Quality assurance of I-125 seeds for prostate brachytherapy using an imaging plate.
OBJECTIVE
OncoSeed is delivered in a sterile environment in the form of a cartridge, so it is impractical to resterilize and reload seeds after calibration. We investigated a new method using an imaging plate dosimetry system to characterize all seeds in the OncoSeed cartridge in a sterile environment.


METHODS
Seeds within the cartridge were placed on an imaging plate, and the imaging plate irradiated. To remove scatter radiation, and improve spatial resolution of seed images, we used X-ray parallel cross grids. The irradiated imaging plate was scanned using a Bio-imaging Analyzer System, and radioactivity intensities of seed images were given in counts. Counts could be translated to profiles, and each seed within the cartridge was analyzed.


RESULTS
Results showed a good correlation between counts and total radioactivity of the seeds within the cartridge. Thus, using a least-squares line, it was possible to characterize a cartridge with unknown apparent activity. By analyzing the profiles, it was possible not only to detect a miscalibrated seed in the cartridge from its relative difference in counts, but also to identify its position in the cartridge. No significant changes in counts were seen between sterile and nonsterile environments.


CONCLUSIONS
Using an imaging plate dosimetry system, all seeds in a cartridge could be characterized in a sterile environment.
Furutani
Shunsuke
S
Department of Radiology, The University of Tokushima, Tokushima, Japan. shun@clin.med.tokushima-u.ac.jp
Saze
Takuya
T
Ikushima
Hitoshi
H
Oita
Masataka
M
Ozaki
Kyousuke
K
Kishida
Yoshiomi
Y
Takegawa
Yoshihiro
Y
Nishitani
Hiromu
H
D001918:Brachytherapy / Q000295:instrumentation* / Q000592:standards; D006801:Humans; D007457:Iodine Radioisotopes / Q000592:standards / Q000627:therapeutic use*; D016018:Least-Squares Analysis; D008297:Male; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011786:Quality Control; D011851:Radioactivity; D011879:Radiotherapy Dosage
D007457:Iodine Radioisotopes