Brachytherapy Techniques Research Articles

Bladder function after conservative surgery and high-dose rate brachytherapy for bladder-prostate rhabdomyosarcoma.

Conservative surgery (CS) brachytherapy (BT) techniques for local therapy in bladder-prostate rhabdomyosarcoma (BP-RMS) seek to retain organ function. We report bladder function after high-dose rate (HDR) BT combined with targeted CS for any vesical component of BP-RMS. Prospective cohort of all BP-RMS patients between 2014 and 2019 receiving HDR-BT (iridium-192, 27.5Gy in five fractions) with/without percutaneous endoscopic polypectomy (PEP) or partial cystectomy (PC). Functional assessment included frequency-volume chart, voided volumes, post-void residual, flow studies, continence status and ultrasound scanning; abnormalities triggered video urodynamics. Thirteen patients (10 male), aged 9months to 4years (median 23months), presented with localised fusion-negative embryonal BP-RMS measuring 23-140mm (median 43mm) in cranio-caudal extent. After induction chemotherapy, local treatment consisted of PC+BT in three, PEP+BT in four and BT alone in six. At a median 3.5years (range 21months to 7years) follow-up, all were alive without relapse. At a median age of 6years (4-9years), the median bladder capacity was 86% (47%-144%) of that expected for age, including 75% (74%-114%) after PC. Radiation dose to the bladder was associated with urinary urgency, but not bladder capacity or nocturnal enuresis. Complications occurred in two: one urethral stricture and one vesical decompensation in a patient with pre-existing high-grade vesico-ureteric reflux (VUR). The remaining patients were dry by day; five with anticholinergic medication for urinary urgency. Three patients are enuretic. Day-time dryness at a median 3.5years after CS-HDR-BT was achieved in 92%, with 85% voiding urethrally, and 62% attaining day-and-night continence aged 4-9years. We report reduced open surgery with minimally invasive percutaneous surgery, with HDR-BT or BT alone being suitable for many.

Early clinical outcomes of hybrid brachytherapy for locally advanced cervical cancer: making adverse situations in a favorable scenario.

PurposeTo investigate the feasibility and early clinical outcomes of combined intra-cavitary (IC) and interstitial (IS) image-guided adaptive brachytherapy (IGABT) as curative and definitive treatment of patients treated with chemoradiotherapy (CCRT) for locally advanced cervical cancer (LACC).Material and methodsData from medical records of all consecutive patients with histologically proven cervical cancer (FIGO 2018 stage IB-IV), treated by brachytherapy after CCRT at our institution between 2017 and 2020 were reviewed.ResultsOne hundred and forty-two patients with LACC FIGO 2018 stages (IB: 20.4%, II: 31.7%, III: 45.8%, IV: 2.1%) underwent brachytherapy at our institution, out of which 53.5% underwent combined brachytherapy technique (IC/IS). Median number of implanted catheters was 3 (range, 1-6 catheters). None of the 142 patients required invasive hemorrhage management. With a median follow-up of 21.6 (95% CI [confidence interval]: 19.1-23.5%) months, local relapse was observed in nine patients (6.3%), with four showing persistent and progressive disease. The estimated 2-year local and pelvic relapse-free survival were 92% (95% CI: 84-96%) and 90% (95% CI: 83-94%), respectively. The estimated 2-year disease-free survival for the entire population was 80% (95% CI: 71-87%). The 2-year overall survival (OS) rate for the entire population was 92% (95% CI: 84-96%). Acute toxicity G3 was reported in two (1.4%) patients. High-grade late toxicity (grade 3) was reported in 9 (6.3%) patients.ConclusionsCombined IC/IS brachytherapy for LACC allows for recommended doses to achieve local control even in large tumors after CCRT improving target volume coverage, with low rates of acute morbidity. Hybrid brachytherapy technique (IC/IS) is essential to have a favorable scenario at the time of brachytherapy to correctly treat locally advanced cervical cancer patients.

Brachytherapy dose changes: comparing in-room and out-room image-guided brachytherapy. A randomized study.

PurposeImage-based brachytherapy, involving an image machine and a brachytherapy unit in the same room (in-room brachytherapy [IRBT]), limits patient movements; however, this technique may not be feasible in high workload centers. In this study, we compared changes in the dose and volume of organs at risk (OARs) with out-room brachytherapy (ORBT) technique, in which patients musted be transferred to a waiting room and then transferred back for brachytherapy delivery.Material and methodsThis was a randomized prospective study comparing changes in D2cc doses and volume of OARs during IRBT and ORBT. Patients underwent CT for treatment planning (CT1) installed in brachytherapy loading room, and another CT immediately before brachytherapy (CT2) during each fraction. While patients remained on CT table after CT1 during treatment planning and delivery in IRBT arm, they were transferred out to waiting room and back to CT table in ORBT arm. CT2 was analyzed with CT1 to evaluate any changes in volumes and doses.ResultsA total of 294 fractions of brachytherapy were considered. The findings indicated no significant differences in the mean D2cc changes (Gy) (CT2 minus CT1) to the bladder, rectum, and sigmoid between IRBT and ORBT (mean ±SD: –0.07 ±0.36 vs. –0.01 ±0.39, p = 0.1426; –0.15 ±0.32 vs. –0.14 ±0.29, p = 0.8898; –0.17 ±0.38 vs. –0.19 ±0.31, p = 0.5221, respectively). Moreover, significant correlations were observed between D2cc changes and volume changes to each of OARs, p < 0.001.ConclusionsIRBT does not result in differences in dose changes between planning and pre-treatment imaging when compared with ORBT. Consequently, ORBT can be considered for routine practice in high workload centers. Correlations in volume change and dose change to OARs were also observed.

Resident training in brachytherapy in France: A 10-year update after the first survey of SFJRO members.

A previous survey conducted in 2012 showed that 82% of radiation oncology residents felt they were not receiving optimal brachytherapy training. With almost 10 years of hindsight, the aim was to update these results. An anonymized questionnaire based on the 2012 survey was submitted to the 161 French residents enrolled in the 2021 French Society of Young Radiation Oncologists (Société Française des Jeunes Radiothérapeutes Oncologues - SFJRO) national brachytherapy courses. With a participation rate of 73%, 86% of the residents were interested in brachytherapy, but 80% consider their training in brachytherapy insufficient. 88% and 69% of the residents stated that they knew gynecological and prostate brachytherapy indications correctly, respectively. The residents have achieved proficiency in the technique of brachytherapy of vaginal vault in 36% (compared with 21% in 2012), utero-vaginal in 13% (12% in 2012), including 4% with interstitial implants, and prostate in only 4% (4% in 2012). In their brachytherapy internships, 18% of the residents declared having no role or an observational role. The main obstacles to training were the need to go to several centers to see several indications (85%), lack of brachytherapy activity in the center (72%), and the difficulty of freeing themselves from hospital duties (71%). With results globally stable compared with 2012, brachytherapy training needs improvement. In the absence of a mandatory internship in a reference center or dedicated fellowships, residents must have protected access to training sites by favoring inter-hospital exchanges.

Long term outcomes of Carcinoma Buccal Mucosa treated with High Dose Rate Interstitial Brachytherapy

To analyze the long-term local control, overall survival and toxicity in Carcinoma Buccal Mucosa patients treated with interstitial brachytherapy. This analysis included patients diagnosed as Carcinoma Buccal Mucosa on biopsy and treated with radical brachytherapy or External Beam Radiotherapy (EBRT) followed by brachytherapy boost. All patients received High dose rate (HDR) interstitial brachytherapy. The total dose was 35 Gy in ten fractions for brachytherapy alone. Patients who received EBRT (50-54 Gy) were boosted by brachytherapy to a dose of 18-24 Gy in 6-8 fractions. All patients were treated using CT based planning. Between 2007 to 2017, a total of 24 patients of Carcinoma Buccal Mucosa received HDR interstitial brachytherapy either alone or as a boost. Majority of the patients were tobacco chewers (80%). 17(71%) patients were clinical stage T2N0M0 and 7(29%) were clinically T1N0M0. At a median follow up of 7 years (3-12 years), the local control rate was 100% in stage I and 88% in stage II. The 5 year overall survival rate was 80%. Two patients developed nodal recurrence and one patient developed distant metastasis within two years of treatment. Tumor size and brachytherapy technique (radical vs. boost) did not impact local control or overall survival (p > 0.05). Majority of the acute toxicities were Grade 1 and 2. One patient developed osteoradionecrosis of the mandible. Interstitial brachytherapy in early-stage Buccal Mucosa cancer either alone or as a boost provides excellent long term local control and overall survival. The acute and late toxicities are acceptable with majority of the patients presenting with Grade 1 or 2 toxicity.

Risk Factors for Late Persistent Fatigue After Chemoradiotherapy in Patients With Locally Advanced Cervical Cancer: An Analysis From the EMBRACE-I Study

This study aimed to evaluate patient- and treatment-related risk factors for late persistent fatigue within the prospective, multicenter EMBRACE-I study. Fatigue was prospectively assessed (Common Terminology Criteria for Adverse Events, version 3) at baseline and during regular follow up in 993 patients with locally advanced cervical cancer after treatment with chemoradiotherapy and magnetic resonance imaging-guided brachytherapy. Risk factors for baseline and late persistent fatigue were evaluated with multivariable logistic regression. Late persistent fatigue was defined when either grade ≥1 or ≥2 was scored in at least half of the follow ups. The median follow-up time was 57 months. Baseline fatigue grade ≥1/≥2 (35.8%/6.3%, respectively) was associated with preexisting comorbidities, World Health Organization performance status, being underweight, severe pain, and tumor volume. Late persistent grade ≥1/≥2 fatigue (36.3%/5.8%, respectively) was associated with patient-related factors (baseline fatigue, younger age, obesity) along with the size of irradiated volumes and the level of radiation doses from external beam radiation therapy (EBRT) and brachytherapy (EBRT: V43Gy, V57Gy; EBRT+brachytherapy: V60Gy equivalent dose in 2-Gy fractions). Large-volume lymph node (LN) boost increased the risk for late persistent fatigue grade ≥2 by 18% and 5% in patients with and without baseline fatigue, respectively, compared with no LN boost. The risk for late persistent fatigue grade ≥1 increased by 7% and 4% with V43Gy <2000 cm³ versus >3000 cm³ in patients with and without baseline fatigue, respectively. Late persistent grade ≥1 fatigue occurred in 13% of patients without late persistent organ-related symptoms (gastrointestinal, genitourinary, and vaginal) versus 34% to 43%, 50% to 58%, and 73% in patients suffering from persistent symptoms involving 1, 2, or 3 organs, respectively. Late persistent fatigue occurs in a considerable number of patients after chemoradiotherapy, and is associated with patient-related factors, the size of volumes irradiated to intermediate and high EBRT and brachytherapy doses, and other persistent organ-related morbidity. These findings support the importance of ongoing efforts to better tailor the target dose and reduce irradiation of healthy tissue without compromising target coverage, using highly conformal EBRT and brachytherapy techniques.

Modern Imaging Techniques and Their Role in Contact Radiation Therapy (Brachytherapy) Planning

The paper considers an algorithm for the diagnostic study of patients with cancer of different localization, the possibility and feasibility of involving imaging techniques in radiation therapy and brachytherapy (BT) planning. The most widely used ultrasound in BT planning does not exclude a subjective assessment of the boundaries of the tumor and organs at risk, as well as the inaccuracies caused by endostatic devices. Magnetic resonance imaging (MRI) provides a high level of achievement of the criteria necessary for BT planning, but it has financial constraints and the need for individual selection of research conditions. Computed tomography (CT) is the most effective technique for visualizing the tumor, endostatic devices, and organs at risk for BT 3D planning. The involvement of MRI and positron emission tomography with CT in BT planning is a promising area that requires equipping with a mathematical tool for double and triple contouring of the tumor and organs at risk and for defining protection priorities. The prescribed and used focal dose should be controlled by direct dosimetry methods to ensure quality assurance.

High-Dose Rate Interstitial Spine Brachytherapy Using an Intraoperative Mobile Computed Tomography-Guided Surgical Navigation System.

Up to 15% of previously irradiated metastatic spine tumors will progress. Re-irradiation of these tumors poses a significant risk of exceeding the radiation tolerance to the spinal cord. High-dose rate (HDR) brachytherapy is a treatment alternative. To develop a novel HDR spine brachytherapy technique using an intraoperative computed tomography-guided navigation (iCT navigation). Patients with progressive metastatic spine tumors were included in the study. HDR brachytherapy catheters were placed under iCT navigation. CT-based planning with magnetic resonance imaging fusion was performed to ensure conformal dose delivery to the target while sparing normal tissue, including the spinal cord. Patients received single fraction radiation treatment. Five patients with thoracolumbar tumors were treated with HDR brachytherapy. Four patients previously received radiotherapy to the same spinal level. Preimplant plans demonstrated median clinical target volume (CTV) D90 of 116.5% (110.8%-147.7%), V100 of 95.7% (95.5%-99.6%), and Dmax of 8.08 Gy (7.65-9.8 Gy) to the spinal cord/cauda equina. Postimplant plans provided median CTV D90 of 113.8% (93.6%-120.1%), V100 of 95.9% (87%-99%), and Dmax of 9.48 Gy (6.5-10.3 Gy) to cord/cauda equina. Patients who presented with back pain (n=3) noted symptomatic improvement at a median follow-up of 22 d after treatment. Four patients demonstrated local tumor control of spinal metastatic tumor at a median follow-up of 92 d after treatment. One patient demonstrated radiographic evidence of local tumor progression 2.7 mo after treatment. HDR spine brachytherapy with iCT navigation is a promising treatment alternative to induce local tumor control and reduce pain symptoms associated with metastatic spine disease.

High dose rate interstitial 192‐Ir brachytherapy for the treatment of a recurrent dermal vascular hamartoma in a horse

SummaryThe successful application of an interstitial brachytherapy course is reported in a 14‐month‐old male Anglo European Studbook (AES) foal for the treatment of a recurrent dermal vascular hamartoma at the dorsal aspect of the pastern on the right hindlimb. The lesion was irradiated four times over 4 days to a total dose of 28 Gy. Progressive tumour shrinkage and necrosis were observed over 2 months. No significant acute side effect was reported at the end of the treatment, with excellent and long‐lasting cosmetic results observed. The only reported late effect was permanent leukotrichia within the treated area, which remained otherwise tumour‐free 1224 days after treatment. Results of this report suggest the potential use of radiation therapy (and specifically brachytherapy techniques), as an effective and safe treatment modality for vascular malformations in horses.

Toxicity Related Patients Factors and Bevasizumab Use in Patients With Locally Advanced Cervical Cancer Treated With Definitive Chemoradiation and HDR Brachytherapy Boost

The purpose of this study is to identify factors associated with severe late toxicity and prognosis in women with locally advanced cervical cancer treated with definitive chemoradiation (CRT) and high dose rate (HDR) radiation therapy boost. An increased rate of GI toxicity when Bevacizumab is administered in combination with high doses of abdominal radiation therapy such as stereotactic body radiotherapy (SBRT) has been demonstrated in other malignancies. Our aim is to compare the risk of Grade 3+ toxicity in patients who receive Bevacizumab after HDR brachytherapy in comparison with other risk factors.Patients with locally advanced cervical cancer treated with CRT from 2010-2019 in a single academic institution were included. Records were reviewed for demographic information, treatment details, toxicities, and outcomes. Patients with and those without severe late gastrointestinal (GI) toxicity and severe late genitourinary (GU) toxicity were compared. Progression free-survival (PFS) was also compared between groups. Smoking status was classified as current smokers, former smokers and non-smokers. Statistical comparisons were performed using t-tests and ANOVA tests.Of 101 patients identified, 10.9% had severe grade 3+ GI toxicity, and 9.1% had severe grade 3+ GU toxicity. Mean duration to follow up was 30 months (range 1-124 months). In patients who received Bevacizumab after completion of definitive treatment, there was a significantly higher rate of Grade 3+ GI or GU toxicity (50% versus 16%, P = 0.005). 83% of Grade 3+ toxicity in the Bevacizumab group was GI related. There was no correlation between the time interval between radiation and Bevacizumab initiation to toxicity. Age was also significantly associated with toxicity, patients 55 and younger had a 10% rate of Grade 3+ toxicity while patients older than 55 had a 28% rate (P = 0.02). Patient who received interstitial versus intracavitary brachytherapy technique also demonstrated high rates of toxicity (30% vs. 8%, P = 0.002). PFS was similar among patients with severe toxicities compared to those without toxicity. In regards to smoking status, there was no significant difference in toxicity. Risk of recurrence was higher in the current smokers and former smokers (40% and 31% respectively) but did not reach statistical significance when compared to non-smokers (25%).In patients with locally advanced cervical cancer, the use of Bevacizumab is significantly associated with increased toxicity after definitive chemoradiation. Similar data has been shown in patients who receive Bevacizumab and abdominal SBRT. Given that the addition of Bevacizumab is first-line therapy and improves survival for recurrent cervical cancer, further investigation is warranted to determine how to optimize the risk-benefit ratio.S. Azghadi: None. P.L. Beagen: None. A. Ahmed: None. R.K. Valicenti: None. R.A. Brooks: None. X. Zhao: None.

Changing Landscape of Radiation Therapy for Advanced Cervical Cancer With a Focus on Interstitial Brachytherapy: A Canadian Practice Patterns Survey

PurposeTo document the evolution of radical radiation therapy and interstitial brachytherapy (ISBT) utilization practice patterns across Canada, including use of imaging, technical details, and usage of anesthesia/analgesia, and to compare advanced (AC) versus nonadvanced (nAC) brachytherapy (BT) center practices. Methods and MaterialsAll Canadian centers with BT services were identified. One gynecology radiation oncologist per center was sent a 64-item questionnaire regarding the center's practice for patients with cervical cancer. Centers were categorized based on availability of advanced BT expertise (AC) versus those referring patients to other centers for advanced BT techniques (nAC). Aggregate responses are reported and compared with practice patterns identified in our previous survey. Descriptive statistics were used to summarize data, and the Fisher exact test, Fisher-Freeman-Halton, or Mann-Whitney-Wilcox test was used for comparisons. ResultsThirty-seven of 38 respondents completed the survey (response rate: 97.4%). Compared with 2015, there has been an increase in utilization of magnetic resonance imaging as the sole imaging modality for BT planning: 3 of 26 (11%) versus 12 of 37 (32%; P = .03). The number of centers with the ability to perform ISBT increased in 2020 compared with 2015 (26/37 [70%] vs 13/26 [50%], P = .710); this trend is likely due to an increase in use of hybrid (Vienna, Utrecht, Venezia) applicators (36% [2015] vs 84% [2020]; P = .175). Fifteen (40%) centers had the ability to perform perineal-ISBT (P-ISBT). Sixteen and 21 centers were identified as AC and nAC, respectively. All 16 AC centers had the ability to perform ISBT, compared with only 10 nAC centers (P < .001). A higher proportion of AC centers had fellowship-trained radiation oncologists performing brachytherapy, compared with nAC centers (94% vs 14%, P < .001). In terms of anesthesia, conscious sedation was the only available choice at low-patient-volume centers (8/37, 21%) performing intracavitary BT only. Those performing ISBT had choice of general, spinal, and epidural anesthesia. ConclusionsIn Canada, high-quality, modern management radiation therapy practices are consistently offered to patients with cervical cancer. There is a trend toward increased utilization of ISBT. Accumulation of evidence toward the use of ISBT, increased utilization of high-quality imaging modalities such as magnetic resonance imaging, and availability of hybrid applicators are potential contributors for this upward trend.

Variation of optimization techniques for high dose rate brachytherapy in cervical cancer treatment

High dose rate (HDR) brachytherapy treatment planning usually involves optimization methods to deliver uniform dose to the target volume and minimize dose to the healthy tissues. Four optimizations were used to evaluate the high-risk clinical target volume (HRCTV) coverage and organ at risk (OAR). Dose-volume histogram (DVH) and dosimetric parameters were analyzed and evaluated. Better coverage was achieved with PGO (mean CI = 0.95), but there were no significant mean CI differences than GrO (p = 0.03322). Mean EQD2 doses to HRCTV (D90) were also superior for PGO with no significant mean EQD2 doses than GrO (p = 0.9410). The mean EQD2 doses to bladder, rectum, and sigmoid were significantly higher for NO plan than PO, GrO, and PGO. PO significantly reduced the mean EQD2 doses to bladder, rectum, and sigmoid but compromising the conformity index to HRCTV. PGO was superior in conformity index (CI) and mean EQD2 doses to HRCTV compared with the GrO plan but not statistically significant. The mean EQD2 doses to the rectum by PGO plan slightly exceeded the limit from ABS recommendation (mean EQD2 dose = 78.08 Gy EQD2). However, PGO can shorten the treatment planning process without compromising the CI and keeping the OARs dose below the tolerance limit.

Local Control and Use of External Beam Parametrial Boost in the Era of Image-Guided Brachytherapy for Locally Advanced Cervical Cancer.

Historically, external beam parametrial boost (EBPB) has been used in locally advanced cervical cancers to supplement radiation dose. However, it has become controversial in the era of image-guided brachytherapy. Modern 3D imaging and brachytherapy techniques have improved delineation and coverage of tumor. Outcomes with and without parametrial boost were analyzed. Women with cervical cancer involving the parametria (clinically or radiographically) diagnosed between 2001 and 2017 were identified. Clinicopathologic and treatment features, survival and patterns of failure data were collected. Univariate and multivariable data analysis was performed to evaluate association of these variables, including parametrial boost, with local failure-free survival and overall survival. Competing risks analysis was performed for cumulative incidence of local failure, with death and other failures treated as competing events. A total of 100 women were identified (median follow-up 26.8 mo). Forty-one (41%) received EBPB; these patients were less likely to have received magnetic resonance imaging, positron emission tomography, interstitial, or high-dose rate brachytherapy. Magnetic resonance imaging, positron emission tomography, dose rate, and treatment era were highly correlated (Cramer's V: 0.43 to 0.68, P<0.01). Two-year overall survival and local failure were 78% and 12% for the entire cohort. While the use of EBPB was not associated with any outcome on multivariable analysis, treatment year after 2009 was highly associated with improved outcomes in all models. In this study, omission of EBPB did not compromise local control or survival in the modern era, supporting a decreased need for standardized use of parametrial boost.

Treatment outcomes of real-time intraoral sonography-guided implantation technique of 198Au grain brachytherapy for T1 and T2 tongue cancer.

It is often challenging to determine the accurate size and shape of oral lesions through computed tomography (CT) or magnetic resonance imaging (MRI) when they are very small or obscured by metallic artifacts, such as dental prostheses. Intraoral ultrasonography (IUS) has been shown to be beneficial in obtaining precise information about total tumor extension, as well as the exact location and guiding the insertion of catheters during interstitial brachytherapy. We evaluated the role of IUS in assessing the clinical outcomes of interstitial brachytherapy with 198Au grains in tongue cancer through a retrospective medical chart review. The data from 45 patients with T1 (n = 21) and T2 (n = 24) tongue cancer, who were mainly treated with 198Au grain implants between January 2005 and April 2019, were included in this study. 198Au grain implantations were carried out, and positioning of the implants was confirmed by IUS, to ensure that 198Au grains were appropriately placed for the deep border of the tongue lesion. The five-year local control rates of T1 and T2 tongue cancers were 95.2% and 95.5%, respectively. We propose that the use of IUS to identify the extent of lesions and the position of implanted grains is effective when performing brachytherapy with 198Au grains.

Comparative Survival Assessment of Two-Dimension (2D) versus Three-Dimension (3D) Brachytherapy Treatment in Locally Advanced Cervical Cancer: A Retrospective Case Control Study

Objective: To assess the efficacy as seen as overall survival, local control, progression free survival (PFS) and toxicities, between two-dimension (2D) and three-dimension (3D) computed tomography (CT) guided brachytherapy (BT) without using interstitial needles among patients with cervical cancer. Materials and Methods: A retrospective case control study was performed among patients with FIGO stage IB-IVA cervical cancer treated between March 1990 and August 2018. Concurrent chemoradiation using external beam radiotherapy followed by BT was the treatment method used in all patients. Patients were divided in two groups based on imaging type during BT to compare between 2D and 3D BT techniques. Clinical endpoints were overall survival, local control, progression free survival, acute toxicities, and late toxicities. Results: One hundred two patients with cervical cancer were included, which 52 patients had been treated with 2D and 50 patients with 3D using CT scan BT without interstitial needles. Baseline characteristics were similar between the groups. External beam was used among all patients during the concurrent chemoradiation period before BT. All patients completed the treatment. Similar 3-year overall survival and local control were reported between 2D and 3D techniques. Overall, the 3-year survival rate was 95.7% in 2D and 91.8% in 3D BT (p=0.188). Local control at the 3-year follow-up was 88.6% for 2D and 93.3% for 3D treatment (p-value=0.571). Progression free survival was better in the 2-D rather than the 3D group with 86.13% in 2D versus 27.4% in the 3D group (p-value=0.006). No grade 3 or 4 toxicity regarding the 3D technique was observed whereas 1.9% of grade 3 presented acute gastrointestinal toxicity (p-value=1), and grade 3 late gastrointestinal and genitourinary toxicities in the 2D technique group at 7.7 and 5.8%, respectively (p=1, both). The 3D BT significantly reduced acute grade 1 to 2 gastrointestinal side effect as 23% in the 2D versus 4% in 3D group (p-value=0.003), and grade 1 to 2 late genitourinary side effect as 50% in the 2D versus 16% in the 3D group (p-value=0.001). Conclusion: Using CT guided 3D BT to treat cervical cancer showed similar outcomes in survival and local control but reduced toxicity compared with the 2D technique. Disease progression including metastasis was better in the 2D BT technique group. CT guided BT helped reduce dose to organs at risk and long-term follow-up for survival outcome and toxicities was needed. Keywords: Cervical cancer; Brachytherapy technique; Brachytherapy; 3D brachytherapy; 2D brachytherapy

Borosilicate glass 60Co high dose rate brachytherapy thermoluminescence dosimetry

Brachytherapy is commonly used in treatment of cervical, prostate, breast and skin cancers, also for oral cancers, typically via the application of sealed radioactive sources that are inserted within or alongside the area to be treated. A particular aim of the various brachytherapy techniques is to accurately transfer to the targeted tumour the largest possible dose, at the same time minimizing dose to the surrounding normal tissue, including organs at risk. The dose fall-off with distance from the sources is steep, the dose gradient representing a prime factor in determining the dose distribution, also representing a challenge to the conduct of measurements around sources. Amorphous borosilicate glass (B2O3) in the form of microscope cover slips is recognized to offer a practicable system for such thermoluminescence dosimetry (TLD), providing for high-spatial resolution (down to < 1 mm), wide dynamic dose range, good reproducibility and reusability, minimal fading, resistance to water and low cost. Herein, investigation is made of the proposed dosimeter using a 1.25 MeV High Dose Rate (HDR) 60Co brachytherapy source, characterizing dose response, sensitivity, linearity index and fading. Analysis of the TL glow curves were obtained using the Tmax-Tstop method and first-order kinetics using GlowFit software, detailing the frequency factors and activation energy.

PO-0249 Comparison of two different Low Dose Rate (LDR) Brachytherapy techniques - a retrospective analysis

PO-0249 Comparison of two different Low Dose Rate (LDR) Brachytherapy techniques - a retrospective analysis

PO12: Interstitial Techniques Study for Brachytherapy Based on Imaging Anatomy of Distal Parametrial Metastases in Cervical Cancer

Purpose: The aims of this study were to modify transvaginal intracavitary/interstitial(IC/IS) techniques for brachytherapy(BT) based on Imaging anatomy of distal parametrial metastases in Cervival Cancer.

PLEN03 Presentation Time: 1:45 PM: HDR Interstitial Spine Brachytherapy Using an Intraoperative CT-Guided Surgical Navigation System Compared with Stereotactic Radiosurgery

Purpose: Stereotactic radiosurgery (SRS) has been used to treat spinal metastases. However, reirradiation to the tumor is limited by spinal cord tolerance due to dose fall off outside the target. In order to escalate dose to the target with high accuracy and precision, we have developed a novel high-dose-rate (HDR) interstitial brachytherapy (IS-BT) technique using an intraoperative mobile 3D CT-guided surgical navigation system and compared dosimetry with SRS.

GSOR05 Presentation Time: 2:50 PM: FINITO (Freehand Interstitial Needles in Addition to Tandem and Ovoid) - A Novel Hybrid Brachytherapy Technique for Locally Advanced Cervical Cancer

GSOR05 Presentation Time: 2:50 PM: FINITO (Freehand Interstitial Needles in Addition to Tandem and Ovoid) - A Novel Hybrid Brachytherapy Technique for Locally Advanced Cervical Cancer