Background: The delivered dose has to be checked and verified with planned dose since precise and accurate dose delivery is essential in Brachytherapy. Sources of uncertainty during Brachytherapy are intra-fraction, i...Background: The delivered dose has to be checked and verified with planned dose since precise and accurate dose delivery is essential in Brachytherapy. Sources of uncertainty during Brachytherapy are intra-fraction, inter-fraction and inter-application variations. In-vivo dosimetry is the direct method to monitor the radiation dose delivered to a patient during radiotherapy. In this study, assessment of the inter-fraction and intra-fraction variations in the interstitial Brachytherapy was done with microMOSFET. Aim: To analyze the inter-fraction variations in dose delivery during interstitial HDR Brachytherapy and to compare the measured point dose with the TPS-calculated point dose, intra-fraction variation, using the microMOSFET in-vivo dosimeter. Materials and Methods: From May 2014 to February 2016, 22 patients with Head and Neck cancers and 8 patients with Soft-Tissue Sarcomas (STS) were selected for this study. All these patients underwent CT imaging more than 24 hours after the application. Brachyvision 3DTPS and GammaMed Plus iX HDR unit were used for treatments. MicroMOSFET in-vivo dosimeter after calibration was used for the measurements of dose inside the treated volume. Intra & Inter-fraction variations were analyzed and reported. Results: The SD of inter-fraction variation among 22 Head & Neck patients ranges from 2.14% to 14.26%. Minimum & maximum dose variation with first fraction dose of patients ranged from -22.33% to +26.71% and the mean doses were -6.42% to +19.76%. Differences of TPS dose and microMOSFET measured first fraction dose, intra-fraction variation, ranged from -12.36% to +5.05%. The SD of inter-fraction variation for 8 STS patients was from 2.81% to 14.43%. Minimum and maximum doses vary from -38.72% to +25.74% and mean dose varies from -21.5% to +12.53%. Differences of point doses of TPS and measured, intra-fraction variation, were from -5.86% to 4.88%. Conclusions: MicroMOSFET has the potential to minimize the gross errors during multi-fractionated Interstitial Brachytherapy. Edema, applicator displacements and placement of microMOSFET are the main influencing factors for inter-fraction uncertainty in dose delivery. Re-planning with re-simulated images should be considered whenever the microMOSFET readings vary more than ±10% of the planned dose inside the CTV measured in two successive fractions.展开更多
Aim: To analyze the inter-fraction, intra-fraction uncertainties and to verify the delivered total dose with planned dose in the combined intracavitary-interstitial brachytherapy of gynaecological cancer patients usin...Aim: To analyze the inter-fraction, intra-fraction uncertainties and to verify the delivered total dose with planned dose in the combined intracavitary-interstitial brachytherapy of gynaecological cancer patients using microMOSFET in-vivo dosimeter. Materials and Methods: Between May 2014 and March 2016, 22 patients who underwent brachytherapy treatments with an applicator combination of CT/MR compatible tandem, ring and Syed-Neblett template-guided rigid needles were included in this study. Specially designed microMOSFET, after calibration, was used to analyze the variations in dosimetry of combined intracavitary-interstitial application. Results: The standard deviation for Inter-fraction variation among 22 combined intracavitary interstitial applications ranged between 0.86% and 10.92%. When compared with the first fraction dose, the minimum and maximum dose variations were −9.5% and 26.36%, respectively. However, the mean doses varied between −5.95% and 14.49%. Intra-fraction variation, which is the difference of TPS calculated dose with first fraction microMOSFET-measured dose ranges from −6.77% to 8.68%. The variations in the delivered total mean dose in 66 sessions with planned doses were −3.09% to 10.83%. Conclusions: It is found that there was a gradual increase in microMOSFET measured doses as compared to the first fraction with that of subsequent fractions in 19 out of 22 applications. Tumor deformation and edema may be the influencing factors, but the applicator movements played a major role for the variations. We find that the microMOSFET is an easy and reliable system for independent verification of uncertainties during ICBT-ISBT treatments.展开更多
文摘Background: The delivered dose has to be checked and verified with planned dose since precise and accurate dose delivery is essential in Brachytherapy. Sources of uncertainty during Brachytherapy are intra-fraction, inter-fraction and inter-application variations. In-vivo dosimetry is the direct method to monitor the radiation dose delivered to a patient during radiotherapy. In this study, assessment of the inter-fraction and intra-fraction variations in the interstitial Brachytherapy was done with microMOSFET. Aim: To analyze the inter-fraction variations in dose delivery during interstitial HDR Brachytherapy and to compare the measured point dose with the TPS-calculated point dose, intra-fraction variation, using the microMOSFET in-vivo dosimeter. Materials and Methods: From May 2014 to February 2016, 22 patients with Head and Neck cancers and 8 patients with Soft-Tissue Sarcomas (STS) were selected for this study. All these patients underwent CT imaging more than 24 hours after the application. Brachyvision 3DTPS and GammaMed Plus iX HDR unit were used for treatments. MicroMOSFET in-vivo dosimeter after calibration was used for the measurements of dose inside the treated volume. Intra & Inter-fraction variations were analyzed and reported. Results: The SD of inter-fraction variation among 22 Head & Neck patients ranges from 2.14% to 14.26%. Minimum & maximum dose variation with first fraction dose of patients ranged from -22.33% to +26.71% and the mean doses were -6.42% to +19.76%. Differences of TPS dose and microMOSFET measured first fraction dose, intra-fraction variation, ranged from -12.36% to +5.05%. The SD of inter-fraction variation for 8 STS patients was from 2.81% to 14.43%. Minimum and maximum doses vary from -38.72% to +25.74% and mean dose varies from -21.5% to +12.53%. Differences of point doses of TPS and measured, intra-fraction variation, were from -5.86% to 4.88%. Conclusions: MicroMOSFET has the potential to minimize the gross errors during multi-fractionated Interstitial Brachytherapy. Edema, applicator displacements and placement of microMOSFET are the main influencing factors for inter-fraction uncertainty in dose delivery. Re-planning with re-simulated images should be considered whenever the microMOSFET readings vary more than ±10% of the planned dose inside the CTV measured in two successive fractions.
文摘Aim: To analyze the inter-fraction, intra-fraction uncertainties and to verify the delivered total dose with planned dose in the combined intracavitary-interstitial brachytherapy of gynaecological cancer patients using microMOSFET in-vivo dosimeter. Materials and Methods: Between May 2014 and March 2016, 22 patients who underwent brachytherapy treatments with an applicator combination of CT/MR compatible tandem, ring and Syed-Neblett template-guided rigid needles were included in this study. Specially designed microMOSFET, after calibration, was used to analyze the variations in dosimetry of combined intracavitary-interstitial application. Results: The standard deviation for Inter-fraction variation among 22 combined intracavitary interstitial applications ranged between 0.86% and 10.92%. When compared with the first fraction dose, the minimum and maximum dose variations were −9.5% and 26.36%, respectively. However, the mean doses varied between −5.95% and 14.49%. Intra-fraction variation, which is the difference of TPS calculated dose with first fraction microMOSFET-measured dose ranges from −6.77% to 8.68%. The variations in the delivered total mean dose in 66 sessions with planned doses were −3.09% to 10.83%. Conclusions: It is found that there was a gradual increase in microMOSFET measured doses as compared to the first fraction with that of subsequent fractions in 19 out of 22 applications. Tumor deformation and edema may be the influencing factors, but the applicator movements played a major role for the variations. We find that the microMOSFET is an easy and reliable system for independent verification of uncertainties during ICBT-ISBT treatments.
