Great job in lighting, tones & contrasts and level of details in this composition. Love how you really made the effort to have the finger bones match up closely to the position of the fingers holding the device. My only suggestion on how to improve the visual impact of this photo is to introduce some color into it to give it more punch. The original had the x-ray illuminated in an electric blue tone. Adding that color similar to that tone into your composition would give it a bit of variety in making that portion stand out from the regular B&W tones of the rest of the image. Adding color to a portion of the image that is a main element or feature will immediately call the eye's attention to it.
now, that's better than the original, but I think if you used a colour image for the xray (blueish like the original) it would have really been strong...congrats on the iphone! 7