The pumpkin contains a Raspberry Pi which projects images onto a screen using a Microvision SHOWWX+ HDMI pico projector. The screen is made of tracing paper. The application displaying the images is Aeskulap http://aeskulap.nongnu.org/.
The steps below include details of how to install the radiology workstation software and get images to the device - but the basic mechanism could be used on any project where a Raspberry Pi is projecting a mirror image so that it appears correctly when it illuminates a screen from behind.
FDA warning: this device is not for clinical or culinary use. The screen isn't bright or sharp enough to meet the guidelines of the American College of Radiology. No strictly documented engineering process was followed nor any attempt was made to adhere to the good manufacturing process outlined in the FDA's 510(k) requirements. However - it is absurd and you're reading this so it might be of some interest.
[Added in edit: The images here belong to the patient (me, the author) are were not downloaded from the clinical servers at the hospital. It's my knee :-)]
PACS - Picture Archive and Communication System. This is what a radiology department typically uses to accept/store/display medical images.
DICOM - Digital Imaging and Communications in Medicine. This is a computer protocol for medical images. It is widely used in Radiology and Cardiology.