Brachytherapy最新文献

{"title":"PO12","authors":"Ke Xu","doi":"10.1016/j.brachy.2023.06.113","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.113","url":null,"abstract":"","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":"135434436","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}

{"title":"PO109","authors":"Juan Wang, Guohui Cao","doi":"10.1016/j.brachy.2023.06.210","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.210","url":null,"abstract":"","PeriodicalId":93914,"journal":{"name":"Brachytherapy","volume":"15 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":"135434513","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}

{"title":"PO60","authors":"Kevin Martell, Breanna Fang, Philip McGeachy, Tyler Meyer, Siraj Husain, Kundan Thind","doi":"10.1016/j.brachy.2023.06.161","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.161","url":null,"abstract":"Purpose Isolated intraprostatic recurrence of prostate adenocarcinoma post radiotherapy presents a clinically challenging situation as surgical salvage options are associated with high morbidity. Brachytherapy can be used in these cases but supportive data are limited. The present study aims to present the acute toxicity results from patients who received salvage high-dose-rate prostate brachytherapy (sHDR-BT) for intraprostatic recurrence of prostate adenocarcinoma. Materials and Methods Fourteen consecutive patients treated with sHDR-BT between 2019 and 2022 were prospectively evaluated. To be considered for sHDR-BT, patients were required to have had received curative intent prostate radiotherapy previously and have biochemical failure. Patients were evaluated with bone scan and CT imaging of the chest abdomen and pelvis or PSMA-PET imaging. All patients had MRI of the prostate and trans-rectal ultrasound (US) guided biopsy proven confirmation of intraprostatic recurrence of disease. For patients who received prior BT, sHDR-BT was standardized with prescribed dose of 27Gy in 2 fractions to prostatic regions with confirmed disease on MR or biopsy. For patients had no history of prior BT, sHDR-BT was standardized with a prescribed dose of 21Gy in 2 fractions to the entire prostate with integrated boost irradiation of 27Gy in 2 fractions to the prostatic zones with confirmed disease on MR or biopsy. All plans were designed using trans-rectally acquired US image sets in Oncentra Prostate®. Post-treatment monitoring consisted of either in person or telephone (due to COVID-19) evaluation with AUA and CTCAE symptom assessments at 1, 3 and 12 months post treatment and yearly thereafter. Descriptive statistics were used to describe outcomes and the Mann-Whitney-Wilcoxon or Fisher-Freeman-Halton test used for comparisons. Results Median (inter-quartile-range) age prior to salvage treatment was 72 (67-76) years for the cohort. Seven (50%) patients had received external beam radiotherapy (EBRT) monotherapy (74-78Gy) as initial treatment for prostate cancer. One (7%) received EBRT (46Gy) + low-dose-rate BT (LDR-BT) (110Gy) and six (43%) received LDR-BT (144Gy) monotherapy as initial treatment. Four (29%) had received elective nodal irradiation (46Gy) with EBRT. Median time from initial radiotherapy to biopsy confirmation of recurrent disease was 77 (54-111) months. At baseline prior to sHDR-BT, 7 (50%) patient had significant lower urinary tract symptoms. Median AUA score was 8 (3-20) prior to sHDR-BT [Table 1]. 3 (21%) patients reported irregular bowel function and 2 (14%) reported hematochezia prior to sHDR-BT. At first fraction of sHDR-BT rectal D100cc was 8 (6-9)Gy, urethra D10% was 12 (11-15)Gy, urethra Dmax was 15 (13-16)Gy. At second fraction of sHDR-BT rectal D100cc was 8 (7-9)Gy, urethra D10% was 12 (12-14)Gy and urethra Dmax was 13 (12-16)Gy. At 1-month post treatment, median AUA score was 13 (18-21; p=0.48). On review of CTCAE scoring, at 1-mont","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":"135434527","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}

{"title":"Miscellaneous Posters PO101","authors":"Melisa Pasli, Sara Cowles, Jasmin Jo, Mahmoud Yaqoub, Hilal A. Kanaan, Andrew Ju, Matthew Sean Peach","doi":"10.1016/j.brachy.2023.06.202","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.202","url":null,"abstract":"Purpose Controversy exists regarding radiotherapy of patients with connective tissue disorders due to increased radiosensitivity. GammaTile® (GT Medical Technologies, Tempe, Arizona) is a novel brachytherapy strategy for intracranial radiotherapy. The suspension of the seeds in this matrix results in more uniformed dose delivery throughout the periphery of resection cavities, potentially reducing necrosis risk and conserving surrounding brain parenchyma. We hypothesized that GammaTile® would result in decreased dose to the scalp and incision wound in a patient with a Grade 3 glioma and limited scleroderma with active disease in the overlying scalp. Materials and Methods Preoperative MRI was used to estimate the number of tiles needed to deliver 60 Gy to a 5mm depth from the resection cavity. The tiles were placed after a right frontotemporal craniotomy with maximal safe resection. Day 1 post-implant dosimetry was performed with MRI and CT utilizing MIM to contour the sources and planning target volume (PTV); a 5mm expansion from the surgical cavity along tumor involved surfaces. A hypothetical standard external beam (EBRT) plan was generated in Eclipse with a 1cm expansion from the cavity and a 5mm expansion to PTV. A similar volume to GammaTile was generated using the CybrerKnife planning system with a 5 mm expansion of the cavity to PTV. Both plans were dosed to 59.3 Gy in 33 fractions to 95% coverage. All dose clouds were imported into Velocity and converted to equivalent dose in 2Gy (EQD2). Organs at risk (OARs) including the scalp and incision scar were contoured and dose volume histograms (DHVs) generated in Velocity. The patient underwent physical exam at 1, 3, and 6 months and MRI brain at 3 and 6 months, with photo documentation of the scalp. Results A total of 10 tiles were ordered and ultimately used with no tiles split to cover a 39.76 cc resection cavity as indicated on Day 1 post implant imaging. The resulting PTV was 31.18 cc with the V100% (60 Gy) of 99% and D90 of 118.7%. Compared to the GammaTile dose cloud, those generated by both EBRT plans resulted in greater irradiation to the surgical scar (Figure 1A-C, green line). Figure 1D-F shows the DVH between GammaTile (green), standard EBRT (red) and CybrerKnife (blue) for the scar, scalp and normal brain parenchyma. Overall, there was significant reduction in dose to these OARs with GammaTile. In particular, the maximum dose delivered to the scar and scalp by GammaTile was reduced to half of that from other external beam techniques (∼25-30 Gy vs ∼55 Gy). MRI imaging at 3 and 6 months lacked evidence of disease recurrence or radionecrosis. At the 6 month follow up visit, the surgical scar was well healed and there were no skin changes to the surrounding scalp at any time during follow up. Conclusions Compared to EBRT techniques, GammaTile brachytherapy is able to deliver considerably less dose to the scalp and scar incision in a Grade 3 glioma patient with limited scleroderma and ac","PeriodicalId":93914,"journal":{"name":"Brachytherapy","volume":"104 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":"135434599","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}

{"title":"PO41","authors":"Palanikumar Gunasekar, Susan Mathews, Francis V. James, Aswin Kumar, John Joseph, Sharika V. Menon, K.M. Jagathnath Krishna","doi":"10.1016/j.brachy.2023.06.142","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.142","url":null,"abstract":"Purpose Cervical cancer is the second most common cancer among Indian women. Radical chemo-radiotherapy is the standard of care for the majority of patients in India since most patients get diagnosed late and have locally advanced disease. Traditional Manchester system based brachytherapy planning and dose delivery continues to be widely practiced. Cervical cancer with disease extension beyond upper vagina presents a unique problem for brachytherapy dose delivery. Ovoid in tandem in the vagina is considered ‘Non-standard application’ in the traditional Manchester system where a lower dose to ‘Point A’ is accepted respecting the tolerances. Even in the era of image based brachytherapy, the number and position of the source channels limit the extent of dose optimization possible within the various normal tissue tolerances. The Rotterdam applicator, with both Ovoids and vaginal cylinder, offers the possibility of improved dose delivery in this group of patients. The potential dosimetric advantage was tested in this study. Methods Consecutive cervical cancer patients with vaginal disease beyond mid vagina at presentation were selected for Rotterdam Application. All patients had MR imaging in addition to standard CT planning. High Risk target volume (HRCTV) and organs at risk (OAR) were contoured on MR images as per the GEC-ESTRO guidelines and dose optimized plans were generated on Oncentra planning system V4.6. Residual disease in the vagina was part of the HRCTV and the length of vagina to be treated (tandem vaginal loading) was decided by the extent of initial disease involvement. The prescription dose was 8 Gy and dose constraints to OARs were (≤6 Gy/fx) to rectal D2cc and (≤7.5 Gy/fx) to the bladder D2cc (Subir Nag HDR BT dosimetry data). Two sets of treatment plans were generated for each application 1) with central tandem loading only (IUT PLAN) and 2) Rotterdam plan where ovoids were loaded in addition to central tandem. The HRCTV D90, D2cc Bladder, D2cc Rectum were documented and compared between the two plans. Data was analyzed statistically using paired t-test (normally distributed) or Wilcoxon signed rank test (Non-normal). A p-value < 0.05 is considered to be statistically significant. Results Between 1st January 2021 and 30th June 2022, 24 patients were eligible for Rotterdam application. However, applicator placement was not feasible in 6 patients (25%) with severe upper vaginal narrowing. MR image based plans were generated for 31 applications. The mean age of the patients included in the study was 59 years. Stage wise distribution was as follows IIB-3, IIIB-4, IIIC1-4, IIIC2-2, & IVA-5. At the time of brachytherapy, 10 patients had minimal residual disease involving cervix and upper vagina. None of the patients had residual disease involving lower vagina. The mean HRCTV volume was 30cc (range- 14.29 cc- 51.92cc). The prescription goal of 8Gy or greater was achieved in 18 Rotterdam applications while with standard loading, 12 applicat","PeriodicalId":93914,"journal":{"name":"Brachytherapy","volume":"18 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":"135434600","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}

{"title":"PO118","authors":"Moti Raj Paudel, Elizabeth A. Barnes, Mohammad Kazem, Amandeep S. Taggar","doi":"10.1016/j.brachy.2023.06.219","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.219","url":null,"abstract":"Purpose There has been increased use of surface mould brachytherapy (SMBT) for treating superficial skin lesions located over curved surface and at locations where a sharp dose fall-off is required. We describe our clinical workflow, dosimetry and initial clinical outcome of treating extramammary Paget's disease (EMPD) using SMBT with 3D printed custom applicator. Materials and Methods CT images acquired with and without a thin metal wire were used for delineating target extent to aid contouring gross disease and designing 1cm thick applicator, respectively, in MIM treatment planning system (MIM Software Inc., Cleveland, OH, USA). CTV was delineated on CT images aided by clinical exam and a uniform lateral margin of 7mm was applied to define target. The standard triangle language (STL) files for the applicator and target were generated and further processed in Autodesk Inventor 2021, Autodesk MeshMixer 2017, and Autodesk MeshEnabler 2021 (Autodesk, Inc. San Rafael, California, USA) to design the applicator. Customized catheter positioning regarding spacing and depth from the skin surface (5-7mm, depending upon the patient anatomy) were designed to cover the target volume and minimize dose to organs at risk (OAR). Applicators were then 3D printed using the Accura ClearVue, a USP class VI transparent resin. Plastic catheters were inserted in the applicator and QA test completed to ensure a safe radiation source delivery before using them to acquire planning CT images. Treatment plans were generated with a uniform prescription (Rx) of 42.5Gy in 10 daily fractions prescribed at the target surface with the aim of Target D90%>35Gy and maximum surface dose (defined by D0.3cc) <130% of Rx. We present initial experience, local control, toxicity and cosmesis results for first five EMPD patients treated with our customized SMBT workflow. Results Median patient age was 77yrs (range 66-94), and 3 were female 2 male. All patients presented with characteristic expanding erythematous plaques with typical histopathology and supportive immunohistochemical and clinical findings for EMPD. Median follow-up was 13.3 months (range 1.5-33.4). Mean Target D90 was 34.5 Gy (range 31.7-36), mean Target D0.1cc 53.1 Gy (range 46.2-58.4), mean Target D0.3cc 51.3 Gy (range 45.3-56.4), and mean Target D0.5cc 50.3 Gy (range 44.9-55.4). Treatment was well tolerated, with complete response in 5/5 patients and marginal relapse in 1 patient (Figure 1) which was outside of the treatment field at 13.6 months post-treatment. Acute dermatitis grade 3 was noted in 4 patients with resolution at mean of 49.2 days (range 44-54) and late toxicity hypopigmentation (grade 1; 3 patients) and telangiectasia (grade 1; 1 patient) was noted in a subset of patients treated. Conclusions SMBT was successfully planned and delivered for EMPD using 3D printed custom applicators. Excellent target coverage was achieved while minimizing dose to OAR, and toxicity and cosmesis rates were good to excellent. The","PeriodicalId":93914,"journal":{"name":"Brachytherapy","volume":"43 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":"135434212","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}

{"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}

{"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}

{"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}

{"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}