[Evaluation of GoldAnchorTM fiducial marker migration during the planning of radiation treatment for patients with prostate cancer].

INTRODUCTION:The use of fiducial markers in patients undergoing teleradiotherapy increases the precision of treatment under the condition that the marker does not displace itself during this treatment. In order to determine the accuracy of the verification method used to establish patient position, it is necessary to establish the possible marker migration range during planning and treatment with radiation therapy. MATERIAL AND METHOD:An analysis of the migration of GoldAnchorTM fiducial markers implanted in the prostate conducted on a group of 29 patients treated with image-guided radiation therapy at the Radiotherapy Department of the Cancer Centre and Institute of Oncology in Gliwice. The migration value was determined based on a comparison of the marker's location with the use of spiral computer tomography and cone-beam computer tomography done on the treatment device. RESULTS:The average values of the given fiducial marker's migration in the superior-inferior (SI), left-right (LR) and anterior-posterior (AP) directions were: 0.07 cm (SD=0.1 cm); 0.06 cm (SD=0.07 cm) and 0.11 cm (SD=0.11 cm), respectively. The average value of the displacement vector computed according to the Pythagorean theorem and using the Euclidean norm was 0.17 cm with SD= 0.13 cm. CONCLUSION:The analysis indicates that migration of markers implanted in the prostate occurs during radiation treatment planning but probably it is not clinically relevant. Because a correlation was determined between the migration value and the time of carrying out the CT as well as the time that had passed from the implantation to the CBCT examination, it is reasonable to start radiation therapy promptly and to control the marker's location during radiation therapy.