In vivo dosimetry with a linear MOSFET array to evaluate the urethra dose during permanent implant brachytherapy using iodine-125.

PURPOSE To develop a technique to monitor the dose rate in the urethra during permanent implant brachytherapy using a linear MOSFET array, with sufficient accuracy and without significantly extending the implantation time. METHODS AND MATERIALS Phantom measurements were performed to determine the optimal conditions for clinical measurements. In vivo measurements were performed in 5 patients during the (125)I brachytherapy implant procedure. To evaluate if the urethra dose obtained in the operating room with the ultrasound transducer in the rectum and the patient in treatment position is a reference for the total accumulated dose; additional measurements were performed after the implantation procedure, in the recovery room. RESULTS In vivo measurements during and after the implantation procedure agree very well, illustrating that the ultrasound transducer in the rectum and patient positioning do not influence the measured dose in the urethra. In vivo dose values obtained during the implantation are therefore representative for the total accumulated dose in the urethra. In 5 patients, the dose rates during and after the implantation were below the maximum dose rate of the urethra, using the planned seed distribution. CONCLUSION In vivo dosimetry during the implantation, using a MOSFET array, is a feasible technique to evaluate the dose in the urethra during the implantation of (125)I seeds for prostate brachytherapy.

[1]  Anatoly Rosenfeld,et al.  Verification of the plan dosimetry for high dose rate brachytherapy using metal-oxide-semiconductor field effect transistor detectors. , 2007, Medical physics.

[2]  P. Wust,et al.  Postimplantation analysis enables improvement of dose-volume histograms and reduction of toxicity for permanent seed implantation. , 2008, International journal of radiation oncology, biology, physics.

[3]  É. Vigneault,et al.  Prostatic edema in 125I permanent prostate implants: dynamical dosimetry taking volume changes into account. , 2006, Medical physics.

[4]  Alex Rijnders,et al.  Tumour and target volumes in permanent prostate brachytherapy: a supplement to the ESTRO/EAU/EORTC recommendations on prostate brachytherapy. , 2007, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[5]  J. Koziol,et al.  Prostate brachytherapy seed migration and dosimetry: analysis of stranded sources and other potential predictive factors. , 2004, Brachytherapy.

[6]  K. Wallner,et al.  The impact of acute urinary morbidity on late urinary function after permanent prostate brachytherapy. , 2007, Brachytherapy.

[7]  Energy and integrated dose dependence of MOSFET dosimeter sensitivity for irradiation energies between 30kV and Co60. , 2006, Medical physics.

[8]  P. Lambin,et al.  In vivo dosimetry using a linear Mosfet-array dosimeter to determine the urethra dose in 125I permanent prostate implants. , 2009, International journal of radiation oncology, biology, physics.

[9]  L. Anderson,et al.  Dosimetry of interstitial brachytherapy sources: Recommendations of the AAPM Radiation Therapy Committee Task Group No. 43 , 1995 .

[10]  Masayuki Matsuo,et al.  Effect of Edema on Postimplant Dosimetry in Prostate Brachytherapy Using CT/MRI Fusion , 2007 .