no DICOM dictionary present in Photoshop

I would like to use Photoshop CC to open images that are stored in DICOM format (e.g. .dcm file) on my Mac. When I try to open in Photoshop CC (am currently at 20.0.2) I simply get the error "Error processing DICOM file:  There is no DICOM dictionary present" and the image is not opened.  I searched the help online support and forums and only found basic help about working with and saving files as DICOM images which all assumed that you could actually open the files and had gotten to the "DICOM File Import dialog box" which I don't get as far as with my error.  I know the files are valid DICOM Files because I can open them in other medical imaging viewer software and see the image and metadata. I tried to contact support directly through the chat and it was not particularly helpful - after 15 minutes they pointed me to a FAQ on saving and exporting files as various types. (Incidentally I did learn that I CAN open a .jpg and then choose save as and save the image as a .dcm and then I can modify the aspects of the DICOM metadata etc. and it is a valid DICOM file.  But if I close that .dcm file that I just created in PS and try to open in PS I get the same "no DICOM dictionary present" error.  Just in case I tried uninstalling Photoshop CC and reinstalling but that didn't help. Can anyone help me figure out how to get this dictionary? Is there some plug-in that I need to install or something? Thanks in advance for any suggestions I really was hoping to use Photoshop to work with these files as it is clearly advertised that I should be able to.