X-ray markers made from tantalum are suitable for direct implantation in the human body as well as radio-graphic indicators in implants made from low density materials like e.g. PEEK. Tantalum (Ta) has a high density (16 g per cm3) which is 50% higher than lead (Pb) and therefore more radio-opaque. For this reason tantalum markers require a lower x-ray dose for examination. Tantalum metal is further highly biocompatible and has been used for surgery for more than 30 years without any severe events reported. Tantalum x-ray markers are among the safest options currently available .
X-ray Markers in Human Tissue
Tantalum markers may be implanted in human tissue in order to carry out RSA (radiostereometric analysis) studies.
X-ray Markers in Implants
For x-ray marking purposes, Tantalum is often used in combination with polymeric materials like PTFE or PEEK in e.g. spinal cages and joint implants and. The metal allows exact determination of the position of the implant during surgery by digital imaging. The markers or indicators may be used in different forms as shown below. Often a set of different shaped markers is used in an implant to allow three dimensional determination of the implant direction.
Typical forms of Tantalum Markers
Marker pins made from tantalum wire or tantalum rod material may be inserted in different lengths in e.g. spinal cages allowing the surgeon to determine the type of implant inserted.
Tantalum beads or balls are commonly used for insertion in human tissue (as the may be inserted by a gun) and in various forms of implants (e.g. hip, knee, spinal etc). The advantage by the spherical markers is that they show up as points in the radio graphs and it is possible to determine to what extend the implant migrates in the body. Implant migration may be determined by RSA techniques where x-rays images obtained from the patient allow surgeons to make precise measurements on prosthesis migration down to approximately 0.1 mm.
Literature on Tantalum X-ray Markers used in RSA