There is a simple method to remove the effects of imager dust in post processing.
First, get and install
DeepSkyStacker. This program is freeware and yes it is intended for astronomical image post processing, but it can eliminate imager dust shadows.
Second, Get in the habit of shooting "flat frames". These are photos that you shoot of a uniformly lit featureless surface. There are many methods that are described on various web sites and in books covering the subject of astronomical photography, but the simplest method that I use is to photograph a pure cloudless smooth sky. Check your histogram to make sure your exposure is set correctly. If your shooting session does not permit a sky shot, then you can resort to the flat frame that you shot previously. To have the flat frame performance be at it's peak, make sure that the camera settings of file format and resolution match the photos. If you are out and use a number of lenses on a shoot, create a flat frame for each lens. With a zoom lens, it's not essential but do try to shoot a flat frame for each focal length that you use. In astronomical photography, your photo is commonly referred to as a "light frame".
In post processing, open the flat frame and drop the saturation down until you have a colorless monochrome uniformly grey image. Do not worry if your lens caused any vignetting where the corners are darker than the center. This process will compensate for that as well and vignette compensation was the primary driver for this aspect of astro photo processing. Save your monochrome flat frame. By eliminating the color, the flat frame will work uniformly across the complete color range of your light frame image.
DeepSkyStacker can work with multiple file formats, just not the Sigma X3F, so if you shoot RAW, I recommend that you save your flat frame and images as 16 bit TIF files.
In DeepSkyStacker, you will need to load only two files at a time. The image or light frame that you need to have imager dust removed from and your monochrome flat frame. DeepSkyStacker is more commonly used to process huge collections of files, but just loading these two will work fine. Then have DeepSkyStacker process the stack. Internally, DeepSkyStacker will adjust the lightness of the light frame by the variations recorded in the flat frame. A particle of dust on the imager will create a shadow in both images and the light frame is brightened to null out the effects of the dust. The output file from DeepSkyStacker can then be returned to your normal post process flow.
With flat frame compensation, you have no need to take any risks cleaning your imager for an occasional dust particle.