High-dose-rate Brachytherapy For Cervical Cancer Research Articles

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.

Comparative Analysis of 60Co and 192Ir Sources in High Dose Rate Brachytherapy for Cervical Cancer.

Simple SummaryHigh-dose-rate (HDR) brachytherapy (BT) is an effective treatment for bulky, middle, and advanced cervical cancer. Both 192Ir and 60Co are radiation sources recommended by the ICRU. Previously, due to the large geometric size of 60Co, 192Ir occupied most of the market share. After continuous technical improvements, the geometry of miniaturized 60Co sources has become comparable to that of 192Ir sources. Another important point is that people suspect that the use of 60Co sources will result in reduced efficacy, increased toxic reactions, and a series of issues. In this paper, we compared 60Co and 192Ir sources for HDR BT in terms of both dosimetry and clinical treatment. The results of reports published on the use of HDR BT for cervical cancer over the past few years as well as our own research show that this treatment is safe and 60Co can be promoted as a good alternative to 192Ir.High-dose-rate (HDR) brachytherapy (BT) is an essential treatment for cervical cancer, one of the most prevalent gynecological malignant tumors. In HDR BT, high radiation doses can be delivered to the tumor target with the minimum radiation doses to organs at risk. Despite the wide use of the small HDR 192Ir source, as the technique has improved, the HDR 60Co source, which has the same miniaturized geometry, has also been produced and put into clinical practice. Compared with 192Ir (74 days), 60Co has a longer half-life (5.3 years), which gives it a great economic advantage for developing nations. The aim of the study was to compare 60Co and 192Ir sources for HDR BT in terms of both dosimetry and clinical treatment. The results of reports published on the use of HDR BT for cervical cancer over the past few years as well as our own research show that this treatment is safe and it is feasible to use 60Co as an alternative source.

Verification of dose distribution in high dose-rate brachytherapy for cervical cancer using a normoxic N-vinylpyrrolidone polymer gel dosimeter.

The polymer gel dosimeter has been proposed for use as a 3D dosimeter for complex dose distribution measurement of high dose-rate (HDR) brachytherapy. However, various shapes of catheter/applicator for sealed radioactive source transport used in clinical cases must be placed in the gel sample. The absorbed dose readout for the magnetic resonance (MR)-based polymer gel dosimeters requires calibration data for the dose-transverse relaxation rate (R2) response. In this study, we evaluated in detail the dose uncertainty and dose resolution of three calibration methods, the multi-sample and distance methods using the Ir-192 source and the linear accelerator (linac) method using 6MV X-rays. The use of Ir-192 sources increases dose uncertainty with steep dose gradients. We clarified that the uniformly irradiated gel sample improved the signal-to-noise ratio (SNR) due to the large slice thickness of MR images and could acquire an accurate calibration curve using the linac method. The curved tandem and ovoid applicator used for intracavitary irradiation of HDR brachytherapy for cervical cancer were reproduced with a glass tube to verify the dose distribution. The results of comparison with the treatment planning system (TPS) calculation by gamma analysis on the 3%/2mm criterion were in good agreement with a gamma pass rate of 90%. In addition, the prescription dose could be evaluated accurately. We conclude that it is easy to place catheter/applicator in the polymer gel dosimeters, making them a useful tool for verifying the 3D dose distribution of HDR brachytherapy with accurate calibration methods.

Automatic segmentation of magnetic resonance images for high-dose-rate cervical cancer brachytherapy using deep learning.

Magnetic resonance (MR) imaging is the gold standard in image-guided brachytherapy (IGBT) due to its superior soft-tissue contrast for target and organs-at-risk (OARs) delineation. Accurate and fast segmentation of MR images are very important for high-quality IGBT treatment planning. The purpose of this work is to implement and evaluate deep learning (DL) models for the automatic segmentation of targets and OARs in MR image-based high-dose-rate (HDR) brachytherapy for cervical cancer. A 2D DL model using residual neural network architecture (ResNet50) was developed to contour the targets (gross tumor volume (GTV), high-risk clinical target volume (HR CTV), and intermediate-risk clinical target volume (IR CTV)) and OARs (bladder, rectum, sigmoid, and small intestine) automatically on axial MR slices of HDR brachytherapy patients. Furthermore, two additional 2D DL models using sagittal and coronal images were also developed. A 2.5D model was generated by combining the outputs from axial, sagittal, and coronal DL models. Similarly, a 2D and 2.5D DL models were also generated for the inception residual neural network (InceptionResNetv2 (InRN)) architecture. The geometric (Dice similarity coefficient (DSCs) and 95th percentile of Hausdorff distance (HD)) and dosimetric accuracy of 2D (axial only) and 2.5D (axial+sagittal+coronal) DL model generated contours were calculated and compared. The mean (range) DSCs of ResNet50 across all contours were 0.674 (0.05-0.96) and 0.715 (0.26-0.96) for the 2D and 2.5D models, respectively. For InRN, these were 0.676 (0.11-0.96) and 0.723 (0.35-0.97) for the 2D and 2.5D models, respectively. The mean HD of ResNet50 across all contours was 15.6mm (1.8-69mm) and 12.1mm (1.7-44mm) for the 2D and 2.5D models, respectively. The similar results for InRN were 15.4mm (2-68mm) and 10.3mm (2.7-39mm) for the 2D and 2.5D models, respectively. The dosimetric parameters (D90) of GTV and HR CTV for manually contoured plans matched better with the 2.5D model (p>0.6) and the results from the 2D model were slightly lower (p<0.08). On the other hand, the IR CTV doses (D90) for all of the models were slightly lower (2D: -1.3 to -1.5Gy and 2.5D: -0.5 to -0.6Gy) and the differences were statistically significant for the 2D model (2D: p<0.000002 and 2.5D: p>0.06). In case of OARs, the 2.5D model segmentations resulted in closer dosimetry than 2D models (2D: p=0.07-0.91 and 2.5D: p=0.16-1.0). The 2.5D DL models outperformed their respective 2D models for the automatic contouring of targets and OARs in MR image-based HDR brachytherapy for cervical cancer. The InceptionResNetv2 model performed slightly better than ResNet50.

Experiences of Women Receiving Multifraction High Dose-Rate Brachytherapy for Cervical Cancer: A Prospective Qualitative Study

Objective: The aim of this study was to establish cervical cancer patients’ expectations and experiences during high dose-rate (HDR) intracavitary brachytherapy procedure, as part of a process to develop guidelines for quality patient-centered care. Methodology: A prospective, qualitative study with a descriptive phenomenological approach was used. Purposive sampling was carried out to recruit 31 women undergoing HDR brachytherapy for cervical cancer from June to August 2020 at the National Institute of Oncology in Rabat. Semi-structured, one-to-one interviews guided by a theme list were conducted by a female radiation oncologist in Arabic before, during and after treatment. The following aspects were discussed: expectations, experiences in the waiting room, in the treatment room, and suggestions for improvement. Data was transcribed, translated and thematic analysis performed. Results: Most of the patients felt unprepared and did not have a clear understanding of brachytherapy. Brachytherapy was a difficult experience causing fear and anxiety throughout treatment. Most women dreaded the procedure, before receiving the first treatment and even after having had one. Pain was a major problem for the participants. Some women compared this pain to childbirth, a process they preferred to brachytherapy. Patients agreed that the preventative medication received was not efficient to relieve the pain. Despite these negative experiences, patients were left with a positive outlook. Dialogue with the healthcare professionals, support from their family and fellow patients, envisaged outcomes and desires to heal were used to cope, whilst faith and spirituality gave them strength to endure the procedure. Conclusion: Women undergoing uterovaginal brachytherapy for cervical cancer experience pain and emotional distress. Providing patients with adequate information, more sensitive support during the procedure and debriefing afterwards could lessen feelings of fear and anxiety. Our findings advocate for the revision of pain management protocols. Further studies should be carried out to define patient-centered recommendations and provide quality care to this group of women.

Demographic and clinical factors associated with variations in opioid administration using conscious sedation during HDR brachytherapy for cervical cancer

PURPOSE/OBJECTIVES To examine patient characteristics that predispose to higher opioid administration during tandem and ovoid (T&O) high-dose rate (HDR) brachytherapy. METHODS A single-institution retrospective review was performed on patients who underwent brachytherapy for cervical cancer. Patients were included if they received at least one fraction of HDR T&O brachytherapy with analgesia administration recorded in the Medication Administration Record. Fentanyl dose was dichotomized as "low" (mean <125 μg per fraction), or "high" (mean ≥ 125 μg per fraction). Descriptive statistics and multiple logistic regression analysis were performed comparing mean opioid dose per fraction with demographic and clinical information. RESULTS From July 2014 through May 2020, 113 patients underwent 531 T&O HDR brachytherapy fractions with oral benzodiazepine and intravenous opioid fentanyl for conscious sedation. The median opioid dose per fraction was 100 μg fentanyl (range 0-250 μg). Using multiple logistic regression analysis, younger age (OR 1.071, p = 0.002) and higher BMI (OR 1.091, p = 0.019) were associated with increased opioid administration during brachytherapy. Black women received less opioid during brachytherapy when compared to White women (OR 0.296, p = 0.047). FIGO stage, ECOG score, smoking status, prior narcotic use, prior illicit drug use, parity, prior cervical procedure, Smit sleeve placement, and distance to treatment center were not associated with high opioid dose. CONCLUSION Cervical cancer patients who are younger or have higher BMI receive more narcotic analgesia during HDR brachytherapy whereas Black women received less narcotic analgesia, irrespective of age and BMI. This underscores the immediate need to address how pain is assessed and managed during brachytherapy.

3T multiparametric MRI–guided high-dose-rate combined intracavitary and interstitial adaptive brachytherapy for the treatment of cervical cancer with a novel split-ring applicator

PurposeTo evaluate the role of 3T-MRI–guided adaptive high-dose-rate (HDR) combined intracavitary and interstitial brachytherapy for cervical cancer using a novel intracavitary split-ring (ICSR) applicator adapter. Methods and MaterialsWe retrospectively reviewed all HDR brachytherapy cases from 2013 to 2015 using an ICSR applicator. Initial optimization was performed using 3T multiparametric MRI (mpMRI) series with an applicator in place. The mpMRI series were discretionarily acquired before subsequent fractions for possible target adaptation. When necessary, interstitial needles (ISNs) were inserted through a novel ICSR adapter or freehand. Dosimetric parameters, clinical outcomes, and toxicities were compared between groups. ResultsSeventeen patients were included, with a mean followup of 32 months. An mpMRI series preceded each initial fraction and 52.9% of patients underwent ≥1 additional pretreatment mpMRI. Among these subsequent fractions, the high-risk clinical target volume was reduced in 80% vs. 41% without pretreatment mpMRI. Five patients had ISN placement (seven insertions) to improve extracervical target coverage. Mean D90 (Gy) per fraction to the high-risk clinical target volume and intermediate-risk clinical target volume with and without an ISN were 7.51 ± 1.07 vs. 6.14 ± 0.52 (p = 0.028) and 6.35 ± 0.75 vs. 5.21 ± 0.49 (p = 0.007), respectively. Mean fractional D2cc (Gy) for organs at risk was comparable. No Grades 3–4 toxicity was reported. Disease-free survival and local control for the ICSR-ISN and ICSR-alone groups were 29.8 months/80.0% and 31.2 months/83.3%, respectively. ConclusionsThe mpMRI acquisition with ICSR applicator in place immediately before HDR brachytherapy for cervical cancer guided successful adaptive treatment optimization and delivery. Our initial experience with a novel interstitial adapter for the split-ring applicator demonstrated excellent target coverage without compromising organs at risk, resulting in good local control and disease-free survival.

Dosimetric comparison between two brachytherapy applicators in cervical cancer treatment

Objective To compare the dosimetric parameters between the use of Tandem and Ring (TR; Nucletron#090.617) or Tandem and Ovoid (TO; Nucletron#189.730) applicators during three-dimensional (3D) high-dose rate (HDR) brachytherapy (BT) for cervical cancer. Methods The records of 40 cervical cancer (ⅡB-ⅣA) patients treated with 3D-image-guided HDR-BT were reviewed. Of these 40 patients, 20 were treated with the TO applicator, and 20 with the TR applicator. The D100% and V150% of the clinical target volume (CTV) and the D2 cc of organs at risk (OAR)(the rectum, bladder, and small intestine) during 3D-HDR-BT using TO and TR were compared using the independent sample t-test. Results Overall metrics: CTV volume: 66.04±13.86 cm3(TR) vs. 65.67±15.08 cm3(TO)(P=0.052); CTV D100: 3.71±0.34 Gy (TR) vs. 3.37±0.49 Gy (TO)(P=0.016); CTV V150%: 0.54±0.02(TR) vs. 0.56±0.04(TO)(P=0.034); rectum D2 cc: 3.38±0.30 Gy (TR) vs. 2.95±0.80 Gy (TO)(P=0.037); bladder D2 cc: 4.33±0.39 Gy (TR) vs. 2.93±1.27 Gy (TO)(P=0.00); and small intestine D2 cc: 3.04±1.02 Gy (TR) vs. 3.41±0.57 Gy (TO)(P=0.171). Conclusions TR has better CTV coverage than TO during 3D HDR brachytherapy for cervical cancer. In addition, D2 cc of the rectum and bladder were both higher with TR than with TO, though there is no significant dosimetric difference in the small intestine between the two applicators. Therefore, tumor location, extent of invasion, and vaginal conditions should be considered when selecting the suitable applicator for the treatment of cervical cancer. Key words: Applicators; Cervical neoplasms/brachytherapy; Dosimetry

Transition from LDR to HDR Brachytherapy for Cervical Cancer: Evaluation of Tumor Control, Survival, and Toxicity

In 2012, our institution transitioned from low dose-rate (LDR) brachytherapy to high dose-rate (HDR) brachytherapy. There is a growing body of literature reporting outcomes of these two treatment techniques across different settings, although large comparative analyses are limited. We report clinical outcomes following brachytherapy for cervical cancer at our institution over a continuous 10-year period.

Transition from LDR to HDR brachytherapy for cervical cancer: Evaluation of tumor control, survival, and toxicity

PurposeIn 2012, our institution transitioned from low-dose-rate (LDR) brachytherapy to high dose-rate (HDR) brachytherapy. We report clinical outcomes after brachytherapy for cervical cancer at our institution over a continuous 10-year period. Methods and MaterialsFrom 2004 to 2014, 258 women (184 LDR and 74 HDR) were treated with tandem and ovoid brachytherapy in the multidisciplinary management of International Federation of Gynecology and Obstetrics Stages IA–IVB cervical cancer. Clinical and treatment-related prognostic factors including age, stage, smoking status, relevant doses, and toxicity data were recorded. ResultsMedian followup for the LDR and HDR groups was 46 months and 12 months, respectively. The majority of patients (92%) received external beam radiotherapy as well as concurrent chemotherapy (83%) before the start of brachytherapy. For all stages, the 1-year local control and overall survival (OS) rates were comparable between the LDR and HDR groups (87% vs. 81%, p = 0.12; and 75% vs. 85%, p = 0.16), respectively. Factors associated with OS on multivariate analysis include age, stage, and nodal involvement. On multivariate analysis, severe toxicity (acute or chronic) was higher with HDR than LDR (24% vs. 10%, p = 0.04). Additional prognostic factors associated with increased severe toxicity include former/current smokers and total dose to lymph nodes. ConclusionsThis comparative retrospective analysis of a large cohort of women treated with brachytherapy demonstrates no significant difference in OS or local control between the LDR and HDR. Acute and chronic toxicity increased shortly after the implementation of HDR, highlighting the importance of continued refinement of HDR methods, including integrating advanced imaging.

Uterine perforation and its dosimetric implications in cervical cancer high-dose-rate brachytherapy

PurposeTo retrospectively assess the incidence of sub-serosal and uterine perforation of intra-uterine tandem in intracavitary high-dose-rate (HDR) brachytherapy for cervical cancer, and to evaluate its dosimetric implications on computed tomography (CT)-based treatment planning.Material and methodsComputed tomography images and brachytherapy plans of cervical cancer patients treated from February 2006 to December 2012 were reviewed for sub-optimal implants (sub-serosal and uterine perforation), and their correlation with cancer FIGO stage and patients’ age. For each patient, the plans showing sub-optimal insertion of intra-uterine tandem were analyzed and compared to plans with adequate insertion. The difference in dose coverage of clinical-target-volume (CTV) and variation of the dose delivered to organs-at-risk (OARs) rectum and bladder were evaluated.ResultsA total of 231 brachytherapy plans for 82 patients were reviewed. We identified 12 (14.6%) patients and 14 (6%) applications with uterine perforation, and 12 (14.6%) patients and 20 (8.6%) applications with sub-serosal insertion of tandem. Data analysis showed that advanced stage correlates with higher incidence of sub-optimal implants (p = 0.005) but not the age (p = 0.18). Dose-volume-histograms (DVHs) analysis showed large variations for CTV dose coverage: D90 significantly decreased with average of –115.7% ± 134.9% for uterine perforation and –65.2% ± 82.8% for sub-serosal insertion (p = 0.025). The rectum and bladder dose assessed by D2cc increased up to 70.3% and 43.8%, respectively, when sub-optimal insertion of uterine tandem occurred.ConclusionsWe report a low incidence of uterine perforation and sub-serosal insertion of uterine tandem in intracavitary HDR brachytherapy for cervical cancer. However, the effects on treatment plan dosimetry can be considerably detrimental. Therefore, we recommend image-guided insertion, at least for the challenging cases.

SU‐F‐19A‐12: Split‐Ring Applicator with Interstitial Needle for Improved Volumetric Coverage in HDR Brachytherapy for Cervical Cancer

Purpose:To evaluate volumetric coverage of a Mick Radionuclear titanium Split‐Ring applicator (SRA) with/without interstitial needle compared to an intracavitary Vienna applicator (VA), interstitial‐intracavitary VA, and intracavitary ring and tandem applicator (RTA).Methods:A 57 year‐old female with FIGO stage IIB cervical carcinoma was treated following chemoradiotherapy (45Gy pelvic and 5.4Gy parametrial boost) with highdose‐ rate (HDR) brachytherapy to 30Gy in 5 fractions using a SRA. A single interstitial needle was placed using the Ellis Interstitial Cap for the final three fractions to increase coverage of left‐sided gross residual disease identified on 3T‐MRI. High‐risk (HR) clinical target volume (CTV) and intermediate‐risk (IR) CTV were defined using axial T2‐weighted 2D and 3D MRI sequences (Philips PET/MRI unit). Organs‐at‐risks (OARs) were delineated on CT. Oncentra planning system was used for treatment optimization satisfying GEC‐ESTRO guidelines for target coverage and OAR constraints. Retrospectively, treatment plans (additional 20 plans) were simulated using intracavitary SRA (without needle), intracavitary VA (without needle), interstitial‐intracavitary VA, and intracavitary RTA with this same patient case. Plans were optimized for each fraction to maintain coverage to HR‐CTV.Results:Interstitial‐intracavitary SRA achieved the following combined coverage for external radiation and brachytherapy (EQD2): D90 HR‐CTV =94.6Gy; Bladder_2cc =88.9Gy; Rectum_2cc =65.1Gy; Sigmoid_2cc =48.9Gy; Left vaginal wall (VW) =103Gy, Right VW =99.2Gy. Interstitial‐intracavitary VA was able to achieve identical D90 HR‐CTV =94.6Gy, yet Bladder_2cc =91.9Gy (exceeding GEC‐ESTRO recommendations of 2cc&lt;90Gy) and Left VW =120.8Gy and Right VW =115.5Gy. Neither the SRA nor VA without interstitial needle could cover HR‐CTV adequately without exceeding dose to Bladder_2cc. Conventional RTA was unable to achieve target coverage for the HR‐CTV &gt;80Gy without severely overdosing OARs.Conclusion:The Ellis Interstitial Cap for the SRA offered superior dosimetric coverage as compared to the interstitialintracavitary VA. This represents the first reported use for this devise, and further investigation is warranted.

Feasibility of Combined Intracavitary-Interstitial High-Dose-Rate Brachytherapy With a Novel MR-Compatible Split-Ring Applicator

The purpose of this study is to demonstrate clinical feasibility and preliminary dosimetric evaluation of combined intracavitary-interstitial HDR brachytherapy for cervical cancer, using a novel split-ring applicator and three-dimensional (3D) volume based treatment planning. A 43-year old female with Stage IIB cervical cancer underwent external beam radiation therapy (EBRT) with a 4-field technique to 45 Gy followed by a left-sided parametrial boost to a total dose of 50.4 Gy. The EBRT was combined with high-dose-rate (HDR) brachytherapy to deliver an additional 30 Gy in six fractions. The HDR brachytherapy was delivered using a novel MR compatible split-ring applicator with needle guide-holes in the split-ring caps allowing placement of interstitial needles (Figure, panel A). MRI and CT were used for delineating high risk clinical target volume (HR-CTV) and intermediate risk clinical target volume (IR-CTV) and 3D volume based treatment planning was performed. The patient had persistent T2 signal abnormality on MRI within the left corpus immediately adjacent to the bladder. Due to the unfavorable organ-at-risk (OAR) topography and extent of disease, a single interstitial needle was placed at the site of the MRI T2 weighted signal abnormality and two treatment plans were generated one with intracavitary applicators alone and the other with combined intracavitary applicators and interstitial needle. The DVHs for HR-CTV and IR-CTV and OARs (rectum, bladder, and bowel) were compared between the intracavitary and the combined intracavitary-interstitial applications for a single HDR application. The placement of the split-ring applicator and interstitial needle was well tolerated by the patient and completed under conscious sedation in a dedicated HDR brachytherapy suite. The MR compatible split ring applicator allowed clear delineation of the target volumes, OARs and their spatial relationships with the applicator when using conventional MRI pulse sequences. Using the intracavitary split-ring applicator alone, the D90 to the HR-CTV was 5.7 Gy. When a combined interstitial and intracavitary approach was employed, the D90 of HR-CTV increased to 7.2 Gy, an increase of 26.3%, which allowed the total EQD2 dose of HR-CTV increasing to about 89Gy (ABS guideline is EQD2 80-90Gy). The dose to the IR-CTV improved marginally (1.5%). The dose to the bladder was reduced from 6.3Gy (EQD2= 99 Gy) to 4.6Gy (Eqd2=86Gy) achieving ABS recommended dose constraints of 90 Gy (EQD2). The Figure demonstrates in panel A the MR compatbile split-ring applicator. In panel B is the axial CT slice showing the titanium needle placed in the target volume. Panel C presents the prescribed isodose distribution and panel D depicts the 3D view of the applicators with respect to patient anatomy. This preliminary study demonstrates the dosimetric advantages and clinical feasibility of using a combined intracavitary and interstitial split-ring applicator in patients with significant residual disease after completing external beam radiation therapy. In this study, the addition of a solitary interstitial needle provided substantial reduction of bladder dose and improved the dose coverage to the high-risk target volume. Further clinical investigation in a larger patient cohort is warranted to explore the dosimetric advantages of this approach and evaluate if these advantages translate into improved clinical outcomes.

Pain Assessment during Conscious Sedation for Cervical Cancer High-Dose-Rate Brachytherapy

This observational study set out to evaluate the effectiveness of conscious sedation anesthesia for pain control during high-dose-rate (hdr) brachytherapy using a ring-and-tandem applicator system for patients with cervical cancer. At the time of initiation of the hdr cervical cancer brachytherapy program at our institution, patients received a detailed symptom assessment during the procedures. Brachytherapy was carried out using a Smit sleeve, together with a ring-and-tandem applicator. Midazolam and an opioid-hydromorphone, morphine, or fentanyl-were the main agents used to achieve conscious sedation. From January 2009 to October 2010, 20 patients (median age: 45 years) underwent 57 procedures. All patients received chemoradiation with curative intent. The median duration of the procedures was 1.4 hours, and no significant cardiovascular events were noted. The total dose of intravenous midazolam used ranged from 0.5 mg to 8.5 mg (median: 2.5 mg). The total dose of intravenous morphine equivalent used ranged from 2.5 mg to 60 mg (median: 8 mg). The mean and median pain scores during the procedures were 1.4 and 1.1 respectively. Brief moments of moderate to severe incidental pain were noted at the time of certain events during the procedure-specifically during insertion of the ring-and-tandem applicator. The maximal pain score during the entire procedure ranged from 0 to 10 (median: 4.7). The period of recovery from conscious sedation was relatively brief (median discharge time: 1 hour). We were able to demonstrate that patients undergoing hdr brachytherapy for cervical cancer can achieve good pain control with conscious sedation.

Dosimetric Evaluation of Autosegmentation Software to Contour Normal Tissues in Multi-fractional HDR Brachytherapy for Cervical Cancer

Previously, it was demonstrated that Atlas-Based Autosegmentation (ABAS, Elekta CMS, St. Louis, MO) could be used to contour normal organs in multi-fractional high dose rate (HDR) brachytherapy cases, despite difficulties that may arise from metal artifacts caused by the applicator. The goal of this study is to quantify the degree of autosegmented contour accuracy that is required to achieve a high level of dosimetric agreement with contours that are outlined by an expert user.

Cone Beam CT-Based Three-Dimensional Planning in High-Dose-Rate Brachytherapy for Cervical Cancer

To evaluate dose-volume histograms (DVHs) of bladder and rectum from the use of cone beam CT (CBCT)-based three-dimensional (3D) treatment planning in intracavitary high-dose-rate brachytherapy (HDRB) for cervical cancer patients and to compare these parameters with International Commission on Radiation Units and Measurements (ICRU) of rectal and bladder reference point dose measurements. Thirteen patients with cervical cancer underwent HDRB insertions. CT-compatible tandem and ovoid applicators were used to obtain intraoperative CBCT images. The use of a rectal tube and injection of bladder contrast before scanning facilitated contouring the rectum and bladder. All patients underwent intraoperative orthogonal x-ray filming, and treatments were prescribed using standard two-dimensional planning and dosimetry. DVHs for the bladder and rectum were constructed for each treatment. The minimum dose in the most irradiated 2.0-cm(3) volume of bladder (B(D2V)) and rectum (R(D2V)) were determined from DVHs and compared to ICRU reference point estimates of bladder (B(ICRU)) and rectum (R(ICRU)) doses. Twenty-six CBCT-based plans were evaluated. The median B(ICRU) dose (347 cGy; range, 164-601 cGy) was significantly lower (p < 0.001) than the median B(D2V) (594 cGy; range, 260-969 cGy). The median R(ICRU) dose (405 cGy; range, 189-700 cGy) was also significantly lower (p = 0.037) than the median R(D2V) (488 cGy; range, 227-786 cGy). CBCT-based 3D planning can be used in HDRB for cervical cancer and is a convenient alternative to CT-based planning, with the advantage of minimizing applicator motion. Correlation with late effects will further define the role of CBCT-based 3D dosimetry in HDRB planning.

140 poster: Chemoradiotherapy or Radiotherapy Including Highdose-rate Brachytherapy for Cervical Cancer in Elderly Women

140 poster: Chemoradiotherapy or Radiotherapy Including Highdose-rate Brachytherapy for Cervical Cancer in Elderly Women

Correlation of Point B and Lymph Node Dose in 3D-Planned High-Dose-Rate Cervical Cancer Brachytherapy

To compare high dose rate (HDR) point B to pelvic lymph node dose using three-dimensional-planned brachytherapy for cervical cancer. Patients with FIGO Stage IB-IIIB cervical cancer received 70 tandem HDR applications using CT-based treatment planning. The obturator, external, and internal iliac lymph nodes (LN) were contoured. Per fraction (PF) and combined fraction (CF) right (R), left (L), and bilateral (Bil) nodal doses were analyzed. Point B dose was compared with LN dose-volume histogram (DVH) parameters by paired t test and Pearson correlation coefficients. Mean PF and CF doses to point B were R 1.40 Gy +/- 0.14 (CF: 7 Gy), L 1.43 +/- 0.15 (CF: 7.15 Gy), and Bil 1.41 +/- 0.15 (CF: 7.05 Gy). The correlation coefficients between point B and the D100, D90, D50, D2cc, D1cc, and D0.1cc LN were all less than 0.7. Only the D2cc to the obturator and the D0.1cc to the external iliac nodes were not significantly different from the point B dose. Significant differences between R and L nodal DVHs were seen, likely related to tandem deviation from irregular tumor anatomy. With HDR brachytherapy for cervical cancer, per fraction nodal dose approximates a dose equivalent to teletherapy. Point B is a poor surrogate for dose to specific nodal groups. Three-dimensional defined nodal contours during brachytherapy provide a more accurate reflection of delivered dose and should be part of comprehensive planning of the total dose to the pelvic nodes, particularly when there is evidence of pathologic involvement.

A Study of Complications Arising From Different Methods of Anesthesia Used in High-Dose-Rate Brachytherapy for Cervical Cancer

The purpose of this report is to review the complications related to different methods of anesthesia for high-dose-rate (HDR) brachytherapy for cervical carcinoma. All patients diagnosed with cervical cancer between 1999 and 2002 treated with 3-channel HDR brachytherapy were entered. Complications due to anesthesia for each fraction of brachytherapy were graded using the Common Toxicity Criteria. Eighty-four fractions of brachytherapy were delivered to 18 patients: 19 fractions with patients under general anesthesia (GA), 41 with patients under topical anesthesia and sedation, 5 with patients under paracervical nerve block, and 19 with patients under conscious sedation. Thirteen complications were reported: 12 related to GA and 1 due to paracervical nerve block. Of complications due to GA, 7 were grade 1 and 5 were grade 2. The complication due to paracervical nerve block (seizure) was grade 3. GA had significantly more complications than topical anesthesia or conscious sedation (both P < 0.001). HDR brachytherapy for cervical cancer under GA has significantly more complications than other methods. Given the increasing use of fractionated 3-channel brachytherapy, further investigation of risks and benefits of anesthetic techniques is required.

The American Brachytherapy Society recommendations for high-dose-rate brachytherapy for carcinoma of the cervix

Purpose: This report presents guidelines for using high-dose-rate (HDR) brachytherapy in the management of patients with cervical cancer, taking into consideration the current availability of resources in most institutions. Methods: Members of the American Brachytherapy Society (ABS) with expertise in HDR brachytherapy for cervical cancer performed a literature review, supplemented their clinical experience to formulate guidelines for HDR brachytherapy of cervical cancer. Results: The ABS strongly recommends that definitive irradiation for cervical carcinoma must include brachytherapy as a component. Each institution should follow a consistent treatment policy when performing HDR brachytherapy, including complete documentation of treatment parameters and correlation with clinical outcome, such as pelvic control, survival, and complications. The goals are to treat Point A to at least a total low-dose-rate (LDR) equivalent of 80–85 Gy for early stage disease and 85–90 Gy for advanced stage. The pelvic sidewall dose recommendations are 50–55 Gy for early lesions and 55–65 Gy for advanced ones. The relative doses given by external beam radiation therapy (EBRT) vs. brachytherapy depend upon the initial volume of disease, the ability to displace the bladder and rectum, the degree of tumor regression during pelvic irradiation, and institutional preference. As with LDR brachytherapy, every attempt should be made to keep the bladder and rectal doses below 80 Gy and 75 Gy LDR equivalent doses, respectively. Interstitial brachytherapy should be considered for patients with disease that cannot be optimally encompassed by intracavitary brachytherapy. While recognizing that many efficacious HDR fractionation schedules exist, some suggested dose and fractionation schemes for combining the EBRT with HDR brachytherapy for each stage of disease are presented. These recommendations are intended only as guidelines, and the suggested fractionation schemes have not been thoroughly tested. The responsibility for the medical decisions ultimately rests with the treating radiation oncologist. Conclusion: Guidelines are established for HDR brachytherapy for cervical cancer. Practitioners and cooperative groups are encouraged to use these guidelines to formulate their treatment and dose-reporting policies. These guidelines will be modified, as image-based treatment becomes more widely available.