Pub Date : 2023-09-01DOI: 10.1016/j.brachy.2023.06.125
Marc Morcos, James McCulloch, Gabi Quintana, Marco Martinez, Mayra Gonzalez-Ng, Yonatan Weiss
Purpose To evaluate the dosimetric impact of bladder fill change between the time of simulation and treatment delivery. Materials and Methods This dosimetric study was completed with 10 individual high-dose-rate brachytherapy implants for cervical cancer patients (7 Gy/fx). Eight implants were performed with the Venezia and two with the Geneva (Elekta Brachy, Veenendaal, The Netherlands). An average of 8.0±1.8 interstitial needles were used. Each implant was imaged at two time point (T0 & T1): once the implant was completed (CT, T0) and approximately an hour later (MR, T1). For this study, optimized treatment plans were generated using the T0 scan. Organs at risk were also contoured on the T1 scan and the unmodified original plan was then applied to the new anatomy (re-digitized, but same dwell times) to assess the impact of anatomical changes to the dosimetrics. EQD2 D2cc for all OARs was calculated assuming an alpha-beta ratio of 3 Gy and a prescription dose of 7 Gy per fraction. Results The mean ± SD bladder fill volume at time, T0, was 222±113 cm3. The bladder fill increased between -100 and +225 cm3 at T1. Changes in EQD2 D2cc to the bladder, rectum, sigmoid and bowel between T0 and T1 are plotted in Figure 2. The impact on EQD2 D2cc changes due to increases in bladder fill volume correlates highly for sigmoid (-0.75), and weakly for bladder (+0.31) and bowel (-0.20). For the rectum, EQD2 D2cc changes are negligibly correlated with respect to bladder fill changes. Conclusions Increases in bladder volume tend to decrease GI (rectum, sigmoid, bowel) OAR doses while increasing dose to the bladder. Ensuring the bladder fill does not decrease at the time of treatment is paramount for protecting GI OARs which have much lower dose limits. Increases in bladder volume should be weighed against the remaining dose tolerance budget for the bladder. Future work will involve acquire more data which may enable the development of quantitative model for predicting patient-specific dosimetric changes based on bladder fill changes. To evaluate the dosimetric impact of bladder fill change between the time of simulation and treatment delivery. This dosimetric study was completed with 10 individual high-dose-rate brachytherapy implants for cervical cancer patients (7 Gy/fx). Eight implants were performed with the Venezia and two with the Geneva (Elekta Brachy, Veenendaal, The Netherlands). An average of 8.0±1.8 interstitial needles were used. Each implant was imaged at two time point (T0 & T1): once the implant was completed (CT, T0) and approximately an hour later (MR, T1). For this study, optimized treatment plans were generated using the T0 scan. Organs at risk were also contoured on the T1 scan and the unmodified original plan was then applied to the new anatomy (re-digitized, but same dwell times) to assess the impact of anatomical changes to the dosimetrics. EQD2 D2cc for all OARs was calculated assuming an alpha-beta ratio of 3 Gy and a prescription dose o
{"title":"PO24","authors":"Marc Morcos, James McCulloch, Gabi Quintana, Marco Martinez, Mayra Gonzalez-Ng, Yonatan Weiss","doi":"10.1016/j.brachy.2023.06.125","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.125","url":null,"abstract":"Purpose To evaluate the dosimetric impact of bladder fill change between the time of simulation and treatment delivery. Materials and Methods This dosimetric study was completed with 10 individual high-dose-rate brachytherapy implants for cervical cancer patients (7 Gy/fx). Eight implants were performed with the Venezia and two with the Geneva (Elekta Brachy, Veenendaal, The Netherlands). An average of 8.0±1.8 interstitial needles were used. Each implant was imaged at two time point (T0 & T1): once the implant was completed (CT, T0) and approximately an hour later (MR, T1). For this study, optimized treatment plans were generated using the T0 scan. Organs at risk were also contoured on the T1 scan and the unmodified original plan was then applied to the new anatomy (re-digitized, but same dwell times) to assess the impact of anatomical changes to the dosimetrics. EQD2 D2cc for all OARs was calculated assuming an alpha-beta ratio of 3 Gy and a prescription dose of 7 Gy per fraction. Results The mean ± SD bladder fill volume at time, T0, was 222±113 cm3. The bladder fill increased between -100 and +225 cm3 at T1. Changes in EQD2 D2cc to the bladder, rectum, sigmoid and bowel between T0 and T1 are plotted in Figure 2. The impact on EQD2 D2cc changes due to increases in bladder fill volume correlates highly for sigmoid (-0.75), and weakly for bladder (+0.31) and bowel (-0.20). For the rectum, EQD2 D2cc changes are negligibly correlated with respect to bladder fill changes. Conclusions Increases in bladder volume tend to decrease GI (rectum, sigmoid, bowel) OAR doses while increasing dose to the bladder. Ensuring the bladder fill does not decrease at the time of treatment is paramount for protecting GI OARs which have much lower dose limits. Increases in bladder volume should be weighed against the remaining dose tolerance budget for the bladder. Future work will involve acquire more data which may enable the development of quantitative model for predicting patient-specific dosimetric changes based on bladder fill changes. To evaluate the dosimetric impact of bladder fill change between the time of simulation and treatment delivery. This dosimetric study was completed with 10 individual high-dose-rate brachytherapy implants for cervical cancer patients (7 Gy/fx). Eight implants were performed with the Venezia and two with the Geneva (Elekta Brachy, Veenendaal, The Netherlands). An average of 8.0±1.8 interstitial needles were used. Each implant was imaged at two time point (T0 & T1): once the implant was completed (CT, T0) and approximately an hour later (MR, T1). For this study, optimized treatment plans were generated using the T0 scan. Organs at risk were also contoured on the T1 scan and the unmodified original plan was then applied to the new anatomy (re-digitized, but same dwell times) to assess the impact of anatomical changes to the dosimetrics. EQD2 D2cc for all OARs was calculated assuming an alpha-beta ratio of 3 Gy and a prescription dose o","PeriodicalId":93914,"journal":{"name":"Brachytherapy","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135434219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-01DOI: 10.1016/j.brachy.2023.06.150
Jessica Cruttenden, Christopher W. Weil, Lindsay M. Burt, Gita Suneja, David K. Gaffney, Cristina M. DeCesaris
Purpose To investigate practice patterns in adjuvant radiation (RT) delivery for patients with FIGO stage II endometrioid endometrial adenocarcinoma treated between 2004-2019. Materials and Methods The National Cancer Database (NCDB) was queried to review patients diagnosed between 2004-2019 with FIGO stage II endometrioid endometrial adenocarcinoma who underwent total hysterectomy and bilateral salpingo-oophorectomy (TH/BSO) and surgical staging. Multivariate regression analysis (MVA) was used to identify prognostic variables for adjuvant RT and RT omission. Results A total of 18,798 patients met inclusion criteria. Median follow-up was 6 years. Median age was 60 years. Twelve percent of patients received chemotherapy (CHT), and 68% received adjuvant RT. Of the study population, 19% received external beam radiation (EBRT) alone, 25% received vaginal brachytherapy (VBT) alone, and 24% received EBRT+VBT. Of those who received CHT, 35% received CHT alone whereas 25% also received EBRT alone, 22% received VBT alone, and 18% received EBRT+VBT. Use of adjuvant RT, including EBRT, VBT, and EBRT+VBT, increased over time, and EBRT+VBT was the most common treatment in 2019 (34% vs 23% in 2004; see Figure 1). On MVA, treatment at a community hospital (OR 1.8, p<0.001) or in the Midwest (OR 1.2, p=0.02), receipt of single agent chemotherapy (OR 6.9, p<0.001), LVSI+ (OR 1.4, p<0.001), and positive surgical margins (OR 1.8, p<0.001) were associated with increased likelihood of receiving any EBRT. No factors were significantly associated with an increased likelihood of receiving any VBT. Age >60 years old (OR 0.86, p=0.02), treatment at a community hospital (OR 0.41, p<0.001), distance from a treatment center >50 miles (OR 0.72, p<0.001), and grade 2 (OR 0.86, p=0.02) or 3 (OR 0.80, p=0.01) disease were associated with decreased likelihood of receiving VBT. Regionally, patients treated in the Midwest (OR 0.84, p=0.02), South (OR 0.54, p<0.001), or West (OR 0.52, p<0.001) were less likely to have received VBT compared to those in the Northeast. Black race (OR 1.2, p=0.03), treatment at a community hospital (OR 1.4, p=0.04), treatment in the South (OR 2.2, p<0.001) or West (OR 2.1, p<0.001), distance from a treatment center >50 miles (OR 1.5, p<0.001), and grade 2 (OR 1.2, p<0.001) or 3 (OR 1.3, p=0.01) disease were associated with an increased likelihood of RT omission. In contrast, receipt of single agent chemotherapy (OR 0.14, p<0.01), >50% myometrial invasion (OR 0.58, p<0.001), and positive surgical margins (OR 0.66, p=0.03) were associated with a decreased likelihood of RT omission. Conclusions Treatment guidelines for FIGO stage II endometrioid endometrial carcinoma support a variety of adjuvant treatment options with little data to direct selection of adjuvant therapy after surgery. Use of adjuvant RT has increased over the years, particularly the use of both EBRT+VBT. Patient-related factors such as race, region, and distance from treatment center were
{"title":"PO49","authors":"Jessica Cruttenden, Christopher W. Weil, Lindsay M. Burt, Gita Suneja, David K. Gaffney, Cristina M. DeCesaris","doi":"10.1016/j.brachy.2023.06.150","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.150","url":null,"abstract":"Purpose To investigate practice patterns in adjuvant radiation (RT) delivery for patients with FIGO stage II endometrioid endometrial adenocarcinoma treated between 2004-2019. Materials and Methods The National Cancer Database (NCDB) was queried to review patients diagnosed between 2004-2019 with FIGO stage II endometrioid endometrial adenocarcinoma who underwent total hysterectomy and bilateral salpingo-oophorectomy (TH/BSO) and surgical staging. Multivariate regression analysis (MVA) was used to identify prognostic variables for adjuvant RT and RT omission. Results A total of 18,798 patients met inclusion criteria. Median follow-up was 6 years. Median age was 60 years. Twelve percent of patients received chemotherapy (CHT), and 68% received adjuvant RT. Of the study population, 19% received external beam radiation (EBRT) alone, 25% received vaginal brachytherapy (VBT) alone, and 24% received EBRT+VBT. Of those who received CHT, 35% received CHT alone whereas 25% also received EBRT alone, 22% received VBT alone, and 18% received EBRT+VBT. Use of adjuvant RT, including EBRT, VBT, and EBRT+VBT, increased over time, and EBRT+VBT was the most common treatment in 2019 (34% vs 23% in 2004; see Figure 1). On MVA, treatment at a community hospital (OR 1.8, p<0.001) or in the Midwest (OR 1.2, p=0.02), receipt of single agent chemotherapy (OR 6.9, p<0.001), LVSI+ (OR 1.4, p<0.001), and positive surgical margins (OR 1.8, p<0.001) were associated with increased likelihood of receiving any EBRT. No factors were significantly associated with an increased likelihood of receiving any VBT. Age >60 years old (OR 0.86, p=0.02), treatment at a community hospital (OR 0.41, p<0.001), distance from a treatment center >50 miles (OR 0.72, p<0.001), and grade 2 (OR 0.86, p=0.02) or 3 (OR 0.80, p=0.01) disease were associated with decreased likelihood of receiving VBT. Regionally, patients treated in the Midwest (OR 0.84, p=0.02), South (OR 0.54, p<0.001), or West (OR 0.52, p<0.001) were less likely to have received VBT compared to those in the Northeast. Black race (OR 1.2, p=0.03), treatment at a community hospital (OR 1.4, p=0.04), treatment in the South (OR 2.2, p<0.001) or West (OR 2.1, p<0.001), distance from a treatment center >50 miles (OR 1.5, p<0.001), and grade 2 (OR 1.2, p<0.001) or 3 (OR 1.3, p=0.01) disease were associated with an increased likelihood of RT omission. In contrast, receipt of single agent chemotherapy (OR 0.14, p<0.01), >50% myometrial invasion (OR 0.58, p<0.001), and positive surgical margins (OR 0.66, p=0.03) were associated with a decreased likelihood of RT omission. Conclusions Treatment guidelines for FIGO stage II endometrioid endometrial carcinoma support a variety of adjuvant treatment options with little data to direct selection of adjuvant therapy after surgery. Use of adjuvant RT has increased over the years, particularly the use of both EBRT+VBT. Patient-related factors such as race, region, and distance from treatment center were ","PeriodicalId":93914,"journal":{"name":"Brachytherapy","volume":"105 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135434359","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-01DOI: 10.1016/j.brachy.2023.06.201
Juan Wang, Hongtao Zhang, Yansong Liang, Jianmin Li
Purpose To study the radiation dose rate and effective dose in ambient environment due to 1I seed implantation in the treatment of the patients suffering abdominal and pelvic tumors, so as to provide reference for occupational protection of different groups. Materials and Methods Within 24hours after operation , the radiation dose rate to 42 patients with abdominal and pelvic tumor with 125I seed implantation was monitored by using pocket dosimeter. The relationships between the total activity in the implanted particles and the measured dose rate, as well as hetween the implanted depth and the dose rate under the standard activity, were obtained by curve fitting. According to the formula, the relationship between the dose rate and the warning time was calculated. Results The dose rates at 30 cm , 50 cm and00 cm of vertical particle implantation site were (6.92+2. 87) , (4. 10+1. 62) and (1.30+0. 48) u.Sv/h. respectively (X'= 73. 71, P<0. 05). The dose rates on the left and right sides were (0. 378+0. 156) and (0.384+0. 153) Sv/h at 30 cm, (0. 170+0. 089) and (0.17+0. 086) uSv/h at 50 cm, (0. 039 +0. 014) and (0. 043+0.017) Sv/h at 100 cm, respectively (X'= 76. 19, 76. 33, P<0. 05). There was a linear relationship between the dose rate at the vertical particle implantation site and the total activity in the implanted particles, and between the dose rate and the implantation depth under the standard activity. The relationship between the warning time and the dose rate to adults in the same bed, co-workers , minors in the same bed and pregnant women were as follows: t (d) = -106. 616+83. 779lnD (t) , t (d) = 26. 556+85. 933lnD (t), t (d) = 3.088 + 85. 017InD (t). Conclusions After's I seed implantation, the radiation dose in the ambient environment is low, ensuring the radiation safety; and the measured dose rate decreases with the decrease in the total activity in the implanted particle and the increase in the implantation depth; at the same time, the warning time for different groups is calculated according to the measured dose rate or the total activity in the implanted particle and the depth of the implanted particle, so as to carry out individualized protection. To study the radiation dose rate and effective dose in ambient environment due to 1I seed implantation in the treatment of the patients suffering abdominal and pelvic tumors, so as to provide reference for occupational protection of different groups. Within 24hours after operation , the radiation dose rate to 42 patients with abdominal and pelvic tumor with 125I seed implantation was monitored by using pocket dosimeter. The relationships between the total activity in the implanted particles and the measured dose rate, as well as hetween the implanted depth and the dose rate under the standard activity, were obtained by curve fitting. According to the formula, the relationship between the dose rate and the warning time was calculated. The dose rates at 30 cm , 50 cm and00 cm of vertical
{"title":"PO100","authors":"Juan Wang, Hongtao Zhang, Yansong Liang, Jianmin Li","doi":"10.1016/j.brachy.2023.06.201","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.201","url":null,"abstract":"Purpose To study the radiation dose rate and effective dose in ambient environment due to 1I seed implantation in the treatment of the patients suffering abdominal and pelvic tumors, so as to provide reference for occupational protection of different groups. Materials and Methods Within 24hours after operation , the radiation dose rate to 42 patients with abdominal and pelvic tumor with 125I seed implantation was monitored by using pocket dosimeter. The relationships between the total activity in the implanted particles and the measured dose rate, as well as hetween the implanted depth and the dose rate under the standard activity, were obtained by curve fitting. According to the formula, the relationship between the dose rate and the warning time was calculated. Results The dose rates at 30 cm , 50 cm and00 cm of vertical particle implantation site were (6.92+2. 87) , (4. 10+1. 62) and (1.30+0. 48) u.Sv/h. respectively (X'= 73. 71, P<0. 05). The dose rates on the left and right sides were (0. 378+0. 156) and (0.384+0. 153) Sv/h at 30 cm, (0. 170+0. 089) and (0.17+0. 086) uSv/h at 50 cm, (0. 039 +0. 014) and (0. 043+0.017) Sv/h at 100 cm, respectively (X'= 76. 19, 76. 33, P<0. 05). There was a linear relationship between the dose rate at the vertical particle implantation site and the total activity in the implanted particles, and between the dose rate and the implantation depth under the standard activity. The relationship between the warning time and the dose rate to adults in the same bed, co-workers , minors in the same bed and pregnant women were as follows: t (d) = -106. 616+83. 779lnD (t) , t (d) = 26. 556+85. 933lnD (t), t (d) = 3.088 + 85. 017InD (t). Conclusions After's I seed implantation, the radiation dose in the ambient environment is low, ensuring the radiation safety; and the measured dose rate decreases with the decrease in the total activity in the implanted particle and the increase in the implantation depth; at the same time, the warning time for different groups is calculated according to the measured dose rate or the total activity in the implanted particle and the depth of the implanted particle, so as to carry out individualized protection. To study the radiation dose rate and effective dose in ambient environment due to 1I seed implantation in the treatment of the patients suffering abdominal and pelvic tumors, so as to provide reference for occupational protection of different groups. Within 24hours after operation , the radiation dose rate to 42 patients with abdominal and pelvic tumor with 125I seed implantation was monitored by using pocket dosimeter. The relationships between the total activity in the implanted particles and the measured dose rate, as well as hetween the implanted depth and the dose rate under the standard activity, were obtained by curve fitting. According to the formula, the relationship between the dose rate and the warning time was calculated. The dose rates at 30 cm , 50 cm and00 cm of vertical ","PeriodicalId":93914,"journal":{"name":"Brachytherapy","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135434370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-01DOI: 10.1016/j.brachy.2023.06.225
Matthew Jalbert, John J. Munro, David C. Medich
Purpose Tungsten-181 is a middle energy radioisotope with an average energy of Eavg=64.3keV and a half-life of T1/2=140d that holds promise as a new HDR brachytherapy source. This is because, except for its two highest energy photons which have energies of 136 keV (yield: 0.0311%) and 156 keV (yield: 0.0083%), this source is dominated by photons which lie between 56 keV to 67 keV. Such photons easily are absorbed by high Z materials but scatter readily in water. This study will investigate the treatment needs and intensity modulation capabilities of W-181 and compare these results to those of Iridium-192 and Ytterbium-169. Materials and Methods Simulations were conducted using the Monte Carlo N-Particle Transport Code (MCNP6.2) to calculate the Dose Rate Constant, Radial Dose Function, photon self-absorption, and treatment activity of a 3.5mm long and 0.6mm diameter pellet encapsulated in stainless steel. We finally evaluated the intensity modulation capabilities of this pellet and compared it to Ir-192 and Yb-169. Results Our W-181 pellet had a Dose Rate Constant of 1.01 ± 0.01cGy∙h-1∙U-1 and a Radial Dose Function, which was fit to a 5th polynomial function to obtain the following coefficients: a0=9.01E-1 a1=8.60E-2 a2=2.96E-2 a3=-1.05E-2 a4=1.00E-3 a5=-3.00E-5. With respect to shielding and intensity modulation, 0.3mm of gold shielding reduced W-181’s absorbed dose by 86%, Yb-169′s dose by 62%, and Ir-192’s dose by 15%. While this isotope therefore can be an excellent candidate for IMBT, we also found that it is limited by a high photon self-absorption due to tungsten's very high density (19.3g/cm3) and atomic number (74). Specifically, we found that a W-181 pellet would provide an absorbed dose rate per unit activity of 1.84 ± 0.01cGy∙Ci-1min-1 to a treatment area 1cm from the source as opposed to Ir-192 and Yb-169’s 31.0 ± 0.37 cGy∙Ci-1∙min-1 and 8.18 ± 0.11 cGy∙Ci-1∙min-1, respectively. A W-181 therapeutic source therefore would require a higher treatment activity than a Yb-169 or Ir-192 source. Conclusions The capabilities of W-181 for intensity modulation outperforms that of Ir-192 and even Yb-169. Given these results, W-181 shows promise as a brachytherapy source, especially in multi-pellet configurations. Tungsten-181 is a middle energy radioisotope with an average energy of Eavg=64.3keV and a half-life of T1/2=140d that holds promise as a new HDR brachytherapy source. This is because, except for its two highest energy photons which have energies of 136 keV (yield: 0.0311%) and 156 keV (yield: 0.0083%), this source is dominated by photons which lie between 56 keV to 67 keV. Such photons easily are absorbed by high Z materials but scatter readily in water. This study will investigate the treatment needs and intensity modulation capabilities of W-181 and compare these results to those of Iridium-192 and Ytterbium-169. Simulations were conducted using the Monte Carlo N-Particle Transport Code (MCNP6.2) to calculate the Dose Rate Constant,
{"title":"PO125","authors":"Matthew Jalbert, John J. Munro, David C. Medich","doi":"10.1016/j.brachy.2023.06.225","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.225","url":null,"abstract":"Purpose Tungsten-181 is a middle energy radioisotope with an average energy of Eavg=64.3keV and a half-life of T1/2=140d that holds promise as a new HDR brachytherapy source. This is because, except for its two highest energy photons which have energies of 136 keV (yield: 0.0311%) and 156 keV (yield: 0.0083%), this source is dominated by photons which lie between 56 keV to 67 keV. Such photons easily are absorbed by high Z materials but scatter readily in water. This study will investigate the treatment needs and intensity modulation capabilities of W-181 and compare these results to those of Iridium-192 and Ytterbium-169. Materials and Methods Simulations were conducted using the Monte Carlo N-Particle Transport Code (MCNP6.2) to calculate the Dose Rate Constant, Radial Dose Function, photon self-absorption, and treatment activity of a 3.5mm long and 0.6mm diameter pellet encapsulated in stainless steel. We finally evaluated the intensity modulation capabilities of this pellet and compared it to Ir-192 and Yb-169. Results Our W-181 pellet had a Dose Rate Constant of 1.01 ± 0.01cGy∙h-1∙U-1 and a Radial Dose Function, which was fit to a 5th polynomial function to obtain the following coefficients: a0=9.01E-1 a1=8.60E-2 a2=2.96E-2 a3=-1.05E-2 a4=1.00E-3 a5=-3.00E-5. With respect to shielding and intensity modulation, 0.3mm of gold shielding reduced W-181’s absorbed dose by 86%, Yb-169′s dose by 62%, and Ir-192’s dose by 15%. While this isotope therefore can be an excellent candidate for IMBT, we also found that it is limited by a high photon self-absorption due to tungsten's very high density (19.3g/cm3) and atomic number (74). Specifically, we found that a W-181 pellet would provide an absorbed dose rate per unit activity of 1.84 ± 0.01cGy∙Ci-1min-1 to a treatment area 1cm from the source as opposed to Ir-192 and Yb-169’s 31.0 ± 0.37 cGy∙Ci-1∙min-1 and 8.18 ± 0.11 cGy∙Ci-1∙min-1, respectively. A W-181 therapeutic source therefore would require a higher treatment activity than a Yb-169 or Ir-192 source. Conclusions The capabilities of W-181 for intensity modulation outperforms that of Ir-192 and even Yb-169. Given these results, W-181 shows promise as a brachytherapy source, especially in multi-pellet configurations. Tungsten-181 is a middle energy radioisotope with an average energy of Eavg=64.3keV and a half-life of T1/2=140d that holds promise as a new HDR brachytherapy source. This is because, except for its two highest energy photons which have energies of 136 keV (yield: 0.0311%) and 156 keV (yield: 0.0083%), this source is dominated by photons which lie between 56 keV to 67 keV. Such photons easily are absorbed by high Z materials but scatter readily in water. This study will investigate the treatment needs and intensity modulation capabilities of W-181 and compare these results to those of Iridium-192 and Ytterbium-169. Simulations were conducted using the Monte Carlo N-Particle Transport Code (MCNP6.2) to calculate the Dose Rate Constant, ","PeriodicalId":93914,"journal":{"name":"Brachytherapy","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135434408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-01DOI: 10.1016/j.brachy.2023.06.118
Juan Wang, Jinxin Zhao, Yansong Liang, Huiming Yu
Purpose To investigate the relationship between dose parameters and tumor volume reduction ratio after 125I seed implantation for recurrent cervical squamous cell carcinoma, and to obtain the better parameters to predict the curative effect. Methods 26 cervical squamous cell carcinoma patients with 30 lesions were studied retrospectively in our clinic. All patients underwent dose verification immediately after operation, and obtained postoperative D90(the minimum peripheral dose accepted by 90% target volume). The patients were followed up regularly. According to the CT images during the actual follow-up, the tumor volume reduction ratio at the end of t months (Rt),the tumor volume reduction ratio 1 month after operation (R1), the first month actual absorbed dose (D1m), the first month efficacy corrected absorbed dose (D1e), the first month sensitivity corrected absorbed dose (D1s) and the t months actual absorbed dose (Dt) were calculated. Curve fitting was performed for postoperative D90 and R1, and curve fitting was performed for postoperative D90, D1m, D1e, D1s and Rt to find the correlation between each parameter and tumor volume reduction ratio. Results The mean values of D90,D1m,D1e,D1s,Rt,R1were (105.4±22.8) Gy,(30.9±7.4)Gy,(37.1±8.9)Gy,(37.8±11.6)Gy,(39.4±17)%,(20.4±12)%. Postoperative D90 and R1, postoperative D90, D1m, D1e, D1s andRt all have positive relationship. The equations are as follows y=6.856×10-7x3-2.66×10-4x2+0.031x-0.879(R2=0.139),y=1.573×10-6x3-4.47×10-4x2+0.045x-0.967(R2=0.027),y=7.11×10-5x3-0.07x2+0.193x-1.402(R2=0.043),y=3.546×10-5x3-0.003x2+0.108x-0.744(R2=0.126),y=1.022×10-5x3-0.001x2+0.048x-0.275(R2=0.243). Conclusion PostoperativeD90, D1m, D1e and D1s were positively correlated with postoperative tumor volume reduction ratio, which can be used to predict the efficacy of primary recurrent cervical squamous cell carcinoma patients with particle implantation. Compared with D90 and D1m, and D1e , D1s can be better predictors . To investigate the relationship between dose parameters and tumor volume reduction ratio after 125I seed implantation for recurrent cervical squamous cell carcinoma, and to obtain the better parameters to predict the curative effect. 26 cervical squamous cell carcinoma patients with 30 lesions were studied retrospectively in our clinic. All patients underwent dose verification immediately after operation, and obtained postoperative D90(the minimum peripheral dose accepted by 90% target volume). The patients were followed up regularly. According to the CT images during the actual follow-up, the tumor volume reduction ratio at the end of t months (Rt),the tumor volume reduction ratio 1 month after operation (R1), the first month actual absorbed dose (D1m), the first month efficacy corrected absorbed dose (D1e), the first month sensitivity corrected absorbed dose (D1s) and the t months actual absorbed dose (Dt) were calculated. Curve fitting was performed for postoperative D90 and R1, and curve fitti
{"title":"PO17","authors":"Juan Wang, Jinxin Zhao, Yansong Liang, Huiming Yu","doi":"10.1016/j.brachy.2023.06.118","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.118","url":null,"abstract":"Purpose To investigate the relationship between dose parameters and tumor volume reduction ratio after 125I seed implantation for recurrent cervical squamous cell carcinoma, and to obtain the better parameters to predict the curative effect. Methods 26 cervical squamous cell carcinoma patients with 30 lesions were studied retrospectively in our clinic. All patients underwent dose verification immediately after operation, and obtained postoperative D90(the minimum peripheral dose accepted by 90% target volume). The patients were followed up regularly. According to the CT images during the actual follow-up, the tumor volume reduction ratio at the end of t months (Rt),the tumor volume reduction ratio 1 month after operation (R1), the first month actual absorbed dose (D1m), the first month efficacy corrected absorbed dose (D1e), the first month sensitivity corrected absorbed dose (D1s) and the t months actual absorbed dose (Dt) were calculated. Curve fitting was performed for postoperative D90 and R1, and curve fitting was performed for postoperative D90, D1m, D1e, D1s and Rt to find the correlation between each parameter and tumor volume reduction ratio. Results The mean values of D90,D1m,D1e,D1s,Rt,R1were (105.4±22.8) Gy,(30.9±7.4)Gy,(37.1±8.9)Gy,(37.8±11.6)Gy,(39.4±17)%,(20.4±12)%. Postoperative D90 and R1, postoperative D90, D1m, D1e, D1s andRt all have positive relationship. The equations are as follows y=6.856×10-7x3-2.66×10-4x2+0.031x-0.879(R2=0.139),y=1.573×10-6x3-4.47×10-4x2+0.045x-0.967(R2=0.027),y=7.11×10-5x3-0.07x2+0.193x-1.402(R2=0.043),y=3.546×10-5x3-0.003x2+0.108x-0.744(R2=0.126),y=1.022×10-5x3-0.001x2+0.048x-0.275(R2=0.243). Conclusion PostoperativeD90, D1m, D1e and D1s were positively correlated with postoperative tumor volume reduction ratio, which can be used to predict the efficacy of primary recurrent cervical squamous cell carcinoma patients with particle implantation. Compared with D90 and D1m, and D1e , D1s can be better predictors . To investigate the relationship between dose parameters and tumor volume reduction ratio after 125I seed implantation for recurrent cervical squamous cell carcinoma, and to obtain the better parameters to predict the curative effect. 26 cervical squamous cell carcinoma patients with 30 lesions were studied retrospectively in our clinic. All patients underwent dose verification immediately after operation, and obtained postoperative D90(the minimum peripheral dose accepted by 90% target volume). The patients were followed up regularly. According to the CT images during the actual follow-up, the tumor volume reduction ratio at the end of t months (Rt),the tumor volume reduction ratio 1 month after operation (R1), the first month actual absorbed dose (D1m), the first month efficacy corrected absorbed dose (D1e), the first month sensitivity corrected absorbed dose (D1s) and the t months actual absorbed dose (Dt) were calculated. Curve fitting was performed for postoperative D90 and R1, and curve fitti","PeriodicalId":93914,"journal":{"name":"Brachytherapy","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135434410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-01DOI: 10.1016/j.brachy.2023.06.158
Philippe Chatigny, Cédric Bélanger, Éric Poulin, Luc Beaulieu
Purpose In the past years, a key improvement in the generation of treatment plans in high-dose-rate (HDR) brachytherapy comes from the development of multicriteria optimization (MCO) algorithms that generate thousands of pareto optimal plans within seconds. This brings a shift, from the objective of generating an acceptable plan to choosing the best plans out of thousands. Not only does the chosen plan depend on the planner, it also takes about 5-10 minutes to choose the preferred plan. The purpose of the present work is to speed up this process and to find a common ground for different specialists regarding the plan quality. Materials and Methods An AI algorithm based on the ResNet deep neural network architecture is developed to choose the best plan(s) from the generated plans. The algorithm classifies the plans, from the 3D dose distribution and anatomical structures, in 3 different classes, (1) violating hard (minimum) criteria, (2) respecting hard criteria and (3) respecting soft criteria, with every class being more stringent than the last one (increase in plan quality). The three classes are based on dosimetric criteria used at our institution for 15 Gy in a single fraction. For the classification, the more confident the model is that a plan belongs to class 3, the better is the plan. To mimic the behaviour of experts, visual-like criteria are implemented for the bladder, rectum and urethra. Visual criteria are defined as 100% and 125% isodose distance from the organ at risk. During training, the algorithm learns the link between the inputs (3D dose and anatomy) and outputs (visual-like and DVH's criteria). 850 previously treated prostate's cancer patients are used for the training and another set of 20 patients previously evaluated by two experts (clinical medical physicist) as part of an inter-observer MCO study are used for validation. For the training, 100 plans are generated for each patient using MCO and 27 000 plans are chosen at random to have the same quantity in each class. A NVIDIA GeForce RTX 3090 is used for training. Results The model takes 20 s to classify 2000 plans in order of preference (vs 5-10 mins for experts to rank 4 preferred plans). Currently, the training time is not optimized and it takes less than 2 days to train on the 27 000 plans with 75 epochs. For the 20 validation patients, 39.9 ± 20.2%, 46.4 ± 15.3% and 14.5 ± 21.9% of the plan are in class 1, 2 and 3 respectively. Table 1 shows the results obtained on 20 cases, each with 2000 plans; the mean and deviation are calculated based on the plan chosen by the model and by the experts. The table includes the best ranked and worst ranked plan of class 3. Looking at the best plan according to the model and comparing it with the plan chosen by the two experts show that the behaviour is similar. Out of the 40 chosen plans by the two experts, on 3 occasions our model ranked the same plan as the best plan. Looking more in depth, we find that the median ranking of the p
{"title":"PO57","authors":"Philippe Chatigny, Cédric Bélanger, Éric Poulin, Luc Beaulieu","doi":"10.1016/j.brachy.2023.06.158","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.158","url":null,"abstract":"Purpose In the past years, a key improvement in the generation of treatment plans in high-dose-rate (HDR) brachytherapy comes from the development of multicriteria optimization (MCO) algorithms that generate thousands of pareto optimal plans within seconds. This brings a shift, from the objective of generating an acceptable plan to choosing the best plans out of thousands. Not only does the chosen plan depend on the planner, it also takes about 5-10 minutes to choose the preferred plan. The purpose of the present work is to speed up this process and to find a common ground for different specialists regarding the plan quality. Materials and Methods An AI algorithm based on the ResNet deep neural network architecture is developed to choose the best plan(s) from the generated plans. The algorithm classifies the plans, from the 3D dose distribution and anatomical structures, in 3 different classes, (1) violating hard (minimum) criteria, (2) respecting hard criteria and (3) respecting soft criteria, with every class being more stringent than the last one (increase in plan quality). The three classes are based on dosimetric criteria used at our institution for 15 Gy in a single fraction. For the classification, the more confident the model is that a plan belongs to class 3, the better is the plan. To mimic the behaviour of experts, visual-like criteria are implemented for the bladder, rectum and urethra. Visual criteria are defined as 100% and 125% isodose distance from the organ at risk. During training, the algorithm learns the link between the inputs (3D dose and anatomy) and outputs (visual-like and DVH's criteria). 850 previously treated prostate's cancer patients are used for the training and another set of 20 patients previously evaluated by two experts (clinical medical physicist) as part of an inter-observer MCO study are used for validation. For the training, 100 plans are generated for each patient using MCO and 27 000 plans are chosen at random to have the same quantity in each class. A NVIDIA GeForce RTX 3090 is used for training. Results The model takes 20 s to classify 2000 plans in order of preference (vs 5-10 mins for experts to rank 4 preferred plans). Currently, the training time is not optimized and it takes less than 2 days to train on the 27 000 plans with 75 epochs. For the 20 validation patients, 39.9 ± 20.2%, 46.4 ± 15.3% and 14.5 ± 21.9% of the plan are in class 1, 2 and 3 respectively. Table 1 shows the results obtained on 20 cases, each with 2000 plans; the mean and deviation are calculated based on the plan chosen by the model and by the experts. The table includes the best ranked and worst ranked plan of class 3. Looking at the best plan according to the model and comparing it with the plan chosen by the two experts show that the behaviour is similar. Out of the 40 chosen plans by the two experts, on 3 occasions our model ranked the same plan as the best plan. Looking more in depth, we find that the median ranking of the p","PeriodicalId":93914,"journal":{"name":"Brachytherapy","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135434422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-01DOI: 10.1016/j.brachy.2023.06.216
Miren Gaztañaga, Virginia Álvarez, Javier De Areba, Saadia Tremolada, Pino Alcántara, Elena Cerezo, Juan Antonio Corona, Anxela Doval, Fernando Puebla, Noelia Sanmamed, Manuel Gonzalo Vázquez
Purpose Perioperative accelerated partial breast irradiation with multicatheter interstitial brachytherapy is an alternative to the postoperative option that offers advantages in terms of specificity and comfort for patients as it avoids a second procedure. Since the simulation CT scan is performed 48 hours after the intervention, immediate tissue changes as air gaps can occasionally be observed. To our knowledge, there is no literature published on this regard, so the aim of this study was to assess the impact of significant air gaps when planning and treating multicatheter perioperative breast cancer brachytherapy. Methods and Materials Two consecutive cases with air gaps > 6 cc were included. For each case, a planning CT scan was performed 48 hours after the surgical procedure (tumorectomy + catheter insertion). Treatment planning was performed according to the department protocol and administered in an ultra-fractionated scheme: 3 fractions of 745 cGy every 12 hours. A second CT scan was performed right after the last treatment fraction, before the catheter removal. The air gaps have been contoured in both pre and post-treatment CTs and their volumes have been compared. The scans have been fused and the dosimetric differences have been evaluated. A total of 13 catheters have been analyzed in both scans. Results A volume reduction (-10% and -30% for each case) has been observed in the post-treatment air gap. Of the 13 catheters compared in the CT scans fusion, the catheter position displacement inside CTV was ≤ 1.5 mm in 12 of them (median displacement 1 mm), with one catheter displaced 2.7 mm in the post-treatment CT. Mean CTVD90 and V100 variation in the pre and post-treatment scans were -1.5 and -1.7% respectively. Dose variations in surrounding organs were: Skin Dmax -10 and -3%, Ribs Dmax +15 and +15% and Ipsilateral Lung Dmax +12 and +13%. Dosimetric disparities did not exceed tolerance and coverage limits in any case. Conclusions With two cases analyzed, the volumetric reduction of the air gaps does not seem to affect the geometry of the implants, with most of the catheters remaining stable in their initial position. Discrete changes in the coverage parameters and doses to OARs fulfill the pre-established constraints. The confirmation of these results as well as the clinical relevance of these changes has to be examined in future studies including more patients. Perioperative accelerated partial breast irradiation with multicatheter interstitial brachytherapy is an alternative to the postoperative option that offers advantages in terms of specificity and comfort for patients as it avoids a second procedure. Since the simulation CT scan is performed 48 hours after the intervention, immediate tissue changes as air gaps can occasionally be observed. To our knowledge, there is no literature published on this regard, so the aim of this study was to assess the impact of significant air gaps when planning and treating multicatheter perioperati
{"title":"PO115","authors":"Miren Gaztañaga, Virginia Álvarez, Javier De Areba, Saadia Tremolada, Pino Alcántara, Elena Cerezo, Juan Antonio Corona, Anxela Doval, Fernando Puebla, Noelia Sanmamed, Manuel Gonzalo Vázquez","doi":"10.1016/j.brachy.2023.06.216","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.216","url":null,"abstract":"Purpose Perioperative accelerated partial breast irradiation with multicatheter interstitial brachytherapy is an alternative to the postoperative option that offers advantages in terms of specificity and comfort for patients as it avoids a second procedure. Since the simulation CT scan is performed 48 hours after the intervention, immediate tissue changes as air gaps can occasionally be observed. To our knowledge, there is no literature published on this regard, so the aim of this study was to assess the impact of significant air gaps when planning and treating multicatheter perioperative breast cancer brachytherapy. Methods and Materials Two consecutive cases with air gaps > 6 cc were included. For each case, a planning CT scan was performed 48 hours after the surgical procedure (tumorectomy + catheter insertion). Treatment planning was performed according to the department protocol and administered in an ultra-fractionated scheme: 3 fractions of 745 cGy every 12 hours. A second CT scan was performed right after the last treatment fraction, before the catheter removal. The air gaps have been contoured in both pre and post-treatment CTs and their volumes have been compared. The scans have been fused and the dosimetric differences have been evaluated. A total of 13 catheters have been analyzed in both scans. Results A volume reduction (-10% and -30% for each case) has been observed in the post-treatment air gap. Of the 13 catheters compared in the CT scans fusion, the catheter position displacement inside CTV was ≤ 1.5 mm in 12 of them (median displacement 1 mm), with one catheter displaced 2.7 mm in the post-treatment CT. Mean CTVD90 and V100 variation in the pre and post-treatment scans were -1.5 and -1.7% respectively. Dose variations in surrounding organs were: Skin Dmax -10 and -3%, Ribs Dmax +15 and +15% and Ipsilateral Lung Dmax +12 and +13%. Dosimetric disparities did not exceed tolerance and coverage limits in any case. Conclusions With two cases analyzed, the volumetric reduction of the air gaps does not seem to affect the geometry of the implants, with most of the catheters remaining stable in their initial position. Discrete changes in the coverage parameters and doses to OARs fulfill the pre-established constraints. The confirmation of these results as well as the clinical relevance of these changes has to be examined in future studies including more patients. Perioperative accelerated partial breast irradiation with multicatheter interstitial brachytherapy is an alternative to the postoperative option that offers advantages in terms of specificity and comfort for patients as it avoids a second procedure. Since the simulation CT scan is performed 48 hours after the intervention, immediate tissue changes as air gaps can occasionally be observed. To our knowledge, there is no literature published on this regard, so the aim of this study was to assess the impact of significant air gaps when planning and treating multicatheter perioperati","PeriodicalId":93914,"journal":{"name":"Brachytherapy","volume":"106 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135434426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-01DOI: 10.1016/j.brachy.2023.06.151
Michael Jason Gutman, Tianming Wu, Christina Son, Hania Al-Hallaq, Yasmin Hasan
Purpose Triple tandem brachytherapy (TTB) provides superior coverage of the uterus and minimizes dose to OARs compared to single or dual tandem therapy, per prior dosimetric analysis of 3 representative cases (1). We report the technical feasibility and dosimetry of TTB in a cohort of patients with medically inoperable endometrial cancer (EC). Materials and Methods An IRB approved retrospective review was performed of all medically inoperable EC patients treated definitively with TTB ± external beam radiotherapy (EBRT) between 2014-2021 at a single institution (n=30). Patients underwent off-line MRI which was fused for planning (n=24, 80%) and all underwent intraoperative transabdominal ultrasound for dilation and device placement. Patients had FIGO stage 1a-4b disease; patients with ≥ stage 2 disease received TTB +/- ovoids. Kaplan-Meier estimates were generated to estimate local failure-free survival (LFFS). The equivalent dose in 2-Gy fractions (EQD2) constraints for dose to 2cc (D2cc) of the bladder, rectum, and bowel were <90Gy, <75Gy, and <65Gy, respectively, per ABS guidelines. The cumulative D90% (minimum dose to 90% of volume) in EQD2 was calculated for GTV and CTV and the organs at risk (OAR) for each patient. Statistics reported are median values and ranges. The dwell time contribution from each tandem was collected. Results Of 30 patients, 93.3% received EBRT and TTB. Mean age at time of diagnosis was 65.3 years (range: 40.5-88.7 years). The median BMI was 48.1 (range: 27.8-69). The median prescribed doses were 45 Gy (range: 21-50.4 Gy) for EBRT and 22.25 Gy in 5 fractions (range: 16.5-49.1 Gy) for brachytherapy. The median cumulative EQD2 to the GTV was 78.6 Gy (range: 67.8- 86.6) and to the CTV was 67.6 Gy (range: 48- 79.8), of which the TTB contributed a median EQD2 of 33.8 Gy and 23.3 Gy to the GTV and CTV, respectively. The central tandem was not placed for 4 patients (13.3%) due to concern for posterior cervix and/or posterior uterine wall perforation. In the entire cohort, the central tandem contributed at least 10% and 15% of the dwell time in 77% (n=23) and 60% (n=18) of patients, respectively (Figure 1). In one third of patients, the central tandem contributed ≥30% of the dwell time. The lateral tandems contributed the majority (82%, range: 32-100%) of total dwells. Median follow up was 32.1 months (1.7-93.6 months). Kaplan-Meier-estimated 1-/5-yr LFFS was 96.2%/84.1%. The cumulative D2cc: 71.0Gy (range: 25.2-91.2Gy) to the bladder, 53.6Gy (range: 25.2-76.2Gy) to the rectum, and 58.1Gy (range: 14.1-72Gy) to the small bowel. No procedure-related perforation, bleeding or acute complication occurred intra- or post-operatively. Conclusions TTB + EBRT for inoperable EC patients was safe and acceptable target coverage was achieved in most cases. While posterior/central tandem insertion may not be feasible for all patients in our experience, this limitation was not prohibitive to adequate dose distribution and local control. Furthe
{"title":"PO50","authors":"Michael Jason Gutman, Tianming Wu, Christina Son, Hania Al-Hallaq, Yasmin Hasan","doi":"10.1016/j.brachy.2023.06.151","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.151","url":null,"abstract":"Purpose Triple tandem brachytherapy (TTB) provides superior coverage of the uterus and minimizes dose to OARs compared to single or dual tandem therapy, per prior dosimetric analysis of 3 representative cases (1). We report the technical feasibility and dosimetry of TTB in a cohort of patients with medically inoperable endometrial cancer (EC). Materials and Methods An IRB approved retrospective review was performed of all medically inoperable EC patients treated definitively with TTB ± external beam radiotherapy (EBRT) between 2014-2021 at a single institution (n=30). Patients underwent off-line MRI which was fused for planning (n=24, 80%) and all underwent intraoperative transabdominal ultrasound for dilation and device placement. Patients had FIGO stage 1a-4b disease; patients with ≥ stage 2 disease received TTB +/- ovoids. Kaplan-Meier estimates were generated to estimate local failure-free survival (LFFS). The equivalent dose in 2-Gy fractions (EQD2) constraints for dose to 2cc (D2cc) of the bladder, rectum, and bowel were <90Gy, <75Gy, and <65Gy, respectively, per ABS guidelines. The cumulative D90% (minimum dose to 90% of volume) in EQD2 was calculated for GTV and CTV and the organs at risk (OAR) for each patient. Statistics reported are median values and ranges. The dwell time contribution from each tandem was collected. Results Of 30 patients, 93.3% received EBRT and TTB. Mean age at time of diagnosis was 65.3 years (range: 40.5-88.7 years). The median BMI was 48.1 (range: 27.8-69). The median prescribed doses were 45 Gy (range: 21-50.4 Gy) for EBRT and 22.25 Gy in 5 fractions (range: 16.5-49.1 Gy) for brachytherapy. The median cumulative EQD2 to the GTV was 78.6 Gy (range: 67.8- 86.6) and to the CTV was 67.6 Gy (range: 48- 79.8), of which the TTB contributed a median EQD2 of 33.8 Gy and 23.3 Gy to the GTV and CTV, respectively. The central tandem was not placed for 4 patients (13.3%) due to concern for posterior cervix and/or posterior uterine wall perforation. In the entire cohort, the central tandem contributed at least 10% and 15% of the dwell time in 77% (n=23) and 60% (n=18) of patients, respectively (Figure 1). In one third of patients, the central tandem contributed ≥30% of the dwell time. The lateral tandems contributed the majority (82%, range: 32-100%) of total dwells. Median follow up was 32.1 months (1.7-93.6 months). Kaplan-Meier-estimated 1-/5-yr LFFS was 96.2%/84.1%. The cumulative D2cc: 71.0Gy (range: 25.2-91.2Gy) to the bladder, 53.6Gy (range: 25.2-76.2Gy) to the rectum, and 58.1Gy (range: 14.1-72Gy) to the small bowel. No procedure-related perforation, bleeding or acute complication occurred intra- or post-operatively. Conclusions TTB + EBRT for inoperable EC patients was safe and acceptable target coverage was achieved in most cases. While posterior/central tandem insertion may not be feasible for all patients in our experience, this limitation was not prohibitive to adequate dose distribution and local control. Furthe","PeriodicalId":93914,"journal":{"name":"Brachytherapy","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135434430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-01DOI: 10.1016/j.brachy.2023.06.172
Hong Zhang, Catherine Liu
Purpose High-Dose-Rate Brachytherapy (HDR-BT) is an effective yet under-utilized treatment option for localized prostate cancer. Many studies have shown excellent long-term biochemical-failure-free survival outcomes with limited toxicity from HDR-BT as monotherapy for low- or intermediate-risk prostate cancer. However, due to higher start-up costs, less reimbursement, and inadequacy in residency training, far fewer radiation facilities are offering BT than external beam radiation (EBRT). Here, we performed a single-center, retrospective cohort study to evaluate the travel burdens put on patients who received BT as monotherapy at our high-volume center and if they had chosen external beam radiation close to home for localized prostate cancer. Materials and Methods From 1/1/2019 to 12/31/2022, 69 men were treated with HDR-BT as monotherapy at our brachytherapy center, receiving 27 Gy in 2 fractions, one week apart. Sixty-eight men had low- or intermediate-risk prostate cancer (Table). The travel burden for HDR-BT as monotherapy was estimated by collecting the distance between each patient's home address to our BT center (BT-D). The distance between each patient's home address and the nearest EBRT facility (EBRT-D) was also collected. The total travel burden for EBRT was then calculated, assuming a standard regiment of 28 fractions was used. Results Of the 69 patients who received BT for prostate cancer, the average age was 67.9 years, the overwhelming majority were white (96%), and all had insurance. The median and average EBRT-D were 5.5 and 8.3 miles, respectively. The median and average BT-D were 21 and 37.4 miles, respectively. However, due to the fewer visits required for BT (2 versus 28 trips), the total BT travel burden (median 84 miles, average 150.0 miles) was significantly less than for these patients if they had chosen EBRT instead (median 308 miles, average 462.5 miles) (p<0.01). On average, by choosing BT instead of EBRT, these patients reduced their travel burden by 312.5 miles. Conclusions We observed a significantly decreased overall travel burden for HDR-BT as monotherapy compared with EBRT in our cohort of patients with localized prostate cancer, despite a longer travel distance to our BT center than a nearby EBRT facility. Our study supports that HDR-BT as monotherapy remains a practical and preferred option for patients with localized prostate cancer, not only for its proven safety and efficacy but also decreased overall travel burden compared with definitive EBRT therapy. High-Dose-Rate Brachytherapy (HDR-BT) is an effective yet under-utilized treatment option for localized prostate cancer. Many studies have shown excellent long-term biochemical-failure-free survival outcomes with limited toxicity from HDR-BT as monotherapy for low- or intermediate-risk prostate cancer. However, due to higher start-up costs, less reimbursement, and inadequacy in residency training, far fewer radiation facilities are offering BT than external be
{"title":"PO71","authors":"Hong Zhang, Catherine Liu","doi":"10.1016/j.brachy.2023.06.172","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.172","url":null,"abstract":"Purpose High-Dose-Rate Brachytherapy (HDR-BT) is an effective yet under-utilized treatment option for localized prostate cancer. Many studies have shown excellent long-term biochemical-failure-free survival outcomes with limited toxicity from HDR-BT as monotherapy for low- or intermediate-risk prostate cancer. However, due to higher start-up costs, less reimbursement, and inadequacy in residency training, far fewer radiation facilities are offering BT than external beam radiation (EBRT). Here, we performed a single-center, retrospective cohort study to evaluate the travel burdens put on patients who received BT as monotherapy at our high-volume center and if they had chosen external beam radiation close to home for localized prostate cancer. Materials and Methods From 1/1/2019 to 12/31/2022, 69 men were treated with HDR-BT as monotherapy at our brachytherapy center, receiving 27 Gy in 2 fractions, one week apart. Sixty-eight men had low- or intermediate-risk prostate cancer (Table). The travel burden for HDR-BT as monotherapy was estimated by collecting the distance between each patient's home address to our BT center (BT-D). The distance between each patient's home address and the nearest EBRT facility (EBRT-D) was also collected. The total travel burden for EBRT was then calculated, assuming a standard regiment of 28 fractions was used. Results Of the 69 patients who received BT for prostate cancer, the average age was 67.9 years, the overwhelming majority were white (96%), and all had insurance. The median and average EBRT-D were 5.5 and 8.3 miles, respectively. The median and average BT-D were 21 and 37.4 miles, respectively. However, due to the fewer visits required for BT (2 versus 28 trips), the total BT travel burden (median 84 miles, average 150.0 miles) was significantly less than for these patients if they had chosen EBRT instead (median 308 miles, average 462.5 miles) (p<0.01). On average, by choosing BT instead of EBRT, these patients reduced their travel burden by 312.5 miles. Conclusions We observed a significantly decreased overall travel burden for HDR-BT as monotherapy compared with EBRT in our cohort of patients with localized prostate cancer, despite a longer travel distance to our BT center than a nearby EBRT facility. Our study supports that HDR-BT as monotherapy remains a practical and preferred option for patients with localized prostate cancer, not only for its proven safety and efficacy but also decreased overall travel burden compared with definitive EBRT therapy. High-Dose-Rate Brachytherapy (HDR-BT) is an effective yet under-utilized treatment option for localized prostate cancer. Many studies have shown excellent long-term biochemical-failure-free survival outcomes with limited toxicity from HDR-BT as monotherapy for low- or intermediate-risk prostate cancer. However, due to higher start-up costs, less reimbursement, and inadequacy in residency training, far fewer radiation facilities are offering BT than external be","PeriodicalId":93914,"journal":{"name":"Brachytherapy","volume":"107 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135434441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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