Brachytherapy最新文献

{"title":"PO26","authors":"Pooja Venkatesh, Juhi Purswani, Nicholas Colangelo, Sofia Perez Otero, Nicole Hindman, Stella Lymberis","doi":"10.1016/j.brachy.2023.06.127","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.127","url":null,"abstract":"Purpose Radiation toxicity to female erectile tissue, specifically the bulboclitoral apparatus, has not been previously investigated. This retrospective cohort study aims to demonstrate the feasibility of contouring the bulboclitoris (BC) and evaluate dose received by the BC in patients who underwent interstitial gynecologic brachytherapy for tumors involving the lower vagina and periurethral region. Materials and Methods Patients were treated with HDR brachytherapy between the years 2017 and 2022. All patients underwent IMRT external beam radiotherapy (EBRT) to the pelvis and bilateral inguinal region (45 Gy in 25 fractions) followed by High Dose Rate Ir-192 interstitial brachytherapy using the CT/MR M.A.C. Interstitial Gyn Template in 5 fractions for a total dose of 25 Gy (range, 22.5 - 27.5 Gy). The bulboclitoris (BC) was contoured retrospectively by a radiation oncologist and a pelvic radiologist using T2 MRI sequences fused to the pre-treatment and brachytherapy CT simulation. Superiorly, the BC was defined as inferior to the pubic symphysis and attached to the suspensory ligament of the clitoris. Laterally, the crura extend on either side of the corpus. Inferiorly, the vestibular bulbs flank the urethra and vagina on either side and do not extend posteriorly beyond the vagina. A representative contour of the bulboclitoral apparatus is depicted in Figure 1. Dosimetric data for the BC were calculated using EQD2 assuming an alpha-beta ratio of 3 Gy. Median follow up, local control, and vaginal morbidity using CTCAE version 4.0 for vaginal stenosis and pain scoring of the BC was evaluated. Results Patients had a median age of 65 years (range, 49-73). Three of the five patients had a diagnosis of squamous cell carcinoma of the vagina, one patient had recurrent cervical cancer in the vagina, and one patient had endometrioid adenocarcinoma involving the vagina. All tumors were located in the lower vagina, near the BC and urethra. The high-risk clinical target volume (HR-CTV), bladder, rectum, and urethra were contoured on patient imaging during initial treatment planning. Mean D90 of the HR-CTV was 79.82 Gy (range, 72.2-89.9 Gy), mean D2cc to the bladder was 66.54 Gy (range, 50.0-87.2 Gy), mean D2cc to the rectum was 60.9 Gy (range, 46.9-72.9), and mean D0.1cc to the urethra was 79.28 Gy (range, 53.9-93 Gy). At a median follow up of 19.6 months, all patients had a complete local response. One patient had systemic progression and died of metastatic disease. The mean pre-treatment volume of the bulboclitoris was 16.6 cc (range, 11.9 - 20.9 cc) and at brachytherapy was 12.66 cc (range, 7.3 - 22.1 cc). The mean IMRT dose to the BC was 45.87 Gy (range, 44.79 - 46.66 Gy) and mean HDR dose was 14.02 Gy (range, 11.23 - 18.88 Gy). Assuming an alpha-beta ratio of 3 Gy, mean bulboclitoral D90 EQD2 was 62.93 Gy (range of 58.72 to 67.22 Gy). In the acute period, all patients reported severe pain in the clitoral glans region and dysuria that completely resolved","PeriodicalId":93914,"journal":{"name":"Brachytherapy","volume":"60 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":"135434382","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":"PO83","authors":"Christopher Jason Tien, Emily Draeger, Fada Guan, David J. Carlson, Zhe Jay Chen","doi":"10.1016/j.brachy.2023.06.184","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.184","url":null,"abstract":"Purpose In order to develop a robust universal model which can accurately predict tumor control probability (TCP), it is necessary to first explore the sensitivity of the model on its input radiobiological parameters. We propose a methodology to derive population-averaged values of TCP based on a computational “clinical trial” with an enrollment of virtual patients orders of magnitude larger than physically-achievable cohort sizes (∼1 million), each with precisely-known radiobiological parameter values. Materials and Methods Each virtual patient was randomly assigned α and α/β values following a randomized distribution based on a previous study by Wang et al, endorsed by AAPM TG137 and TG265: α to a log-normal distribution function with mean (µ) of 0.15 Gy-1 and standard deviation (σ) of 0.04 Gy-1; α/β to a Gaussian function with µ=3.1 Gy and σ= 0.5 Gy; the initial clonogenic population was a fixed value of 1.6 x 106 (low-risk patient cohort). Next, after establishing the cohort, the TCP was calculated for each patient using the linear-quadratic (LQ) model assuming Poisson statistics for a range of doses from 0 to 140 Gy. The fractional TCP value was compared against a random number generator value to ultimately determine the binary patient outcome (i.e. TCP or fail). This process was repeated for each patient in the trial and the final population-based TCP was calculated by the ratio of successes to the number of patients in the trial. A series of new trials was created with one million patients to test α and α/β dependence with intentional variations in α or α/β values for α values from 0.7 to 0.23 Gy-1 and α/β values from 1.5 to 5.0 Gy. Results A series of 11 TCP curves was generated. For each curve, one million patients were created and assigned values of α, α/β. For the reference cohort using both the Gaussian and log-normal functions, the TCP90% and TCP50% were 89.4 and 68.9 Gy. With only a fixed log-normal α function, TCP90% was 70.3, 84.3, 89.4, 93.1, 101 Gy and TCP50% was 56.4, 65.9, 69.6, 71.8, 77.7 Gy for α/β=1.5, 2.6, 3.1, 3.6, 5 Gy, respectively. With only a fixed Gaussian α/β function, TCP90% was 126.1, 92.3, 74.0, 62.3 53.5 and TCP50% was 114.3, 89.8, 67.4, 56.4, 48.3 Gy for α=0.07, 0.11, 0.15, 0.19, 0.23 Gy-1, respectively. As illustrated in the Figure, larger values of α or smaller α/β ratios shift the TCP curve to lower TCP90% and TCP50%. Additionally, choosing a distribution of α values centered on 0.15 Gy-1 rather than a fixed α=0.15 Gy-1 significantly flattens the slope of the TCP curve, while using a distribution of α/β values produced indistinguishable TCP curves. Conclusions By leveraging the Law of Large Numbers and raw computing power, we were able to create multiple heterogeneous cohorts each containing 1 million virtual patients to generate realistic TCP curves based on previously published distributions of plausible α and α/β values, such as those endorsed by AAPM TG137 and TG265. This virtual clinical trial was able ","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":"135434413","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":"PO108","authors":"Ke Xu","doi":"10.1016/j.brachy.2023.06.209","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.209","url":null,"abstract":"","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":"135434425","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":"PO08","authors":"Jill Bennett, Cédric Bélanger, Philippe Chatigny, Luc Beaulieu, Alexandra Rink","doi":"10.1016/j.brachy.2023.06.109","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.109","url":null,"abstract":"Purpose Brachytherapy (BT) is an essential pillar in the treatment of cervical cancer. One method of gynecological (GYN) BT uses a transperineal catheter-guiding template in combination with an intrauterine (IU) tandem. Typically, catheter locations are decided using pre-BT imaging, and radiation treatment plans are then determined based on imaging taken after catheter insertion. Due to changes in patient anatomy once the IU tandem is inserted, this approach can lead to suboptimal tumor coverage, and often unused catheters, which contribute to increased implantation time, unnecessary tissue injury, and increased risk of bleeds. Images taken after insertion of the Template and APPlicator (post-TAPP) used in conjunction with a simple geometric catheter placement optimization algorithm may result in fewer unused catheters with better or equivalent dosimetry. In previous studies on prostate BT, the use of a Centroidal Voronoi Tessellation (CVT) algorithm for catheter optimization led to equivalent or superior treatment plans using fewer IS catheters compared to clinical cases. This work aims to verify these findings for cervical cancer BT. Materials and Methods Cases of locally advanced cervical cancer treated from 2016 to 2020 using IS BT with a Syed Neblett template were selected (N=12). Post-insertion imaging with target, organ-at-risk (OAR), and clinical catheter delineations were retrieved from the first BT fraction for each patient. CVT was used to simulate post-TAPP optimized catheters for each case by uniformly distributing catheters throughout a 2D projection of the target volume. The number of catheters in the CVT arrangement was equal to the number of catheters in the clinical implant, or the number of available template positions in the CVT planning region (defined as the high risk clinical target volume [HR-CTV] minus OARs projected onto the template plane), whichever number was lower. Treatment plans were then manually generated by a single expert for both the CVT and clinical catheter arrangements. Plan acceptability was evaluated via compliance with the EMBRACE-II dose-volume histogram limits in equieffective dose in 2 Gy per fraction (EQD2). Measures of dose inhomogeneity (%V150HR-CTV and %V200HR-CTV) were also recorded. Results The mean time for catheter optimization using CVT was 11.49 s. In all cases but 1, the CVT arrangements led to improved or EMBRACE-II compliant treatment plans with as many or fewer inserted catheters compared to the clinical cases (Figure 1). An increase in mean D90HR-CTV, D98HR-CTV, and D98IR-CTV was observed in the CVT group compared to the clinical group, as well as a statistically significant 2.2 Gy increase in mean D98GTVres (p < 0.05). A 2.2% increase in mean %V150HR-CTV was observed in the CVT group (p < 0.05). The mean number of unused catheters decreased from 4 in the clinical plans to 0 in the CVT plans (p < 0.001), and the acceptability rate increased from 50% with clinical catheters to 66.67% wit","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":"135434429","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":"PO54","authors":"Joel Poder, Philip Turner, Yaw Chin, Nadine Beydoun, Ese Enari, Andrew Howie","doi":"10.1016/j.brachy.2023.06.155","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.155","url":null,"abstract":"Purpose Low dose rate (LDR) brachytherapy has been proven to be an effective modality for monotherapy treatment of low-intermediate risk prostate cancer. The most commonly used treatment workflow follows a pre-planning approach utilising trans-rectal ultrasound (TRUS) images acquired under sedation, or nomogram planning based on manual measurements of prostate volume and dimensions. This study presents an alternative approach in which diagnostic magnetic resonance images (MRI) are used for the purpose of treatment planning, eliminating the necessity of an additional operating theatre procedure for the purposes of treatment planning, whilst tailoring the plan specifically to the patient's anatomy. Materials and Methods A retrospective study (n=10) was performed comparing the MRI and TRUS pre-planned approaches. The MRI pre-planned approach was retrospectively simulated by creating an LDR brachytherapy plan on diagnostic MR images using the Varian Variseed (v9.0.03) brachytherapy treatment planning system according to local protocols. This plan was then copied onto previously obtained TRUS planning images for the same patient. TRUS and MRI pre-plans were compared by evaluating plan quality metrics such as: the volume of the prostate receiving 100% (V100%), 150% (V150%), and 200% (V200%), dose to 90% of the prostate volume (D90%), as well as the rectum V100%, and urethra V125%. The prescription dose used in each plan was 145 Gy. The number of needles and number of seeds used in each approach was also compared. Statistical significance was tested for via the paired two sides t-test (p < 0.05). A prospective comparison study of operating theatre time usage is ongoing. Results Retrospective comparison of the planning approaches showed no statistically significant differences in plan quality metrics, apart from for the rectum V100%. The TRUS and MRI pre-planned approaches achieved an average rectum V100% of 0.14 cc and 0.33 cc (p = 0.008), respectively. Both approaches easily met the clinical constraint of rectum V100% < 1 cc, and thus the difference between the techniques was not clinically significant. All other plan quality metrics met departmentally defined clinical planning constraints for both the TRUS and MRI planned technique. Preliminary results comparing operating theatre time usage has shown significant time savings using the MRI-pre planning technique. Conclusions The MRI pre-planned approach for LDR prostate brachytherapy has been shown to achieve dosimetrically equivalent plans to TRUS based pre-plans, using less operating theatre resources. This technique is a safe and effective form of LDR prostate brachytherapy treatment planning for eligible patients. Low dose rate (LDR) brachytherapy has been proven to be an effective modality for monotherapy treatment of low-intermediate risk prostate cancer. The most commonly used treatment workflow follows a pre-planning approach utilising trans-rectal ultrasound (TRUS) images acquired under sedati","PeriodicalId":93914,"journal":{"name":"Brachytherapy","volume":"42 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":"135434512","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":"PO45","authors":"Shubhangi Shah, Xiaoyan Deng, Emma Fields, Dipankar Bandyopadhyay, Bridget Quinn","doi":"10.1016/j.brachy.2023.06.146","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.146","url":null,"abstract":"Purpose Endometrial cancer (EC) is the most common gynecologic malignancy and the fourth most common cancer in women [1]. Treatment is composed of a total hysterectomy, possibly followed by adjuvant chemotherapy or radiation therapy (RT) based on risk factors and staging [2]. Consistent follow up after treatment is integral to assessing for both toxicities and recurrence. Encouraging adjuvant vaginal dilator use has been shown to prevent vaginal stenosis, a common side effect of both surgery and RT [2]. However, about 9% of the female population in the USA face significant geographical barriers to receiving gynecologic cancer treatment [3]. Furthermore, previous studies showed being over 50 miles from a high-volume hospital was associated with increased risk of non-adherence care and increased mortality [4]. Increased time from endometrial biopsy to surgery is one documented factor that increased risk of poor outcomes [5]. This retrospective study evaluates if geographical location is associated with access to endometrial cancer care and post-radiation vaginal stenosis. Materials and Methods Patients enrolled in the study underwent surgery +/- RT for Stage I-IIIC endometrial cancer. Vaginal dilator use was recommended to all patients receiving RT. Vaginal length at follow up visits was measured with a vaginal sound. Data from patient charts was used to determine patient demographics, location, and follow up care. Results Forty-two patients had sufficient data for analysis. Average distance from the treatment hospital was 40.9 miles, 54% of patients lived in an urban county. Average number of days from an endometrial biopsy to surgical treatment was 43 days. Living >80 miles from the hospital was associated with an 80% increase in the days between an endometrial biopsy and surgery, compared to those living within 20 miles (p<0.01). Average months of follow up after surgery was 31. There was no impact of an increased distance from the hospital affecting months of follow-up care, vaginal stenosis, or dilator adherence. Conclusions This study provides evidence that living extreme distances from a high-volume cancer center is associated with delayed access to care. Furthermore, there's no direct impact of geography on post-RT vaginal dilation or adherence to care. Our findings suggest reduced discrimination in EC care despite geographical barriers. Further studies to evaluate impact of geography on mortality rates are needed. References: 1. BRAUN MM, OVERBEEK-WAGER EA, GRUMBO RJ. Diagnosis and Management of Endometrial Cancer. Am Fam Physician. 2016;93(6):468-474. Accessed January 30, 2023. https://www.aafp.org/pubs/afp/issues/2016/0315/p468.html2. Quinn, BA, et al. Change in Vaginal Length and Sexual Function in Women Who Undergo Surgery ± Radiation Therapy for Endometrial Cancer . Brachytherapy, 2023. In press.3. Shalowitz DI, Vinograd AM, Giuntoli RL. Geographic access to gynecologic cancer care in the United States. Gynecol Oncol. 2015;138(1):115-","PeriodicalId":93914,"journal":{"name":"Brachytherapy","volume":"9 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":"135434515","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":"PO09","authors":"Sergej Sergeich Romanenko","doi":"10.1016/j.brachy.2023.06.110","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.110","url":null,"abstract":"According to our experience, intracavitary brachytherapy of metastasis into vagina is not effective, especially in the case of volumetric tumor. As a rule we use intratissue brachytherapy with an intracavitary applicator of maximal diameter. Patient and Methods In 2020 Ca of transverse colon was diagnosed in a patient 58 years old, female. Ultrasonography, CT, MRI investigations and biopsy confirmed mts in both ovarian, pathological retroperitoneal, mesenteric and intracranial lymph nodes, left lobe of liver. First line of treatment included surgery, chemotherapy and hormone therapy. Operations: median laparotomy, right-sided hemicolectomy, atypical resection of the left lobe of liver. Chemotherapy (14 courses) - 8 courses with oxaliplatin and capecitabine and 6 courses with irinotecan. Mts into vagina were revealed a month after completing the treatment. 39,6 Gy (2.2 Gy*18 fractions) to pelvis with concomitant intracavitary brachytherapy 7Gy*4, total dose 28 Gy with normalization 5 mm from mucosa was delivered. In three months volumetric lesion in vagina right wall was confirmed at CT scans and visually. Intratissue brachytherapy with rigid needles was decided to use. Dose distribution and needle location is shown at the Figure. Needle insertion was done by freehand under anesthesia. Doses amounted to 30 Gy (1 time per week, 10 Gy fraction). Treatment was carried out at Microselectron 30 channels on the base of CT scans. Radiation reactions (burning and profuse discharge) lasted one month approximately. Results In 3 months CT with contrast did not show the presence of pathological foci in the body. And visually vagina had no signs of a tumor. Conclusion It was shown that intratissue brachytherapy is effective in the treatment of tumors affecting vagina. According to our experience, intracavitary brachytherapy of metastasis into vagina is not effective, especially in the case of volumetric tumor. As a rule we use intratissue brachytherapy with an intracavitary applicator of maximal diameter. In 2020 Ca of transverse colon was diagnosed in a patient 58 years old, female. Ultrasonography, CT, MRI investigations and biopsy confirmed mts in both ovarian, pathological retroperitoneal, mesenteric and intracranial lymph nodes, left lobe of liver. First line of treatment included surgery, chemotherapy and hormone therapy. Operations: median laparotomy, right-sided hemicolectomy, atypical resection of the left lobe of liver. Chemotherapy (14 courses) - 8 courses with oxaliplatin and capecitabine and 6 courses with irinotecan. Mts into vagina were revealed a month after completing the treatment. 39,6 Gy (2.2 Gy*18 fractions) to pelvis with concomitant intracavitary brachytherapy 7Gy*4, total dose 28 Gy with normalization 5 mm from mucosa was delivered. In three months volumetric lesion in vagina right wall was confirmed at CT scans and visually. Intratissue brachytherapy with rigid needles was decided to use. Dose distribution and needle location is shown ","PeriodicalId":93914,"journal":{"name":"Brachytherapy","volume":"184 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":"135434520","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":"PO78","authors":"Karel Arthur Hinnen, Iris Kuitems, Robbert Den Butter, Benjamin Arnods, Theo De Reijke, Zdenko Van Kesteren, Jette Bloemberg, Paul Breedveld, Bradley Pieters","doi":"10.1016/j.brachy.2023.06.179","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.179","url":null,"abstract":"","PeriodicalId":93914,"journal":{"name":"Brachytherapy","volume":"79 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":"135434522","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":"Author Index of the Abstracts of the 2023 American Brachytherapy Society Annual Meeting","authors":"","doi":"10.1016/j.brachy.2023.09.003","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.09.003","url":null,"abstract":"","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":"135434597","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":"PO84","authors":"Margaret Barker, Michael Campbell, Lisa Turner, A． Nisar M. Syed, Randy Wei, Peyman Kabolizadeh","doi":"10.1016/j.brachy.2023.06.185","DOIUrl":"https://doi.org/10.1016/j.brachy.2023.06.185","url":null,"abstract":"Purpose Interstitial HDR brachytherapy involves precise, localized delivery to a high risk clinical target volume (HRCTV) with high dose gradients, sparing adjacent critical organs at risk (OAR). Due to the proximity of the rectum and bladder to the HRCTV, deviations in the applicator or catheter with respect to patient anatomy can change dose to those structures. Utilizing plastic interstitial catheters allows the patient to receive hyperthermia therapy during their course of interstitial treatment, however, the plastic catheters were observed to show significant deflection when the metal stylets are removed for treatment. The hyperthermia electrodes and the HDR source cable are both wires of approximately the same thickness. The purpose of this study is to assess the magnitude and deflection of the plastic catheters for gynecologic interstitial plans and determine whether using flexible wires for visualization on pre-treatment imaging is suitable for reconstructing the actual treatment received. Materials and Methods Eight patients with a total of 16 plans with re-treatment CT images where the metal stylets were utilized for plastic catheter (Best Medical) visualization were registered to a subsequent CT scan with the metal stylets removed. The originally planned (Brachyvision, Varian) treatment dwell positions and times were adjusted to the second CT to evaluate three-dimensional catheter displacement and dose distributions calculated for the bladder, rectum, and target. Results Absolute 3D displacement for all patients was 3.5 mm ± 5.4 mm (n = 3217 catheter dwell positions for all treatment plans and patients, mean ± SD, p < 0.001) comparing plans with the stylet in versus out. Absolute catheter deflection magnitude for interstitial treatments increased with the removal of the metal stylets with a difference of 0.75° ± 0.49° (n = 299 catheters for all treatment plans and patients, mean ± SD, p < 0.01). The plans were subsequently reconstructed on a pre-planning CT with flexible 20-gauge wires instead of metal stylets and are observed to correlate with the plans with no stylets with absolute 3D displacement and angular deflection of 1.1 ± 0.6 mm and 0.35 ± 0.3 respectively (n = 39 catheters, mean ± SD, p > 0.2). While the average target EQD2 D90 reduced by 5% ± 5%, four patients would have experienced a deviation from the prescription by >10%. There was an overall decrease in bladder D2cc and overall increase in rectal D2cc in the plans with the stylets removed. Conclusions Catheter reconstruction in interstitial gynecological treatments with CT imaging revealed significant changes in catheter positioning with respect to the target volume once the stylets are removed for treatment. Using flexible wires of similar thickness to the source cable allow for more accurate tracking during planning without distorting the final treatment plan. Interstitial HDR brachytherapy involves precise, localized delivery to a high risk clinical target volume (HRC","PeriodicalId":93914,"journal":{"name":"Brachytherapy","volume":"61 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":"135434601","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}