A computer-implemented method for determining a positional shift of a region of interest, the method comprising partitioning a medical image, wherein partitioning the medical image comprises the following steps: a) image data is acquired which describes the medical image being an image of a surface of a patient and a surface of at least one object, wherein the image data is acquired by means of a 3D scanning device, wherein the 3D scanning device is one of a structured light scanning device, a time-of-flight scanning device, a light detection and ranging LIDAR device or a stereoscopic camera comprising two cameras having a parallax; b) thermal data is acquired which describes a measured temperature of the surface of the patient and the surface of the at least one object; c) registration data is acquired which describes a relative spatial relationship between the acquiring of the image data and the acquiring of the thermal data; d) condition data is acquired which describes a condition for the measured temperature; e) association data is determined based on the image data, the thermal data and the registration data, wherein the association data describes an association between at least one element of the image data and at least one element of the thermal data; f) condition compliance data is determined based on the condition data and the association data, wherein the condition compliance data describes a subset of the association data, wherein the subset fulfils the condition and describes a part of the medical image, wherein the part of the medical image or a subregion of the part of the medical image is the region of interest; and wherein the method further comprises the following steps: live image data is acquired which describes at least one subsequent medical image of the surface of the patient and the surface of the at least one object; positional shift data is determined based on the live image data and the region of interest, wherein the positional shift data describes a positional shift of the region of interest. a) image data is acquired which describes the medical image being an image of a surface of a patient and a surface of at least one object, wherein the image data is acquired by means of a 3D scanning device, wherein the 3D scanning device is one of a structured light scanning device, a time-of-flight scanning device, a light detection and ranging LIDAR device or a stereoscopic camera comprising two cameras having a parallax; b) thermal data is acquired which describes a measured temperature of the surface of the patient and the surface of the at least one object; c) registration data is acquired which describes a relative spatial relationship between the acquiring of the image data and the acquiring of the thermal data; d) condition data is acquired which describes a condition for the measured temperature; e) association data is determined based on the image data, the thermal data and the registration data, wherein the association data describes an association between at least one element of the image data and at least one element of the thermal data; f) condition compliance data is determined based on the condition data and the association data, wherein the condition compliance data describes a subset of the association data, wherein the subset fulfils the condition and describes a part of the medical image, live image data is acquired which describes at least one subsequent medical image of the surface of the patient and the surface of the at least one object; positional shift data is determined based on the live image data and the region of interest, wherein the positional shift data describes a positional shift of the region of interest.