Stability, visibility, and histologic analysis of a new implanted fiducial for use as a kilovoltage radiographic or radioactive marker for patient positioning and monitoring in radiotherapy.

Purpose: To analyze the stability, visibility, and histology of a novel implantable soft-tissue marker (nonradioactive and radioactive) implanted in dog prostate and rabbit liver.

Methods And Materials: A total of 34 nonradioactive and 35 radioactive markers were implanted in 1 dog and 16 rabbits. Stability was assessed by measuring intermarker distance (IMD) variation relative to IMDs at implantation.