controlling an apparatus as previously described is provided. The computer program element, when being executed by the processing unit, is adapted for performing the method steps as previously described.

[0035] According to a fifth aspect of the present application, a computer readable medium having stored the computer program element of the previously described is provided.

[0036] In this paper, the term "region of interest" refers to a portion of the patient imaged by an X-ray imaging device. In the case of a chest examination, the region of interest is located below the patient's neck and above the diaphragm, but it will be appreciated that the region of interest can be imaged from many different angles. For example, posterior-anterior or anterior-posterior imaging methods are commonly used. The region of interest can also be a portion of the patient's lateral profile seen from either side. For example, the region of interest can be a portion of the chest image as an angle obtained through a mobile X-ray imaging device.

[0037] In this paper, the term "diaphragm" can refer to the X-ray projection of the diaphragm onto an X-ray detector, thus forming an X-ray image of the diaphragm (e.g., from the posterior or anterior direction). Therefore, the term "diaphragm line" defines the path in an X-ray image that traces the shape of the diaphragm's trajectory in the X-ray image. Although the boundary can move, depending on the degree of thoracic cavity expansion, the diaphragm typically presents as a cup-shaped boundary at the base of the lung lobes.

[0038] In this document, the terms "rib" or "clavicle" may refer to the X-ray projection of the rib onto an X-ray detector, thus forming an X-ray image of the rib (e.g., also from the posterior or anterior direction). Therefore, the term "rib line" defines a line in the X-ray image corresponding to the shape of the ribs in a patient.

[0039] Depending on the imaging angle and image type, as well as the degree of the patient's inhalation or exhalation, the rib lines may be more or less curved and may intersect with the diaphragm or other rib lines.

[0040] In this paper, the term "crossing condition" is defined as a situation in which an area of ​​an X-ray image containing the portion of the diaphragm coincides with a portion of an X-ray image containing the rib line. Therefore, "crossing" is not a physical crossing occurring in the patient's body, but a crossing condition created by the geometric projection of the X-ray beam through the patient's chest, thereby projecting the trajectory of the diaphragm and at least one rib onto the X-ray detector to form a rib line or diaphragm line.

[0041] In this context, the term "cross-over condition rule" defines a logical condition defining whether a rib line intersects with a diaphragm line, and vice versa. For example, it can be considered that for the eighth rib, a cross-over condition can be reliably defined in which the transversal 4 / 7 space of the eighth rib lies within the outer half of the diaphragm. If this condition is met, the cross-over condition is declared true. If this condition is not met, the cross-over condition is defined as false. It will be appreciated that many cross-over condition rules can be envisaged, involving specific cross-over ranges between diaphragm and rib. Different cross-over condition rules are possible for anterior-posterior (AP), posterior-anterior (PA) or lateral views, or different X-ray source or detector imaging angles. Alternatively or additionally, the cross-over condition rule can vary depending on patient-specific data, such as the patient's age, sex or body morphology.

[0042] In this context, the term "predetermined X-ray image inhalation quality monitoring rule" enables a determination of whether a good or poor image is present. The X-ray image inhalation quality monitoring rule can use one or more rib cross-over conditions to determine whether a good quality X-ray image is present. In its simplest form, the predetermined X-ray image inhalation quality monitoring rule requires only a true cross-over condition between one rib, for example the tenth rib, and the diaphragm. In a more complex predetermined X-ray image inhalation quality monitoring rule, for example, there are conditions present for good X-ray image inhalation quality based on the cross-over of several ribs with the diaphragm. The rule can be a basic logical condition or a more complex evaluation involving continuous quantities, such as probabilities.

[0043] It can thus be seen that the basic idea of the present invention is to automatically identify the presence of a cross-over point between diaphragm and rib lines in an X-ray image. The presence of this cross-over point can be used for further testing to define whether such a cross-over point meets a cross-over condition rule and a predetermined X-ray image inhalation quality monitoring rule to enable derivation of an X-ray image inhalation quality measure. This enables an automatic evaluation of the inhalation state of a subject for the purpose of preventing potential errors in the evaluation of X-ray image quality. BRIEF DESCRIPTION OF DRAWINGS

[0044] Exemplary embodiments of the present invention will be described below with reference to the following drawings:

[0045] Figure 1a Figures la) and lb) show X-ray images of the thorax in inspiration and expiration, respectively.

[0046] Figure 2a Figures 2a) and 2b) show clavicular line and diaphragm cross-over techniques.

[0047] Figure 3 A method according to the first aspect is shown.

[0048] Figure 4a) and 4b) show a chest that has been processed using an exemplary version of the algorithm discussed herein.

[0049] Figure 5a ) and 5b) are Figure 4a ) and 4b) a simplified line representation of the chest.

[0050] Figure 6 An apparatus according to the second aspect is shown.

[0051] Figure 7 A system according to the third aspect is shown. DETAILED DESCRIPTION

[0052] Chest radiography is a commonly performed clinical imaging examination. Chest X-ray plays an important role in the detection and diagnosis of diseases of the chest. The quality of an image acquired by chest radiography can be defined in terms of the inclusion of the appropriate anatomy within the field of view, the contrast of the structures of interest with respect to the background signal, and the positioning of the patient's chest with respect to the X-ray equipment, for example. The evaluation of image quality focuses on meeting the minimum requirements defined for each type of examination. The assessment of these minimum requirements depends on the skill of the system operator. Typically, a pre-defined standard operating procedure should be followed. In particular, the positioning of the patient with respect to the X-ray detector requires the cooperation of the patient.

[0053] The typical projection geometry for chest radiography is the posterior-anterior (PA) view. In this view, the X-ray source is positioned such that the X-ray beam enters through the back of the chest and exits through the front of the patient before reaching the detector. Diagnostic guidelines, such as those defined by the European Commission in "European Guidelines on Quality Criteria for Diagnostic Radiographic Images, 1996", define that the acquisition should take place with a pause in respiration at maximum patient inspiration. The reason for this is to maximize the projected area of the lung parenchymal tissue on the image detector, thereby avoiding the superimposition of other opaque structures (e.g. abdominal tissue). The inflation of the visualized parenchymal tissue is maximized, and the vascular crowded area is moved out of the imaged lung field. The basic mechanism of respiration is that when the diaphragm contracts (pulling the bottom of the chest cavity down), the chest cavity expands, thereby reducing the pressure within the chest cavity. To balance the pressure, air rushes into the lungs. When the diaphragm relaxes (moves up), the elasticity of the lungs and chest wall causes the chest wall to contract, thereby pushing air out of the lungs.

[0054] Figure 1a ) and 1b) show X-ray images showing the difference in image quality between images acquired during the inhalation and exhalation states of the same patient.

[0055] Figure 1a) shows the lung in inhalation. In the inhalation state, the curvature of the ribs from front to back is clearly visible, and the lung field 10 is enlarged because the diaphragm 12 pulls the entire thoracic structure downwards. This imaging state is the preferred state for a high-quality chest X-ray.

[0056] Figure 1b ) shows the lung in exhalation. The lung field 14 is smaller. In addition, the opacity 16 is not as clearly visible in Figure 1b whether the opacity 16 involves an underlying medical condition or simply the vascular bundle of the blood vessels around the heart.

[0057] Therefore, medical professionals prefer to image the lung in the state shown in Figure 1a ).

[0058] Figure 2a ) shows the lung in inhalation. Figure 1a ). The right clavicle 18 is at right angles to the spine 20. These bones have been highlighted. The clavicular dividing line 22 has been superimposed, and it is seen that this line crosses the diaphragm 12. The point at which the clavicular dividing line 22 crosses the diaphragm is a previously known lung image quality monitoring measure.

[0059] Figure 2b ) shows the lung in exhalation. Figure 1b ). The right clavicle 24 is now shown at an angle to the spine 20, and thus to Figure 2a ), the clavicular dividing line 26 crosses the diaphragm 12 at a more central point than in the case of

[0060] Currently, diagnostic guidelines involving lung shadows and diaphragm interaction depend on the skill level of the operator in controlling the many acquisition factors that can influence image quality. For example, the timing of the X-ray exposure should coincide with the maximum inhalation of the patient's breathing cycle. If the radiologist does not sufficiently instruct the patient, or the patient has specific difficulties in performing the instructions properly, the quality of the X-ray image is negatively affected. Currently, after acquisition, the image is visually evaluated by the operator who performed the image acquisition to determine whether the quality of the X-ray image is sufficient to send for further diagnostic interpretation. Therefore, the skill level of the operator is also an important factor in the decision of the image quality and about whether a specific image is rejected or accepted before the patient leaves the imaging room. Therefore, there is a need for an improved method of X-ray image evaluation. Therefore, according to a first aspect of the present invention, a method for X-ray image inhalation quality monitoring is provided. The method comprises the following steps:

[0061] a) receiving 30 an X-ray image of a region of interest of a patient;

[0062] b) generating 32 a diaphragm line representing a path of the diaphragm in the X-ray image, and generating a rib line representing a path of the ribs in the X-ray image;

[0063] c) detecting 34 the diaphragm line, and detecting the rib line;

[0064] d) evaluating 36 the X-ray image for the presence of a crossing condition between (i) the diaphragm line and (ii) the rib line, wherein the crossing condition of the diaphragm line and the rib line is defined according to a crossing condition rule; and

[0065] e) comparing 38 the presence of a crossing condition between the rib line and the diaphragm line to a predetermined X-ray image inhalation quality monitoring rule specifying an image inhalation state according to the crossing condition to yield an X-ray image inhalation quality measure.

[0066] Figure 3 A method according to the first aspect is illustrated. In step a) an X-ray image is received, typically from a digital flat panel X-ray detector. This assumes that a process of positioning a patient in a desired position in the X-ray detector has taken place, and that an X-ray image has been taken.

[0067] Alternatively, the X-ray image can be received from a digital scanning device. A conventional X-ray machine can be used to provide a film exposure of the region of interest, which can then be digitized and analyzed for exposure quality according to this aspect of the invention.

[0068] In step b) a diaphragm line is identified in the X-ray image. Typically, when the region of interest is a human chest, the diaphragm follows a curved path through the bottom of the chest region. The diaphragm separates different textures of tissue, and has a unique shape, with a right "dome" that is slightly higher than a left dome. Thus, a line along the path of the diaphragm in the X-ray image is suitable for detection by image processing techniques. Although as Figure 1a ) and 1b) show that the human diaphragm is a single connected boundary, in practice it is possible to detect different parts of the diaphragm, such as a left part and a right part.

[0069] Optionally, the diaphragm can be detected by gradient detection, texture detection of the region within the thorax, a flood fill algorithm, or by deploying knowledge learned from training images about expected shapes to be found in the image. The shape of the diaphragm follows a curve, and is thus suitable for modeling using a spline method.

[0070] The rib line can also be extracted using alternative image processing techniques. Optionally, the rib line can be numbered using a labeling algorithm.

[0071] In step c) there is a step of detecting the diaphragm line and detecting the rib lines. It is known to the skilled person that recognition of the contours of the rib shadows and delineation of the position of the diaphragm border at the bottom of the lung shadow can be extracted from the X-ray image.

[0072] Optionally, the geometric reasoning engine can infer the number of lower rib portions (posterior and anterior) whose shadows project above the diaphragm line and label the rib lines according to their rib position. Typically, the rib closest to the patient's head is designated as "1". The "true ribs" suspend down as ribs 1 through 7, and the "false ribs" 8-12 suspend up. Ribs 11-12 are sometimes referred to as "floating ribs".

[0073] In step d) a rib crossing condition is identified. The rib crossing condition in its simplest form refers to a situation in which in the X-ray image, one rib line shares a point of the X-ray image with one diaphragm line.

[0074] Optionally, the presence of the rib crossing condition is defined in terms of the number of ribs. Depending on various rules, different numbered ribs can be defined as crossing the diaphragm or not crossing the diaphragm, which will be discussed further below. It is not excluded that the rib crossing condition can involve more than one rib crossing the diaphragm.

[0075] Step e) is applied after confirming the presence of a crossing condition of a diaphragm line and a rib line. In a simple example, it can be the case that the presence of any crossing of a particular rib line with the diaphragm is indicative of the lung field being sufficiently expanded. This will be the case for higher numbered ribs, for example. However, the position of some rib lines should be such that even if they cross the diaphragm, the lung field will not be enlarged enough to conclude that a high quality image has been taken. Thus, it can be seen that the predetermined X-ray image inhalation quality rule applies a further filter on whether a high quality X-ray image has been taken or not.

[0076] According to embodiments which can be combined with any other embodiments in this specification, in step b) a plurality of rib lines is generated in the X-ray image, wherein each rib line of the plurality of rib lines represents a line of a different rib. In case a plurality of rib lines is generated, in step c) the plurality of rib lines is detected. In step d) a rib line from the plurality of rib lines is evaluated for a crossing with the diaphragm line. In this case, the crossing condition rule can include details of the crossing condition of one or more rib lines.

[0077] Once it is confirmed that there is a crossing of a rib line and a diaphragm line and that this crossing satisfies the condition for a high quality lung field to be shown in the X-ray image, the X-ray image inhalation quality measure is output.

[0078] Optionally, there is a step f) of outputting the X-ray image inhalation quality measure.

[0079] Optionally, in step f), the X-ray image inhalation quality measure is output on a computer display screen.

[0080] Optionally, the X-ray image inhalation quality measure is a simple binary indicator, which indicates whether the image has good or poor quality, thereby implying that no or a re- shot of the X-ray image is needed. This allows a simpler presentation of the determined result.

[0081] Optionally, in step f), the X-ray image inhalation quality measure is output as an illuminated warning light or a warning sound.

[0082] Optionally, in step f), the X-ray image inhalation quality measure is output as a bit map "watermark" inserted in a portion of the X-ray image provided by the X-ray device.

[0083] Optionally, the X-ray image inhalation quality measure is a discretized category, for example selected from the group of "poor, medium, good".

[0084] Optionally, the cross-over condition rule can be customized to the imaging angle of the X-ray source and / or detector. There is a step of inputting the imaging device setting angle. There is a step of selecting the cross-over condition rule based on the input imaging device setting angle. In this way, image variations caused by geometric projection effects can be taken into account.

[0085] Optionally, the X-ray image inhalation quality measure is a continuous value, for example a percentage. This allows an experienced operator to self-assess the quality of the image.

[0086] According to an embodiment, the cross-over condition rule and / or the predetermined X-ray image inhalation quality monitoring rule can be provided as a data record linked to specific imaging standards (for example, "European Guidelines on Quality Criteria for Diagnostic Images") to enable following regional or national imaging standards. These standard rules are provided in a data carrier format, such as a CD-ROM, or by download or update from the internet.

[0087] According to an embodiment, the cross-over condition rule and / or the predetermined X-ray image inhalation quality monitoring rule can be pre-programmed by a medical imaging professional to predefined standards or to specific protocols required by a healthcare institution. As discussed below, parameters of the rule can be pre-programmed using a computer interface.

[0088] Figure 4a ) and Figure 4b) respectively show a PA chest radiograph in inspiration and expiration conditions. The rib lines and diaphragm line generated and detected according to the annotation process known in the art and discussed above show exemplary applications of the above method, which will be discussed in detail below. Annotation line 30 is the diaphragm line. Annotation line 32 represents the sixth rib. Annotation line 34 represents the eighth rib. Annotation line 36 represents the tenth rib. The ribs that are considered to cross the diaphragm line 30 are represented with dashed lines; otherwise, the lines are solid.

[0089] In the illustrated case, the crossing condition rule has been applied, wherein if the anterior face of the sixth rib crosses the diaphragm, it is considered to cross the diaphragm line and is dotted.

[0090] An alternative crossing condition rule, not shown, is that a predetermined portion of the posterior face of more than the eighth, ninth or tenth rib is located below the diaphragm, they are considered to cross.

[0091] Figure 4a ) shows a chest X-ray showing a high quality inspiration. In this case, the crossing condition rule for the sixth rib is that the anterior face of the sixth rib crosses the diaphragm line. In Figure 4a ) the method does not find that the crossing condition is satisfied since the sixth rib 40 does not cross the diaphragm line 42. Therefore, no dashed line is shown. Moreover, in this case, the predetermined X-ray image inspiration quality monitoring rule provides that there is a "good quality" image when the crossing condition rule for the sixth rib is not satisfied, enabling the X-ray image inspiration quality measure to be provided to the user.

[0092] Figure 4b ) shows a chest X-ray showing a poor quality inspiration. In the case of Figure 4b ) the anterior face of the sixth rib does cross the diaphragm line 44. Therefore, the crossing condition is fulfilled and the sixth rib line 46 is marked as dotted. As Figure 4a ) the predetermined X-ray image inspiration quality monitoring rule defines that there is a "good quality" image when the crossing condition rule for the sixth rib is not satisfied. Therefore, since the sixth rib line crosses the diaphragm line, it is indicated that there is a "poor quality" image, thus enabling the X-ray image inspiration quality measure to be provided to the user.

[0093] Figure 4b ) also shows that the distal portion of the third rib (the tip) crosses the diaphragm line. An additional third rib crossing condition rule can be defined, for example, that the third rib line crosses the diaphragm line only when the crossing of the third rib with the diaphragm is within 50% of the medial side of the third rib. Therefore, "false negative" results due to accidental crossing of the tip of the third rib can be prevented.

[0094] In short, for a rib under interrogation, the crossing condition rule can be considered to answer the question "does this rib cross the diaphragm?". It can be considered that a predetermined X-ray image inhalation quality monitoring rule continues to ask the question "does the fact that this rib satisfies the crossing condition rule imply that there is a poor quality image?". This determination thus enables the provision of an X-ray image inhalation quality measure to the user.

[0095] Thus, in Figure 4a In 3a) and 3b), the diaphragm line is determined from the rib lines. In 4a) and 4b), the rib centerlines have been used to quantify the inhalation status of the subject and to establish an image quality measure resulting therefrom. The marking of the individual rib lines is determined based on rules defined per rib, which depend on the presence of a crossing of the rib and the diaphragm.

[0096] In Figure 4a In 3a) and 3b), the diaphragm line is determined from the rib lines. In 4a) and 4b), the rib centerlines have been used to quantify the inhalation status of the subject and to establish an image quality measure resulting therefrom. The marking of the individual rib lines is determined based on rules defined per rib, which depend on the presence of a crossing of the rib and the diaphragm.

[0097] Continuing, the lowest rib for which all ribs above are inside the lung field is determined (the lung field can be easily segmented as known to the person skilled in the art). According to the imaging guidelines, for good inhalation quality, the lowest rib for which all ribs above are inside the lung field should be the tenth rib on both sides. This is an example of a predetermined X-ray image inhalation quality monitoring rule.

[0098] According to an embodiment, the predetermined X-ray image inhalation quality monitoring rule is outputting a positive X-ray image inhalation quality measure when the posterior part of the tenth rib line satisfies the crossing condition rule defining a crossing of the tenth rib line with the diaphragm line.

[0099] Figure 5a Figures 4a) and 4b) show Figure 4a Figures 4a) and 4b) show

[0100] Figure 5a Figure 5a) shows a schematic view of the right half of a thorax with an inhalation level necessary to provide a "good quality" image. The schematic view shows a lung field 80. Seven rib lines numbered according to medical convention are shown in the lung field. A diaphragm line 82 separates the eighth rib line from the ninth rib line. The diaphragm 82 does not cross the rib lines and thus the crossing condition rule is false.

[0101] Figure 5b) shows a schematic view of the right half of a thorax with an inhalation level that would result in a "poor" image. Eight rib lines numbered according to medical convention are shown in the lung field. The diaphragm line 84 separates the eighth rib line from the ninth rib line. The diaphragm 84 crosses the eighth rib line at point 86. If the crossing condition rule in this case is simply that any crossing of the eighth rib line and the diaphragm line causes the crossing condition rule to be satisfied, then in this case the crossing condition rule is satisfied and the eighth rib is defined as crossing the diaphragm line. Furthermore, it can be assumed in this example that the image inhalation status is defined as poor quality if the eighth rib line crosses the diaphragm line. Thus, in this case the detection algorithm would claim that there is a poor quality image. More complex image inhalation status can be defined with rules that incorporate the crossing status of multiple ribs, or defined as the transverse extent along the rib or diaphragm that the rib or diaphragm crosses.

[0102] According to an embodiment of the method, there is a step of marking, e.g. in a numerical order, the rib elements.

[0103] According to an embodiment of the method, the crossing condition rule comprises a first crossing condition rule to be applied to initially marked ribs and a second crossing condition rule to be applied to subsequently marked ribs. The first and second rib crossing condition rules are different.

[0104] Alternatively, the first rib crossing condition rule and the second rib crossing condition rule are the same. This is useful in case the first rib and the second rib are at the same level of the thorax but on the right side and the left side of the thorax.

[0105] According to this embodiment, the two marked ribs have different crossing rules applied to them in order to determine the presence of two or one crossing with the diaphragm. The fact that different crossing rules can be applied to different ribs means that natural anatomical variations of higher numbered ribs compared to lower numbered ribs can be meaningfully taken into account to provide a more accurate quality estimate.

[0106] According to an embodiment of the method, the crossing condition rule further comprises a third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh or twelfth crossing condition rule. These crossing condition rules correspond respectively to the numbering of the ribs in a thorax of a human being. It is not necessary that all of the crossing condition rules of the foregoing list of twelve crossing condition rules exist and any combination of them can yield a beneficial effect depending on what combination of anatomical features represents a consideration of a good quality X-ray image.

[0107] According to an embodiment of the method, the crossing condition rule as defined above comprises a pixel of the rib line having at least one pixel position that is identical to a pixel position of a pixel of the diaphragm line in the X-ray image.

[0108] According to an embodiment of the method, the cross-over condition rule is considered to be not fulfilled if the cross-over is positioned in lateral 2 / 7, 3 / 7, 4 / 7, 5 / 7, 6 / 7 of the diaphragm line.

[0109] An image processing algorithm can be applied to distinguish between parts of the ribs in the x-ray image. For example, the anterior and posterior parts can be distinguished by examining the change in curvature of the ribs.

[0110] According to an embodiment of the method, the cross-over condition rule comprises an anterior cross-over condition rule. This means that only image information related to the anterior part of the ribs is used to make a decision about the cross-over of the ribs with the diaphragm. The anterior condition rule can optionally be different for each rib. The anterior cross-over condition rule can optionally be different for the right or left side of the thorax.

[0111] According to an embodiment of the method, the cross-over condition rule comprises a posterior cross-over condition rule. This means that only image information related to the posterior part of the ribs is used to make a decision about the cross-over of the ribs with the diaphragm. The posterior condition rule can optionally be different for each rib. The posterior cross-over condition rule can optionally be different for the right or left side of the thorax.

[0112] According to an embodiment of the method, the cross-over condition rule comprises an anterior and / or posterior cross-over condition rule. The anterior and / or posterior cross-over condition rule can optionally be different for each rib. The anterior and / or posterior cross-over condition rule can optionally be different for the right or left side of the thorax.

[0113] According to an embodiment of the method, the cross-over condition rule comprises a cross-over of the seventh rib line using a horizontal anterior view with the diaphragm line such that six ribs appear in the lung field above the diaphragm line.

[0114] According to an embodiment of the method, the cross-over condition rule comprises a cross-over of the tenth rib line using a horizontal posterior view with the diaphragm line such that nine ribs appear in the lung field above the diaphragm line.

[0115] According to an embodiment of the method, a width measure of the examined rib is stored and a cross-over condition is considered to exist when a segment of a rib line moves within a width of 100%, 50%, 25%, 10% or 1% of the width measure of the examined rib.

[0116] According to an embodiment of the method, a predefined quality monitoring rule is provided which defines that a poor quality image exists if the cross-over condition rule is fulfilled.

[0117] According to an embodiment of the method, a predefined quality monitoring rule is provided which defines that a poor quality image exists if the cross-over condition rule is fulfilled.

[0118] According to an embodiment of the method, predefined quality monitoring rules are provided which combine a plurality of per-rib crossing condition rules in order to determine whether a suboptimal image is present.

[0119] According to an embodiment of the method, the predefined quality monitoring rules comprise a numerical likelihood value.

[0120] According to an embodiment of the method, the X-ray image is taken using a posterior-anterior (PA), an anterior-posterior (AP) or a lateral view.

[0121] According to an embodiment of the method, image view direction information is provided and specific crossing condition rules and specific X-ray image inhalation quality rules can be provided for each view direction. Thus, optimal image results can be ensured regardless of the image viewing direction.

[0122] According to an embodiment of the method, a method as previously described is provided, wherein each rib line has a specific crossing condition rule for determining the crossing condition. In case a plurality of rib lines is provided, each rib line also has a specific crossing condition rule for determining the crossing condition.

[0123] According to an embodiment of the method, the predefined X-ray image inhalation quality monitoring rules determine whether the twelfth, eleventh, tenth, ninth, eighth, sixth or fifth rib crosses the diaphragm.

[0124] According to an embodiment of the method, step b) further comprises a step b1):

[0125] b1) dividing the X-ray image into a right lung field portion and a left lung field portion;

[0126] wherein in step c) the steps of detecting the diaphragm line and the rib lines are performed in the left lung field portion, the right lung field portion or both;

[0127] wherein steps d) and e) are repeated to enable calculation of a left lung X-ray image inhalation quality measure and / or a right lung X-ray image inhalation quality measure.

[0128] According to this embodiment, a patient with deformities or a patient who cannot be imaged on one side can still have an evaluation of the image quality using an X-ray image inhalation quality measure defined for only one lung.

[0129] According to an embodiment of the method, step e) further comprises a step of finding a ratio of the left lung X-ray image inhalation quality measure to the right lung X-ray image inhalation quality measure.

[0130] Thus, according to this embodiment, asymmetries in the image can be identified from the calculated right / left ratio.

[0131] According to an embodiment of the method, the method further comprises steps b2) and e1), and e2):

[0132] b2) identifying a consolidation area in the left lung field or in the right lung field of the X-ray image;

[0133] e1) providing the right lung X-ray image inhalation quality measure as the X-ray image inhalation quality measure if a consolidation area is identified in the left lung field; or

[0134] e2) providing the left lung X-ray image inhalation quality measure as the X-ray image inhalation quality measure if a consolidation area is identified in the right lung field.

[0135] If a condition such as tuberculosis is present in the patient's chest, there can be a large consolidation area (an area of lung tissue filled with liquid). Thus, in a radiograph taken in expiration, an opaque area is observed and can be misinterpreted. According to this embodiment of the application, the right lung or the left lung can be excluded from the inhalation quality measure if a consolidation area is identified in their respective lung field. Thus, if an abnormality is identified (e.g. using an image processing algorithm such as a texture or shape recognition algorithm). If a lung abnormality is detected, the unaffected lung side can be used as a basis for the X-ray image inhalation quality measure. Such a single-sided measure is often a reliable accurate measure.

[0136] According to an embodiment of the method, step b) further comprises step b1):

[0137] b1) detecting a clavicle line representing a path of a clavicle in the X-ray image;

[0138] wherein step c) further comprises the following steps:

[0139] c1) generating a clavicle division line representing a line dividing the clavicle line in the X-ray image;

[0140] c2) evaluating the X-ray image for the presence of a clavicle crossing condition of the clavicle division line with the diaphragm line;

[0141] wherein in step c) the intersection of the clavicle division line with the diaphragm line is used to define the crossing condition rule.

[0142] The clavicle line can be identified using the same algorithm as the rib line, with minor modifications to allow for the difference in radius of curvature of the clavicle compared to the ribs. The clavicle division line can be found as a fraction of the clavicle line, or along a certain proportion thereof. Thus, the point where the clavicle division line crosses the diaphragm line forms a point on the diaphragm line which can be used as a discriminator of whether a rib is considered to cross the diaphragm line. This discriminator is linked to the overall patient posture. Thus, a detection rule involving the crossing of the clavicle line and the rib line is provided, offering the opportunity of a high detection accuracy for poor images.

[0143] According to an embodiment of the method, step a) further comprises steps a3), d3) and g1):

[0144] a3) receiving imaging guideline configuration information comprising rib count configuration information; and further comprising steps e4) and g1):

[0145] d3) comparing the number of further rib lines located within the lung field with the rib count configuration information to produce a guideline inhalation state comparison;

[0146] e1) displaying the guideline inhalation state comparison.

[0147] Common cross-over condition rules useful for X-ray image diagnosis and predetermined X-ray image inhalation quality rules can be obtained from common medical guidelines, which can be provided on a data carrier or via a network as guideline configuration information.

[0148] Thus, patient examinations can be compared with standard imaging guidelines in an efficient manner.

[0149] According to an embodiment of the method, the predetermined X-ray image inhalation quality monitoring rule provides that a positive X-ray image inhalation quality measure shall be output when a tenth rib line of the rib lines satisfies a tenth rib cross-over condition rule.

[0150] In diagnostic imaging practice, the cross-over of the tenth rib line with the diaphragm line is a preferred measure.

[0151] According to an embodiment of the method, the method according to any of the preceding examples further comprises the following steps after step a):

[0152] a4) segmenting the X-ray image.

[0153] According to a second aspect of the present invention, there is provided an apparatus for X-ray image inhalation quality monitoring.

[0154] Figure 6 is a block diagram of an apparatus 50 for X-ray image inhalation quality monitoring.

[0155] The apparatus 50 comprises a processing unit 52.

[0156] An apparatus 50 for X-ray image inhalation quality monitoring comprises a processing unit.

[0157] The processing unit 52 is configured to receive an X-ray image of a region of interest of a patient, to generate a diaphragm line representing a path of a diaphragm in the X-ray image, to generate rib lines representing paths of ribs in the X-ray image, to detect the diaphragm line, and to detect the rib lines, to evaluate the X-ray image for the presence of a cross-over condition between (i) the diaphragm line and (ii) the rib lines.

[0158] The crossing condition of the diaphragm line and the rib line is defined according to a crossing condition rule, and wherein the processor is configured to compare the presence of a crossing condition between the rib line and the diaphragm line with a predetermined X-ray image inhalation quality monitoring rule that specifies an image inhalation state in dependence of the crossing condition rule, and to produce an X-ray image inhalation quality measure.

[0159] According to an example, the X-ray image inhalation quality measure is a binary condition. Thus, if the image quality is good, a true condition is returned, and if the image quality is poor, a false condition is returned.

[0160] According to an example, the X-ray image inhalation quality measure is a continuous measure. The continuous measure can enable the inhalation quality measure to be differentiated for different patients or different conditions.

[0161] According to an embodiment, the rib line has a specific crossing condition rule for determining the crossing condition. In case there are multiple rib lines, each of the multiple rib lines has a specific crossing condition rule for determining the crossing condition.

[0162] According to an embodiment, the first rib line has a first crossing condition rule, and the second rib line has a second crossing condition rule that is different from the first rule, and wherein the first and second rules are used to determine the crossing condition.

[0163] According to an embodiment, the crossing condition rule can be tailored to the imaging angle of the X-ray source and / or detector. The processor 52 is configured to receive an imaging device setting angle. The processor is configured to select the crossing condition rule based on the input imaging device setting angle. In this way, variations in the image caused by geometric projection effects can be taken into account.

[0164] For example, as seen in Figure 1a The crossing state between the rib line and the diaphragm line is qualitative and can vary depending on the rib considered. Thus, according to this embodiment, it is possible to attribute an individual rib line to a specific rib crossing rule that determines whether a specific rib line is considered to cross the diaphragm or not. For example, if the rib number 8 touches the outside 3 / 7 of the diaphragm line, rib number 8 can be considered to cross, but if rib 7 touches the outside 4 / 7 of the diaphragm line, rib 7 can be considered to cross.

[0165] According to an embodiment, there is provided an apparatus as previously described, wherein the processing unit is further configured to divide the X-ray image into a right lung field portion and a left lung field portion, detect the diaphragm line and the rib line in the left lung field portion, the right lung field portion, or both, and repeat the detection to enable calculation of a left lung X-ray image inhalation quality measure and / or a right lung X-ray image inhalation quality measure. Further, a right and left inhalation quality comparison can be generated by comparing the left lung field portion and right lung field portion measurements.

[0166] According to this embodiment, it is possible to determine the inhalation quality relying on measurements of the right lung only or the left lung only. This is important when the chest X-ray is interrupted by a metallic element, such as a hard cardiac pacemaker or other implant or surgical metal work. The assessment of the lung inhalation quality can be assessed using the right lung only or the left lung only.

[0167] Further, by comparing the right lung and left lung inhalation quality, it is possible to assess the symmetry of the inhalation state.

[0168] According to an embodiment of the present application, there is provided an apparatus as previously described, wherein the processing unit is further configured to identify a consolidation area in the left lung field or the right lung field of the X-ray image, and wherein the processing unit is configured to provide a right lung X-ray image inhalation quality measure as the X-ray image inhalation quality measure if a consolidation area is identified in the left lung field, or to provide the X-ray image inhalation quality measure as a left lung X-ray image inhalation quality measure if a consolidation area is identified in the right lung field. According to an embodiment, there is provided an apparatus as previously described, wherein the processing unit is further configured to detect a clavicle line representing a path of a clavicle in the X-ray image, generate a clavicle division line representing a line dividing the clavicle line in the X-ray image, and assess the X-ray image with respect to the presence of a clavicle crossing condition of the clavicle division line with the diaphragm line. The crossing condition rule is defined as the intersection point of the clavicle division line with the diaphragm line.

[0169] According to an embodiment, there is provided an apparatus as previously described. The predetermined X-ray image inhalation quality monitoring rule is that a positive X-ray image inhalation quality measure shall be output when the tenth rib line of the rib line satisfies the tenth rib crossing condition rule.

[0170] It has been found useful to define that there is a good inhalation condition when the tenth rib line crosses the diaphragm.

[0171] According to an embodiment, there is provided an apparatus 50 as previously described, further comprising

[0172] an input unit.

[0173] The input unit is configured to receive the X-ray image from an X-ray detector.

[0174] According to an embodiment, there is provided an apparatus 50 as previously described, further comprising

[0175] an output unit.

[0176] The output unit is configured to display the X-ray image inhalation quality measure.

[0177] Optionally, the X-ray image inhalation quality measure can be displayed as a simple red or green warning light, an alarm sound or a numerical or alphanumeric readout. This enables simple image quality feedback to be given to the user.

[0178] Optionally, the output unit is configured to display the X-ray image inhalation quality measure as a numerical value indicative of the image quality.

[0179] According to embodiments of the application, the output unit is configured to display the X-ray image inhalation quality measure on the X-ray image itself, or on a digital tablet display, or introduced on an analog x-ray plate. Thus, the medical professional evaluating the image can be given an estimate of the quality of the X-ray exposure.

[0180] According to embodiments of the application, there is provided an apparatus as previously described, wherein the processing unit is further configured to receive imaging guideline configuration information including rib count configuration information, compare the number of additional rib lines located within the lung field to the rib count configuration information, produce a guideline inhalation status comparison, and the output unit is further configured to display the guideline inhalation status comparison using the output unit.

[0181] In this way, the processing unit can receive information from a regulatory agency and automatically apply that information to the X-ray image when the X-ray image is taken.

[0182] According to a third aspect of the application, an X-ray imaging system 60 comprises:

[0183] an X-ray image acquisition device 62 having an X-ray source 64 and an X-ray detector 66; and

[0184] an apparatus 68 connected to the X-ray detector, and

[0185] an output 74.

[0186] The X-ray image acquisition device 62 is configured to acquire X-ray image data of a region of interest of a patient and provide the X-ray imaging data to the apparatus 68. The apparatus 68 is configured to operate as in any of the embodiments discussed above. The apparatus 68 is configured to output an X-ray image inhalation quality measure to a user via the output 74.

[0187] Figure 7An X-ray imaging system 60 is shown. The system includes an X-ray source 62, typically of the rotating anode type. The X-ray source 62 can be positioned so that radiation is emitted in the direction of an X-ray detector 66, e.g., of the pixelated flat panel type, at which it is received. As before, the X-ray detector 66 is connected to a device 68.

[0188] In use, a patient's region of interest is positioned in front of the X-ray source 62. The source is activated and an exposure of the patient is completed. The device 68 evaluates the quality of the image according to the rib crossing rule and the predetermined X-ray image inhalation quality rule as described above. The device 68 produces an X-ray image inhalation quality measure which is output to the user on a screen 74. Optionally, the output can be a light or a simple audible warning. Optionally, the device can be part of a computer, such as a PC, provided with input modules such as a keyboard 76 and a mouse 78.

[0189] Optionally, the X-ray detector 62 can be located in a stand-alone detector 70 or in a bed 72. Thus, the patient's chest can be imaged in a standing position or a sitting position.

[0190] According to a fourth aspect of the application, a computer program element for controlling a device according to one of the preceding descriptions is provided, wherein the computer program element is executed by a processing unit to perform the method steps according to any of the preceding method steps.

[0191] According to an aspect of the application, a computer readable medium storing a program element as described before is provided.

[0192] According to a fifth aspect of the application, a computer readable medium storing a program element as described before is provided.

[0193] The computer program element might therefore be stored on a computer unit, which might also be an embodiment of the present application. This computing unit can be adapted to perform or induce a performing of the steps of the method described above. Moreover, it can be adapted to operate the components of the apparatus described above. The computing unit can be adapted to operate automatically and / or it can be adapted to be controlled by a user. The computer program can be loaded into working memory of the data processor from a storage medium or from a network. The data processor is thereby equipped for carrying out the method of the application.

[0194] This exemplary embodiment of the present application covers computer programs that are installed on a computer from the start and computer programs that are updated so that existing programs become programs using the present application.

[0195] A computer program can be stored / distributed on a suitable medium, such as an optical storage medium or a solid-state storage medium supplied together with or as part of other hardware, but can also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems. However, the computer program can also be presented in a form suitable for use with the Internet or other computer network, such as a web page, a server, a cloud or other electronic means. Thus, a means of presentation can be any manner allowed by the technical possibilities. Moreover, such a computer program can be updated and / or distributed over the Internet or other computer network, for example by means of software updates which are available via the Internet or other computer network.

[0196] According to another exemplary embodiment of the present application, a medium for making a computer program element available for downloading is provided, wherein the computer program element is arranged to perform a method according to one of the previously described embodiments of the present application.

[0197] In the claims, the word "comprising" does not exclude other elements or steps, and the words "a" or "an" do not exclude a plurality. A single processor or other unit can fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures can not be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. An apparatus (50) for X-ray image inhalation quality monitoring, comprising: a processing unit (52); wherein the processing unit (52) is configured to receive an X-ray image of a region of interest of a patient, to generate a diaphragm line representing a path of a diaphragm in the X-ray image, to generate a rib line representing a path of a rib in the X-ray image, to detect the diaphragm line, and to detect the rib line, to assess the X-ray image for a presence of a crossing condition between (i) the diaphragm line and (ii) the rib line, wherein the crossing condition of the diaphragm line and the rib line is defined according to a crossing condition rule, and wherein the processing unit is configured to compare the presence of the crossing condition between the rib line and the diaphragm line to a predetermined X-ray image inhalation quality monitoring rule that specifies an image inhalation status in dependence on the crossing condition, and to produce an X-ray image inhalation quality measure.

2. The apparatus (50) of claim 1, wherein a first rib line has a first crossing condition rule, and a second rib line has a second crossing condition rule that is different from the first crossing condition rule, and wherein the first and second crossing condition rules are used to determine the crossing condition.

3. The apparatus (50) of claim 1 or 2, wherein the processing unit (52) is further configured to divide the X-ray image into a right lung field portion and a left lung field portion, to detect the diaphragm line and the rib line in the left lung field portion, the right lung field portion, or both, and to repeat the detection to enable computation of a left lung X-ray image inhalation quality measure and / or a right lung X-ray image inhalation quality measure.

4. The apparatus (50) of claim 3, wherein the processing unit (52) is further configured to identify a consolidation in the left lung field or the right lung field of the X-ray image, and wherein the processing unit is configured to provide the right lung X-ray image inhalation quality measure as the X-ray image inhalation quality measure in case a consolidation is identified in the left lung field, or to provide the left lung X-ray image inhalation quality measure as the X-ray image inhalation quality measure in case a consolidation is identified in the right lung field.

5. The apparatus (50) of claim 2, wherein, the processing unit is further configured to detect a clavicle line representing a path of a clavicle in the X-ray image, to generate a clavicle division line dividing the clavicle line in the X-ray image, and to assess the X-ray image for a presence of a clavicle crossing condition of the clavicle division line with the diaphragm line, wherein the crossing condition rule is defined as a crossing point of the clavicle division line with the diaphragm line.

6. The apparatus (50) of claim 1 or 2, wherein the predetermined X-ray image inhalation quality monitoring rule is to output a positive X-ray image inhalation quality measure when a posterior portion of a tenth rib line fulfills a crossing condition rule defining a crossing of the tenth rib line with the diaphragm line.

7. The apparatus (50) of claim 1 or 2, further comprising: an output unit; wherein the output unit is configured to display the X-ray image inhalation quality measure.

8. The apparatus (50) of claim 7, wherein the processing unit (52) is further configured to receive imaging guideline configuration information comprising rib count configuration information, and to compare a number of further rib lines positioned in a lung field to the rib count configuration information to produce a guideline inhalation status comparison, and wherein the output unit is further configured to display the guideline inhalation status comparison.

9. A method for X-ray image inhalation quality monitoring, comprising the steps of: a) receiving an X-ray image of a region of interest of a patient; b) generating a diaphragm line representing a path of a diaphragm in the X-ray image, and generating rib lines representing paths of ribs in the X-ray image; c) detecting the diaphragm line, and detecting the rib lines; d) evaluating the X-ray image for a presence of a crossing condition between (i) the diaphragm line and (ii) the rib lines, wherein the crossing condition of the diaphragm line and the rib lines is defined according to a crossing condition rule; and e) comparing the presence of the crossing condition between the rib lines and the diaphragm line to a predetermined X-ray image inhalation quality monitoring rule that specifies an image inhalation status in dependence on the crossing condition to produce an X-ray image inhalation quality measure.

10. The method of claim 9, wherein a first rib line has a first crossing condition rule, and a second rib line has a second crossing condition rule different from the first crossing condition rule, and wherein the first and second crossing condition rules are used to determine the crossing condition.

11. The method of claim 9 or 10, wherein step b) further comprises step bl): bl) dividing the X-ray image into a right lung field portion and a left lung field portion; wherein, in step c), the steps of detecting the diaphragm line and the rib lines are performed in the left lung field portion, the right lung field portion, or both; wherein steps d) and e) are repeated to enable computation of a left lung X-ray image inhalation quality measure and / or a right lung X-ray image inhalation quality measure.

12. The method of claim 11, further comprising steps b2) and el) and e2): b2) identifying a consolidation in the left lung field or the right lung field of the X-ray image; el) providing the right lung X-ray image inhalation quality measure as the X-ray image inhalation quality measure in case a consolidation is identified in the left lung field; or e2) providing the left lung X-ray image inhalation quality measure as the X-ray image inhalation quality measure in case a consolidation is identified in the right lung field.

13. An X-ray imaging system (60), comprising: an X-ray image acquisition device (62) having an X-ray source (64) and an X-ray detector (66); and the apparatus of any one of claims 1 to 8; ​ wherein the X-ray image acquisition device is configured to acquire X-ray image data of a region of interest of a patient and to provide the X-ray image data to the apparatus.

14. An apparatus for X-ray image inhalation quality monitoring, comprising: a module for receiving an X-ray image of a region of interest of a patient; a module for generating a diaphragm line representing a path of a diaphragm in the X-ray image and generating a rib line representing a path of a rib in the X-ray image; a module for detecting the diaphragm line and detecting the rib line; a module for assessing the X-ray image for a presence of a crossing condition between (i) the diaphragm line and (ii) the rib line, wherein the crossing condition of the diaphragm line and the rib line is defined according to a crossing condition rule; and a module for comparing the presence of the crossing condition between the rib line and the diaphragm line to a predetermined X-ray image inhalation quality monitoring rule that specifies an image inhalation state in dependence of the crossing condition to yield an X-ray image inhalation quality measure.

15. The apparatus of claim 14, wherein a first rib line has a first crossing condition rule and a second rib line has a second crossing condition rule different from the first crossing condition rule, and wherein the first and second crossing condition rules are used to determine the crossing condition.

16. The apparatus of claim 14 or 15, wherein, the module for generating the diaphragm line representing a path of a diaphragm in the X-ray image and generating the rib line representing a path of a rib in the X-ray image further comprises: a module for dividing the X-ray image into a right lung field portion and a left lung field portion; wherein the detection of the diaphragm line and the rib line is performed in the left lung field portion, the right lung field portion, or both; wherein the assessment and the comparison are repeated to enable computation of a left lung X-ray image inhalation quality measure and / or a right lung X-ray image inhalation quality measure.

17. The apparatus of claim 16, further comprising: a module for identifying a consolidation in a left lung field or a right lung field of the X-ray image; a module for providing the right lung X-ray image inhalation quality measure as the X-ray image inhalation quality measure in case a consolidation is identified in the left lung field; or a module for providing the left lung X-ray image inhalation quality measure as the X-ray image inhalation quality measure in case a consolidation is identified in the right lung field.

18. A computer readable medium having stored a computer program for controlling an apparatus according to any one of claims 1 to 8, which computer program, when executed by a processing unit, is adapted to perform the steps of the method according to any one of claims 9 to 12.

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