TITLE:
Imaging and Dosimetric Consideration for Titanium Prosthesis Implanted within the Irradiated Region by Cobalt-60 Teletherapy Unit
AUTHORS:
Vaino Indongo, Samuel Nii Adu Tagoe, Kwame Kyere, Cyril Schandorf
KEYWORDS:
Phantom, Co-60, Dosimetric, Imaging, Titanium, Implant, Prosthesis, Prowess Panther
JOURNAL NAME:
International Journal of Medical Physics, Clinical Engineering and Radiation Oncology,
Vol.7 No.2,
May
8,
2018
ABSTRACT: The aim
of this research is to observe dose distributions in the vicinity of titanium
prosthetic implants during radiotherapy procedures on 60Co teletherapy machine,
Prowess Panther treatment planning system (TPS). Data were obtained using a
locally fabricated tissue equivalent phantom CT images with titanium prosthesis
which was irradiated with 60Co gamma radiation.
Prowess TPS (1.25 MeV) estimated less variations. Proximal ends of the metal recorded
slight increase in doses as a result of backscatter with dose increment below
acceptable tolerance of ±3%. Doses measured decreases on the distal side of the
prosthesis at a distance less than dmax from the plate on each
beam energy. The depth dose increases marginally after a certain depth level
which generally originated from the unperturbed dose due to increase in the
electron fluence. The percentage of depth doses decrease with the increase in
plate thickness. A reduction in the above trend was also noticed with an
increase in beam energy primarily because scattered photons are more forwardly
directed. Prowess TPS (convolution superposition algorithm) was found to be
better at reducing dose variation when correction for artifact. Manual calculations
on blue phantom data agree with results from Prowess. This treatment system is
capable of simulating dose around titanium prosthesis as its range of
densities, 0.00121 to 2.83, excludes titanium density (rED for titanium is
3.74).