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Smith, Benjamin D.

Publications and source records attributed to Smith, Benjamin D..

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Geographic Access to Radiation Therapy Facilities in the United States

The current distribution of radiation therapy (RT) facilities in the United States is not well established. A comprehensive inventory of U.S. RT facilities was last assessed in 2005, based on data from state regulatory agencies and dosimetric quality assurance bodies. We updated this database to characterize population-level measures of geographic access to RT and analyze changes over the past 15 years.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Patient Selection for Clinical Trials Eliminating Surgery for HER2-Positive Breast Cancer Treated with Neoadjuvant Systemic Therapy

Background: Patients with epidermal growth factor receptor 2-positive (HER2+) breast cancer and pathologic complete response (pCR) after neoadjuvant systemic therapy (NST) may be candidates for nonoperative clinical trials if residual invasive and in situ disease are eradicated. Methods: This study analyzed 280 patients with clinical T1-2N0-1 HER2+ breast cancer who underwent NST followed by surgical resection to determine key characteristics of patients with pCR in the breast and lymph nodes compared with those with residual disease. Results: Of the 280 patients, 102 (36.4%) had pCR in the breast and lymph nodes after NST, and 50 patients (17.9%) had residual ductal carcinoma in situ (DCIS) in the breast only. For 129 patients (46.1%), DCIS was present on the pretreatment biopsy, and NST failed to eradicate the DCIS component in 64.3%. Patients with residual disease were more likely to have hormone receptor-positive (HR+) tumors than those with negative tumors (73.4% vs. 50.8%; p < 0.0001). Radiologic response (odds ratio [OR], 5.62; p = 0.002) and HR+ status (OR, 2.56; p < 0.0001) were predictive of residual disease. Combined imaging methods after NST had a sensitivity of 97.1% and a negative predictive value of 70.6% for detection of residual disease. Patients with invasive disease and DCIS shown on the pretreatment core biopsy were less likely than those without DCIS to achieve pCR in the breast (31% vs. 43%; p = 0.038). Conclusion: The study results delineate and identify unique characteristics associated with HER2+ breast cancers that are important in selecting patients for inclusion in clinical trials assessing nonoperative management after NST, and the low negative predictive value of imaging mandates image-guided biopsy for selection.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Neoadjuvant Radiotherapy to Facilitate Immediate Breast Reconstruction: A Systematic Review and Current Clinical Trials

Background: Postmastectomy radiotherapy currently is used for locally advanced breast cancers that carry a high risk of locoregional failure. However, radiotherapy can have deleterious effects on immediate breast reconstruction (IBR). Neoadjuvant radiotherapy (NART) to facilitate postmastectomy IBR is an emerging new therapeutic sequence. A systematic review was undertaken to evaluate the current evidence on the feasibility and safety of this sequence. Methods: A comprehensive search of MEDLINE, EMBASE, Cochrane Library, Web of Science, and ClinicalTrials.gov from inception to 2018 was conducted, resulting in 592 records. The review included 18 retrospective and prospective studies of NART and IBR. Results: The majority of the studies used whole-breast radiotherapy with 50 Gy, conventionally fractionated, and waited 6–8 weeks before surgery. The IBR methods were varied, with both implant and autologous reconstructions. No intraoperative complications occurred, and the postoperative complication rates ranged from 3 to 36%. The partial and total flap loss rates were very low. Studies reporting cosmetic outcomes rated the majority of cases as good or excellent. The pathologic complete response rates ranged from 17 to 55%, and the locoregional recurrence rates were low (≤ 10%), with a short follow-up period. The current MD Anderson Cancer Center prospective clinical trial is described. Conclusions: The initial results of NART and IBR demonstrate the safety of this treatment both technically and oncologically. Longer follow-up evaluation of these studies and larger prospective controlled clinical trials are needed to establish this new therapeutic sequence as a standard of care.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

The Radiation Oncology Job Market: The Economics and Policy of Workforce Regulation

Examinations of the US radiation oncology workforce offer inconsistent conclusions, but recent data raise significant concerns about an oversupply of physicians. Despite these concerns, residency slots continue to expand at an unprecedented pace. Employed radiation oncologists and professional corporations with weak contracts or loose ties to hospital administrators would be expected to suffer the greatest harm from an oversupply. The reduced cost of labor, however, would be expected to increase profitability for equipment owners, technology vendors, and entrenched professional groups. Policymakers must recognize that the number of practicing radiation oncologists is a poor surrogate for clinical capacity. There is likely to be significant opportunity to augment capacity without increasing the number of radiation oncologists by improving clinic efficiency and offering targeted incentives for geographic redistribution. Payment policy changes significantly threaten radiation oncologists' income, which may encourage physicians to care for greater patient loads, thereby obviating more personnel. Furthermore, the implementation of alternative payment models such as Medicare's Oncology Care Model threatens to decrease both the utilization and price of radiation therapy by turning referring providers into cost-conscious consumers. Medicare funds the vast majority of graduate medical education, but the extent to which the expansion in radiation oncology residency slots has been externally funded is unclear. Excess physician capacity carries a significant risk of harm to society by suboptimally allocating intellectual resources and creating comparative shortages in other, more needed disciplines. There are practical concerns associated with a market-based solution in which medical students self-regulate according to job availability, but antitrust law would likely forbid collaborative self-regulation that purports to restrict supply. Because Congress is unlikely to create one central body to govern residency controls for all specialties, we recommend better reporting of program-specific employment metrics and careful, intellectually honest re-evaluation of existing Accreditation Council for Graduate Medical Education accreditation standards.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2016

Outcomes of Post Mastectomy Radiation Therapy in Patients Receiving Axillary Lymph Node Dissection After Positive Sentinel Lymph Node Biopsy

Purpose: We sought to determine the rate of postmastectomy radiation therapy (PMRT) among women treated with axillary lymph node dissection (ALND) after positive sentinel lymph node (SLN) biopsy results and to establish the effect of negative ALND results and PMRT on locoregional recurrence (LRR) and overall survival (OS). Methods and Materials: All patients were treated with mastectomy and ALND after positive SLN biopsy results. All patients had clinical N0 or NX disease at the time of mastectomy and received no neoadjuvant therapy. The presence of lymphovascular space invasion, presence of multifocality, number of positive SLNs and non-SLNs, clinical and pathologic stage, extranodal extension, age, and use of PMRT were evaluated for significance regarding the rates of OS and LRR. Results: A total of 345 patients were analyzed. ALND after positive SLN biopsy results was negative in 235 patients (68.1%), and a total of 112 patients (32.5%) received radiation therapy. On multivariate analysis, only pathologic stage III predicted for lower OS (hazard ratio, 3.32; P<.001). The rate of 10-year freedom from LRR was 87.9% and 95.3% in patients with positive ALND results and patients with negative ALND results, respectively. In patients with negative ALND results with ≥3 positive SLNs, the rate of freedom from LRR was 74.7% compared with 96.7% in those with <3 positive SLNs (P=.009). In patients with negative ALND results, ≥3 positive SLNs predicted for an increase in LRR on multivariate analysis (hazard ratio, 10.10; P=.034). Conclusions: A low proportion of cT1-2, N0 patients with positive SLNs who undergo mastectomy receive PMRT after ALND. Even in this low-risk cohort, patients with ≥3 positive SLNs and negative ALND results are at increased risk of LRR and may benefit from PMRT.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Contemporary Toxicity Profile of Breast Brachytherapy Versus External Beam Radiation After Lumpectomy for Breast Cancer

Purpose: We compared toxicities after brachytherapy versus external beam radiation therapy (EBRT) in contemporary breast cancer patients. Methods and Materials: Using MarketScan healthcare claims, we identified 64,112 women treated from 2003 to 2012 with lumpectomy followed by radiation (brachytherapy vs EBRT). Brachytherapy was further classified by multichannel versus single-channel applicator approach. We identified the risks and predictors of 1-year infectious and noninfectious postoperative adverse events using logistic regression and temporal trends using Cochran-Armitage tests. We estimated the 5-year Kaplan-Meier cumulative incidence of radiation-associated adverse events. Results: A total of 4522 (7.1%) patients received brachytherapy (50.2% multichannel vs 48.7% single-channel applicator). The overall risk of infectious adverse events was higher after brachytherapy than after EBRT (odds ratio [OR] = 1.21; 95% confidence interval [CI] 1.09-1.34, P<.001). However, over time, the frequency of infectious adverse events after brachytherapy decreased, from 17.3% in 2003 to 11.6% in 2012, and was stable after EBRT at 9.7%. Beyond 2007, there were no longer excess infections with brachytherapy (P=.97). The overall risk of noninfectious adverse events was higher after brachytherapy than after EBRT (OR=2.27; 95% CI 2.09-2.47, P<.0001). Over time, the frequency of noninfectious adverse events detected increased: after multichannel brachytherapy, from 9.1% in 2004 to 18.9% in 2012 (Ptrend = .64); single-channel brachytherapy, from 12.8% to 29.8% (Ptrend<.001); and EBRT, from 6.1% to 10.3% (Ptrend<.0001). The risk was significantly higher with single-channel than with multichannel brachytherapy (hazard ratio = 1.32; 95% CI 1.03-1.69, P=.03). Of noninfectious adverse events, 70.9% were seroma. Seroma significantly increased breast pain risk (P<.0001). Patients with underlying diabetes, cardiovascular disease, and treatment with chemotherapy had increased infectious and noninfectious adverse events. The 5-year incidences of fat necrosis, breast pain, and rib fracture were slightly higher after brachytherapy than after EBRT (13.7% vs 8.1%, 19.4% vs 16.0%, and 1.6% vs 1.3%, respectively), but the risks were not significantly different for multichannel versus single-channel applicators. Conclusion: Toxicities after breast brachytherapy were distinct from those after EBRT. Temporal toxicity trends may reflect changing technology and evolving practitioner experience with brachytherapy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Practical Implications of the Publication of Consensus Guidelines by the American Society for Radiation Oncology: Accelerated Partial Breast Irradiation and the National Cancer Data Base

Purpose: To examine utilization trends of accelerated partial breast irradiation (APBI) in the American College of Surgeons' National Cancer Database and changes in APBI use after the 2009 publication of the American Society for Radiation Oncology (ASTRO) guidelines. Methods and Materials: A total of 399,705 women were identified who were diagnosed from 2004 to 2011 with nonmetastatic invasive breast cancer or ductal carcinoma in situ who were treated with breast-conserving surgery and radiation therapy to the breast. Patients were divided by the type of treatment received (whole breast irradiation or APBI) and by suitability to receive APBI as defined by the ASTRO guidelines. Logistic regression was applied to study APBI use overall and within guideline categorization, and a multivariable model was created to determine predictors of treatment with brachytherapy-based APBI based on guideline categorization. Results: For all patients, APBI use increased, from 3.8% in 2004 to 10.6% in 2011 (P<.0001). Overall rates of APBI utilization were higher among “suitable” than “cautionary”/“unsuitable” patients (14.8% vs 7.1%, P<.0001). The majority of APBI treatment was delivered using brachytherapy, for which use peaked in 2008. Starting in 2009, among “suitable” patients, utilization of APBI via brachytherapy plateaued, whereas for “cautionary”/“unsuitable” patients, treatment with brachytherapy-based APBI declined and then plateaued. Conclusion: Use of APBI across all patient groups increased from 2004 through 2008. After publication of the ASTRO APBI guidelines in 2009, rates of brachytherapy-based APBI treatment plateaued among “suitable” patients and declined and then plateaued among “cautionary”/“unsuitable” patients. Our study highlights how large national databases can be used to assess national trends in radiation use in response to the publication of guidelines.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Adoption of Intensity Modulated Radiation Therapy For Early-Stage Breast Cancer From 2004 Through 2011

Purpose: Intensity modulated radiation therapy (IMRT) is a newer method of radiation therapy (RT) that has been increasingly adopted as an adjuvant treatment after breast-conserving surgery (BCS). IMRT may result in improved cosmesis compared to standard RT, although at greater expense. To investigate the adoption of IMRT, we examined trends and factors associated with IMRT in women under the age of 65 with early stage breast cancer. Methods and Materials: We performed a retrospective study of early stage breast cancer patients treated with BCS followed by whole-breast irradiation (WBI) who were ≤65 years old in the National Cancer Data Base from 2004 to 2011. We used logistic regression to identify factors associated with receipt of IMRT (vs standard RT). Results: We identified 11,089 women with early breast cancer (9.6%) who were treated with IMRT and 104,448 (90.4%) who were treated with standard RT, after BCS. The proportion of WBI patients receiving IMRT increased yearly from 2004 to 2009, with 5.3% of WBI patients receiving IMRT in 2004 and 11.6% receiving IMRT in 2009. Further use of IMRT declined afterward, with the proportion remaining steady at 11.0% and 10.7% in 2010 and 2011, respectively. Patients treated in nonacademic community centers were more likely to receive IMRT (odds ratio [OR], 1.36; 95% confidence interval [CI], 1.30-1.43 for nonacademic vs academic center). Compared to privately insured patients, the uninsured patients (OR, 0.81; 95% CI, 0.70-0.95) and those with Medicaid insurance (OR, 0.87; 95% CI, 0.79-0.95) were less likely to receive IMRT. Conclusions: The use of IMRT rose from 2004 to 2009 and then stabilized. Important nonclinical factors associated with IMRT use included facility type and insurance status.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Considerations for Observational Research Using Large Data Sets in Radiation Oncology

The radiation oncology community has witnessed growing interest in observational research conducted using large-scale data sources such as registries and claims-based data sets. With the growing emphasis on observational analyses in health care, the radiation oncology community must possess a sophisticated understanding of the methodological considerations of such studies in order to evaluate evidence appropriately to guide practice and policy. Because observational research has unique features that distinguish it from clinical trials and other forms of traditional radiation oncology research, the International Journal of Radiation Oncology, Biology, Physics assembled a panel of experts in health services research to provide a concise and well-referenced review, intended to be informative for the lay reader, as well as for scholars who wish to embark on such research without prior experience. This review begins by discussing the types of research questions relevant to radiation oncology that large-scale databases may help illuminate. It then describes major potential data sources for such endeavors, including information regarding access and insights regarding the strengths and limitations of each. Finally, it provides guidance regarding the analytical challenges that observational studies must confront, along with discussion of the techniques that have been developed to help minimize the impact of certain common analytical issues in observational analysis. Features characterizing a well-designed observational study include clearly defined research questions, careful selection of an appropriate data source, consultation with investigators with relevant methodological expertise, inclusion of sensitivity analyses, caution not to overinterpret small but significant differences, and recognition of limitations when trying to evaluate causality. This review concludes that carefully designed and executed studies using observational data that possess these qualities hold substantial promise for advancing our understanding of many unanswered questions of importance to the field of radiation oncology.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
NASA NTRS2014

Using Modern Methodologies with Maintenance Software

Jet Propulsion Laboratory uses multi-mission software produced by the Mission Planning and Sequencing (MPS) team to process, simulate, translate, and package the commands that are sent to a spacecraft. MPS works under the auspices of the Multi-Mission Ground Systems and Services (MGSS). This software consists of nineteen applications that are in maintenance. The MPS software is classified as either class B (mission critical) or class C (mission important). The scheduling of tasks is difficult because mission needs must be addressed prior to performing any other tasks and those needs often spring up unexpectedly. Keeping track of the tasks that everyone is working on is also difficult because each person is working on a different software component. Recently the group adopted the Scrum methodology for planning and scheduling tasks. Scrum is one of the newer methodologies typically used in agile development. In the Scrum development environment, teams pick their tasks that are to be completed within a sprint based on priority. The team specifies the sprint length usually a month or less. Scrum is typically used for new development of one application. In the Scrum methodology there is a scrum master who is a facilitator who tries to make sure that everything moves smoothly, a product owner who represents the user(s) of the software and the team. MPS is not the traditional environment for the Scrum methodology. MPS has many software applications in maintenance, team members who are working on disparate applications, many users, and is interruptible based on mission needs, issues and requirements. In order to use scrum, the methodology needed adaptation to MPS. Scrum was chosen because it is adaptable. This paper is about the development of the process for using scrum, a new development methodology, with a team that works on disparate interruptible tasks on multiple software applications.

Scrum↗
NASA NTRS2013

Uplink Summary Generator (ULSGEN) Version 1.0

The Uplink Summary Generator (ULSGEN) provides a convenient means of gathering together a set of uplink related files, parsing and analyzing these files, and producing a summary of their contents, which may then be electronically signed by one or more reviewers to verify the commands. Spacecraft operations personnel view this summary as a final sanity check before actual radiation of the uplink data.

Wang, Yeou-Fang↗
NASA NTRS2005

Model Checking Artificial Intelligence Based Planners: Even the Best Laid Plans Must Be Verified

Automated planning systems (APS) are gaining acceptance for use on NASA missions as evidenced by APS flown On missions such as Orbiter and Deep Space 1 both of which were commanded by onboard planning systems. The planning system takes high level goals and expands them onboard into a detailed of action fiat the spacecraft executes. The system must be verified to ensure that the automatically generated plans achieve the goals as expected and do not generate actions that would harm the spacecraft or mission. These systems are typically tested using empirical methods. Formal methods, such as model checking, offer exhaustive or measurable test coverage which leads to much greater confidence in correctness. This paper describes a formal method based on the SPIN model checker. This method guarantees that possible plans meet certain desirable properties. We express the input model in Promela, the language of SPIN and express the properties of desirable plans formally.

model checking↗
NASA NTRS2001

The RadarSAT-MAMM automated mission planner

The RadarSAT Modified Antarctic Mapping Mission (MAMM) ran from September to November 2000. It consisted of over 2400 synthetic aperture radar (SAR) data takes over Antarctica that had to satisfy coverage and other scientific criteria while obeying tight resource and operational constraints. Developing these plans is a time and knowledge intensive effort. It required over a work-year to manually develop a comparable plan for AMM-1, the precursor mission to MAMM. This paper describes the automated mission planning system for MAMM, which dramatically reduced mission-planning costs to just a few workweeks, and enabled rapid generation of 'what-if' scenarios for evaluating mission-design trades. This latter capability informed several critical design decisions and was instrumental in accurately costing the mission.

RadarSAT Modified Antarctic Mapping Mission (MAMM)↗
NASA NTRS2001

Reducing costs of the modified Antarctic Mapping mission through automated planning

This paper describes the automated mission planning system for MAMM, which dramatically reduced mission-planning costs to just a few workweeks, and enabled rapid generation of 'what-if' scenarios for evaluating mission-design trades. This latter capability informed several critical design decisions and was instrumental in accurately costing the mission.

reduce mission costs↗
NASA NTRS1996

Induction as Knowledge Integration

Two key issues for induction algorithms are the accuracy of the learned hypothesis and the computational resources consumed in inducing that hypothesis. One of the most promising ways to improve performance along both dimensions is to make use of additional knowledge. Multi-strategy learning algorithms tackle this problem by employing several strategies for handling different kinds of knowledge in different ways. However, integrating knowledge into an induction algorithm can be difficult when the new knowledge differs significantly from the knowledge the algorithm already uses. In many cases the algorithm must be rewritten. This paper presents Knowledge Integration framework for Induction (KII), a KII, that provides a uniform mechanism for integrating knowledge into induction. In theory, arbitrary knowledge can be integrated with this mechanism, but in practice the knowledge representation language determines both the knowledge that can be integrated, and the costs of integration and induction. By instantiating KII with various set representations, algorithms can be generated at different trade-off points along these dimensions. One instantiation of KII, called RS-KII, is presented that can implement hybrid induction algorithms, depending on which knowledge it utilizes. RS-KII is demonstrated to implement AQ-11, as well as a hybrid algorithm that utilizes a domain theory and noisy examples. Other algorithms are also possible.

Smith, Benjamin D.↗