Brachytherapy For Cervical Cancer Research Articles

The prognostic effect of tumor volume, reduction ratio, and cumulative doses on external beam radiotherapy with central-shielding method and image-guided adaptive brachytherapy for cervical cancer.

To evaluate the prognostic effect of tumor volume at diagnosis, tumor reduction ratio during external beam radiotherapy (EBRT) with central-shielding method, and cumulative minimal dose to 90% of the high-risk clinical target volume (CTVHR D90) on combined EBRT and image-guided adaptive brachytherapy (IGABT) for cervical cancer. Consecutive patients who underwent definitive radiotherapy or concurrent chemoradiotherapy for cervical cancer at Gunma University Hospital between January 2010 and December 2019 were retrospectively reviewed. Tumor volume at diagnosis and reduction ratio were calculated using magnetic resonance imaging at diagnosis and before the first IGABT session. The cumulative dose of EBRT and IGABT was calculated as an equivalent dose in 2 Gy fractions (EQD2). Optimal cutoff values were determined according to a receiver operating characteristic curve. Treatment outcomes were evaluated using the Kaplan-Meier method and compared using the log-rank test and Cox proportional hazards regression. A total of 254 patients were included in the analysis. The median follow-up for all patients was 57 (2-134) months. The 5-year overall survival (OS) was 81.9%, progression-free survival (PFS) was 71.3%, and local control (LC) was 94.5%. The patients were divided into four groups according to tumor volume at diagnosis and reduction ratio. The group with tumor volume at diagnosis ≥ 34.1 cm3 and reduction ratio < 68.8% showed significantly worse OS, PFS, and LC than the other three groups (All p < 0.05). In this group, the patients with a cumulative CTVHR D90 < 69.6 GyEQD2 showed significantly worse PFS and LC (p = 0.042 and p = 0.027, respectively). In the multivariate analysis of OS, adenocarcinoma/adenosquamous carcinoma, International Federation of Gynecology and Obstetrics 2009 stage III/IV, and a reduction ratio of < 68.8% were independent significant poor prognostic factors (p = 0.045, p = 0.009 and p = 0.001, respectively). In the univariate analysis of LC, a reduction ratio of < 68.8% was the only poor prognostic factor (p = 0.041). The patients with large and poorly responding tumors had significantly worse prognoses in terms of OS, PFS, and LC, suggesting that dose escalation should be considered for such tumors.

794: Clinical outcomes of 3 vs 4 Fractions of MRI-guided brachytherapy in cervical cancer

794: Clinical outcomes of 3 vs 4 Fractions of MRI-guided brachytherapy in cervical cancer

502: Virtual-reality assisted training system for interstitial brachytherapy in cervical cancer

502: Virtual-reality assisted training system for interstitial brachytherapy in cervical cancer

1783: Dwell locations and dwell time prediction of cervical cancer brachytherapy using 3D U-net

1783: Dwell locations and dwell time prediction of cervical cancer brachytherapy using 3D U-net

Dosimetric and toxicity comparison between Syed-Neblett and Fletcher-Suit-Delclos Tandem and Ovoid applicators in high dose rate cervix cancer brachytherapy

PURPOSETo compare patient and tumor characteristics, dosimetry, and toxicities between interstitial Syed-Neblett and intracavitary Fletcher-Suit-Delclos Tandem and Ovoid (T&O) applicators in high dose rate (HDR) cervical cancer brachytherapy. METHODSA retrospective analysis was performed for cervical cancer patients treated with 3D-based HDR brachytherapy from 2011 to 2023 at a single institution. Dosimetric parameters for high-risk clinical target volume and organs at risk were obtained. Toxicities were evaluated using the Common Terminology Criteria for Adverse Events version 5.0. RESULTSA total of 115 and 58 patients underwent Syed and T&O brachytherapy, respectively. Patients treated with Syed brachytherapy were more likely to have larger tumors and FIGO stage III or IV disease. The median D2cc values to the bladder, small bowel, and sigmoid colon were significantly lower for Syed brachytherapy. Patients treated with Syed brachytherapy were significantly more likely to be free of acute gastrointestinal (44% vs. 21%, p = 0.003), genitourinary (58% vs. 36%, p = 0.01), and vaginal toxicities (60% vs. 33%, p = 0.001) within 6 months following treatment compared to patients treated with T&O applicators. In contrast, Syed brachytherapy patients were more likely to experience late gastrointestinal (68% vs. 49%, p = 0.082), genitourinary (51% vs. 35%, p = 0.196), and vaginal toxicities (70% vs. 57%, p = 0.264). CONCLUSIONSSyed-Neblett and T&O applicators are suitable for HDR brachytherapy for cervical cancer in distinct patient populations. Acute toxicities are more prevalent with T&O applicators, while patients treated with Syed-Neblett applicators are more likely to develop late toxicities.

Predicting treatment plan approval probability for high-dose-rate brachytherapy of cervical cancer using adversarial deep learning

Objective. Predicting the probability of having the plan approved by the physician is important for automatic treatment planning. Driven by the mathematical foundation of deep learning that can use a deep neural network to represent functions accurately and flexibly, we developed a deep-learning framework that learns the probability of plan approval for cervical cancer high-dose-rate brachytherapy (HDRBT). Approach. The system consisted of a dose prediction network (DPN) and a plan-approval probability network (PPN). DPN predicts organs at risk (OAR) D 2cc and CTV D 90% of the current fraction from the patient’s current anatomy and prescription dose of HDRBT. PPN outputs the probability of a given plan being acceptable to the physician based on the patients anatomy and the total dose combining HDRBT and external beam radiotherapy sessions. Training of the networks was achieved by first training them separately for a good initialization, and then jointly via an adversarial process. We collected approved treatment plans of 248 treatment fractions from 63 patients. Among them, 216 plans from 54 patients were employed in a four-fold cross validation study, and the remaining 32 plans from other 9 patients were saved for independent testing. Main results. DPN predicted equivalent dose of 2 Gy for bladder, rectum, sigmoid D 2cc and CTV D 90% with a relative error of 11.51% ± 6.92%, 8.23% ± 5.75%, 7.12% ± 6.00%, and 10.16% ± 10.42%, respectively. In a task that differentiates clinically approved plans and disapproved plans generated by perturbing doses in ground truth approved plans by 20%, PPN achieved accuracy, sensitivity, specificity, and area under the curve 0.70, 0.74, 0.65, and 0.74. Significance. We demonstrated the feasibility of developing a novel deep-learning framework that predicts a probability of plan approval for HDRBT of cervical cancer, which is an essential component in automatic treatment planning.

Changes of the Vagina After Concurrent Radiochemotherapy and Brachytherapy in Cervical Cancer Anatomical and Physiological Changes

The objective of the study: The aim of our study was to highlight the anatomical and physiological changes of the vagina after external radiotherapy and brachytherapy in cervical cancer. Materials and Methods: This was a prospective descriptive study conducted over a period of 6 months, from March to August 2022. A total of 123 women with cervical cancer, treated with concurrent radiochemotherapy and uterovaginal brachytherapy, who reported having had sexual intercourse in the six months prior, were included in the study. Patients were interviewed and examined during post-therapeutic follow-up consultations. Results and Statistical Analysis: The age of the patients (n=123) ranged from 33 to 67 years, with a mean of 49.35 ± 9.84 years. The post-therapeutic follow-up duration ranged from 6 months to 7 years. The most common histological type was squamous cell carcinoma, and the most common FIGO stage was stage II. Treatment consisted of concurrent radiochemotherapy and uterovaginal brachytherapy. Interviews revealed several changes related to the vagina after treatment. More than 65% of patients (n=81) reported the onset or worsening of vaginal dryness, over 50% (n=63) reported the onset or worsening of dyspareunia. Nearly 70% (n=83) reported a decrease in sexual desire frequency or dissatisfaction, and over 60% (n=78) became indifferent to sexual life. Gynecological examination revealed a vaginal length ranging from 2 to 10 cm with a mean of 5.66 ± 2.09 cm, the presence of synechiae and/or stenosis in nearly 43% (n=53), and bleeding in nearly 40% (n=47). In univariate analysis, vaginal dryness and dyspareunia significantly increased with age. Resumption of sexual activity was slower in younger and older women. Among patients followed for two years or less, there was a significant increase in synechiae or stenosis, as well as bleeding. Conversely, the prevalence of vaginal dryness and dyspareunia increased with follow-up duration, especially in those exceeding two years. In groups with vaginal dryness or dyspareunia, a large proportion of patients reported a decrease in sexual desire and indifference to their sexual life. Conclusion: This study revealed that patients with cervical cancer experienced significant anatomical and physiological changes in the vagina after treatment with concurrent radiochemotherapy and uterovaginal brachytherapy, leading to chronic sequelae and sexual disorders. It is therefore essential to implement measures to prevent or limit certain side effects associated with these treatments.

Assessing Heterogeneity Effects on Points A, B, and Organs at Risk Doses in High-dose-Rate Brachytherapy for Cervical Cancer - A Comparison of 192Ir and 60Co Sources Using Monte Carlo N-Particle 5.

The present article deals with investigating the effects of tissue heterogeneity consideration on the dose distribution of 192Ir and 60Co sources in high-dose-rate brachytherapy (HDR-BT). A Monte Carlo N-Particle 5 (MCNP5) code was developed for the simulation of the dose distribution in homogeneous and heterogeneous phantoms for cervical cancer patients. The phantoms represented water-equivalent and human body-equivalent tissues. Treatment data for a patient undergoing HDR-BT with a 192Ir source were used as a reference for validation, and for 60Co, AAPM Task Group 43 methodology was also applied. The dose values were calculated for both source types in the phantoms. The results showed a good agreement between the calculated dose in the homogeneous phantom and the real patient's treatment data, with a relative difference of less than 5% for both sources. However, when comparing the absorbed doses at critical points such as Point A right, Point A left, Point B right, Point B left, bladder International Commission on Radiation Units and Measurement (ICRU) point, and recto-vaginal ICRU point, the study revealed significant percentage differences (approximately 5.85% to 12.02%) between the homogeneous and heterogeneous setups for both 192Ir and 60Co sources. The analysis of dose-volume histograms (DVH) indicated that organs at risk, notably the rectum and bladder, still received doses within recommended limits. The study concludes that 60Co and 192Ir sources can be effectively used in HDR-BT, provided that careful consideration is given to tissue heterogeneity effects during treatment planning to ensure optimal therapeutic outcomes.

Results of Definitive (Chemo)radiotherapy Using Computed Tomography-based Brachytherapy for Cervical Cancer.

Concurrent cisplatin-based chemoradiotherapy (CCRT) is the standard treatment for locally advanced cervical cancer. Especially, CCRT with magnetic resonance imaging (MRI) or computed tomography-based image-guided brachytherapy (CT-based 3D-IGBT) for cervical cancer has resulted in good LC rates. However, progression-free survival (PFS) and overall survival (OS) rates for locally advanced cervical cancer are still low and could be improved. The aim of the study was to evaluate treatment efficacy and late toxicity of external beam radiotherapy (EBRT) and CT-based IGBT with or without concurrent chemotherapy in patients with squamous cell carcinoma of the uterine cervix and investigate patterns of failure. We retrospectively analyzed clinical data of cervical squamous cell carcinoma patients treated with definitive radiotherapy with or without concurrent chemotherapy at Saitama Medical University International Medical Center. Local control (LC), PFS, patterns of failure, and late toxicity were the evaluated outcomes. Overall, 290 patients were enrolled in the study. Median follow-up was 51.5 months. During follow-up, 74 patients developed recurrence: 10 patients with intra-pelvic failure only, 45 with extra-pelvic failure only, and 19 with both. The 3-year LC was 100% for T1b-T2a, 96.8% for T2b, 89.5% for T3b, and 88.5% for T4 disease. The 3-year PFS was 100% for stage IB-IIA, 89.0% for stage IIB, 70.7% for stage IIIB, 72.6% for stage IIIC1r, and 40.1% for stage IVA. The incidence of grade 3-4 gastrointestinal and genitourinary toxicities was 3.0% and 1.7%, respectively. Combination of EBRT and CT-based IGBT with or without concurrent chemotherapy produced favorable LC with acceptable rates of late toxicities. However, extra-pelvic failures frequently occurred and PFS was less satisfactory in patients with stage III-IVA disease, which indicated the need for additional treatment in these patients.

Evaluating outcomes and toxicities for a newly implemented MRI-based brachytherapy program for cervical cancer

ObjectiveWe report an updated analysis of the outcomes and toxicities of MRI-based brachytherapy for locally advanced cervical cancer from a U.S. academic center. MethodsA retrospective review was performed on patients treated with MRI-based brachytherapy for cervical cancer. EBRT was standardly 45 Gy in 25 fractions with weekly cisplatin. MRI was performed with the brachytherapy applicator in situ. Dose specification was most commonly 7 Gy for 4 fractions with optimization aim of D90 HR-CTV EQD2 of 85–95 Gyα/β=10 Gy in 2 implants each delivering 2 fractions. ResultsNinety-eight patients were included with median follow up of 24.5 months (IQR 11.9–39.8). Stage IIIA-IVB accounted for 31.6% of cases. Dosimetry results include median GTV D98 of 101.0 Gy (IQR 93.3–118.8) and HR-CTV D90 of 89 Gy (IQR 86.1–90.6). Median D2cc bladder, rectum, sigmoid, and bowel doses were 82.1 Gy (IQR 75.9–88.0), 65.9 Gy (IQR 59.6–71.2), 65.1 Gy (IQR 57.7–69.6), and 55 Gy (IQR 48.9–60.9). Chronic grade 3+ toxicities were seen in the bladder (8.2%), rectosigmoid (4.1%), and vagina (1.0%). Three-year LC, PFS, and OS were estimated to be 84%, 61.7%, and 76.1%, respectively. ConclusionMRI-based brachytherapy demonstrates excellent local control and acceptable rates of high-grade morbidity. These results are possible in our population with relatively large volume primary tumors and extensive local disease.

Effects of pain management using nonsteroidal anti-inflammatory drug suppositories during brachytherapy for cervical cancer: A single-center prospective observational study

IntroductionNo standardized pain management protocol exists for intracavitary brachytherapy, and various methods of analgesia have been used in different countries and institutions. This study aimed to investigate the effects of pain management during intracavitary brachytherapy using non-steroidal anti-inflammatory drugs (NSAIDs) or acetaminophen suppositories. MethodsIn this single-center, prospective, observational study, patients undergoing intracavitary brachytherapy for cervical cancer completed a questionnaire survey after each brachytherapy session, which comprised questions regarding pain intensity, satisfaction with analgesia, and desire for effective anesthesia. ResultsData analysis was performed using data from 100 brachytherapy sessions of 27 patients. The median numerical rating scale (NRS; 0–10) score for each intracavitary brachytherapy session was 3–4. The median satisfaction scale score for analgesia (5-point scale, 1–5) for each session was approximately 4. Eight patients (29.6%) answered that they desired anesthesia more effective than suppositories at any session of brachytherapy. A comparison of the high (NRS≥4) and low (NRS≤3) NRS groups during the first session revealed that the high NRS group tended to have higher NRS scores and lower satisfaction with analgesia during all sessions. A positive correlation was observed between tumor size and the NRS score during the first brachytherapy session. ConclusionsThe NRS score was approximately 3–4, and satisfaction with analgesia was approximately 4 out of 5 when NSAIDs or acetaminophen suppositories were used as analgesics during intracavitary brachytherapy for cervical cancer. Although the current pain management protocol is clinically acceptable, inadequate analgesia is indicated in approximately 30% of patients.

Dosimetric Comparison of Inverse Planning Simulated Annealing and Manual Optimization for Intracavitary Cervix Brachytherapy

Background/Aims: Different optimization methods in brachytherapy treatment planning is used. The aim of this study is to evaluate dosimetric differences between manual optimization (MO) and inverse planning simulated annealing (IPSA) planning techniques commonly used in brachytherapy of cervical cancer. Methods: Fifteen cervical cancer patients were included in this study. Nucletron standard tandem-ovoid (TO) applicators were used for treatment. High-risk clinical tumor volume (HR-CTV), bladder, rectum, and sigmoid contouring were performed according to GEC-ESTRO recommendations. Two plans were created for each patient using IPSA and MO techniques. While a dose of 700 cGy was prescribed to the target volume during the planning phase, an effort was made to protect the organs at risk in the best way possible. IPSA and MO planning techniques were compared via dose volume histogram (DVH). Results: There was no significant difference between HR-CTV and CI values for MO and IPSA techniques. There was a significant difference between IPSA and MO techniques for the 2cm3 volume of the rectum (p= 0.002). It was observed that the bladder was better protected by the IPSA technique. There was a 6.26% dose difference between IPSA and MO for the bladder. A significant difference was found between IPSA and MO techniques for the 2cm3 volume of the sigmoid (p= 0.002). The IPSA technique was superior to the MO technique in terms of time. Conclusions: The IPSA technique was superior to the MO technique in terms of protecting organs at risk (OARs). IPSA provides a faster and higher quality plan in cervical brachytherapy.

Transrectal ultrasound for intraoperative interstitial needle guidance in cervical cancer brachytherapy

ObjectiveThis study aimed to prospectively assess the visibility of interstitial needles on transrectal ultrasound (TRUS) in cervical cancer brachytherapy patients and evaluate its impact on implant and treatment plan quality.Material and methodsTRUS was utilized during and after applicator insertion, with each needle’s visibility documented through axial images at the high-risk clinical target volume’s largest diameter. Needle visibility on TRUS was scored from 0 (no visibility) to 3 (excellent discrimination, margins distinct). Quantitative assessment involved measuring the distance between tandem and each needle on TRUS and comparing it to respective magnetic resonance imaging (MRI) measurements. Expected treatment plan quality based on TRUS images was rated from 1 (meeting all planning objectives) to 4 (violation of High-risk clinical target volume (CTVHR) and/or organ at risk (OAR) hard constraints) and compared to the final MRI-based plan.ResultsAnalysis included 23 patients with local FIGO stage IB2-IVA, comprising 41 applications with a total of 230 needles. A high visibility rate of 99.1% (228/230 needles) was observed, with a mean visibility score of 2.5 ± 0.7 for visible needles. The maximum and mean difference between MRI and TRUS measurements were 8 mm and –0.1 ± 1.6 mm, respectively, with > 3 mm discrepancies in 3.5% of needles. Expected treatment plan quality after TRUS assessment exactly aligned with the final MRI plan in 28 out of 41 applications with only minor deviations in all other cases.ConclusionReal-time TRUS-guided interstitial needle placement yielded high-quality implants, thanks to excellent needle visibility during insertion. This supports the potential of TRUS-guided brachytherapy as a promising modality for gynecological indications.

The impact of a positive COVID-19 test on timeliness of radiation in patients receiving brachytherapy

BACKGROUNDDelays in initiating and completing brachytherapy may have adverse oncologic outcomes for patients with cervical, uterine, and prostate cancer. The impact of the COVID-19 pandemic on brachytherapy in the United States has not been well-characterized. OBJECTIVESWe aim to evaluate how a positive COVID-19 test affected timeliness of treatment for patients undergoing brachytherapy for cervical, uterine, and prostate cancer. METHODSWe queried the National Cancer Database to identify patients diagnosed with cervical, uterine, and prostate cancer in 2019 and 2020 who received brachytherapy in their treatment. Patients who tested positive for COVID-19 between cancer diagnosis and start of radiation were compared to those who did not test positive for COVID-19. Time in days from cancer diagnosis to initiation of radiation was compared using two-sample t-tests with p < 0.05 signifying significant differences. RESULTSWe identified 38,341 patients with cervical (n = 6,925), uterine (n = 18,587), and prostate cancer (n = 12,829). Rates of COVID-19 positivity were cervical cancer (n = 135; 2%), uterine cancer (n = 236; 1.3%), and prostate cancer (n = 141; 1%). Of those, 35% of cervical, 49% of uterine, and 43% of prostate cancer patients tested positive between their cancer diagnosis and initiation of radiation. Median days to radiation was significantly longer in these patients: 78 versus 51 for cervical cancer (p < 0.01), 150 versus 104 for uterine cancer (p < 0.01), and 154 versus 124 for prostate cancer (p < 0.01). CONCLUSIONSFor patients with cervical, uterine, and prostate cancer diagnosed between 2019–2020, testing positive for COVID-19 after their cancer diagnosis was associated with a delay to initiation of radiation by 4–7 weeks.

Dosimetric Comparison of Isodose Surface Volume and Total Reference Air Kerma (TRAK) based Volume in Cervical Cancer Brachytherapy.

We aim to compare TRAK & TPS based isodose volumes in cervical cancer brachytherapy and assess the feasibility, accuracy and potential future implications of TRAK in this regard and as a newer emerging tool to assess treatment intensity in cervical cancer brachytherapy. one hundred patients with histologically proven squamous cell carcinoma of cervix uteri were assessed for brachytherapy (after completion of external radiation) and prospectively enrolled for the study. 60 Gy, 75 Gy, and 85 Gy isodose volumes were obtained from the TPS (VTPS) for 50, 25 & 25 patients with Manchester, Fletcher & interstitial implant respectively, receiving various fractionation schedules by Ir192 HDR remote after-loading system. Using the formula Vpred=4965(TRAK/dref)3/2+170(TRAK/dref)-1.5 the TRAK based isodose surface volumes (Vpred) were derived. Reference doses (dref) were calculated based on accumulated EBRT and brachytherapy doses. The two sets of volume were compared with respect to applicator type, standard, and optimised plan. Surrogate point A dose was also correlated. VTPS - Vpred were 5.24 ± 2.7%, all volumes being predicted within 10%. Correlation of TRAK vs VTPS60/ VTPS75/ VTPS85 showed R2 of 0.994, 0.987 and 0.971 respectively. There was no significant difference in predicted volumes with respect to applicator type. The surrogate point A showed mean volume and standard deviation of 7.44 ± 13.4%, 17.63 ± 16.38 and 3.5 ± 0.95 for Manchester optimised, Fletcher optimised and standard plans respectively. TRAK with point A (R2=0.5632), bladder (R2=0.2015) and rectal doses (R2=0.121) yielded no correlation. Volumes calculated by TRAK correlate with TPS obtained volumes significantly and the formula predicting isodose surface volumes within 10% accuracy for ICBT applications and not for pure interstitial implants. However, TRAK fails to correlate with surrogate point A, bladder and rectal doses hence has questionable utility as a marker for biological response & treatment intensity.

Radiochemotherapy and interstitial brachytherapy for cervical cancer: clinical results and patient-reported outcome measures

ObjectiveTo evaluate clinical results and long-term patient-reported outcome measures (PROMs) on quality of life in cervical cancer patients following radiochemotherapy (RCT) and brachytherapy (BT) as definitive treatment.Materials and methodsBetween 2003 and 2023, a total of 132 patients with advanced cervical cancer were evaluated for possible treatment. Patients treated by postoperative RCT, palliative radiotherapy, and those treated for recurrent disease were excluded. Thus, 46 patients receiving standard RCT and BT as their curative treatment were included in this study. PROMs were assessed prospectively by patients’ self-completion of the EORTC-QLQ-C30 and EORTC-QLQ-CX24 questionnaires.ResultsFive-year overall survival (OS), distant metastases-free survival (DMFS), and pelvic tumor-free survival rates (PTFS) were 53%, 54%, and 83%, respectively. A significant impact on OS was seen for FIGO (International Federation of Gynecologic Oncology) stage (IIB–IIIA: 79% vs. IIIB–IVA: 33%, p = 0.015), for overall treatment time (OTT; 50–65 d: 64% vs. > 65 d: 38%, p = 0.004), and for rectal D2cc (≤ 73 Gy: 50% vs. > 73 Gy: 38%, p = 0.046). The identical parameters were significantly associated with DMFS (FIGO stage: p = 0.012, OTT: p = 0.008, D2cc: p = 0.024). No parameters with a significant influence on PTFS were seen. In multivariate analysis, an impact of FIGO stage on OS (p = 0.05) and DMFS (p = 0.014) was detected, and of rectal D2cc on DMFS (p = 0.031). The overall QoL score was 63/100. Cognitive function was the least impaired (84/100), while role functioning was the worst (67/100). On the symptom scale, insomnia (46/100), fatigue (41/100), dyspnea (32/100), pain (26/100), and financial difficulties (25/100) were scored the worst. According to EORTC-QLQ-CX24, peripheral neuropathy (36/100) and lymphedema (32/100) occurred most frequently. Impaired sexual/vaginal functioning (32/100) and body image (22/100) were also frequently recorded.ConclusionIn patients with advanced cervical cancer, a combination of RCT and BT remains an excellent treatment option. In terms of patient-reported long-term quality of life, specific support is needed to alleviate symptoms including lymphedema, peripheral neuropathy, and impaired sexual activity.

Multibody dynamic modeling of the behavior of flexible instruments used in cervical cancer brachytherapy.

The steep radiation dose gradients in cervical cancer brachytherapy (BT) necessitate a thorough understanding of the behavior of afterloader source cables or needles in the curved channels of (patient-tailored) applicators. The purpose of this study is to develop and validate computer models to simulate: (1) BT source positions, and (2) insertion forces of needles in curved applicator channels. The methodology presented can be used to improve the knowledge of instrument behavior in current applicators and aid the development of novel (3D-printed) BT applicators. For the computer models, BT instruments were discretized in finite elements. Simulations were performed in SPACAR by formulating nodal contact force and motion input models and specifying the instruments' kinematic and dynamic properties. To evaluate the source cable model, simulated source paths in ring applicators were compared with manufacturer-measured source paths. The impact of discrepancies on the dosimetry was estimated for standard plans. To validate needle models, simulated needle insertion forces in curved channels with varying curvature, torsion, and clearance, were compared with force measurements in dedicated 3D-printed templates. Comparison of simulated with manufacturer-measured source positions showed 0.5-1.2mm median and<2.0mm maximum differences, in all but one applicator geometry. The resulting maximum relative dose differences at the lateral surface and at 5mm depth were 5.5% and 4.7%, respectively. Simulated insertion forces for BT needles in curved channels accurately resembled the forces experimentally obtained by including experimental uncertainties in the simulation. The models developed can accurately predict source positions and insertion forces in BT applicators. Insights from these models can aid novel applicator design with improved motion and force transmission of BT instruments, and contribute to the estimation of overall treatment precision. The methodology presented can be extended to study other applicator geometries, flexible instruments, and afterloading systems.

Outcome and toxicity of chemoradiation using volumetric modulated arc therapy followed by 3D image-guided brachytherapy for cervical cancer: Vietnam National Cancer Hospital experience.

Volumetric modulated arc therapy (VMAT) and 3D image-guided brachytherapy (3D-IGBT) have recently been introduced in Vietnam for the treatment of locally advanced cervical cancer. This study aims to assess the outcomes and toxicities of chemoradiation using VMAT followed by 3D-IGBT in Vietnamese cervical cancer patients. A prospective interventional study on 72 patients with 2018 International Federation of Gynecology and Obstetrics (FIGO) stage IB3-IIIC2 disease who underwent concurrent chemoradiation using VMAT, followed by 3D-IGBT according to EMBRACE-II protocol. Primary endpoints were locoregional control; secondary endpoints were systemic control and toxicity. Median body volume received 43 Gy was 1589.1 cm3 (range 1214.8-2574.8). Median high-risk clinical target volume (CTV-HR) was 18.8 cm3 (range 8.6-61.2) with a median dose to 90% (D90) of CTV-HR of 90.6 Gy (range 86.8-99.6). Mean doses to 2cc (D2cc) of bladder, rectum, and sigmoid were 75.8, 55.2, and 62.1 Gy, respectively. At median 19-month follow-up (range 12-25), locoregional control and systemic control were 95.8% and 81.9%, respectively. Systemic control was the lowest in N2 disease (54.5%). Grade ≥ 3 acute toxicities were less than 10%, except neutropenia (31.9%). Extended-field radiation increased significantly nausea, fatigue, and thrombocytopenia. No grade ≥ 3 proctitis or cystitis; 8.3% had grade 3 vaginal stenosis. VMAT-based chemoradiation therapy followed by 3D-IGBT achieved high locoregional control with manageable toxicities in locally advanced cervical cancer. Systemic control correlated with disease stage.

Factors affecting the dosimetry of high-dose rate intracavitary brachytherapy in cervical cancer

Abstract Background: Intracavitary brachytherapy (ICBT) is essential in managing locally advanced cervical cancer. Brachytherapy as a modality has the advantage of a higher dose to the tumour with a dose fall off at the periphery as per the inverse square law. The dose per fraction is much higher than external beam radiotherapy. So proper application and dosimetry are of paramount importance to reduce late toxicity. Methods: A retrospective analysis of 69 patients who underwent three ICBT applications of 7 Gray in each fraction was done. The factors under consideration were the type of pain management (spinal anaesthesia (SA) versus conscious sedation (CS)), the initial size of the disease (bulky and non-bulky) and subsequent fractions (first fraction versus third fraction). The dosimetric parameters analysed were the doses received by points A, B and P and that of the critical organs (bladder, rectum and sigmoid colon). Results: The dose received by critical organs was comparable concerning all the factors under consideration. The dose to point P on the left side was significantly lower in the CS group than in the SA group (p-value = 0·031). Also, the dose to point P on the right side was significantly lower in the third fraction compared with the first fraction (p-value = 0·016). Conclusions: ICBT under spinal anaesthesia resulted in a higher dose to the pelvic wall. The initial size of the tumour or the subsequent fractions does not significantly affect the dose received by critical organs.

High-dose-rate brachytherapy in uterine cervix carcinoma: a comparison of dosimetry and clinical outcomes among three fractionation schedules.

To assess the differences among three dose-fractionation schedules of image-guided adaptive brachytherapy (IGABT) in cervical squamous cell carcinoma (CSCC) by comparing the dosimetry and clinical outcomes. Forty-five patients with CSCC who underwent chemoradiotherapy and IGABT were retrospectively enrolled and divided into three groups based on their dose-fractionation schedules of brachytherapy as: Group-5.5 (5.5 Gy × 6 fractions), Group-6.0 (6.0 Gy × 5 fractions), and Group-7.0 (7.0 Gy × 4 fractions). The analyzed dose-volume histogram parameters included D90% and D98% of the high-risk clinical target volume (HR-CTV), D90% and D98% of intermediate-risk clinical target volume (IR-CTV), and D0.1cc and D2cc of the organs-at-risk (OARs, namely the bladder, rectum, sigmoid and small intestine). Furthermore, the therapeutic efficacy and late toxicities were also compared among the three groups. The doses of HR-CTV and IR-CTV in Group-5.5 were found to be the highest among the three groups, followed by those in Group-6.0. Significant differences were found for the doses of HR-CTV between Group-5.5 and the other groups. There were no significant differences in the bladder, sigmoid and small intestine dose among the three groups. However, Group-6.0 yielded the lowest rectum received doses, with a significant difference in D0.1cc being detected between Group-6.0 and Group-5.5. The median follow-up time was 30.08 months [range, 6.57-46.3]. The numbers of patients with complete response in Group-5.5, Group-6.0 and Group-7.0 were 13, 14 and 14, respectively (P > 0.05). In regard to the toxicitiy, the incidence of radiation cystitis and proctitis in Group-6.0 was lower than that in Group-5.5 and Group-7.0 (P > 0.05). The dose-fractionation schedule of 6.0 Gy × 5 fractions provided the most beneficial effects with relatively low OARs doses, suggesting that this dose-fractionation schedule should be prioritized in the clinical application of brachytherapy in cervical cancer.