Volumetric (3D) bladder dose parameters are more reproducible than point (2D) dose parameters in vaginal vault high-dose-rate brachytherapy.
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ABSTRACT:
SUBMITTER: Sapienza LG
PROVIDER: S-EPMC4906382 | biostudies-other | 2016 Jun
REPOSITORIES: biostudies-other
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Project description:OBJECTIVE: This quality assurance study assesses whether CT image-guided verification has led to improvements in the technique when compared with previous studies. METHODS: The CT images were studied from a cohort of 105 consecutive patients with endometrial cancer having adjuvant brachytherapy to the vaginal vault in 2010. Images were taken at first insertion, checked for air gaps and treatment delivered. Images were later transferred to the planning system and air gaps between vaginal mucosa and vaginal cylinder were measured. Comparisons were made with the 2008 results from this centre and the literature series. RESULTS: Images from two patients were not assessable owing to artefacts from hip replacements. Air gaps >2 mm were seen in 11/103 patients. Repositioning or use of a larger cylinder reduced air gaps to 7/103 patients. In total, 96/103 patients (over 93%) were able to achieve good vaginal contact throughout the treatment volume. This shows a significant improvement in applicator positioning in our centre since 2008 and also a significant improvement over the total data published in 2010 (Pearson χ(2) test=46.19; p<0.0001). CONCLUSION: The vaginal cylinder technique with CT imaging was proven to be effective for 96/103 patients. It is necessary to consider whether there is a better technique for the few patients with air gaps >2 mm. ADVANCES IN KNOWLEDGE: For the vast majority of patients, this technique is well tolerated, without the need for analgesia, and will continue to be the first choice technique in this centre.
| S-EPMC3608053 | biostudies-other
Project description:This study was designed to determine whether volumetric imaging could identify consistent alternative prescription methods to Manchester/point A when prescribing radiation dose in the treatment of cervical cancer using HDR intracavitary brachy-therapy (ICBT). One hundred and twenty-five treatment plans of 25 patients treated for carcinoma of the cervix were reviewed retrospectively. Each patient received 5 fractions of HDR ICBT following initial cisplatin-based pelvic chemoradiation, and radiation dose was originally prescribed to point A (ICRU-38). The gross tumor volume (GTV) and high-risk clinical target volume (HR-CTV) were contoured in three dimensions on the CT datasets, and inferior-superior, anterior-posterior, and left-right dimensions HR-CTV were recorded along with multiple anatomic and skeletal dimensions for each patient. The least square-best fit regression lines were plotted between one half of the HR-CTV width and pelvic cavity dimension at femoral head level and at maximum cavity dimension. The points in both plots lie reasonably close to straight lines and are well defined by straight lines with slopes of 0.15 and 0.17; intercept on y-axes of -0.08 and -0.03, point A, at the same level as defined based on applicator coordinates, is defined using this correlation, which is a function of distance between femoral heads/dimensions of maximum pelvic cavity width. Both relations, defined by straight lines, provide an estimated location of point A, which provides adequate coverage to the HR-CTV compared to the point A defined based on applicator coordinates. The point A defined based on femoral head distance would, therefore, be a reasonable surrogate to use for dose prescription because of subjective variation of cavity width dimension. Simple surrogate anatomic/skeletal landmarks can be useful for prescribing radiation dose when treating cervical cancer using intracavitary brachytherapy in limited-resource settings. Our ongoing work will continue to refine these models.
| S-EPMC5690503 | biostudies-literature
Project description:PurposeThe goal of this study was to assess the effectiveness of dysphagia relief and overall survival in patients with advanced esophageal cancer treated with palliative high-dose-rate (HDR) brachytherapy (BT) without computed tomography-based planning.Material and methodsPalliative 2D HDR-BT was used to treat 93 patients with advanced or incurable esophageal cancer in a regional cancer center from October 2010 to December 2016. Before the treatment patients presented the following grades of dysphagia: 0 - 0%, I - 57%, II - 33.3%, III - 6.5%, IV - 3.2%. The planned dose was 22.5 Gy in 3 fractions. The median age of patients was 65 years (45-88). Squamous cell carcinoma was diagnosed in 59.4%, adenocarcinoma in 22.6%, and other histological types of tumors in 6.7% of cases. The histopathological report was unknown in 11.3% of patients.ResultsThe mean follow-up was 5.0 months (range 1-43). The median tumor length was 72.5 mm. Due to BT dysphagia was significantly decreased: grade 0 - 38.7%, I - 31.2%, II - 20.4%, IV - 1.1% (p < 0.001). Dysphagia relief was achieved in 55% of patients and lasted for a mean time of 4.6 months; stabilization occurred in 31% and deterioration in 14%. The patients with partial or complete dysphagia relief lived longer (5.8 vs. 4.1 months, p = 0.02). The patients with a length of the tumor less than 72.5 mm, histopathologically confirmed adenocarcinoma or after dilatation with a metal stent subsequently to BT had improved overall survival as well (7.1 vs. 3.6; 8.0 vs. 4.1; 6.5 vs. 4.0 months, respectively; p < 0.05). The primary localization and primary grade of dysphagia were not factors that influenced the survival of patients. The logistic regression model did not reveal any predictors for treatment response.Conclusions2D HDR-BT reduces dysphagia and prolongs survival in patients who respond to the treatment. It meets the assumption of palliative treatment for advanced esophageal cancer because of its simplicity and effectiveness.
| S-EPMC6964340 | biostudies-literature
Project description:Radiotherapy of lung and liver lesions has changed from normofractioned 3D-CRT to stereotactic treatment in a single or few fractions, often employing volumetric arc therapy (VMAT)-based techniques. Potential unintended interference of respiratory target motion and dynamically changing beam parameters during VMAT dose delivery motivates establishing 4D quality assurance (4D QA) procedures to assess appropriateness of generated VMAT treatment plans when taking into account patient-specific motion characteristics. Current approaches are motion phantom-based 4D QA and image-based 4D VMAT dose simulation. Whereas phantom-based 4D QA is usually restricted to a small number of measurements, the computational approaches allow simulating many motion scenarios. However, 4D VMAT dose simulation depends on various input parameters, influencing estimated doses along with mitigating simulation reliability. Thus, aiming at routine use of simulation-based 4D VMAT QA, the impact of such parameters as well as the overall accuracy of the 4D VMAT dose simulation has to be studied in detail-which is the topic of the present work. In detail, we introduce the principles of 4D VMAT dose simulation, identify influencing parameters and assess their impact on 4D dose simulation accuracy by comparison of simulated motion-affected dose distributions to corresponding dosimetric motion phantom measurements. Exploiting an ITV-based treatment planning approach, VMAT treatment plans were generated for a motion phantom and different motion scenarios (sinusoidal motion of different period/direction; regular/irregular motion). 4D VMAT dose simulation results and dose measurements were compared by local 3% / 3 mm γ-evaluation, with the measured dose distributions serving as ground truth. Overall γ-passing rates of simulations and dynamic measurements ranged from 97% to 100% (mean across all motion scenarios: 98% ± 1%); corresponding values for comparison of different day repeat measurements were between 98% and 100%. Parameters of major influence on 4D VMAT dose simulation accuracy were the degree of temporal discretization of the dose delivery process (the higher, the better) and correct alignment of the assumed breathing phases at the beginning of the dose measurements and simulations. Given the high γ-passing rates between simulated motion-affected doses and dynamic measurements, we consider the simulations to provide a reliable basis for assessment of VMAT motion effects that-in the sense of 4D QA of VMAT treatment plans-allows to verify target coverage in hypofractioned VMAT-based radiotherapy of moving targets. Remaining differences between measurements and simulations motivate, however, further detailed studies.
| S-EPMC5322962 | biostudies-literature
Project description:PURPOSE:To compare clinical outcomes of MR-based versus CT-based high-dose-rate interstitial brachytherapy (ISBT) for vaginal recurrence of endometrioid endometrial cancer (EC). METHODS AND MATERIALS:We reviewed 66 patients with vaginal recurrent EC; 18 had MR-based ISBT on a prospective clinical trial and 48 had CT-based treatment. Kaplan-Meier survival modeling was used to generate estimates for local control (LC), disease-free interval (DFI), and overall survival (OS), and multivariate Cox modeling was used to assess prognostic factors. Toxicities were evaluated and compared. RESULTS:Median followup was 33 months (CT 30 months, MR 35 months). Median cumulative equivalent dose in 2-Gy fractions was 75.5 Gy for MR-ISBT and 73.8 Gy for CT-ISBT (p = 0.58). MR patients were older (p = 0.03) and had larger tumor size (>4 cm vs. ? 4 cm) compared to CT patients (p = 0.04). For MR-based versus CT-based ISBT, 3-year KM rate for local control was 100% versus 78% (p = 0.04), DFI was 69% versus 55% (p = 0.1), and OS was 63% versus 75% (p = 0.81), respectively. On multivariate analysis, tumor Grade 3 was associated with worse OS (HR 3.57, 95% CI 1.25, 11.36) in a model with MR-ISBT (HR 0.56, 95% CI 0.16, 1.89). Toxicities were not significantly different between the two modalities. CONCLUSION:Despite worse patient prognostic features, MR-ISBT was associated with a significantly better (100%) 3-year local control, comparable survival, and improved DFI rates compared to CT. Toxicities did not differ compared to CT-ISBT patients. Tumor grade contributed as the most significant predictor for survival. Larger prospective studies are needed to assess the impact of MR-ISBT on survival outcomes.
| S-EPMC5698152 | biostudies-literature
Project description:PurposeTo analytically assess the heterogeneity effect of vaginal cylinders (VC) made of high-density plastics on dose calculations, considering the prescription point (surface or 5 mm beyond the surface), and benchmark the accuracy of a commercial model-based dose calculation (MBDC) algorithm using Monte Carlo (MC) simulations.Methods and materialsThe GEANT4 MC code was used to simulate a commercial 192 Ir HDR source and VC, with diameters ranging from 20 to 35 mm, inside a virtual water phantom. Standard plans were generated from a commercial treatment planning system [TPS-BrachyVision ACUROS (BV)] optimized for a treatment length of 5 cm through two dose calculation approaches: (1) assuming all the environment as water (i.e., Dw,w-MC & Dw,w-TG43 ) and (2) accounting for the heterogeneity of VC applicators (i.e., Dw,w-App-MC & Dw,w-App-MBDC ). The compared isodose lines, and dose & energy difference maps were extracted for analysis. In addition, the dose difference on the peripheral surface, along the applicator and at middle of treatment length, as well as apical tip was evaluated.ResultsThe Dw,w-App-MC results indicated that the VC heterogeneity can cause a dose reduction of (up to) % 6.8 on average (for all sizes) on the peripheral surface, translating to 1 mm shrinkage of the isodose lines compared to Dw,w-MC . In addition, the results denoted that BV overestimates the dose on the peripheral surface and apical tip of about 3.7% and 17.9%, respectively, (i.e., Dw,w-App-MBDC vs Dw,w-App-MC ) when prescribing to the surface. However, the difference between the two were negligible at the prescription point when prescribing to 5 mm beyond the surface.ConclusionThe VCs' heterogeneity could cause dose reduction when prescribing dose to the surface of the applicator, and hence increases the level of uncertainty. Thus, reviewing the TG43 results, in addition to ACUROS, becomes prudent, when evaluating the surface coverage at the apex.
| S-EPMC10795442 | biostudies-literature
Project description:INTRODUCTION AND HYPOTHESIS: The objective of this study was to report 1 year anatomical and functional outcomes of trocar-guided total tension-free vaginal mesh (Prolift) repair for post-hysterectomy vaginal vault prolapse with one continuous piece of polypropylene mesh. METHODS: We conducted a prospective observational cohort study of 46 patients. A minimum sample size of 35 patients was needed to detect a recurrence rate of less than 20% at 12 months. Instruments of measurement used were pelvic organ prolapse quantification and validated questionnaires. RESULTS: Overall anatomical success was 91% (95% confidence interval 83-99), with significant improvement in experienced bother and quality of life. Mesh exposure occurred in seven patients (15%). No adverse effects on sexual function could be detected. CONCLUSIONS: Trocar-guided total tension-free vaginal mesh (Prolift) repair with one continuous piece of mesh for post-hysterectomy vaginal vault prolapse is well tolerated and anatomically and functionally highly effective. Results of controlled trials will determine its position in the operative armamentarium.
| S-EPMC2744794 | biostudies-other
Project description:In radiotherapy, air-filled ion chamber detectors are ubiquitously used in routine dose measurements for treatment planning. However, its use has been restricted by intrinsic low spatial resolution barriers. We developed one procedure for patient-specific quality assurance (QA) in arc radiotherapy by coalescing two adjacent measurement images into a single image to improve spatial resolution and sampling frequency, and investigated how different spatial resolutions affect the QA results. PTW 729 and 1500 ion chamber detectors were used for dosimetric verification via coalescing two measurements with 5 mm-couch shift and the isocenter, and only isocenter measurement, which we call coalescence and standard acquisition (SA). Statistical process control (SPC), process capability analysis (PCA), and receiver operating characteristic (ROC) curve were used to compare the performance of the two procedures in determining tolerance levels and identifying clinically relevant errors. By analyzing 1256 γ values calculated on interpolated data points, our results indicated that detector 1500 showed higher averages in coalescence cohorts at different tolerance criteria and the dispersion degrees were spread out smaller. Detector 729 yielded a slightly lower process capability of 0.79, 0.76, 1.10, and 1.34, but detector 1500 exhibited somewhat different results of 0.94, 1.42, 1.19, and 1.60 in magnitude. The results of SPC individual control chart showed that cases in coalescence cohorts with γ values lowering its lower control limit (LCL) were greater than those in SA cohorts for detector 1500. A combination of the width of multi-leaf collimator (MLC) leaf, the cross-sectional area of the single detector, and the spacing between adjacent detectors might lead to discrepancies in percent γ values across diverse spatial resolution scenarios. The accuracy of reconstructed volume dose is mainly determined by the interpolation algorithm used in dosimetric systems. The magnitude of filling factor in the ion chamber detectors determined its ability to detect dose deviations. SPC and PCA results indicated that coalescence procedure could detect more potential failure QA results than SA while enhancing action thresholds.
| S-EPMC10006091 | biostudies-literature
Project description:Derivation of dose-volume correlated with toxicity for multi-modal treatments can be difficult due to the perceived need for voxel-by-voxel dose accumulation. With data available for a single-institution cohort with long follow-up, an investigation was undertaken into rectal dose-volume effects for gastrointestinal toxicities after deformably-registering each phase of a combined external beam radiotherapy (EBRT)/high-dose-rate (HDR) brachytherapy prostate treatment.One hundred and eighteen patients received EBRT in 23 fractions of 2 Gy and HDR (TG43 algorithm) in 3 fractions of 6.5 Gy. Results for the Late Effects of Normal Tissues - Subjective, Objective, Management and Analytic toxicity assessments were available with a median follow-up of 72 months. The HDR CT was deformably-registered to the EBRT CT. Doses were corrected for dose fractionation. Rectum dose-volume histogram (DVH) parameters were calculated in two ways. (1) Distribution-adding: parameters were calculated after the EBRT dose distribution was 3D-summed with the registered HDR dose distribution. (2) Parameter-adding: the EBRT DVH parameters were added to HDR DVH parameters. Logistic regressions and Mann-Whitney U-tests were used to correlate parameters with late peak toxicity (dichotomised at grade 1 or 2).The 48-80, 40-63 and 49-55 Gy dose regions from distribution-adding were significantly correlated with rectal bleeding, urgency/tenesmus and stool frequency respectively. Additionally, urgency/tenesmus and anorectal pain were associated with the 25-26 Gy and 44-48 Gy dose regions from distribution-adding respectively. Parameter-adding also indicated the low-mid dose region was significantly correlated with stool frequency and proctitis.This study confirms significant dose-histogram effects for gastrointestinal toxicities after including deformable registration to combine phases of EBRT/HDR prostate cancer treatment. The findings from distribution-adding were in most cases consistent with those from parameter-adding. The mid-high dose range and near maximum doses were important for rectal bleeding. The distribution-adding mid-high dose range was also important for stool frequency and urgency/tenesmus. We encourage additional studies in a variety of institutions using a variety of dose accumulation methods with appropriate inter-fraction motion management.NCT NCT00193856 . Retrospectively registered 12 September 2005.
| S-EPMC5087115 | biostudies-literature
Project description:BackgroundIn Japan, 8000 women were newly diagnosed with cervical cancer in 2018. The healthcare insurance policy in Japan allows physicians to utilize vaginal volt cytology tests and serum biomarker measurement at every visit and imaging analysis at an adequate interval with screening for recurrence after initial treatment. However, the major surveillance guidelines published in the United States and European countries recommend focusing on pelvic examinations and symptom reviews to avoid unnecessary tests. This study aimed to reassess the benefits of standard surveillance methods adopted in this study by retrospective analysis.MethodsFrom January 2009 to December 2015, the medical records of patients with recurrence who were initially diagnosed with International Federation of Gynecology and Obstetrics stage I-III cervical cancer were collected for this study. Clinicopathological data were statistically analyzed to identify significant factors. In the first 2 years, the patients underwent regular surveillance, including pelvic examination, serum tumor marker tests, vaginal vault cytology every 1-3 months, and imaging analysis at 6- to 12-month intervals. In the following 2 years, the patients received a regular check with the same methods every 4 months and an annual imaging analysis. Afterward, the patients had regular screening every 6 to 12 months.ResultsIn the study period, 84 of the 981 patients experienced recurrence, and 88.1% had an asymptomatic recurrence. The disease-free interval was not related to the recurrence site. In univariate analysis, primary treatment, recurrence site, and diagnostic method were significant factors for survival outcomes. In contrast, multivariate analysis indicated that only primary treatment was a significant factor. In patients with local recurrence, multivariate analysis demonstrated that radiation as salvage therapy was an independent predictive factor for overall survival after recurrence.ConclusionsIn this retrospective study, routine imaging analysis and serum biomarker measurement did not contribute to patient prognosis after recurrence. In contrast, vaginal vault cytology can improve survival after recurrence in some patients. Tailored surveillance methods based on individual disease conditions and treatment modalities can improve post-recurrent survival outcomes.
| S-EPMC10116747 | biostudies-literature