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Evaluation of an automatic needles loading system
Abstract
Abstract: To evaluate the dosimetric capabilities and the radiation protection (RP) performances of a new automatic needles loading system for permanent prostate implants, the Isoloader (Mentor Corp.), which has already been used in more than 100 clinical cases at our institution.
The Isoloader is a computerized workstation which allows automated seeds testing by a solid state CdZnTe radiation detector and loading in surgical needles. The seeds are received in a shielded and ready-to-use cartridge. RP measurements were done on a cartridge filled with 67 125I seeds and during the dosimetric seeds verification and the loading of needles. The reproducibility of the detector was tested and its accuracy was determined by comparison to specified activities of six calibration seeds and to their measurements in a calibrated well-chamber (WC). Finally, the times required to complete a dosimetric verification and the loading of a needle were evaluated.
The cartridge was found to be adequately shielded since no significant amount of radiation was detected around it. Radiation during the seeds assay was found to be worst at the cartridge's bottom where it has a value of 15,2 mSv/h (1.4 mSv/h at 10 cm). For the needle-loading task, measurements were performed with a typical needle (3 seeds) at the shielded needle holder surface yielding 307.2 mSv/h (8.3 mSv/h at 20 cm). The dosimetric verification of seeds takes an average of 15 s/seed while it takes a mean time of 50 s/needle to complete the loading task. Measurements of the six seeds activities were within 0,65% of the ordered activities and 1,9% higher on average than those from the WC (min=0,7%, max=3,5%). The reproducibility of the measurements of the CdZnTe detector was excellent with an average of 0,01% of deviation from a reference measurement (N=120 ; s =1,9%).
The results presented in this paper allow us to conclude that the Isoloader is a safe, fast and effective needle loading system.
Key words: brachytherapy, I-125, seeds safe handling, radiation safety, seed assay
PACS number(s): 87.53.Jw
The Isoloader is a computerized workstation which allows automated seeds testing by a solid state CdZnTe radiation detector and loading in surgical needles. The seeds are received in a shielded and ready-to-use cartridge. RP measurements were done on a cartridge filled with 67 125I seeds and during the dosimetric seeds verification and the loading of needles. The reproducibility of the detector was tested and its accuracy was determined by comparison to specified activities of six calibration seeds and to their measurements in a calibrated well-chamber (WC). Finally, the times required to complete a dosimetric verification and the loading of a needle were evaluated.
The cartridge was found to be adequately shielded since no significant amount of radiation was detected around it. Radiation during the seeds assay was found to be worst at the cartridge's bottom where it has a value of 15,2 mSv/h (1.4 mSv/h at 10 cm). For the needle-loading task, measurements were performed with a typical needle (3 seeds) at the shielded needle holder surface yielding 307.2 mSv/h (8.3 mSv/h at 20 cm). The dosimetric verification of seeds takes an average of 15 s/seed while it takes a mean time of 50 s/needle to complete the loading task. Measurements of the six seeds activities were within 0,65% of the ordered activities and 1,9% higher on average than those from the WC (min=0,7%, max=3,5%). The reproducibility of the measurements of the CdZnTe detector was excellent with an average of 0,01% of deviation from a reference measurement (N=120 ; s =1,9%).
The results presented in this paper allow us to conclude that the Isoloader is a safe, fast and effective needle loading system.
Key words: brachytherapy, I-125, seeds safe handling, radiation safety, seed assay
PACS number(s): 87.53.Jw
Keywords
Brachytherapy, I-125, Seeds Safe Handling, Radiation Safety, Seed Assay