Dataset Information

Gantry-Mounted Linear Accelerator-Based Stereotactic Body Radiation Therapy for Low- and Intermediate-Risk Prostate Cancer.

ABSTRACT: Purpose:To establish the safety and efficacy of gantry-mounted linear accelerator-based stereotactic body radiation therapy (SBRT) for low- and intermediate-risk prostate cancer. Methods:We pooled 921 patients enrolled on 7 single-institution prospective phase II trials of gantry-based SBRT from 2006 to 2017. The cumulative incidences of biochemical recurrence (defined by the Phoenix definition) and physician-scored genitourinary (GU) and gastrointestinal (GI) toxicities (defined per the original trials using Common Terminology Criteria for Adverse Events) were estimated using a competing risk framework. Multivariable logistic regression was used to evaluate the relationship between late toxicity and prespecified covariates: biologically effective dose, every other day versus weekly fractionation, intrafractional motion monitoring, and acute toxicity. Results:Median follow-up was 3.1 years (range, 0.5-10.8 years). In addition, 505 (54.8%) patients had low-risk disease, 236 (25.6%) had favorable intermediate-risk disease, and 180 (19.5%) had unfavorable intermediate-risk disease. Intrafractional motion monitoring was performed in 78.0% of patients. The 3-year cumulative incidence of biochemical recurrence was 0.8% (95% confidence interval [CI], 0-1.7%), 2.2% (95% CI, 0-4.3%), and 5.1% (95% CI, 1.0-9.2%) for low-, favorable intermediate-, and unfavorable intermediate-risk disease. Acute grade ?2 GU and GI toxicity occurred in 14.5% and 4.6% of patients, respectively. Three-year cumulative incidence estimates of late grade 2 GU and GI toxicity were 4.1% (95% CI, 2.6-5.5%) and 1.3% (95% CI, 0.5-2.1%), respectively, with late grade ?3 GU and GI toxicity estimates of 0.7% (95% CI, 0.1-1.3%) and 0.4% (95% CI, 0-0.8%), respectively. The only identified significant predictors of late grade ?2 toxicity were acute grade ?2 toxicity (P < .001) and weekly fractionation (P < .01), although only 12.4% of patients were treated weekly. Conclusions:Gantry-based SBRT for prostate cancer is associated with a favorable safety and efficacy profile, despite variable intrafractional motion management techniques. These findings suggest that multiple treatment platforms can be used to safely deliver prostate SBRT.

SUBMITTER: Dang AT

PROVIDER: S-EPMC7276661 | biostudies-literature | 2020 May-Jun

REPOSITORIES: biostudies-literature

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Gantry-Mounted Linear Accelerator-Based Stereotactic Body Radiation Therapy for Low- and Intermediate-Risk Prostate Cancer.

Dang Audrey T AT Levin-Epstein Rebecca G RG Shabsovich David D Cao Minsong M King Christopher C Chu Fang-I FI Mantz Constantine A CA Stephans Kevin L KL Reddy Chandana A CA Loblaw D Andrew DA Cheung Patrick P Scorsetti Marta M Cozzi Luca L DeNittis Albert S AS Wang Yue Y Zaorsky Nicholas N Nickols Nicholas G NG Kupelian Patrick A PA Steinberg Michael L ML Kishan Amar U AU

Advances in radiation oncology 20191014 3

<h4>Purpose</h4>To establish the safety and efficacy of gantry-mounted linear accelerator-based stereotactic body radiation therapy (SBRT) for low- and intermediate-risk prostate cancer.<h4>Methods</h4>We pooled 921 patients enrolled on 7 single-institution prospective phase II trials of gantry-based SBRT from 2006 to 2017. The cumulative incidences of biochemical recurrence (defined by the Phoenix definition) and physician-scored genitourinary (GU) and gastrointestinal (GI) toxicities (defined ...[more]

PMID: 32529134

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Project description:PurposeTo assess clinically relevant image quality metrics (IQMs) of helical fan beam kilovoltage (kV) fan beam computed tomography (CT).Methods and materialskVCT IQMs were evaluated on an Accuray Radixact unit equipped with helical fan beam kVCT to assess the capabilities of this newly available modality. kVCT IQMs were evaluated and compared to a kVCT simulator and linear accelerator-based cone beam CTs (CBCT) using a commercial CBCT image quality phantom. kVCTs were acquired on the Accuray Radixact for all combinations of kVp and mAs in fine mode using a 440-mm field of view (FOV). Evaluated IQMs were spatial resolution, overall uniformity, subject contrast, contrast-to-noise ratio (CNR), and effective slice thickness. Imaging dose was assessed for planar kV imaging.ResultsOn this kVCT system spatial resolution and contrast were consistent across all settings with 0.28 ± 0.03 lp/mm and 9.8% ± 0.7% (both 95% confidence interval). CNR strongly depended on selected mode (views per rotation) and body size (mA per view) and ranged between 7.9 and 34.9. Overall uniformity was greater than 97% for all settings. Large FOV was not found to substantially affect the IQMs whereas small FOV affected IQMs due to its effect on pitch. Technique-matched CT simulator scans were comparable for uniformity and contrast, while spatial resolution was higher (0.43 ± 0.06 lp/mm), and CNR was between 4% (140 kVp) and 51% (100 kVp) lower. For kV-CBCT, spatial resolutions ranging from 0.37 to 0.44 lp/mm were achieved with comparable contrast, CNR, and uniformity to kVCT. All kVCT scans exhibit imaging artifacts due to helical acquisition. Clinical acquisitions of megavoltage (MV) CT, kV-CBCT, and kVCT on the same patient showed improved and comparable image quality of kVCT compared to MVCT and kV-CBCT, respectively.ConclusionsHelical fan beam kVCT allows for daily image guidance for localization and setup verification with comparable performance to existing kV-CBCT systems. Scan parameters must be selected carefully to maximize image quality for the desired tasks. Due to the large effective slice thicknesses for all parameter combinations, kVCT scans should not be used for simulation or planning of stereotactic procedures. Finally, improved image quality over MVCT has the potential to greatly improve manual and automated adaptive monitoring and planning.

Project description:Our previous work on early PSA kinetics following prostate stereotactic body radiation therapy (SBRT) demonstrated that an initial rapid and then slow PSA decline may result in very low PSA nadirs. This retrospective study sought to evaluate the PSA nadir 5 years following SBRT for low- and intermediate-risk prostate cancer (PCa).65 low- and 80 intermediate-risk PCa patients were treated definitively with SBRT to 35-37.5 Gy in 5 fractions at Georgetown University Hospital between January 2008 and October 2011. Patients who received androgen deprivation therapy were excluded from this study. Biochemical relapse was defined as a PSA rise >2 ng/ml above the nadir and analyzed using the Kaplan-Meier method. The PSA nadir was defined as the lowest PSA value prior to biochemical relapse or as the lowest value recorded during follow-up. Prostate ablation was defined as a PSA nadir <0.2 ng/ml. Univariate logistic regression analysis was used to evaluate relevant variables on the likelihood of achieving a PSA nadir <0.2 ng/ml.The median age at the start of SBRT was 72 years. These patients had a median prostate volume of 36 cc with a median 25% of total cores involved. At a median follow-up of 5.6 years, 86 and 37% of patients achieved a PSA nadir ≤0.5 and <0.2 ng/ml, respectively. The median time to PSA nadir was 36 months. Two low and seven intermediate risk patients experienced a biochemical relapse. Regardless of the PSA outcome, the median PSA nadir for all patients was 0.2 ng/ml. The 5-year biochemical relapse free survival (bRFS) rate for low- and intermediate-risk patients was 98.5 and 95%, respectively. Initial PSA (p = 0.024) and a lower testosterone at the time of the PSA nadir (p = 0.049) were found to be significant predictors of achieving a PSA nadir <0.2 ng/ml.SBRT for low- and intermediate-risk PCa is a convenient treatment option with low PSA nadirs and a high rate of early bRFS. Fewer than 40% of patients, however, achieved an ablative PSA nadir. Thus, the role of further dose escalation is an area of active investigation.

Project description:IntroductionParaspinal stereotactic body radiotherapy (SBRT) involves risks of severe complications. We evaluated the safety of the paraspinal SBRT program in a large academic hospital by applying failure modes and effects analysis.MethodsThe analysis was conducted by a multidisciplinary committee (two therapists, one dosimetrist, four physicists, and two radiation oncologists). The paraspinal SBRT workflow was segmented into four phases (simulation, treatment planning, delivery, and machine quality assurance (QA)). Each phase was further divided into a sequence of sub-processes. Potential failure modes (PFM) were identified from each subprocess and scored in terms of the frequency of occurrence, severity and detectability, and a risk priority number (RPN). High-risk PFMs were identified based on RPN and were studied for root causes using fault tree analysis.ResultsOur paraspinal SBRT process was characterized by eight simulations, 11 treatment planning, nine delivery, and two machine QA sub-processes. There were 18, 29, 19, and eight PFMs identified from simulation, planning, treatment, and machine QA, respectively. The median RPN of the PFMs was 62.9 for simulation, 68.3 for planning, 52.9 for delivery, and 22.0 for machine QA. The three PFMs with the highest RPN were: previous radiotherapy outside the institution is not accurately evaluated (RPN: 293.3), incorrect registration between diagnostic magnetic resonance imaging and simulation computed tomography causing incorrect contours (273.0), and undetected patient movement before ExacTrac baseline (217.8). Remedies to the high RPN failures were implemented, including staff education, standardized magnetic resonance imaging acquisition parameters, and an image fusion process, and additional QA on beam steering.ConclusionsA paraspinal SBRT workflow in a large clinic was evaluated using a multidisciplinary and systematic risk analysis, which led to feasible solutions to key root causes. Treatment planning was a major source of PFMs that systematically affect the safety and quality of treatments. Accurate evaluation of external treatment records remains a challenge.

Project description:ImportanceStereotactic body radiotherapy harnesses improvements in technology to allow the completion of a course of external beam radiotherapy treatment for prostate cancer in the span of 4 to 5 treatment sessions. Although mounting short-term data support this approach, long-term outcomes have been sparsely reported.ObjectiveTo assess long-term outcomes after stereotactic body radiotherapy for low-risk and intermediate-risk prostate cancer.Design, setting, and participantsThis cohort study analyzed individual patient data from 2142 men enrolled in 10 single-institution phase 2 trials and 2 multi-institutional phase 2 trials of stereotactic body radiotherapy for low-risk and intermediate-risk prostate cancer between January 1, 2000, and December 31, 2012. Statistical analysis was performed based on follow-up from January 1, 2013, to May 1, 2018.Main outcomes and measuresThe cumulative incidence of biochemical recurrence was estimated using a competing risk framework. Physician-scored genitourinary and gastrointestinal toxic event outcomes were defined per each individual study, generally by Radiation Therapy Oncology Group or Common Terminology Criteria for Adverse Events scoring systems. After central review, cumulative incidences of late grade 3 or higher toxic events were estimated using a Kaplan-Meier method.ResultsA total of 2142 men (mean [SD] age, 67.9 [9.5] years) were eligible for analysis, of whom 1185 (55.3%) had low-risk disease, 692 (32.3%) had favorable intermediate-risk disease, and 265 (12.4%) had unfavorable intermediate-risk disease. The median follow-up period was 6.9 years (interquartile range, 4.9-8.1 years). Seven-year cumulative rates of biochemical recurrence were 4.5% (95% CI, 3.2%-5.8%) for low-risk disease, 8.6% (95% CI, 6.2%-11.0%) for favorable intermediate-risk disease, 14.9% (95% CI, 9.5%-20.2%) for unfavorable intermediate-risk disease, and 10.2% (95% CI, 8.0%-12.5%) for all intermediate-risk disease. The crude incidence of acute grade 3 or higher genitourinary toxic events was 0.60% (n = 13) and of gastrointestinal toxic events was 0.09% (n = 2), and the 7-year cumulative incidence of late grade 3 or higher genitourinary toxic events was 2.4% (95% CI, 1.8%-3.2%) and of late grade 3 or higher gastrointestinal toxic events was 0.4% (95% CI, 0.2%-0.8%).Conclusions and relevanceIn this study, stereotactic body radiotherapy for low-risk and intermediate-risk disease was associated with low rates of severe toxic events and high rates of biochemical control. These data suggest that stereotactic body radiotherapy is an appropriate definitive treatment modality for low-risk and intermediate-risk prostate cancer.

Project description:The purpose of this study is to characterize the dosimetric properties and accuracy of a novel treatment platform (Edge radiosurgery system) for localizing and treating patients with frameless, image-guided stereotactic radiosurgery (SRS) and stereotactic body radiotherapy (SBRT). Initial measurements of various components of the system, such as a comprehensive assessment of the dosimetric properties of the flattening filter-free (FFF) beams for both high definition (HD120) MLC and conical cone-based treatment, positioning accuracy and beam attenuation of a six degree of freedom (6DoF) couch, treatment head leakage test, and integrated end-to-end accuracy tests, have been performed. The end-to-end test of the system was performed by CT imaging a phantom and registering hidden targets on the treatment couch to determine the localization accuracy of the optical surface monitoring system (OSMS), cone-beam CT (CBCT), and MV imaging systems, as well as the radiation isocenter targeting accuracy. The deviations between the percent depth-dose curves acquired on the new linac-based system (Edge), and the previously published machine with FFF beams (TrueBeam) beyond D(max) were within 1.0% for both energies. The maximum deviation of output factors between the Edge and TrueBeam was 1.6%. The optimized dosimetric leaf gap values, which were fitted using Eclipse dose calculations and measurements based on representative spine radiosurgery plans, were 0.700 mm and 1.000 mm, respectively. For the conical cones, 6X FFF has sharper penumbra ranging from 1.2-1.8 mm (80%-20%) and 1.9-3.8 mm (90%-10%) relative to 10X FFF, which has 1.2-2.2mm and 2.3-5.1mm, respectively. The relative attenuation measurements of the couch for PA, PA (rails-in), oblique, oblique (rails-out), oblique (rails-in) were: -2.0%, -2.5%, -15.6%, -2.5%, -5.0% for 6X FFF and -1.4%, -1.5%, -12.2%, -2.5%, -5.0% for 10X FFF, respectively, with a slight decrease in attenuation versus field size. The systematic deviation between the OSMS and CBCT was -0.4 ± 0.2 mm, 0.1± 0.3mm, and 0.0 ± 0.1 mm in the vertical, longitudinal, and lateral directions. The mean values and standard deviations of the average deviation and maximum deviation of the daily Winston-Lutz tests over three months are 0.20 ± 0.03 mm and 0.66 ± 0.18 mm, respectively. Initial testing of this novel system demonstrates the technology to be highly accurate and suitable for frameless, linac-based SRS and SBRT treatment.

Dataset Information

Gantry-Mounted Linear Accelerator-Based Stereotactic Body Radiation Therapy for Low- and Intermediate-Risk Prostate Cancer.

Publications

Gantry-Mounted Linear Accelerator-Based Stereotactic Body Radiation Therapy for Low- and Intermediate-Risk Prostate Cancer.

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