title: Feasibility of insertion/implantation of 2.0-mm-diameter gold internal fiducial markers for precise setup and real-time tumor tracking in radiotherapy.
abstract: OBJECTIVE
  To examine the feasibility and reliability of insertion of internal fiducial markers into various organs for precise setup and real-time tumor tracking in radiotherapy (RT).
  
  
  METHODS
  Equipment and techniques for the insertion of 2.0-mm-diameter gold markers into or near the tumor were developed for spinal/paraspinal lesions, prostate tumors, and liver and lung tumors. Three markers were used to adjust the center of the mass of the target volume to the planned position in spinal/paraspinal lesions and prostate tumors (the three-marker method). The feasibility of the marker insertion and the stability of the position of markers were tested using stopping rules in the clinical protocol (i.e., the procedure was abandoned if 2 of 3 or 3 of 6 patients experienced marker dropping or migration). After the evaluation of the feasibility, the stability of the marker positions was monitored in those patients who entered the dose-escalation study.
  
  
  RESULTS
  Each of the following was shown to be feasible: bronchoscopic insertion for the peripheral lung; image-guided transcutaneous insertion for the liver; cystoscopic and image-guided percutaneous insertion for the prostate; and surgical implantation for spinal/paraspinal lesions. Transcutaneous insertion of markers for spinal/paraspinal lesions and bronchoscopic insertion for central lung lesions were abandoned. Overall, marker implantation was successful and was used for real-time tumor tracking in RT in 90 (90%) of 100 lesions. No serious complications related to the marker insertion were noted for any of the 100 lesions. Using three markers surgically implanted into the vertebral bone, the mean +/- standard deviation in distance among the three markers was within 0.2 +/- 0.6 mm (range -1.4 to 0.8) through the treatment period of 30 days. The distance between the three markers gradually decreased during RT in five of six prostate cancers, consistent with a mean rate of volume regression of 9.3% (range 0.015-13%) in 10 days.
  
  
  CONCLUSIONS
  Internal 2.0-mm-diameter gold markers can be safely inserted into various organs for real-time tumor tracking in RT using the prescribed equipment and techniques. The three-marker method has been shown to be a useful technique for precise setup for spinal/paraspinal lesions and prostate tumors.
authors.affiliation: Department of Radiology, Hokkaido University School of Medicine, Sapporo, Japan. hshirato@radi.med.hokudai.ac.jp
authors.forename: Hiroki
authors.initials: H
authors.lastname: Shirato
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Harada
authors.forename: Tooru
authors.initials: T
authors.lastname: Harabayashi
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Hida
authors.forename: Hideho
authors.initials: H
authors.lastname: Endo
authors.forename: Kei
authors.initials: K
authors.lastname: Kitamura
authors.forename: Rikiya
authors.initials: R
authors.lastname: Onimaru
authors.forename: Koichi
authors.initials: K
authors.lastname: Yamazaki
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Kurauchi
authors.forename: Tadashi
authors.initials: T
authors.lastname: Shimizu
authors.forename: Nobuo
authors.initials: N
authors.lastname: Shinohara
authors.forename: Michiaki
authors.initials: M
authors.lastname: Matsushita
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Dosaka-Akita
authors.forename: Kazuo
authors.initials: K
authors.lastname: Miyasaka
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy; D003199:Computer Systems; D005240:Feasibility Studies; D005471:Fluoroscopy; D005548:Foreign-Body Migration; D006046:Gold; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008863:Microspheres; D009038:Motion; D009442:Neurilemmoma / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy; D010316:Particle Size; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy; D019736:Prostheses and Implants; D011867:Radioisotope Teletherapy / Q000379:methods; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation*; D020266:Radiotherapy, Conformal / Q000379:methods; D011882:Radiotherapy, High-Energy / Q000379:methods; D015203:Reproducibility of Results; D013125:Spinal Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D006046:Gold