Patient positioning based on a radioactive tracer implanted in patients with localized prostate cancer: a performance and safety evaluation.
OBJECTIVE
To evaluate the performance and safety of a radiation therapy positioning system (RealEye) based on tracking a radioactive marker (Tracer) implanted in patients with localized prostate cancer.


METHODS
We performed a single-arm multi-institutional trial in 20 patients. The iridium-192 ((192)Ir)-containing Tracer was implanted in the patient together with 4 standard gold seed fiducials. Patient prostate-related symptoms were evaluated with the International Prostate Symptom Score (IPSS) questionnaire. Computed tomography (CT) was performed for treatment planning, during treatment, and after treatment to evaluate the migration stability of the Tracer. At 5 treatment sessions, cone beam CT was performed to test the positioning accuracy of the RealEye.


RESULTS
The Tracer was successfully implanted in all patients. No device or procedure-related adverse events occurred. Changes in IPSS scores were limited. The difference between the mean change in Tracer-fiducial distance and the mean change in fiducial-fiducial distance was -0.39 mm (95% confidence interval [CI] upper boundary, -0.22 mm). The adjusted mean difference between Tracer position according to RealEye and the Tracer position on the CBCT for all patients was 1.34 mm (95% CI upper boundary, 1.41 mm).


CONCLUSIONS
Implantation of the Tracer is feasible and safe. Migration stability of the Tracer is good. Prostate patients can be positioned and monitored accurately by using RealEye.
Institute Verbeeten, Tilburg, The Netherlands. kruijf.de.w@bvi.nl
Willy J M
WJ
de Kruijf
Jan
J
Verstraete
David
D
Neustadter
Benjamin W
BW
Corn
Sandra
S
Hol
Jack L M
JL
Venselaar
Rob J
RJ
Davits
Bart P
BP
Wijsman
Laura
L
Van den Bergh
Tom
T
Budiharto
Raymond
R
Oyen
Karin
K
Haustermans
Philip M P
PM
Poortmans
D057918:Fiducial Markers; D006046:Gold; D006801:Humans; D007496:Iridium Radioisotopes; D008297:Male; D009068:Movement; D056888:Patient Positioning / Q000379:methods*; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000532:radiotherapy; D011877:Radionuclide Imaging; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D061089:Radiotherapy, Image-Guided / Q000379:methods
D007496:Iridium Radioisotopes; D006046:Gold