ABSTRACT
Objective: The objective of the study is to test whether three-dimensional (3D)-printed template can be used reproducibly for guiding malignant tumors brachytherapy and study the dosimetric consistency and adequacy between pre- and post-plan. Materials and Methods: Between January and December 2016 in our hospital, a total of 14 patients underwent 3D-printed template-guided brachytherapy. All the patients were fixed into position using a vacuum cushion before undertaking a computed tomography (CT) scan. After the preplan was designed, the templates were printed. The tumors were punctured through predesigned needle holes. Following this, another CT scan was used to confirm the locations of needles, and then the 125 I radioactive seeds were implanted into the tumor according to the preplan. Postplan was performed after the operation. Data of the D90 (minimum absorbed dose of 90% target volume), V90 (90% prescription dose coverage volume percentage of target volume), V100, V150, and seed number pre- and post-operation were collected and compared. Results: The mean D90, V90, V100, V150, and seed number preoperation were 94.96 ± 16.43 Gy, 94.64% ± 1.43%, 91.21% ± 1.59%, 65.01% ± 5.78%, and 46.67 ± 21.87, respectively. The mean D90, V90, V100, V150, and seed number postoperation were 91.97 ± 17.54 Gy, 93.35% ± 2.45%, 89.35% ± 3.21%, 63.40% ± 6.36%, and 46.60 ± 22.85, respectively. No significant difference between pre- and post-operation was observed across the data (P >0.05). Conclusion: For immobilized malignant tumors, 3D-printed template can be used reproducibly. The dose parameters in preplan can be achieved easily and satisfactorily by 3D-printed template guided brachytherapy, and it may become an easily reproducible standardized procedure in the future
ABSTRACT
As a standard method for early stage prostate cancer, 125Ⅰ seed implantations are used widely in America. Although there are guidelines from American Brachytherapy Society and American Association of Physicists in Medicine, some hospitals still cannot implant the seeds properly according to the guidelines. Complications were observed inevitably. The medical events about seeds implantation in America from 2002 were investigated and the reasons were analyzed in this paper. Additionally, some solutions were given to avoid the medical events, so that the practitioners in China can learn from it and make sure the 125Ⅰ seeds implantation can be developed healthily and smoothly.
ABSTRACT
Objective To study the dosimetric effect of two source patterns, including equal spacing and peripheral dense intermediate sparse by assuming a tumor shrinking speed of 20%per month after 125 I seed implantation. Methods A virtual cylindrical tumor with 4 cm in height and 5 cm in diameter was contoured on a three-dimensional treatment planning system ( TPS ) . Two groups of preoperative plans were made with 1. 85 × 107 Bq 125 I seeds using two source patterns respectively. It was assumed that the tumor height was unchanged, while the diameter of tumor would decrease at a speed of 20%per month, and the locations of seeds would concentrate towards the tumor core. The 90%target volume dose ( D90 ) , the ratio of 90%isodose volume over the target volume ( V90 ) , and the ratio of 150%isodose volume over the target volume (V150) were calculated at 0, 1, 2, 3 months after 125I implantation respectively. Results In equal spacing group, 85 seeds were implanted. The values of D90 were 126. 20, 130. 41, 133. 82 and 139. 48 Gy after 0, 1, 2 and 3 months respectively. The values of V90 were 97. 0%, 98. 1%, 99. 3%and 100%, while those of V150 were 70. 2%, 69. 9%, 71. 1% and 71. 5%. The dense in-periphery and sparse-in the middle group was loaded with 75 seeds. The D90 values were 126. 46, 125. 41, 123. 50 and 128. 83 Gy, the V9095. 2%, 95. 7%, 94. 9%and 97. 6%, and the V15052. 8%, 60. 4%, 62. 7%and 59. 3%after 0, 1, 2 and 3 months, respectiviely. Conclusions When the tumor diameter reduces at a rate of 20%per month after 125 I seed implantation, the expected tumor dose absorption will gradually increase using the equal spacing sources pattern. However, the expected dose does not vary withsource distribution of dense-in the-surrounding and sparse-in-middle, which also reduces high dose volume more than the equal spacing pattern.
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Objective To explore the relationship between the peripheral dose and radioactive counts of 125I seeds detected by SPECT/CT.Methods Six 125I seeds(1.48×107 Bq, 1.85×107 Bq, 2.22×107 Bq, 2.59×107 Bq, 2.96×107 Bq, 3.33×107 Bq) were put into the solid water phantoms respectively. SPECT/CT was applied to scan the seeds. The radioactive counts (x) at the distance of 1-15 mm from the center of seeds were recorded respectively, while the corresponding doses (y, cGy) were calculated. SPSS 18.0 was used to analyze the relationship between the radioactive counts and peripheral dose. Results There was an exponential relationship between the peripheral dose of 125I seeds and the radioactive counts. The formula was as follow: y=507.849×1.004x. Conclusion SPECT/CT can visualize the peripheral dose of 125I seed, which may provide a method for dosimetric verification after brachytherapy.
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Objective To investigate the dosimetric effect of same activity and same number of 125I seeds arranged in axial train but with different spacing.Methods A total of 27 film dosimeters were randomly and equally divided into group A,B and C.Each film was irradiated by three 125I seeds (activity of 1.48×107 Bq).The seeds were arranged in line,and their axial spacing was 1 mm,5 mm and 10 mm respectively.Image analysis software was used to draw iso-gray contour curves of 20,25,30 and 40 gray value on the films,and to calculate the areas contained by each curve.Results Multi-sample mean comparison variance analysis showed that the differences in area contained by 20 and 25 iso-gray contour curves were statistically significant between each other among the three groups (P＜0.001).The difference in area contained by 30 iso-gray contour curve between group A and group B was not statistically significant (P＞ 0.05),while the difference in area contained by 30 iso-gray contour curve between group A and group C as well as between group B and group C was statistically significant (P＜0.001).No statistically significant difference in area contained by 40 iso-gray contour curve existed between each other among the three groups (P=0.99).Conclusion Different spacing arrangement of same activity and same number of 125I seeds can directly influence the peripheral dose distribution.In specific dose range,seed-spacing of 1 mm arrangement may obtain better dose distribution than seed-spacing of 5 mm or 10 mm arrangement can do.
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Objective To evaluate the safety and efficacy of CT-guided radioactive 125I seed implantation in treating retroperitoneal lymph node metastasis due to recurrent cervical cancer after radiotherapy.Methods A total of 10 patients with retroperitoneal lymph node metastasis (12 lesions in total)due to recurrent cervical cancer after radiotherapy,who were treated with CT-guided 125I seed implantation during the periodfrom November 2011 to October 2015,were included in this study.The diameters,that were perpendicular to each other,of the involved lymph nodesranged from 1.7 cm×1 cm to 6.5 cm×5 cm,the diameter of 6 involved lymph nodes (50％) was ＜5.0 cm and the diameter of other 6 involved lymph nodes (50％) was ≥5.0 cm.With the help of treatment planning system for brachytherapy,the source distribution was formulated.Under CT guidance,the 125l seedswith the activity of 0.3-0.7 mCi were implanted.Postoperative validation showed that D90 (90％ minimum prescription dose received by the target volume) was 36-110 Gy (median 59 Gy).After the treatment,the changes in lesion size,pain relief and complications were recorded.Results The 10 patients were followed up for 4.3-16.1 months,the median follow-up time was 9.7 months.The 2-month local control rate and the 2-month effective rate were 100％ and 58.3％,respectively.The 2-month,6-month and 12-month survival rates were 100％,66.7％ and 58.3％,respectively.The median survival time was 12.1 months.One patient (10％) died of gastrointestinal bleeding at five months after treatment,six patients (60％) died of distant metastases,three patients (30％) survived withno evidence of local recurrence.No major complications such as massive hemorrhage,intestinal infection,bone marrow suppression or other 125I seed-related complications occurred.Conclusion For the treatment of retroperitoneal lymph node metastasis due to recurrent cervical cancer after radiotherapy,CT-guided radioactive 125I seed implantation has satisfactory short-term curative effect,and this technique is safe and feasible.
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Objective To discuss the commonly used puncturing approaches in CT-guided 125I seed implantation for lumbar lymph node metastases in order to provide safe and reliable technical guidance for clinical practice.Methods Under CT guidance,125I seed implantation for lumbar lymph node metastases was performed.According to different locations of metastatic lymphadenopathy (left waist,right waist or middle waist),the corresponding puncture route and implantation method were adopted.Meanwhile,different puncturing approach was designed in order to avoid damage to vital organs.Results For the performance of 125I seed implantation for the lymphadenopathy located at the left waist,right waist and middle waist,the commonly used puncturing approaches were percutaneous transthoracic lumboiliac costal muscle method (i.e.back approach),trans-hepatic trans-duodenal method (i.e.lateral approach) or back approach method,and trans-mesenteric approach together with coaxial needle method (i.e.anterior approach) respectively.Conclusion It is clinically feasible to use different puncturing approaches in performing 125I seed implantation for lumbar lymph node metastases,the suitable puncturing approach can ensure a successful and safe operation.
ABSTRACT
As a standard method for early stage prostate cancer, 125Ⅰ seed implantations are used widely in America. Although there are guidelines from American Brachytherapy Society and American Association of Physicists in Medicine, some hospitals still cannot implant the seeds properly according to the guidelines. Complications were observed inevitably. The medical events about seeds implantation in America from 2002 were investigated and the reasons were analyzed in this paper. Additionally, some solutions were given to avoid the medical events, so that the practitioners in China can learn from it and make sure the 125Ⅰ seeds implantation can be developed healthily and smoothly.
ABSTRACT
Objective To study the dosimetric effect of two source patterns, including equal spacing and peripheral dense intermediate sparse by assuming a tumor shrinking speed of 20%per month after 125 I seed implantation. Methods A virtual cylindrical tumor with 4 cm in height and 5 cm in diameter was contoured on a three-dimensional treatment planning system ( TPS ) . Two groups of preoperative plans were made with 1. 85 × 107 Bq 125 I seeds using two source patterns respectively. It was assumed that the tumor height was unchanged, while the diameter of tumor would decrease at a speed of 20%per month, and the locations of seeds would concentrate towards the tumor core. The 90%target volume dose ( D90 ) , the ratio of 90%isodose volume over the target volume ( V90 ) , and the ratio of 150%isodose volume over the target volume (V150) were calculated at 0, 1, 2, 3 months after 125I implantation respectively. Results In equal spacing group, 85 seeds were implanted. The values of D90 were 126. 20, 130. 41, 133. 82 and 139. 48 Gy after 0, 1, 2 and 3 months respectively. The values of V90 were 97. 0%, 98. 1%, 99. 3%and 100%, while those of V150 were 70. 2%, 69. 9%, 71. 1% and 71. 5%. The dense in-periphery and sparse-in the middle group was loaded with 75 seeds. The D90 values were 126. 46, 125. 41, 123. 50 and 128. 83 Gy, the V9095. 2%, 95. 7%, 94. 9%and 97. 6%, and the V15052. 8%, 60. 4%, 62. 7%and 59. 3%after 0, 1, 2 and 3 months, respectiviely. Conclusions When the tumor diameter reduces at a rate of 20%per month after 125 I seed implantation, the expected tumor dose absorption will gradually increase using the equal spacing sources pattern. However, the expected dose does not vary withsource distribution of dense-in the-surrounding and sparse-in-middle, which also reduces high dose volume more than the equal spacing pattern.