Purpose: Changes in tumor volume are used for therapy response monitoring in preclinical studies. Unlike prior studies, this article introduces in-air micro-computed tomography (micro-CT) image volume as reference tum...Purpose: Changes in tumor volume are used for therapy response monitoring in preclinical studies. Unlike prior studies, this article introduces in-air micro-computed tomography (micro-CT) image volume as reference tumor volume in rodent tumor models. Tumor volumes determined using imaging modalities such as magnetic resonance imaging (MRI), micro-CT and ultrasound (US), and with an external caliper are compared with the reference tumor volume. Materials and Methods: In vivo MR, US and micro-CT imaging was performed 4, 6, 9, 11 and 13 days after tumor cell inoculation into nude rats. On the day of the imaging study, in vivo caliper measurements were also made. After in vivo imaging, tumors were excised followed by in-air micro-CT imaging and ex vivo caliper measurements of excised tumors. The in-air micro-CT image volume of excised tumors was determined as reference tumor volume. Then tumor volumes were calculated using formula V = (π/6) × a × b × c, where a, b and c are maximum diameters in three perpendicular dimensions determined by the three image modalities and caliper, and compared with reference tumor volume by linear regression analysis as well as Bland-Altman plots. Results: The correlation coefficients (R2) of the regression lines for in vivo tumor volumes measured by the three imaging modalities were 0.9939, 0.9669 and 0.9806 for MRI, US and micro-CT respectively. For caliper measurements, the coefficients were 0.9274 and 0.9819 for caliperin vivo and caliperex vivo respectively. In Bland-Altman plots, the average of tumor volume difference from reference tumor volume (bias) was significant for caliper and micro-CT, but not for MRI and US. Conclusion: Using the in-air micro-CT image volume as reference tumor volume, tumor volume measured by MRI was the most accurate among the three imaging modalities. In vivo caliper volume measurements showed unreliability while ex vivo caliper measurements reduced errors.展开更多
In intensity modulated radiation treatment (IMRT) planning, the use of asymmetrically collimated fields that are placed on central axis or its off-set is mostly required. Output is the main topic discussed today for e...In intensity modulated radiation treatment (IMRT) planning, the use of asymmetrically collimated fields that are placed on central axis or its off-set is mostly required. Output is the main topic discussed today for extremely small and/or severe irregularly shaped fields. The air scatter data are involved directly or indirectly in obtaining the output. Despite the fact that extensive data have been published in many studies to provide a guide on the magnitude of output factor for clinical accelerators, there are very few data reviewed about output factor in-air or phantom for off-set fields. This study was aimed to investigate the impact of these conditions for small fields. This study was conducted in Elekta Synergy linear accelerator which produces 6 MV X-ray energy. The in-air output factor (Sc) has been measured by CC04 ion chamber with brass-alloy “build-up” cap and Dose-1 electrometer, and the total output (Scp) measurements were carried on at dose maximum depth in phantom by the same chamber and Thermoluminescence dosimeter (TLD) for 1 - 10 cm2 fields. The all measurements at center of isocenter and off-set fields at three directions (X2, Y1, Diagonal) were done. By decreasing field size from 10 to 2 cm2 at isocenter, the Sc value using CC04 was decreased to 5.4% and Scp using CC04 and TLD to 14.5% and 11% respectively. By increasing off-set value, the Sc and Scp values were increased in all directions comparing to central fields. The maximum increase was obtained in Y1 direction for Sc and Scp. TLD results for Scp is slightly higher than CC04. The dosimetric properties of small fields and their off-set should be evaluated and modelled appropriately in the treatment planning system to ensure accurate dose calculation in Intensity Modulated Radiation Treatment.展开更多
AIM:To introduce an air insufflation procedure and to investigate the effectiveness of air insufflation in preventing pancreatic fistula(PF).of 185 patients underwent pancreaticoduodenectomy(PD)at our institution,and ...AIM:To introduce an air insufflation procedure and to investigate the effectiveness of air insufflation in preventing pancreatic fistula(PF).of 185 patients underwent pancreaticoduodenectomy(PD)at our institution,and 74 patients were not involved in this study for various reasons.The clinical outcomes of 111 patients were retrospectively analyzed.The air insufflation test was performed in 46 patients to investigate the efficacy of the pancreaticojejunal anastomosis during surgery,and 65 patients who did not receive the air insufflation test served as controls.Preoperative assessments and intraoperative outcomes were compared between the 2 groups.Univariate and multivariate analyses were performed to identify the risk factors for PF.RESULTS:The two patient groups had similar baseline demographics,preoperative assessments,operative factors,pancreatic factors and pathological results.The overall mortality,morbidity,and PF rates were1.8%,48.6%,and 26.1%,respectively.No significant differences were observed in either morbidity or mortality between the two groups.The rate of clinical PF(grade B and grade C PF)was significantly lower in the air insufflation test group,compared with the nonair insufflation test group(6.5%vs 23.1%,P=0.02).Univariate analysis identified the following parameters as risk factors related to clinical PF:estimated blood loss;pancreatic duct diameter≤3 mm;invagination anastomosis technique;and not undergoing air insufflation test.By further analyzing these variables with multivariate logistic regression,estimated blood loss,pancreatic duct diameter≤3 mm and not undergoing air insufflation test were demonstrated to be independent risk factors.CONCLUSION:Performing an air insufflation test could significantly reduce the occurrence of clinical PF after PD.Not performing an air insufflation test was an independent risk factor for clinical PF.展开更多
文摘Purpose: Changes in tumor volume are used for therapy response monitoring in preclinical studies. Unlike prior studies, this article introduces in-air micro-computed tomography (micro-CT) image volume as reference tumor volume in rodent tumor models. Tumor volumes determined using imaging modalities such as magnetic resonance imaging (MRI), micro-CT and ultrasound (US), and with an external caliper are compared with the reference tumor volume. Materials and Methods: In vivo MR, US and micro-CT imaging was performed 4, 6, 9, 11 and 13 days after tumor cell inoculation into nude rats. On the day of the imaging study, in vivo caliper measurements were also made. After in vivo imaging, tumors were excised followed by in-air micro-CT imaging and ex vivo caliper measurements of excised tumors. The in-air micro-CT image volume of excised tumors was determined as reference tumor volume. Then tumor volumes were calculated using formula V = (π/6) × a × b × c, where a, b and c are maximum diameters in three perpendicular dimensions determined by the three image modalities and caliper, and compared with reference tumor volume by linear regression analysis as well as Bland-Altman plots. Results: The correlation coefficients (R2) of the regression lines for in vivo tumor volumes measured by the three imaging modalities were 0.9939, 0.9669 and 0.9806 for MRI, US and micro-CT respectively. For caliper measurements, the coefficients were 0.9274 and 0.9819 for caliperin vivo and caliperex vivo respectively. In Bland-Altman plots, the average of tumor volume difference from reference tumor volume (bias) was significant for caliper and micro-CT, but not for MRI and US. Conclusion: Using the in-air micro-CT image volume as reference tumor volume, tumor volume measured by MRI was the most accurate among the three imaging modalities. In vivo caliper volume measurements showed unreliability while ex vivo caliper measurements reduced errors.
文摘In intensity modulated radiation treatment (IMRT) planning, the use of asymmetrically collimated fields that are placed on central axis or its off-set is mostly required. Output is the main topic discussed today for extremely small and/or severe irregularly shaped fields. The air scatter data are involved directly or indirectly in obtaining the output. Despite the fact that extensive data have been published in many studies to provide a guide on the magnitude of output factor for clinical accelerators, there are very few data reviewed about output factor in-air or phantom for off-set fields. This study was aimed to investigate the impact of these conditions for small fields. This study was conducted in Elekta Synergy linear accelerator which produces 6 MV X-ray energy. The in-air output factor (Sc) has been measured by CC04 ion chamber with brass-alloy “build-up” cap and Dose-1 electrometer, and the total output (Scp) measurements were carried on at dose maximum depth in phantom by the same chamber and Thermoluminescence dosimeter (TLD) for 1 - 10 cm2 fields. The all measurements at center of isocenter and off-set fields at three directions (X2, Y1, Diagonal) were done. By decreasing field size from 10 to 2 cm2 at isocenter, the Sc value using CC04 was decreased to 5.4% and Scp using CC04 and TLD to 14.5% and 11% respectively. By increasing off-set value, the Sc and Scp values were increased in all directions comparing to central fields. The maximum increase was obtained in Y1 direction for Sc and Scp. TLD results for Scp is slightly higher than CC04. The dosimetric properties of small fields and their off-set should be evaluated and modelled appropriately in the treatment planning system to ensure accurate dose calculation in Intensity Modulated Radiation Treatment.
文摘AIM:To introduce an air insufflation procedure and to investigate the effectiveness of air insufflation in preventing pancreatic fistula(PF).of 185 patients underwent pancreaticoduodenectomy(PD)at our institution,and 74 patients were not involved in this study for various reasons.The clinical outcomes of 111 patients were retrospectively analyzed.The air insufflation test was performed in 46 patients to investigate the efficacy of the pancreaticojejunal anastomosis during surgery,and 65 patients who did not receive the air insufflation test served as controls.Preoperative assessments and intraoperative outcomes were compared between the 2 groups.Univariate and multivariate analyses were performed to identify the risk factors for PF.RESULTS:The two patient groups had similar baseline demographics,preoperative assessments,operative factors,pancreatic factors and pathological results.The overall mortality,morbidity,and PF rates were1.8%,48.6%,and 26.1%,respectively.No significant differences were observed in either morbidity or mortality between the two groups.The rate of clinical PF(grade B and grade C PF)was significantly lower in the air insufflation test group,compared with the nonair insufflation test group(6.5%vs 23.1%,P=0.02).Univariate analysis identified the following parameters as risk factors related to clinical PF:estimated blood loss;pancreatic duct diameter≤3 mm;invagination anastomosis technique;and not undergoing air insufflation test.By further analyzing these variables with multivariate logistic regression,estimated blood loss,pancreatic duct diameter≤3 mm and not undergoing air insufflation test were demonstrated to be independent risk factors.CONCLUSION:Performing an air insufflation test could significantly reduce the occurrence of clinical PF after PD.Not performing an air insufflation test was an independent risk factor for clinical PF.
