Publications by authors named "Lawrence B Marks"

281 Publications

Primary Hypothyroidism in Childhood Cancer Survivors Treated With Radiation Therapy: A PENTEC Comprehensive Review.

Int J Radiat Oncol Biol Phys 2021 Mar 17. Epub 2021 Mar 17.

Department of Oncology, Section of Radiotherapy, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.

Purpose: From the Pediatric Normal Tissue Effects in the Clinic (PENTEC) initiative, a systematic review and meta-analysis of publications reporting on radiation dose-volume effects for risk of primary hypothyroidism after radiation therapy for pediatric malignancies was performed.

Methods And Materials: All studies included childhood cancer survivors, diagnosed at age <21 years, whose radiation therapy fields exposed the thyroid gland and who were followed for primary hypothyroidism. Children who received pituitary-hypothalamic or total-body irradiation were excluded. PubMed and the Cochrane Library were searched for studies published from 1970 to 2017. Data on age at treatment, patient sex, radiation dose to neck or thyroid gland, specific endpoints for hypothyroidism that were used in the studies, and reported risks of hypothyroidism were collected. Radiation dose-volume effects were modeled using logistic dose response. Relative excess risk of hypothyroidism as a function of age at treatment and sex was assessed by meta-analysis of reported relative risks (RR) and odds ratios.

Results: Fifteen publications (of 1709 identified) were included for systematic review. Eight studies reported data amenable for dose-response analysis. At mean thyroid doses of 10, 20, and 30 Gy, predicted rates of uncompensated (clinical) hypothyroidism were 4%, 7%, and 13%, respectively. Predicted rates of compensated (subclinical) hypothyroidism were 12%, 25%, and 44% after thyroid doses of 10, 20, and 30 Gy, respectively. Female sex (RR = 1.7, P < .0001) and age >15 years at radiation therapy (RR = 1.3, P = .005) were associated with higher risks of hypothyroidism. After a mean thyroid dose of 20 Gy, predicted risks of hypothyroidism were 13% for males <14 years of age, increasing to 29% for females >15 years of age.

Conclusion: A radiation dose response for risk of hypothyroidism is evident; a threshold radiation dose associated with no risk is not observed. Thyroid dose exposure should be minimized when feasible. Data on hypothyroidism after radiation therapy should be better reported to facilitate pooled analyses.
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http://dx.doi.org/10.1016/j.ijrobp.2021.02.001DOI Listing
March 2021

NTCP modeling and dose-volume correlations for acute xerostomia and dry eye after whole brain radiation.

Radiat Oncol 2021 Mar 21;16(1):56. Epub 2021 Mar 21.

Department of Radiation Oncology, University of North Carolina, 101 Manning Dr., Chapel Hill, NC, 27599-7512, USA.

Background: Whole brain radiation (WBRT) may lead to acute xerostomia and dry eye from incidental parotid and lacrimal exposure, respectively. We performed a prospective observational study to assess the incidence/severity of this toxicity. We herein perform a secondary analysis relating parotid and lacrimal dosimetric parameters to normal tissue complication probability (NTCP) rates and associated models.

Methods: Patients received WBRT to 25-40 Gy in 10-20 fractions using 3D-conformal radiation therapy without prospective delineation of the parotids or lacrimals. Patients completed questionnaires at baseline and 1 month post-WBRT. Xerostomia was assessed using the University of Michigan xerostomia score (scored 0-100, toxicity defined as ≥ 20 pt increase) and xerostomia bother score (scored from 0 to 3, toxicity defined as ≥ 2 pt increase). Dry eye was assessed using the Subjective Evaluation of Symptom of Dryness (SESoD, scored from 0 to 4, toxicity defined as ≥ 2 pt increase). The clinical data were fitted by the Lyman-Kutcher-Burman (LKB) and Relative Seriality (RS) NTCP models.

Results: Of 55 evaluable patients, 19 (35%) had ≥ 20 point increase in xerostomia score, 11 (20%) had ≥ 2 point increase in xerostomia bother score, and 13 (24%) had ≥ 2 point increase in SESoD score. For xerostomia, parotid V-V correlated best with toxicity, with AUC 0.68 for xerostomia score and 0.69-0.71 for bother score. The values for the D, m and n parameters of the LKB model were 22.3 Gy, 0.84 and 1.0 for xerostomia score and 28.4 Gy, 0.55 and 1.0 for bother score, respectively. The corresponding values for the D, γ and s parameters of the RS model were 23.5 Gy, 0.28 and 0.0001 for xerostomia score and 32.0 Gy, 0.45 and 0.0001 for bother score, respectively. For dry eye, lacrimal V-V were found to correlate best with toxicity, with AUC values from 0.67 to 0.68. The parameter values of the LKB model were 53.5 Gy, 0.74 and 1.0, whereas of the RS model were 54.0 Gy, 0.37 and 0.0001, respectively.

Conclusions: Xerostomia was most associated with parotid V-V, and dry eye with lacrimal V-V. NTCP models were successfully created for both toxicities and may help clinicians refine dosimetric goals and assess levels of risk in patients receiving palliative WBRT.
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http://dx.doi.org/10.1186/s13014-021-01786-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7981795PMC
March 2021

The impact of pathologic staging of the hilar/mediastinal nodes on outcomes in patients with early-stage NSCLC receiving stereotactic body radiotherapy.

J Thorac Dis 2021 Feb;13(2):1045-1054

Department of Radiation Oncology, University of North Carolina Hospitals, Chapel Hill, NC, USA.

Background: The importance of invasive mediastinal nodal staging in early-stage non-small cell lung cancer (NSCLC) in the PET/CT era is dependent on tumor factors that increase risk of nodal metastasis. At our institution, patients undergo biopsy via either CT-guidance (without nodal staging) or navigational bronchoscopy with endobronchial ultrasound transbronchial needle aspiration for nodal staging. This study aims to compare outcomes after stereotactic body radiotherapy (SBRT) stratified by receipt of invasive mediastinal nodal staging.

Methods: In this retrospective study, records of all consecutive patients undergoing SBRT for early-stage NSCLC between 2010 and 2017 were analyzed. The association between time-to event outcomes (recurrence and survival) were evaluated with covariates of interest including tumor size, location, histology, smoking history, prior lung cancer history, radiation dose and receipt of nodal staging. Both univariable and multivariable analyses were used to examine these comparisons.

Results: Overall, 158 patients were treated with SBRT. One hundred forty-nine out of one hundred fifty-eight patients (94%) underwent PET/CT staging, and all patients underwent tumor-directed biopsy. Seventy-nine patients underwent navigational bronchoscopy with nodal staging and 79 patients underwent CT-guided biopsy without nodal staging. Receipt of nodal staging was not associated with tumor size (P=0.35), yet was associated with central tumor location (P<0.001). There was no statistically significant association between receipt of nodal staging and time-to-event recurrence or survival outcomes; for example 3-year overall survival (OS) was 65% 67% (P=0.65) and 3-year freedom from nodal failure was 84% 69% (P=0.1) for those with and without nodal staging, respectively.

Conclusions: Similar recurrence and survival outcomes were observed after SBRT regardless of receipt of invasive mediastinal nodal staging. Further prospective evaluation can help identify which patients might derive greatest benefit from invasive staging of the mediastinum in the PET/CT era.
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http://dx.doi.org/10.21037/jtd-20-2808DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7947488PMC
February 2021

Stereotactic Body Radiation Therapy for Spinal Metastases: Tumor Control Probability Analyses and Recommended Reporting Standards.

Int J Radiat Oncol Biol Phys 2021 Jan 27. Epub 2021 Jan 27.

Department of Radiation Oncology, University of California at Davis, Sacramento, California.

Purpose: We sought to investigate the tumor control probability (TCP) of spinal metastases treated with stereotactic body radiation therapy (SBRT) in 1 to 5 fractions.

Methods And Materials: PubMed-indexed articles from 1995 to 2018 were eligible for data extraction if they contained SBRT dosimetric details correlated with actuarial 2-year local tumor control rates. Logistic dose-response models of collected data were compared in terms of physical dose and 3-fraction equivalent dose.

Results: Data were extracted from 24 articles with 2619 spinal metastases. Physical dose TCP modeling of 2-year local tumor control from the single-fraction data were compared with data from 2 to 5 fractions, resulting in an estimated α/β = 6 Gy, and this was used to pool data. Acknowledging the uncertainty intrinsic to the data extraction and modeling process, the 90% TCP corresponded to 20 Gy in 1 fraction, 28 Gy in 2 fractions, 33 Gy in 3 fractions, and (with extrapolation) 40 Gy in 5 fractions. The estimated TCP for common fractionation schemes was 82% at 18 Gy, 90% for 20 Gy, and 96% for 24 Gy in a single fraction, 82% for 24 Gy in 2 fractions, and 78% for 27 Gy in 3 fractions.

Conclusions: Spinal SBRT with the most common fractionation schemes yields 2-year estimates of local control of 82% to 96%. Given the heterogeneity in the tumor control estimates extracted from the literature, with variability in reporting of dosimetry data and the definition of and statistical methods of reporting tumor control, care should be taken interpreting the resultant model-based estimates. Depending on the clinical intent, the improved TCP with higher dose regimens should be weighed against the potential risks for greater toxicity. We encourage future reports to provide full dosimetric data correlated with tumor local control to allow future efforts of modeling pooled data.
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http://dx.doi.org/10.1016/j.ijrobp.2020.11.021DOI Listing
January 2021

Assessment of Radiation Therapy Technologists' Workload and Situation Awareness: Monitoring 2 Versus 3 Collocated Display Monitors.

Adv Radiat Oncol 2021 Jan-Feb;6(1):100572. Epub 2020 Sep 28.

Department of Radiation Oncology, University of North Carolina at Chapel Hill, North Carolina.

Purpose: This study aimed to assess the effect of monitoring 2 versus 3 collocated displays on radiation therapist technologists' (RTTs) workload (WL) and situation awareness (SA) during routine treatment delivery tasks.

Methods And Materials: Seven RTTs completed 4 simulated treatment delivery scenarios (2 scenarios per experimental condition; 2 vs 3 collocated displays) in a within-subject experiment. WL was subjectively measured using the National Aeronautics and Space Administration (NASA) Task Load Index, and objectively measured using eye activity measures. SA was subjectively measured using the SA rating technique, and objectively measured using the SA global assessment technique. Two-tailed paired tests were conducted to test for differences in means when parametric assumptions were satisfied, otherwise Wilcoxon signed-rank tests were conducted. A .05 level of significance was applied to all statistical tests.

Results: No statistically and clinically significant differences were observed between monitoring 2 versus 3 monitors on eye tracking measures (blink rate: 9.4 [4.8] vs 9.6 [4.0]; task evoked pupillary response: 0.16 [0.14] vs 0.21 [0.15]; NASA Task Load Index: 34.7 [19.8] vs 35.3 [20.4]; SA rating technique: 19.3 [6.2] vs 19.5 [7.0]; and SA global assessment technique scores: 100 [0] vs 100 [0]).

Conclusions: Our preliminary findings suggest that monitoring 3 collocated displays by 1 RTT does not impact WL and SA compared with monitoring 2 collocated displays. Only 2 of many possible configurations were investigated. If institutions removed the 3rd display based on the results of this study, there could be unforeseen error(s) if that display helped in situations not assessed in this study.
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http://dx.doi.org/10.1016/j.adro.2020.09.012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7811123PMC
September 2020

Tumor Control Probability of Radiosurgery and Fractionated Stereotactic Radiosurgery for Brain Metastases.

Int J Radiat Oncol Biol Phys 2020 Dec 31. Epub 2020 Dec 31.

Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland.

Purpose: As part of the American Association of Physicists in Medicine Working Group on Stereotactic Body Radiotherapy, tumor control probability (TCP) after stereotactic radiosurgery (SRS) and fractionated stereotactic radiosurgery (fSRS) for brain metastases was modeled based on pooled dosimetric and clinical data from published English-language literature.

Methods And Materials: PubMed-indexed studies published between January 1995 and September 2017 were used to evaluate dosimetric and clinical predictors of TCP after SRS or fSRS for brain metastases. Eligible studies had ≥10 patients and included detailed dose-fractionation data with corresponding ≥1-year local control (LC) data, typically evaluated as a >20% increase in diameter of the targeted lesion using the pre-SRS diameter as a reference.

Results: Of 2951 potentially eligible manuscripts, 56 included sufficient dose-volume data for analyses. Accepting that necrosis and pseudoprogression can complicate the assessment of LC, for tumors ≤20 mm, single-fraction doses of 18 and 24 Gy corresponded with >85% and 95% 1-year LC rates, respectively. For tumors 21 to 30 mm, an 18 Gy single-fraction dose was associated with 75% LC. For tumors 31 to 40 mm, a 15 Gy single-fraction dose yielded ∼69% LC. For 3- to 5-fraction fSRS using doses in the range of 27 to 35 Gy, 80% 1-year LC has been achieved for tumors of 21 to 40 mm in diameter.

Conclusions: TCP for SRS and fSRS are presented. For small lesions ≤20 mm, single doses of ≈18 Gy appear generally associated with excellent rates of LC; for melanoma, higher doses seem warranted. For larger lesions >20 mm, local control rates appear to be ≈ 70% to 75% with usual doses of 15 to 18 Gy, and in this setting, fSRS regimens should be considered. Greater consistency in reporting of dosimetric and LC data is needed to facilitate future pooled analyses. As systemic and biologic therapies evolve, updated analyses will be needed to further assess the necessity, efficacy, and toxicity of SRS and fSRS.
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http://dx.doi.org/10.1016/j.ijrobp.2020.10.034DOI Listing
December 2020

A Primer on Dose-Response Data Modeling in Radiation Therapy.

Int J Radiat Oncol Biol Phys 2020 Dec 23. Epub 2020 Dec 23.

Department of Machine Learning, Moffitt Cancer Center, Tampa, Florida.

An overview of common approaches used to assess a dose response for radiation therapy-associated endpoints is presented, using lung toxicity data sets analyzed as a part of the High Dose per Fraction, Hypofractionated Treatment Effects in the Clinic effort as an example. Each component presented (eg, data-driven analysis, dose-response analysis, and calculating uncertainties on model prediction) is addressed using established approaches. Specifically, the maximum likelihood method was used to calculate best parameter values of the commonly used logistic model, the profile-likelihood to calculate confidence intervals on model parameters, and the likelihood ratio to determine whether the observed data fit is statistically significant. The bootstrap method was used to calculate confidence intervals for model predictions. Correlated behavior of model parameters and implication for interpreting dose response are discussed.
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http://dx.doi.org/10.1016/j.ijrobp.2020.11.020DOI Listing
December 2020

Impact of Simulation-Based Training on Radiation Therapists' Workload, Situation Awareness, and Performance.

Adv Radiat Oncol 2020 Nov-Dec;5(6):1106-1114. Epub 2020 Sep 29.

Department of Radiation Oncology, University of North Carolina, Chapel Hill, North Carolina.

Purpose: This study aimed to assess the impact of simulation-based training intervention on radiation therapy therapist (RTT) mental workload, situation awareness, and performance during routine quality assurance (QA) and treatment delivery tasks.

Methods And Materials: As part of a prospective institutional review board-approved study, 32 RTTs completed routine QA and treatment delivery tasks on clinical scenarios in a simulation laboratory. Participants, randomized to receive (n = 16) versus not receive (n = 16) simulation-based training had pre- and postintervention assessments of mental workload, situation awareness, and performance. We used linear regression models to compare the postassessment scores between the study groups while controlling for baseline scores. Mental workload was quantified subjectively using the NASA Task Load Index. Situation awareness was quantified subjectively using the situation awareness rating technique and objectively using the situation awareness global assessment technique. Performance was quantified based on procedural compliance (adherence to preset/standard QA timeout tasks) and error detection (detection and correction of embedded treatment planning errors).

Results: Simulation-based training intervention was associated with significant improvements in overall performance ( < .01), but had no significant impact on mental workload or subjective/objective quantifications of situation awareness.

Conclusions: Simulation-based training might be an effective tool to improve RTT performance of QA-related tasks.
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http://dx.doi.org/10.1016/j.adro.2020.09.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7718555PMC
September 2020

Balancing the Benefits and Harms of Postmastectomy Radiation Therapy.

Int J Radiat Oncol Biol Phys 2020 12 18;108(5):1131. Epub 2020 Nov 18.

Department of Radiation Oncology, University of North Carolina School of Medicine, Chapel Hill, North Carolina.

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http://dx.doi.org/10.1016/j.ijrobp.2020.01.037DOI Listing
December 2020

Single- and Multifraction Stereotactic Radiosurgery Dose/Volume Tolerances of the Brain.

Int J Radiat Oncol Biol Phys 2020 Sep 11. Epub 2020 Sep 11.

Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland.

Purpose: As part of the American Association of Physicists in Medicine Working Group on Stereotactic Body Radiotherapy investigating normal tissue complication probability (NTCP) after hypofractionated radiation therapy, data from published reports (PubMed indexed 1995-2018) were pooled to identify dosimetric and clinical predictors of radiation-induced brain toxicity after single-fraction stereotactic radiosurgery (SRS) or fractionated stereotactic radiosurgery (fSRS).

Methods And Materials: Eligible studies provided NTCPs for the endpoints of radionecrosis, edema, or symptoms after cranial SRS/fSRS and quantitative dose-volume metrics. Studies of patients with only glioma, meningioma, vestibular schwannoma, or brainstem targets were excluded. The data summary and analyses focused on arteriovenous malformations (AVM) and brain metastases.

Results: Data from 51 reports are summarized. There was wide variability in reported rates of radionecrosis. Available data for SRS/fSRS for brain metastases were more amenable to NTCP modeling than AVM data. In the setting of brain metastases, SRS/fSRS-associated radionecrosis can be difficult to differentiate from tumor progression. For single-fraction SRS to brain metastases, tissue volumes (including target volumes) receiving 12 Gy (V1) of 5 cm, 10 cm, or >15 cm were associated with risks of symptomatic radionecrosis of approximately 10%, 15%, and 20%, respectively. SRS for AVM was associated with modestly lower rates of symptomatic radionecrosis for equivalent V12. For brain metastases, brain plus target volume V20 (3-fractions) or V24 (5-fractions) <20 cm was associated with <10% risk of any necrosis or edema, and <4% risk of radionecrosis requiring resection.

Conclusions: The risk of radionecrosis after SRS and fSRS can be modeled as a function of dose and volume treated. The use of fSRS appears to reduce risks of radionecrosis for larger treatment volumes relative to SRS. More standardized dosimetric and toxicity reporting is needed to facilitate future pooled analyses that can refine predictive models of brain toxicity risks.
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http://dx.doi.org/10.1016/j.ijrobp.2020.08.013DOI Listing
September 2020

Restructuring Our Approach to Peer Review: A Critical Need to Improve the Quality and Safety of Radiation Therapy.

Pract Radiat Oncol 2020 Sep - Oct;10(5):321-323

Department of Radiation Oncology, University of North Carolina, School of Medicine, Chapel Hill, North Carolina; Department of Radiation Medicine, Northwell Health Cancer Institute, Lake Success NY and Zucker School of Medicine, Hempstead, New York.

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http://dx.doi.org/10.1016/j.prro.2020.07.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7459359PMC
July 2020

Effect of Simulation-Based Training and Neurofeedback Interventions on Radiation Technologists' Workload, Situation Awareness, and Performance.

Pract Radiat Oncol 2021 Mar-Apr;11(2):e124-e133. Epub 2020 Aug 24.

Department of Radiation Oncology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.

Purpose: Our purpose was to assess the effect of a combined intervention - simulation-based training supported by neurofeedback sessions - on radiation technologists' (RTs') workload, situation awareness, and performance during routine quality assurance and treatment delivery tasks.

Methods And Materials: As part of a prospective institutional review board approved study, 32 RTs previously randomized to receive versus not receive simulation-based training focused on patient safety were again randomized to receive versus not receive a 3-week neurofeedback intervention (8 sessions of alpha-theta protocol) focused on stress reduction as well as conscious precision, strong focus, and ability to solve arising problems. Perceived workload was quantified using the NASA Task Load Index. Situation awareness was quantified using the situation awareness rating technique. Performance score was calculated using procedural compliance with time-out components and error detection.

Results: RTs randomized to simulation-based training followed by neurofeedback sessions demonstrated no significant changes in perceived workload or situation awareness scores, but did have better performance compared with other study groups (P < .01).

Conclusions: This finding is encouraging and provides basis for using neurofeedback as means to possibly augment performance improvements gained during simulation-based training.
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http://dx.doi.org/10.1016/j.prro.2020.08.005DOI Listing
August 2020

Common Error Pathways in CyberKnife™ Radiation Therapy.

Front Oncol 2020 8;10:1077. Epub 2020 Jul 8.

Department of Radiation Oncology, University of North Carolina Hospitals, Chapel Hill, NC, United States.

Stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) may be considered "high risk" due to the high doses per fraction. We analyzed CyberKnife™ (CK) SRS and SBRT-related incidents that were prospectively reported to our in-house incident learning system (ILS) in order to identify severity, contributing factors, and common error pathways. From 2012 to 2019, 221 reported incidents related to the 4,569 CK fractions delivered (5.8%) were prospectively analyzed by our multi-professional Quality and Safety Committee with regard to severity, contributing factors, as well as the location where the incident occurred (), where it was discovered (), and the safety barriers that were traversed on the CK process map. Based on the particular step in the process map that incidents , we categorized incidents into general error pathways. There were 205 severity grade 1-2 (did not reach patient or no clinical impact), 11 grade 3 (clinical impact unlikely), 5 grade 4 (altered the intended treatment), and 0 grade 5-6 (life-threatening or death) incidents, with human performance being the most common contributing factor (79% of incidents). Incidents most commonly near the time when the practitioner requested CK simulation (e.g., pre-CK simulation fiducial marker placement) and most commonly during the physics pre-treatment checklist. The four general error pathways included pre-authorization, billing, and scheduling issues (= 119); plan quality (= 30); administration of IV contrast during simulation or pre-medications during treatment (= 22); and image guidance (= 12). Most CK incidents led to little or no patient harm and most were related to billing and scheduling issues. Suboptimal human performance appeared to be the most common contributing factor to CK incidents. Additional study is warranted to develop and share best practices to reduce incidents to further improve patient safety.
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http://dx.doi.org/10.3389/fonc.2020.01077DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7360810PMC
July 2020

Impact of Workspace Design on Radiation Therapist Technicians' Physical Stressors, Mental Workload, Situation Awareness, and Performance.

Pract Radiat Oncol 2021 Jan-Feb;11(1):e3-e10. Epub 2020 Jul 21.

Department of Radiation Oncology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; School of Information and Library Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; Carolina Health Informatics Program, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.

Purpose: Our purpose was to assess the effect of workspace configuration on radiation therapists' (RTs) physical stressors, mental workload (WL), situational awareness (SA), and performance during routine treatment delivery tasks in a simulated environment.

Methods And Materials: Fourteen RTs were randomized to 2 workspace configurations while performing 4 simulated scenarios: current (not ergonomically optimized; n = 7) and enhanced (ergonomically optimized, n = 7). Physical stressors were objectively assessed using a rapid upper limb assessment tool. Mental WL was measured at the end of each simulated scenario subjectively using the NASA Task-Load Index and objectively throughout the scenario using eye-tracking metrics (pupil diameter and blink rate). SA was measured at the end of each simulated scenario subjectively using the situation awareness and review technique. Performance was measured objectively via assessment of time-out compliance, error detection, and procedural compliance. Analysis of variance was used to test the effect of workspace configuration on physical stressors, mental WL, SA, and performance.

Results: The enhanced configuration significantly reduced physical stressors (rapid upper limb assessment; P < .01) and resulted in a higher rate of time-out compliance (P = .01) compared with current workspace configuration. No significant effect on other metrics was measured.

Conclusions: Our results suggest that an ergonomically designed workspace may minimize physical stressors and improve the performance of RTs.
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http://dx.doi.org/10.1016/j.prro.2020.07.002DOI Listing
July 2020

Breast conservation therapy versus mastectomy for breast cancer.

Lancet Oncol 2020 04;21(4):492-493

Department of Radiation Oncology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7512, USA. Electronic address:

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http://dx.doi.org/10.1016/S1470-2045(20)30172-8DOI Listing
April 2020

Spinal Cord Dose Tolerance to Stereotactic Body Radiation Therapy.

Int J Radiat Oncol Biol Phys 2019 Oct 10. Epub 2019 Oct 10.

Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York.

Spinal cord tolerance data for stereotactic body radiation therapy (SBRT) were extracted from published reports, reviewed, and modelled. For de novo SBRT delivered in 1 to 5 fractions, the following spinal cord point maximum doses (D) are estimated to be associated with a 1% to 5% risk of radiation myelopathy (RM): 12.4 to 14.0 Gy in 1 fraction, 17.0 Gy in 2 fractions, 20.3 Gy in 3 fractions, 23.0 Gy in 4 fractions, and 25.3 Gy in 5 fractions. For reirradiation SBRT delivered in 1 to 5 fractions, reported factors associated with a lower risk of RM include cumulative thecal sac equivalent dose in 2 Gy fractions with an alpha/beta of 2 (EQD2) D ≤70 Gy; SBRT thecal sac EQD2 D ≤25 Gy, thecal sac SBRT EQD2 D to cumulative EQD2 D ratio ≤0.5, and a minimum time interval to reirradiation of ≥5 months. Larger studies containing complete institutional cohorts with dosimetric data of patients treated with spine SBRT, with and without RM, are required to refine RM risk estimates.
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http://dx.doi.org/10.1016/j.ijrobp.2019.09.038DOI Listing
October 2019

Incorporating Human Factors Analysis and Classification System (HFACS) Into Analysis of Reported Near Misses and Incidents in Radiation Oncology.

Pract Radiat Oncol 2020 Sep - Oct;10(5):e312-e321. Epub 2019 Sep 14.

Department of Radiation Oncology and Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina.

Purpose: Human factors analysis and classification system (HFACS) is a framework for investigation into causation of human errors. We herein assess whether radiation oncology professionals, with brief training, can conduct HFACS on reported near misses or safety incidents (NMSIs) in a reliable (eg, with a high level of agreement) and practical (eg, timely and with user satisfaction) manner.

Methods And Materials: We adapted a classical HFACS framework by selecting and modifying main headings, subheadings, and nano-codes that were most likely to apply to radiation oncology settings. The final modified HFACS included 3 main headings, 8 subheadings, and 20 nano-codes. The modified HFACS was first tested in a simulated trial on 8 NMSI and was analyzed by 5 to 10 radiation oncology professionals, with 2 endpoints: (1) agreement among participants at the main-heading, subheading, and nano-code level, and (2) time to complete the analysis. We then performed a prospective trial integrating this approach into a weekly NMSI review meeting, with 10 NMSIs analyzed by 8 to 13 radiation oncology professionals with the same endpoints, while also collecting survey data on participants' satisfaction.

Results: In the simulated trial, agreement among participants was 85% on the main headings, 73% on the subheadings, and 70% on the nano-codes. Participants needed, on average, 16.4 minutes (standard deviation, 5.7 minutes) to complete an analysis. In the prospective trial, agreement between participants was 81% on the main headings, 75% on the subheadings, and 74% on the nano-codes. Participants needed, on average, 8.3 minutes (standard deviation, 4.7 minutes) to complete an analysis. The average satisfaction with the proposed HFACS approach was 3.9 (standard deviation 1.0) on a scale from 1 to 5.

Conclusions: This study demonstrates that, after relatively brief training, radiation oncology professionals were able to perform HFACS analysis in a reliable and timely manner and with a relatively high level of satisfaction.
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http://dx.doi.org/10.1016/j.prro.2019.09.005DOI Listing
September 2019

Using Artificial Intelligence to Improve the Quality and Safety of Radiation Therapy.

J Am Coll Radiol 2019 Sep;16(9 Pt B):1267-1272

Department of Radiation Oncology, University of North Carolina, Chapel Hill, North Carolina.

Within artificial intelligence, machine learning (ML) efforts in radiation oncology have augmented the transition from generalized to personalized treatment delivery. Although their impact on quality and safety of radiation therapy has been limited, they are increasingly being used throughout radiation therapy workflows. Various data-driven approaches have been used for outcome prediction, CT simulation, clinical decision support, knowledge-based planning, adaptive radiation therapy, plan validation, machine quality assurance, and process quality assurance; however, there are many challenges that need to be addressed with the creation and usage of ML algorithms as well as the interpretation and dissemination of findings. In this review, the authors present current applications of ML in radiation oncology quality and safety initiatives, discuss challenges faced by the radiation oncology community, and suggest future directions.
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http://dx.doi.org/10.1016/j.jacr.2019.06.001DOI Listing
September 2019

Prospective Assessment of Patient-Reported Dry Eye Syndrome After Whole Brain Radiation.

Int J Radiat Oncol Biol Phys 2019 11 24;105(4):765-772. Epub 2019 Jul 24.

Department of Radiation Oncology, University of North Carolina Hospitals, Chapel Hill, North Carolina.

Purpose: Dry eye is not typically considered a toxicity of whole brain radiation therapy (WBRT). We analyzed dry eye syndrome as part of a prospective study of patient-reported outcomes after WBRT.

Methods And Materials: Patients receiving WBRT to 25 to 40 Gy were enrolled on a study with dry mouth as the primary endpoint and dry eye syndrome as a secondary endpoint. Patients received 3-dimensional WBRT using opposed lateral fields. Per standard practice, lacrimal glands were not prospectively delineated. Patients completed the Subjective Evaluation of Symptom of Dryness (SESoD, scored 0-4, with higher scores representing worse dry eye symptoms) at baseline, immediately after WBRT (EndRT), and at 1 month (1M), 3 months, and 6 months. Patients with baseline SESoD ≥3 (moderate dry eye) were excluded. The endpoints analyzed were ≥1-point and ≥2-point increase in SESoD score at 1M. Lacrimal glands were retrospectively delineated with fused magnetic resonance imaging scans.

Results: One hundred patients were enrolled, 70 were eligible for analysis, and 54 were evaluable at 1M. Median bilateral lacrimal V20Gy was 79%. At 1M, 17 patients (32%) had a ≥1-point increase in SESoD score, and 13 (24%) a ≥2-point increase. Lacrimal doses appeared to be associated with an increase in SESoD score of both ≥1 point (V10Gy: P = .042, odds ratio [OR] 1.09/%; V20Gy: P = .071, OR 1.03/%) and ≥2 points (V10Gy: P = .038, OR 1.15/%; V20Gy: P = .063, OR 1.04/%). The proportion with increase in dry eye symptoms at 1M for lacrimal V20Gy ≥79% versus <79% was 46% versus 15%, respectively, for ≥1 point SESoD increase (P = .02) and 36% versus 12%, respectively, for ≥2 point SESoD increase (P = .056).

Conclusions: Dry eye appears to be a relatively common, dose/volume-dependent acute toxicity of WBRT. Minimization of lacrimal gland dose may reduce this toxicity, and patients should be counseled regarding the existence of this potential side effect and treatments for dry eye.
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http://dx.doi.org/10.1016/j.ijrobp.2019.07.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7384248PMC
November 2019

The Impact of Set-Up Uncertainty on Dose-Response Estimates.

Int J Radiat Oncol Biol Phys 2019 11 15;105(3):477-478. Epub 2019 Jul 15.

University of North Carolina at Chapel Hill, Department of Radiation Oncology, Lineberger Comprehensive Cancer Center, Chapel Hill, North Carolina. Electronic address:

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http://dx.doi.org/10.1016/j.ijrobp.2019.07.007DOI Listing
November 2019

Elevated Risk of Radiation Therapy-Associated Second Malignant Neoplasms in Young African-American Women Survivors of Stage I-IIIA Breast Cancer.

Int J Radiat Oncol Biol Phys 2019 10 12;105(2):275-284. Epub 2019 Jun 12.

Department of Radiation Oncology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.

Purpose: To estimate the effect of radiation therapy (RT) on nonbreast second malignant neoplasms (SMNs) in young women survivors of stage I-IIIA breast cancer.

Methods And Materials: Women aged 20 to 44 years who received a diagnosis of stage I-IIIA breast cancer (1988-2008) were identified in the Surveillance, Epidemiology, and End Results 9 registries. Bootstrapping approach and competing-risk proportional hazards models were used to evaluate the effect of RT on nonbreast SMN risk. The analysis was repeated in racial subgroups. Radiotolerance score analysis of normal airway epithelium was performed using Gene Expression Omnibus (GEO) data sets.

Results: Within records of 30,003 women with primary breast cancer, 20,516 eligible patients were identified, including 2,183 African Americans (AAs) and 16,009 Caucasians. The 25-year cumulative incidences of SMN were 5.2% and 3.6% (RT vs no-RT) for AAs, with 12.8-year and 17.4-year (RT vs no-RT) median follow-up (hazard ratio [HR] = 1.81; 95% bootstrapping confidence interval [BCI], 1.02-2.50; P < .05), respectively, and 6.4% and 5.9% (RT vs no-RT) for Caucasians with 14.3-year and 18.1-year (RT vs no-RT) median follow-up (HR = 1.10; 95% BCI, 0.61-1.40; P > .05), respectively. The largest portion of excess RT-related SMN risk was lung cancer (AA: HR = 2.08, 95% BCI, 1.02-5.39, P < .05; Caucasian: HR = 1.50, 95% BCI, 0.84-5.38, P > .05). Subpopulation Treatment Effect Pattern Plot (STEPP) analysis revealed higher post-RT nonbreast SMN risk in those 20 to 44 years of age, with larger HRs for RT in AAs. Radiotolerance score (RTS) of normal airway epithelium from young AA women was significantly lower than that from young Caucasian women (P = .038).

Conclusions: With a projected 25-year follow-up, RT is associated with elevated risk of nonbreast SMNs, particularly second lung cancer, in young women survivors of stage I-IIIA breast cancer. Nonbreast SMNs associated with RT are higher in AA women than Caucasian women.
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http://dx.doi.org/10.1016/j.ijrobp.2019.06.010DOI Listing
October 2019

Variations in Medicaid Payment Rates for Radiation Oncology.

Int J Radiat Oncol Biol Phys 2019 07 1;104(3):488-493. Epub 2019 Apr 1.

Department of Radiation Oncology, the University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.

Purpose: Interstate variations in Medicaid reimbursements can be significant, and patients who live in states with low Medicaid reimbursements tend to have worse access to care. This analysis describes the extent of variations in Medicaid reimbursements for radiation oncology services across the United States.

Methods And Materials: The Current Procedural Terminology codes billed for a course of whole breast radiation were identified for this study. Publicly available fee schedules were queried for all 50 states and Washington, DC, to determine the reimbursement for each service and the total reimbursement for the entire episode of care. The degree of interstate payment variation was quantified by computing the range, mean, standard deviation, and coefficient of variation. The cost of care for the entire episode of treatment was compared to the publicly available Kaiser Family Foundation (KFF) Medicaid-to-Medicare fee index to determine if the pattern of payment variation in medical services generally is predictive of the variation seen in radiation oncology specifically.

Results: Data were available for 48 states and Washington, DC. The total episode reimbursement (excluding image guidance for respiratory tracking) varied from $2945 to $15,218 (mean, $7233; standard deviation, $2248 or 31%). The correlation coefficient of the KFF index to the calculated entire episode of care for each state was 0.55.

Conclusions: There is considerable variability in coverage and payments rates for radiation oncology services under Medicaid, and these variations track modestly with broader medical fees based on the KFF index. These variations may have implications for access to radiation oncology services that warrant further study.
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http://dx.doi.org/10.1016/j.ijrobp.2019.02.031DOI Listing
July 2019

Immunomodulatory Effects of Stereotactic Body Radiation Therapy: Preclinical Insights and Clinical Opportunities.

Int J Radiat Oncol Biol Phys 2019 Mar 2. Epub 2019 Mar 2.

Department of Radiation Oncology and Molecular Radiation Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland.

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http://dx.doi.org/10.1016/j.ijrobp.2019.02.046DOI Listing
March 2019

Biological Principles of Stereotactic Body Radiation Therapy (SBRT) and Stereotactic Radiation Surgery (SRS): Indirect Cell Death.

Int J Radiat Oncol Biol Phys 2019 Mar 2. Epub 2019 Mar 2.

Department of Radiation Oncology, University of Minnesota Medical School, Minneapolis, Minnesota.

Purpose: To review the radiobiological mechanisms of stereotactic body radiation therapy stereotactic body radiation therapy (SBRT) and stereotactic radiation surgery (SRS).

Methods And Materials: We reviewed previous reports and recent observations on the effects of high-dose irradiation on tumor cell survival, tumor vasculature, and antitumor immunity. We then assessed the potential implications of these biological changes associated with SBRT and SRS.

Results: Irradiation with doses higher than approximately 10 Gy/fraction causes significant vascular injury in tumors, leading to secondary tumor cell death. Irradiation of tumors with high doses has also been reported to increase the antitumor immunity, and various approaches are being investigated to further elevate antitumor immunity. The mechanism of normal tissue damage by high-dose irradiation needs to be further investigated.

Conclusions: In addition to directly killing tumor cells, high-dose irradiation used in SBRT and SRS induces indirect tumor cell death via vascular damage and antitumor immunity. Further studies are warranted to better understand the biological mechanisms underlying the high efficacy of clinical SBRT and SRS and to further improve the efficacy of SBRT and SRS.
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http://dx.doi.org/10.1016/j.ijrobp.2019.02.047DOI Listing
March 2019

A Prospective Analysis of Radiation Oncologist Compliance With Early Peer Review Recommendations.

Int J Radiat Oncol Biol Phys 2019 07 23;104(3):494-500. Epub 2019 Feb 23.

Department of Radiation Oncology, University of North Carolina Hospitals, Chapel Hill, North Carolina; Lineberger Comprehensive Cancer Center, University of North Carolina Hospitals, Chapel Hill, North Carolina. Electronic address:

Purpose: We conducted a prospective observational cohort study of physician compliance with daily early pretreatment planning peer review recommendations and quantified factors associated with compliance.

Methods And Materials: All patient cases in our department are presented at 2 peer review conferences: (1) "early" preplanning, occurring daily for patients who have undergone simulation review, and (2) "late" (chart rounds), occurring weekly for patients who have started treatment. Peer review recommendations were prospectively recorded during early review, and compliance with recommendations was determined at chart rounds. Recommendations were assigned magnitude scores (minor, moderate, or major). We analyzed the association of patient, physician, and recommendation characteristics and compliance (scored as a binary variable) with early peer review recommendations, using logistic regression with a mixed effects model.

Results: From February 2017 to May 2018, 1271 patient cases underwent early peer review, and 326 (26%) received peer-based recommendations. Of 356 recommendations, 37% were minor, 36% were moderate, and 27% were major. Overall compliance was 59% (95% confidence interval, 54%-64%). On univariate analysis, compliance decreased as the recommendation magnitude increased (minor, 65%; moderate, 60%; major, 47%; P = .019; odds ratio, 0.71 per increase in magnitude). Compliance also differed among different treating physicians (range, 38%-73%, χ test, P = .003) but was not associated with other physician characteristics. Disease group and treatment technique were not associated with compliance. On multivariable analysis, increasing recommendation magnitude remained significantly associated with decreased compliance (multivariate P = .042; odds ratio, 0.74).

Conclusions: Daily early peer review resulted in a substantial proportion of recommended changes. Compliance with early peer review recommendations was fair but varied among physicians. Compliance declined with increasing recommendation magnitude, suggesting that physicians may be reluctant to adopt major changes. These results highlight the potential importance of peer review timing.
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http://dx.doi.org/10.1016/j.ijrobp.2019.02.036DOI Listing
July 2019

Effect of internal mammary vessels radiation dose on outcomes of free flap breast reconstruction.

Breast J 2019 03 8;25(2):286-289. Epub 2019 Feb 8.

Department of Radiation Oncology, University of North Carolina, Chapel Hill, North Carolina.

To assess the impact of internal mammary (IM) vessels radiation dose on autologous free-flap based breast reconstruction outcomes. We retrospectively evaluated the medical records of breast cancer patients who underwent mastectomy and free-flap breast reconstruction after postoperative radiation therapy (RT) to the breast/chest wall with (n = 9) or without (n = 11) electively including the IM lymph nodes. Twenty patients were included. Median age at diagnosis was 50 years (range, 33-63). The median time interval between the start of RT and reconstructive surgery was 16 months (range, 6-45). The maximal IM vessels dose was not associated with the risk of all complications (P = 0.44) or fat necrosis (P = 0.31). The mean IM vessels dose was not significant for the risk of all complications (P = 0.13) but was significant for fat necrosis (P = 0.04). A high mean IM vessels dose was related to the occurrence of fat necrosis.
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http://dx.doi.org/10.1111/tbj.13202DOI Listing
March 2019

Carolina Hurricanes.

Int J Radiat Oncol Biol Phys 2019 03;103(3):775-776

University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina.

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http://dx.doi.org/10.1016/j.ijrobp.2018.11.015DOI Listing
March 2019

Mastectomy May Be an Inferior Oncologic Approach Compared to Breast Preservation.

Int J Radiat Oncol Biol Phys 2019 01 12;103(1):78-80. Epub 2018 Dec 12.

Department of Surgery, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina.

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http://dx.doi.org/10.1016/j.ijrobp.2018.07.2021DOI Listing
January 2019

Predicting Radiation Therapy Process Reliability Using Voluntary Incident Learning System Data.

Pract Radiat Oncol 2019 Mar 7;9(2):e210-e217. Epub 2018 Dec 7.

Division of Health Care Engineering, Radiation Oncology Department, University of North Carolina, Chapel Hill, North Carolina; School of Information and Library Science, University of North Carolina, Chapel Hill, North Carolina. Electronic address:

Purpose: This study aimed to present an innovative approach to quantify, visualize, and predict radiation therapy (RT) process reliability using data captured from a voluntary incident learning system, with an overall aim to improve patient safety outcomes.

Methods And Materials: We analyzed 111 reported deviations that were tripped and caught within 159 mapped RT process steps included within 7 major stages of RT delivery, 94 of which were any type of quality assurance (QA) controls. This allowed for us to compute the trip rate and fail-to-catch-rate (FCR) per each QA control with the available data. Next, we used a logistic regression model to identify significant variables predictive of FCRs, predicted FCRs for each QA control without available data, and thus, attempted to quantify RT process reliability expressed as percentage of patients with uncaught deviations after treatment planning, before their first treatment, and during treatment delivery.

Results: Using the predicted FCRs, we computed the upper 95% likelihood that a deviation remains uncaught in a patient's course of treatment at the following RT process stages: immediately after treatment planning at 10.26%; before the first treatment at 0.0052%; and throughout treatment delivery at 0.0276%.

Conclusions: The results suggest that RT process reliability can be predicted and visualized using data from incident learning systems. If implemented and used as a safety metric, this could help RT clinics to proactively maintain their preoccupation with patient safety. RT process reliability may also help guide future work on standardization and continuous improvement of the design of RT QA programs.
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http://dx.doi.org/10.1016/j.prro.2018.11.012DOI Listing
March 2019