Transrectal implantation and stability of gold markers in prostate bed for salvage radiotherapy of macroscopic recurrences.
OBJECTIVE
The objective of the study was to verify the stability of gold markers in the prostatic bed (PB) during salvage radiotherapy.


METHODS
Seven patients, diagnosed with a macroscopic nodule visible on MRI, underwent targeted MRI-guided biopsies. Three gold markers were implanted into the PB close to the relapsing nodule for CT/MRI fusion. A dose of 60Gy was delivered using IMRT to the PB followed by a dose escalation up to 72Gy to the macroscopic nodule. Daily anterior and left-lateral kV-images were acquired for repositioning. The coordinates of the center of each marker were measured on the two kV-images. The distance variations (Dvar) of the markers in the first session and the subsequent ones were compared.


RESULTS
No marker was lost during treatment. The average distance between markers was 7.8mm. The average Dvar was 0.8mm, in absolute value. A total of 380/528 (72%) Dvar were ⩽1mm. A Dvar greater than 2mm was observed in 5.7% of measurements, with a maximum value of 4.8mm.


CONCLUSIONS
Despite the absence of the prostate, the implantation of gold markers in the PB remains feasible, with Dvar often less than 2mm, and could be used to develop new approaches of salvage focal radiotherapy on the macroscopic relapse after prostatectomy.
Department of Radiation Oncology, Centre Hospitalier Lyon Sud, 165 Chemin du Grand Revoyet, 69495 Pierre-Benite, France.
Shakir I
SI
Shakir
Department of Radiation Oncology, Centre Hospitalier Lyon Sud, 165 Chemin du Grand Revoyet, 69495 Pierre-Benite, France; Department of Medical Physics, Centre Hospitalier Lyon Sud, 165 Chemin du Grand Revoyet, 69495 Pierre Benite, France.
Corina
C
Udrescu
Department of Radiation Oncology, Centre Hospitalier Lyon Sud, 165 Chemin du Grand Revoyet, 69495 Pierre-Benite, France.
Ciprian
C
Enachescu
Department of Urological Radiology, Hôpital Edouard Herriot, 5 Place d'Arsonval, 69003 Lyon, France.
Olivier
O
Rouviere
Department of Urological Radiology, Hôpital Edouard Herriot, 5 Place d'Arsonval, 69003 Lyon, France.
Simona
S
Arion
Department of Radiation Oncology, Centre Hospitalier Lyon Sud, 165 Chemin du Grand Revoyet, 69495 Pierre-Benite, France.
Ionela
I
Caraivan
Department of Radiation Oncology, Centre Hospitalier Lyon Sud, 165 Chemin du Grand Revoyet, 69495 Pierre-Benite, France. Electronic address: olivier.chapet@chu-lyon.fr.
Olivier
O
Chapet
D057918:Fiducial Markers; D006046:Gold; D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D019736:Prostheses and Implants; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated / Q000592:standards*; D012007:Rectum; D012008:Recurrence; D016879:Salvage Therapy / Q000592:standards*; D014057:Tomography, X-Ray Computed
D006046:Gold
Dose escalation; Gold markers stability; IMRT-IGRT; Local recurrence in prostate bed