Publications by authors named "Shiva Das"

104 Publications

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

Initial Data Pooling for Radiation Dose-Volume Tolerance for Carotid Artery Blowout and Other Bleeding Events in Hypofractionated Head and Neck Retreatments.

Int J Radiat Oncol Biol Phys 2021 May 11;110(1):147-159. Epub 2021 Feb 11.

Department of Radiation Oncology, Bon Secours Mercy Health System, Youngstown, Ohio.

Purpose: Dose-volume data for injury to carotid artery and other major vessels in stereotactic body radiation therapy (SBRT)/SABR head and neck reirradiation were reviewed, modeled, and summarized.

Methods And Materials: A PubMed search of the English-language literature (stereotactic and carotid and radiation) in April 2018 found 238 major vessel maximum point doses in 6 articles that were pooled for logistic modeling. Two subsequent studies with dose-volume major vessel data were modeled separately for comparison. Attempts were made to separate carotid blowout syndrome from other bleeding events (BE) in the analysis, but we acknowledge that all except 1 data set has some element of BE interspersed.

Results: Prior radiation therapy (RT) dose was not uniformly reported per patient in the studies included, but a course on the order of conventionally fractionated 70 Gy was considered for the purposes of the analysis (with an approximately ≥6-month estimated interval between prior and subsequent treatment in most cases). Factors likely associated with reduced risk of BE include nonconsecutive daily treatment, lower extent of circumferential tumor involvement around the vessel, and no surgical manipulation before or after SBRT.

Conclusions: Initial data pooling for reirradiation involving the carotid artery resulted in 3 preliminary models compared in this Hypofractionated Treatment Effects in the Clinic (HyTEC) report. More recent experiences with alternating fractionation schedules and additional risk-reduction strategies are also presented. Complications data for the most critical structures such as spinal cord and carotid artery are so limited that they cannot be viewed as strong conclusions of probability of risk, but rather, as a general guideline for consideration. There is a great need for better reporting standards as noted in the High Dose per Fraction, Hypofractionated Treatment Effects in the Clinic introductory paper.
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http://dx.doi.org/10.1016/j.ijrobp.2020.12.037DOI Listing
May 2021

Farewell Editorial: Jeffrey F. Williamson Editor-in-Chief, Shiva K. Das Therapy Physics Editor, Mitchell M. Goodsitt Imaging Physics Editor.

Med Phys 2020 Dec;47(12):5969-5971

Radiology Department, Univ Michigan, 1500 E Medical Center Dr, Med Inn Bldg Room C445, Ann Arbor, MI, 48109-5842, USA.

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http://dx.doi.org/10.1002/mp.14578DOI Listing
December 2020

Early F-FDG-PET Response During Radiation Therapy for HPV-Related Oropharyngeal Cancer May Predict Disease Recurrence.

Int J Radiat Oncol Biol Phys 2020 11 13;108(4):969-976. Epub 2020 Aug 13.

Department of Radiation Oncology, Duke Cancer Institute, Duke University School of Medicine, Durham, North Carolina; Department of Head and Neck Surgery & Communication Sciences, Duke University School of Medicine, Durham, North Carolina.

Purpose: Early indication of treatment outcome may guide therapeutic de-escalation strategies in patients with human papillomavirus (HPV)-related oropharyngeal cancer (OPC). This study investigated the relationships between tumor volume and F-fluorodeoxyglucose positron emission tomography (PET) parameters before and during definitive radiation therapy with treatment outcomes.

Methods And Materials: Patients undergoing definitive (chemo)radiation for HPV-related/p16-positive OPC were prospectively enrolled on an institutional review board-approved study. F-fluorodeoxyglucose PET/computed tomography scans were performed at simulation and after 2 weeks at a dose of ∼20 Gy. Tumor volume and standardized uptake value (SUV) characteristics were measured. SUV was normalized to blood pool uptake. Tumor volume and PET parameters associated with recurrence were identified through recursive partitioning (RPART). Recurrence-free survival (RFS) and overall survival (OS) curves between RPART-identified cohorts were estimated using the Kaplan-Meier method, and Cox models were used to estimate the hazard ratios (HRs).

Results: From 2012 to 2016, 62 patients with HPV-related OPC were enrolled. Median follow-up was 4.4 years. RPART identified patients with intratreatment SUV (normalized to blood pool SUV) <6.7 or SUV (normalized to blood pool SUV) ≥6.7 with intratreatment SUV ≥2.75 as less likely to recur. For identified subgroups, results of Cox models showed unadjusted HRs for RFS and OS (more likely to recur vs less likely) of 7.33 (90% confidence interval [CI], 2.97-18.12) and 6.09 (90% CI, 2.22-16.71), respectively, and adjusted HRs of 6.57 (90% CI, 2.53-17.05) and 5.61 (90% CI, 1.90-16.54) for RFS and OS, respectively.

Conclusions: PET parameters after 2 weeks of definitive radiation therapy for HPV-related OPC are associated with RFS and OS, thus potentially informing an adaptive treatment approach.
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http://dx.doi.org/10.1016/j.ijrobp.2020.08.029DOI Listing
November 2020

The role of machine and deep learning in modern medical physics.

Med Phys 2020 Jun;47(5):e125-e126

Department of Radiation Oncology, University of North Carolina, Chapel Hill, NC, 277103, USA.

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http://dx.doi.org/10.1002/mp.14088DOI Listing
June 2020

Evaluation of a commercial DIR platform for contour propagation in prostate cancer patients treated with IMRT/VMAT.

J Appl Clin Med Phys 2020 Feb;21(2):14-25

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

Purpose: To assess the performance and limitations of contour propagation with three commercial deformable image registration (DIR) algorithms using fractional scans of CT-on-rails (CTOR) and Cone Beam CT (CBCT) in image guided prostate therapy patients treated with IMRT/VMAT.

Methods: Twenty prostate cancer patients treated with IMRT/VMAT were selected for analysis. A total of 453 fractions across those patients were analyzed. Image data were imported into MIM (MIM Software, Inc., Cleveland, OH) and three DIR algorithms (DIR Profile, normalized intensity-based (NIB) and shadowed NIB DIR algorithms) were applied to deformably register each fraction with the planning CT. Manually drawn contours of bladder and rectum were utilized for comparison against the DIR propagated contours in each fraction. Four metrics were utilized in the evaluation of contour similarity, the Hausdorff Distance (HD), Mean Distance to Agreement (MDA), Dice Similarity Coefficient (DSC), and Jaccard indices. A subfactor analysis was performed per modality (CTOR vs. CBCT) and time (fraction). Point estimates and 95% confidence intervals were assessed via a Linear Mixed Effect model for the contour similarity metrics.

Results: No statistically significant differences were observed between the DIR Profile and NIB algorithms. However, statistically significant differences were observed between the shadowed NIB and NIB algorithms for some of the DIR evaluation metrics. The Hausdorff Distance calculation showed the NIB propagated contours vs. shadowed NIB propagated contours against the manual contours were 14.82 mm vs. 8.34 mm for bladder and 15.87 mm vs. 11 mm for rectum, respectively. Similarly, the Mean Distance to Agreement calculation comparing the NIB propagated contours vs. shadowed NIB propagated contours against the manual contours were 2.43 mm vs. 0.98 mm for bladder and 2.57 mm vs. 1.00 mm for rectum, respectively. The Dice Similarity Coefficients comparing the NIB propagated contours and shadowed NIB propagated contours against the manual contours were 0.844 against 0.936 for bladder and 0.772 against 0.907 for rectum, respectively. The Jaccard indices comparing the NIB propagated contours and shadowed NIB propagated contours against the manual contours were 0.749 against 0.884 for bladder and 0.637 against 0.831 for rectum, respectively. The shadowed NIB DIR, which showed the closest agreement with the manual contours performed significantly better than the DIR Profile in all the comparisons. The OAR with the greatest agreement varied substantially across patients and image guided radiation therapy (IGRT) modality. Intra-patient variability of contour metric evaluation was insignificant across all the DIR algorithms. Statistical significance at α = 0.05 was observed for manual vs. deformably propagated contours for bladder for all the metrics except Hausdorff Distance (P = 0.01 for MDA, P = 0.02 for DSC, P = 0.01 for Jaccard), whereas the corresponding values for rectum were: P = 0.03 for HD, P = 0.01 for MDA, P < 0.01 for DSC, P < 0.01 for Jaccard. The performance of the different metrics varied slightly across the fractions of each patient, which indicates that weekly contour propagation models provide a reasonable approximation of the daily contour propagation models.

Conclusion: The high variance of Hausdorff Distance across all automated methods for bladder indicates widely variable agreement across fractions for all patients. Lower variance across all modalities, methods, and metrics were observed for rectum. The shadowed NIB propagated contours were substantially more similar to the manual contours than the DIR Profile or NIB contours for both the CTOR and CBCT imaging modalities. The relationship of each algorithm to similarity with manual contours is consistent across all observed metrics and organs. Screening of image guidance for substantial differences in bladder and rectal filling compared with the planning CT reference could aid in identifying fractions for which automated DIR would prove insufficient.
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http://dx.doi.org/10.1002/acm2.12787DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7020979PMC
February 2020

Initial assessment of 3D magnetic resonance fingerprinting (MRF) towards quantitative brain imaging for radiation therapy.

Med Phys 2020 Mar 30;47(3):1199-1214. Epub 2019 Dec 30.

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

Purpose: Magnetic resonance fingerprinting (MRF) provides quantitative T1/T2 maps, enabling applications in clinical radiotherapy such as large-scale, multi-center clinical trials for longitudinal assessment of therapy response. We evaluated the feasibility of a quantitative three-dimensional-MRF (3D-MRF) towards its radiotherapy applications of primary brain tumors.

Methods: A fast whole-brain 3D-MRF sequence initially developed for diagnostic radiology was optimized using flexible body coils, which is the typical MR imaging setup for radiotherapy treatment planning and for MR imaging (MRI)-guided treatment delivery. Optimization criteria included the accuracy and the precision of T1/T2 quantifications of polyvinylpyrrolidone (PVP) solutions, compared to those from the 3D-MRF using a 32-channel head coil. The accuracy of T1/T2 quantifications from the optimized MRF was first examined in healthy volunteers with two different coil setups. The intra- and inter-scanner variations of image intensity from the optimized sequence were quantified by longitudinal scans of the PVP solutions on two 3T scanners. Using a 3D-printed MRI geometry phantom, susceptibility-induced distortion with the optimized 3D-MRF was quantified as the Dice coefficient of phantom contours, compared to those from CT images. By introducing intentional head motion during 10% of the scan, the robustness of the optimized 3D-MRF towards motion was evaluated through visual inspection of motion artifacts and through quantitative analysis of image sharpness in brain MRF maps.

Results: The optimized sequence acquired whole-brain T1, T2 and proton density maps and with a resolution of 1.2 × 1.2 × 3 mm in 10 min, similar to the total acquisition time of 3D T1- and T2-weighted images of the same resolution. In vivo T1 and T2 values of the white and gray matter were consistent with literature. The intra- and inter-scanner variability of the intensity-normalized MRF T1 was 1.0% ± 0.7% and 2.3% ± 1.0% respectively, in contrast to 5.3% ± 3.8% and 3.2% ± 1.6% from the normalized T1-weighted MRI. Repeatability and reproducibility of MRF T1 were independent of intensity normalization. Both phantom and human data demonstrated that the optimized 3D-MRF is more robust to subject motion and artifacts from subject-specific susceptibility difference. Compared to CT contours, the Dice coefficient of phantom contours from 3D-MRF was 0.93, improved from 0.87 from the T1-weighted MRI.

Conclusion: Compared to conventional MRI, the optimized 3D-MRF demonstrated improved repeatability across time points and reproducibility across scanners for better tissue quantification, as well as improved robustness to subject-specific susceptibility and motion artifacts under a typical MR imaging setup for radiotherapy. More importantly, quantitative MRF T1/T2 measurements lead to promising potentials towards longitudinal quantitative assessment of treatment response for better adaptive therapy and for large-scale, multi-center clinical trials.
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http://dx.doi.org/10.1002/mp.13967DOI Listing
March 2020

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

Human Error Bowtie Analysis to Enhance Patient Safety in Radiation Oncology.

Pract Radiat Oncol 2019 Nov 16;9(6):465-478. Epub 2019 Jul 16.

Division of Healthcare Engineering, Department of Radiation Oncology, University of North Carolina School of Medicine, Chapel Hill, North Carolina; Carolina Health Informatics Program, School of Information and Library Science, University of North Carolina, Chapel Hill, North Carolina.

Purpose: Ensuring safety within RT is of paramount importance. To further support and augment patient safety efforts, the purpose of this research was to test and refine a robust methodology for analyzing human errors that defeat individual controls within RT quality assurance (QA) programs.

Methods: The method proposed for performing Bowtie Analysis (BTA) was based on training and recommendations from practitioners in the field of Human Factors and Ergonomics practice. Multidisciplinary meetings to iteratively develop BTA focused on incorrect site setup instructions was conducted.

Results: From November 2015 to February 2017, we had 12 reported incidents related to site setup notes that could have led to site setup errors. Based on this data, we conducted five BTA analyses related to incorrect site setup instructions. None of the individual controls within our QA program designed to check for potential errors with site setup instructions met the level of robustness to be classified as key safeguards or barriers.

Conclusions: The relatively low number of incidents causing patient harm has led us to typically assume that we have sufficient and effective controls in place to prevent serious human errors from leading to severe patient consequences. Based on our BTA, we question how well we truly understand the details of our individual controls. To meet the level of safety achieved by high reliability organizations (HROs), we need to better ensure that our controls are as reliable and robust as we assume.
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http://dx.doi.org/10.1016/j.prro.2019.06.022DOI Listing
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

Task Group 174 Report: Utilization of [ F]Fluorodeoxyglucose Positron Emission Tomography ([ F]FDG-PET) in Radiation Therapy.

Med Phys 2019 Oct 6;46(10):e706-e725. Epub 2019 Sep 6.

Department of Radiology, University of Washington, Seattle, WA, USA.

The use of positron emission tomography (PET) in radiation therapy (RT) is rapidly increasing in the areas of staging, segmentation, treatment planning, and response assessment. The most common radiotracer is F-fluorodeoxyglucose ([ F]FDG), a glucose analog with demonstrated efficacy in cancer diagnosis and staging. However, diagnosis and RT planning are different endeavors with unique requirements, and very little literature is available for guiding physicists and clinicians in the utilization of [ F]FDG-PET in RT. The two goals of this report are to educate and provide recommendations. The report provides background and education on current PET imaging systems, PET tracers, intensity quantification, and current utilization in RT (staging, segmentation, image registration, treatment planning, and therapy response assessment). Recommendations are provided on acceptance testing, annual and monthly quality assurance, scanning protocols to ensure consistency between interpatient scans and intrapatient longitudinal scans, reporting of patient and scan parameters in literature, requirements for incorporation of [ F]FDG-PET in treatment planning systems, and image registration. The recommendations provided here are minimum requirements and are not meant to cover all aspects of the use of [ F]FDG-PET for RT.
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http://dx.doi.org/10.1002/mp.13676DOI Listing
October 2019

Organs at Risk Considerations for Thoracic Stereotactic Body Radiation Therapy: What Is Safe for Lung Parenchyma?

Int J Radiat Oncol Biol Phys 2021 May 26;110(1):172-187. Epub 2018 Nov 26.

Memorial Sloan Kettering Cancer Center, New York, New York.

Purpose: Stereotactic body radiation therapy (SBRT) has become the standard of care for inoperable early-stage non-small cell lung cancer and is often used for recurrent lung cancer and pulmonary metastases. Radiation-induced lung toxicity (RILT), including radiation pneumonitis and pulmonary fibrosis, is a major concern for which it is important to understand dosimetric and clinical predictors.

Methods And Materials: This study was undertaken through the American Association of Physicists in Medicine's Working Group on Biological Effects of Stereotactic Body Radiotherapy. Data from studies of lung SBRT published through the summer of 2016 that provided detailed information about RILT were analyzed.

Results: Ninety-seven studies were ultimately considered. Definitions of the risk organ and complication endpoints as well as dose-volume information presented varied among studies. The risk of RILT, including radiation pneumonitis and pulmonary fibrosis, was reported to be associated with the size and location of the tumor. Patients with interstitial lung disease appear to be especially susceptible to severe RILT. A variety of dosimetric parameters were reported to be associated with RILT. There was no apparent threshold "tolerance dose-volume" level. However, most studies noted safe treatment with a rate of symptomatic RILT of <10% to 15% after lung SBRT with a mean lung dose (MLD) of the combined lungs ≤8 Gy in 3 to 5 fractions and the percent of total lung volume receiving more than 20 Gy (V) <10% to 15%.

Conclusions: To allow more rigorous analysis of this complication, future studies should standardize reporting by including standardized endpoint and volume definitions and providing dose-volume information for all patients, with and without RILT.
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http://dx.doi.org/10.1016/j.ijrobp.2018.11.028DOI Listing
May 2021

Fitting NTCP models to SBRT dose and carotid blowout syndrome data.

Med Phys 2018 Oct 31;45(10):4754-4762. Epub 2018 Aug 31.

Department of Radiation Oncology, Hacettepe University, Faculty of Medicine Sihhiye, Ankara, Turkey.

Purpose: To estimate the radiobiological parameters of three popular NTCP models, which describe the dose-response relations of carotid blowout syndrome (CBOS) after stereotactic body radiotherapy (SBRT). To evaluate the goodness-of-fit and the correlation of those models with CBOS.

Methods: The study included 61 patients with inoperable locally recurrent head and neck cancer treated with SBRT using CyberKnife (Accuray, Sunnyvale, CA) at the Department of Radiation Oncology, Hacettepe University, Ankara, Turkey between June 2007 and March 2011. The dose-volume histograms of the internal carotid were exported from the plans of all the patients. The follow-up results regarding the end point of carotid blowout syndrome were collected retrospectively. Initially, univariable analyses (Wilcoxon rank-sum or Chi-square tests) and a multivariate logistic regression analysis were performed between the outcome data and a list of clinical and treatment factors to identify significant correlations. Additionally, the Lyman-Kutcher-Burman (LKB), Relative Seriality (RS), and Logit NTCP models were used to fit the clinical data. The fitting of the different models was assessed through the area under the receiver operating characteristic curve (AUC), Akaike information criterion (AIC), and Odds Ratio methods.

Results: The clinical/treatment factors that were found to have a significant or close to significant correlations with acute CBOS were Age at the time of CK (P-value = 0.03), Maximum carotid dose (P-value = 0.06), and CK prescription dose (P-value = 0.08). Using D , physical DVH, and EQD -DVH as the dosimetric metrics in the NTCP models, the derived LKB model parameters were: (a) D  = 45.8 Gy, m = 0.24, n = n/a; (b) D  = 44.8 Gy, m = 0.28, n = 0.01; and (c) D  = 115.8 Gy, m = 0.45, n = 0.01, respectively. The AUC values for the dosimetric metrics were 0.70, 0.68, and 0.61, respectively. The differences in AIC between the different models were less than 2 and ranged within ±0.9.

Conclusion: The maximum dose to the internal carotid less than 34 Gy appears to significantly reduce the risk for CBOS. Age at the time of CK, Maximum carotid dose, and CK prescription dose were also found to correlate with CBOS. The values of the parameters of three NTCP models were determined for this endpoint. A threshold of gEUD <34.5 Gy appears to be significantly associated with lower risks of CBOS.
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http://dx.doi.org/10.1002/mp.13121DOI Listing
October 2018

Redefining and reinvigorating the role of physics in clinical medicine: A Report from the AAPM Medical Physics 3.0 Ad Hoc Committee.

Med Phys 2018 Jul 10. Epub 2018 Jul 10.

University of Sydney, Australia.

Derived from 2 yr of deliberations and community engagement, Medical Physics 3.0 (MP3.0) is an effort commissioned by the American Association of Physicists in Medicine (AAPM) to devise a framework of strategies by which medical physicists can maintain and improve their integral roles in, and contributions to, health care and its innovation under conditions of rapid change and uncertainty. Toward that goal, MP3.0 advocates a broadened and refreshed model of sustainable excellence by which medical physicists can and should contribute to health care. The overarching conviction of MP3.0 is that every healthcare facility can benefit from medical physics and every patient's care can be improved by a medical physicist. This large and expansive challenge necessitates a range of strategies specific to each area of medical physics: clinical practice, research, product development, and education. The present paper offers a summary of the Phase 1 deliberations of the MP3.0 initiative pertaining to strategic directions of the discipline primarily but not exclusively oriented toward the clinical practice of medical physics in the United States.
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http://dx.doi.org/10.1002/mp.13087DOI Listing
July 2018

Developing and assessing electronic checklists for safety mindfulness, workload, and performance.

Pract Radiat Oncol 2018 Nov - Dec;8(6):458-467. Epub 2018 May 16.

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

Purpose: The aim of this study is to propose a set of innovative principles for the effective design of electronic checklists to enhance safety mindfulness (a specific safety mindful mindset that offers the opportunity to operate more preemptively during routine quality assurance tasks) and discuss some of our preliminary results from testing our proposed electronic checklist with dosimetrists and physicists.

Methods And Materials: A multidisciplinary team designed, developed, and evaluated the utility of the electronic checklist (vs paper-based checklist) to promote safety mindfulness. Subjective workload was measured at the end of each assessment/scenario. Performance was quantified on the basis of discovery of purposefully embedded errors, time to complete the scenario, and additional concerns that were documented by the participants.

Results: Use of the electronic checklist was associated with decreases in time to scenario completion (P < .01) and increases in documentation of additional patient safety and plan quality concerns (P = .04) but had no significant impact on the recognition of purposefully embedded errors or perceptions of workload.

Conclusions: Our proposed principles for the design of electronic checklists may improve the efficiency of quality assurance procedures while enhancing users' safety mindfulness. Future research is needed to better understand the utility of our proposed design principles on patient safety from a long-term use perspective.
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http://dx.doi.org/10.1016/j.prro.2018.05.001DOI Listing
January 2019

Correlation of Regional Lung Ventilation and Gas Transfer to Red Blood Cells: Implications for Functional-Avoidance Radiation Therapy Planning.

Int J Radiat Oncol Biol Phys 2018 08 14;101(5):1113-1122. Epub 2018 Apr 14.

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

Purpose: To investigate the degree to which lung ventilation and gas exchange are regionally correlated, using the emerging technology of hyperpolarized (HP)-Xe magnetic resonance imaging (MRI).

Methods And Materials: Hyperpolarized-Xe MRI studies were performed on 17 institutional review board-approved human subjects, including 13 healthy volunteers, 1 emphysema patient, and 3 non-small cell lung cancer patients imaged before and approximately 11 weeks after radiation therapy (RT). Subjects inhaled 1 L of HP-Xe mixture, followed by the acquisition of interleaved ventilation and gas exchange images, from which maps were obtained of the relative HP-Xe distribution in three states: (1) gaseous, in lung airspaces; (2) dissolved interstitially, in alveolar barrier tissue; and (3) transferred to red blood cells (RBCs), in the capillary vasculature. The relative spatial distributions of HP-Xe in airspaces (regional ventilation) and RBCs (regional gas transfer) were compared. Further, we investigated the degree to which ventilation and RBC transfer images identified similar functional regions of interest (ROIs) suitable for functionally guided RT. For the RT patients, both ventilation and RBC functional images were used to calculate differences in the lung dose-function histogram and functional effective uniform dose.

Results: The correlation of ventilation and RBC transfer was ρ = 0.39 ± 0.15 in healthy volunteers. For the RT patients, this correlation was ρ = 0.53 ± 0.02 before treatment and ρ = 0.39 ± 0.07 after treatment; for the emphysema patient it was ρ = 0.24. Comparing functional ROIs, ventilation and RBC transfer demonstrated poor spatial agreement: Dice similarity coefficient = 0.50 ± 0.07 and 0.26 ± 0.12 for the highest-33%- and highest-10%-function ROIs in healthy volunteers, and in RT patients (before treatment) these were 0.58 ± 0.04 and 0.40 ± 0.04. The average magnitude of the differences between RBC- and ventilation-derived functional effective uniform dose, fV20Gy, fV10Gy, and fV5Gy were 1.5 ± 1.4 Gy, 4.1% ± 3.8%, 5.0% ± 3.8%, and 5.3% ± 3.9%, respectively.

Conclusion: Ventilation may not be an effective surrogate for true regional lung function for all patients.
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http://dx.doi.org/10.1016/j.ijrobp.2018.04.017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6689416PMC
August 2018

Promoting safety mindfulness: Recommendations for the design and use of simulation-based training in radiation therapy.

Adv Radiat Oncol 2018 Apr-Jun;3(2):197-204. Epub 2018 Feb 7.

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

There is a need to better prepare radiation therapy (RT) providers to safely operate within the health information technology (IT) sociotechnical system. Simulation-based training has been preemptively used to yield meaningful improvements during providers' interactions with health IT, including RT settings. Therefore, on the basis of the available literature and our experience, we propose principles for the effective design and use of simulated scenarios and describe a conceptual framework for a debriefing approach to foster successful training that is focused on safety mindfulness during RT professionals' interactions with health IT.
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http://dx.doi.org/10.1016/j.adro.2018.01.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6000160PMC
February 2018

Association of Interim FDG-PET Imaging During Chemoradiation for Squamous Anal Canal Carcinoma With Recurrence.

Int J Radiat Oncol Biol Phys 2018 11 4;102(4):1046-1051. Epub 2018 May 4.

Department of Radiation Oncology, Duke University, Durham, North Carolina. Electronic address:

Purpose: Imaging parameters from 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) before and after chemoradiation therapy (CRT) for anal canal cancer correlate with clinical outcomes. This prospective, hypothesis-generating pilot study investigates the relationship between interim PET imaging during CRT for anal canal cancer and clinical outcome.

Methods And Materials: From June 2012 to August 2015, 30 patients with anal canal cancer were enrolled in a prospective clinical study of PET prior to and during CRT after ∼30 Gy. PET parameters of the primary site included maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG). MTV and TLG were calculated based on 40% SUVmax (MTV40, TLG40) or SUV 2.5 (MTV2.5, TLG2.5) thresholds for pretreatment and interim images. Absolute and change in PET parameters were assessed for association with freedom from local and regional recurrence (FFLR) using single-predictor Cox regression models. Local and regional recurrence were primary and nodal (in-field) recurrences, respectively.

Results: Twenty-three patients were eligible for analysis. Patients were excluded with nonsquamous cell histology, recurrent anal cancer, and incomplete studies due to treatment toxicity or patient choice. Median follow-up was 2.5 years. Pretreatment MTV40 (HR 1.4 [95% CI 1.02-2.05]), interim MTV2.5 (1.4 [1.04-1.89]), and interim TLG2.5 (1.1 [1.01-1.21]) were associated with FFLR.

Conclusions: In this prospective pilot study, interim PET parameters were associated with FFLR. These results warrant further investigation assessing the value of interim PET as a biomarker of response in the treatment of patients with anal cancer.
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http://dx.doi.org/10.1016/j.ijrobp.2018.04.062DOI Listing
November 2018

How Advances in Imaging Will Affect Precision Radiation Oncology.

Int J Radiat Oncol Biol Phys 2018 06 31;101(2):292-298. Epub 2018 Jan 31.

The D-Lab: Decision Support for Precision Medicine, GROW -School for Oncology, Maastricht University Medical Centre+, Maastricht, the Netherlands.

Radiation oncology is 1 of the most structured disciplines in medicine. It is of a highly technical nature with reliance on robotic systems to deliver intervention, engagement of diverse expertise, and early adoption of digital approaches to optimize and execute the application of this highly effective cancer treatment. As a localized intervention, the dependence on sensitive, specific, and accurate imaging to define the extent of disease, its heterogeneity, and adjacency to normal tissues directly affects the therapeutic ratio. Image-based in vivo temporal monitoring of the response to treatment enables adaptation and further affects the therapeutic ratio. Thus, more precise intervention will enable fractionation schedules that better interoperate with advances such as immunotherapy. In the data set-rich era that promises precision and personalized medicine, the radiation oncology field will integrate these new data into highly protocoled pathways of care that begin with multimodality prediction and enable patient-specific adaptation of therapy based on quantitative measures of the individual's dose-volume temporal trajectory and midtherapy predictions of response. In addition to advancements in computed tomography imaging, emerging technologies, such as ultra-high-field magnetic resonance and molecular imaging will bring new information to the design of treatments. Next-generation image guided radiation therapy systems will inject high specificity and sensitivity data and stimulate adaptive replanning. In addition, a myriad of pre- and peritherapeutic markers derived from advances in molecular pathology (eg, tumor genomics), automated and comprehensive imaging analytics (eg, radiomics, tumor microenvironment), and many other emerging biomarkers (eg, circulating tumor cell assays) will need to be integrated to maximize the benefit of radiation therapy for an individual patient. We present a perspective on the promise and challenges of fully exploiting imaging data in the pursuit of personalized radiation therapy, drawing from the presentations and broader discussions at the 2016 American Society of Therapeutic Radiation Oncology-National Cancer Institute workshop on Precision Medicine in Radiation Oncology (Bethesda, MD).
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http://dx.doi.org/10.1016/j.ijrobp.2018.01.047DOI Listing
June 2018

Fitting NTCP models to bladder doses and acute urinary symptoms during post-prostatectomy radiotherapy.

Radiat Oncol 2018 Feb 2;13(1):17. Epub 2018 Feb 2.

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

Background: To estimate the radiobiological parameters of three popular normal tissue complication probability (NTCP) models, which describe the dose-response relations of bladder regarding different acute urinary symptoms during post-prostatectomy radiotherapy (RT). To evaluate the goodness-of-fit and the correlation of those models with those symptoms.

Methods: Ninety-three consecutive patients treated from 2010 to 2015 with post-prostatectomy image-guided intensity modulated radiotherapy (IMRT) were included in this study. Patient-reported urinary symptoms were collected pre-RT and weekly during treatment using the validated Prostate Cancer Symptom Indices (PCSI). The assessed symptoms were flow, dysuria, urgency, incontinence, frequency and nocturia using a Likert scale of 1 to 4 or 5. For this analysis, an increase by ≥2 levels in a symptom at any time during treatment compared to baseline was considered clinically significant. The dose volume histograms of the bladder were calculated. The Lyman-Kutcher-Burman (LKB), Relative Seriality (RS) and Logit NTCP models were used to fit the clinical data. The fitting of the different models was assessed through the area under the receiver operating characteristic curve (AUC), Akaike information criterion (AIC) and Odds Ratio methods.

Results: For the symptoms of urinary urgency, leakage, frequency and nocturia, the derived LKB model parameters were: 1) D = 64.2Gy, m = 0.50, n = 1.0; 2) D = 95.0Gy, m = 0.45, n = 0.50; 3) D = 83.1Gy, m = 0.56, n = 1.00; and 4) D = 85.4Gy, m = 0.60, n = 1.00, respectively. The AUC values for those symptoms were 0.66, 0.58, 0.64 and 0.64, respectively. The differences in AIC between the different models were less than 2 and ranged within 0.1 and 1.3.

Conclusions: Different dose metrics were correlated with the symptoms of urgency, incontinence, frequency and nocturia. The symptoms of urinary flow and dysuria were poorly associated with dose. The values of the parameters of three NTCP models were determined for bladder regarding four acute urinary symptoms. All the models could fit the clinical data equally well. The NTCP predictions of urgency showed the best correlation with the patient reported outcomes.
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http://dx.doi.org/10.1186/s13014-018-0961-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5797360PMC
February 2018

Imaging Radiation-Induced Normal Tissue Injury to Quantify Regional Dose Response.

Semin Radiat Oncol 2017 10;27(4):325-331

UNC Hospitals, Department of Radiation Oncology, Chapel Hill, NC.

Noninvasive imaging has and will continue to play a pivotal role in the assessment of radiation-induced normal tissue toxicity. In this review, we will examine key literature regarding the use of anatomic and physiological imaging in relation to radiation-induced normal tissue toxicity. Additionally, this review contains a novel methodology for potentially incorporating dose-response data into treatment planning and normal tissue toxicity modeling.
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http://dx.doi.org/10.1016/j.semradonc.2017.04.004DOI Listing
October 2017

Assessment of PlanIQ Feasibility DVH for head and neck treatment planning.

J Appl Clin Med Phys 2017 Sep 30;18(5):245-250. Epub 2017 Aug 30.

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

Introduction: Designing a radiation plan that optimally delivers both target coverage and normal tissue sparing is challenging. There are limited tools to determine what is dosimetrically achievable and frequently the experience of the planner/physician is relied upon to make these determinations. PlanIQ software provides a tool that uses target and organ at risk (OAR) geometry to indicate the difficulty of achieving different points for organ dose-volume histograms (DVH). We hypothesized that PlanIQ Feasibility DVH may aid planners in reducing dose to OARs.

Methods And Materials: Clinically delivered head and neck treatments (clinical plan) were re-planned (re-plan) putting high emphasis on maximally sparing the contralateral parotid gland, contralateral submandibular gland, and larynx while maintaining routine clinical dosimetric objectives. The planner was blinded to the results of the clinically delivered plan as well as the Feasibility DVHs from PlanIQ. The re-plan treatments were designed using 3-arc VMAT in Raystation (RaySearch Laboratories, Sweden). The planner was then given the results from the PlanIQ Feasibility DVH analysis and developed an additional plan incorporating this information using 4-arc VMAT (IQ plan). The DVHs across the three treatment plans were compared with what was deemed "impossible" by PlanIQ's Feasibility DVH (Impossible DVH). The impossible DVH (red) is defined as the DVH generated using the minimal dose that any voxel outside the targets must receive given 100% target coverage.

Results: The re-plans performed blinded to PlanIQ Feasibilty DVH achieved superior sparing of aforementioned OARs compared to the clinically delivered plans and resulted in discrepancies from the impossible DVHs by an average of 200-700 cGy. Using the PlanIQ Feasibility DVH led to additionalOAR sparing compared to both the re-plans and clinical plans and reduced the discrepancies from the impossible DVHs to an average of approximately 100 cGy. The dose reduction from clinical to re-plan and re-plan to IQ plan were significantly different even when taking into account multiple hypothesis testing for both the contralateral parotid and the larynx (P < 0.004 for all comparisons). No significant differences were observed between the three plans for the contralateral parotid when considering multiple hypothesis testing.

Conclusions: Clinical treatment plans and blinded re-plans were found to suboptimally spare OARs. PlanIQ could aid planners in generating treatment plans that push the limits of OAR sparing while maintaining routine clinical target coverage goals.
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http://dx.doi.org/10.1002/acm2.12165DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5874967PMC
September 2017

Noninvasive measurement of tissue blood oxygenation with Cerenkov imaging during therapeutic radiation delivery.

Opt Lett 2017 Aug;42(16):3101-3104

Tumor tissue oxygenation significantly affects the outcome of radiotherapy. Real-time monitoring of tumor hypoxia is highly desirable for effective radiotherapy, and is the basis for improved treatment because hypoxic tumor cells are more resistant to radiation damage than fully oxygenated cells. We propose to use Cerenkov imaging to monitor tumor hypoxia by means of tissue blood oxygenation without the need for any exogenous contrast agent. Using a rodent hypoxia model, we demonstrate that Cerenkov imaging can be used as a noninvasive and noncontact method to measure tissue blood oxygenation level during radiation delivery. The data from Cerenkov imaging were validated using near infrared spectrometry methods. The results demonstrate the feasibility of using Cerenkov imaging to monitor tumor hypoxia during therapeutic radiation delivery.
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http://dx.doi.org/10.1364/OL.42.003101DOI Listing
August 2017

Dosimetric Predictors of Patient-Reported Xerostomia and Dysphagia With Deintensified Chemoradiation Therapy for HPV-Associated Oropharyngeal Squamous Cell Carcinoma.

Int J Radiat Oncol Biol Phys 2017 08 27;98(5):1022-1027. Epub 2017 Mar 27.

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

Purpose/objective(s): To estimate the association between different dose-volume metrics of the salivary glands and pharyngeal constrictors with patient reported severity of xerostomia/dysphagia in the setting of deintensified chemoradiation therapy (CRT).

Methods And Materials: Forty-five patients were treated on a phase 2 study assessing the efficacy of deintensified CRT for favorable-risk, HPV-associated oropharyngeal squamous cell carcinoma. Patients received 60 Gy intensity modulated radiation therapy with concurrent weekly cisplatin (30 mg/m), and reported the severity of their xerostomia/dysphagia (before and after treatment) using the patient-reported outcome version of the Common Terminology Criteria for Adverse Events (CTCAE) (PRO-CTCAE). Individual patient dosimetric data of the contralateral parotid and submandibular glands and pharyngeal constrictors were correlated with changes in PRO-CTCAE severity. A change in severity (from baseline) of ≥2 was considered clinically meaningful. Associations between dose-volume metrics and patient outcomes were assessed with receiver operating characteristic (ROC) curve and logistic regression model.

Results: Six months after CRT, patients reporting <2 change in xerostomia severity (n=14) had an average D = 22 ± 9 Gy to the sum of the contralateral glands (parotid + submandibular) compared with the patients reporting ≥2 change (n=21), who had an average D = 34 ± 8 Gy. V15 to V55 for the combined contralateral glands showed the strongest association with xerostomia (area under the curve [AUC] = 0.83-0.86). Based on the regression analysis, a 20% risk of toxicity was associated with V15 = 48%, V25 = 30%, and D=21 Gy. Six months after CRT, patients reporting <2 change in dysphagia severity (n=26) had an average V55 = 76 ± 13 (%) to the superior pharyngeal constrictor compared with the patients reporting ≥2 change in severity (n=9), who had average V55 = 89 ± 13 (%). V55to V60 had the strongest association with dysphagia (AUC = 0.70-0.75). Based on the regression analysis, a 20% risk of toxicity was associated with V55 = 78%, V60 = 40%. The findings at 12 months were similar.

Conclusions: After deintensified CRT, the rate of patient-reported xerostomia/dysphagia appears to be associated with the V15 of the combined contralateral salivary glands and V55 to V60 of the superior pharyngeal constrictors.
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http://dx.doi.org/10.1016/j.ijrobp.2017.03.034DOI Listing
August 2017

Dose-volume toxicity modeling for de-intensified chemo-radiation therapy for HPV-positive oropharynx cancer.

Radiother Oncol 2017 08 13;124(2):240-247. Epub 2017 Jul 13.

Department of Radiation Oncology, University of North Carolina, Chapel Hill, United States; Lineberger Comprehensive Cancer Center, University of North Carolina Hospitals, Chapel Hill, United States.

Background And Purpose: The aim is to determine the radiobiological parameters of four popular normal tissue complication probability (NTCP) models that describe the dose-response relations of salivary glands and pharyngeal constrictors to the severity of patient reported xerostomia and dysphagia, respectively 6 and 12months post chemo-radiotherapy, furthermore, to evaluate the goodness-of-fit of the NTCP models for different combinations of glands and constrictors.

Material And Methods: Forty-three patients were treated on a prospective multi-institutional phase II study (ClinicalTrials.gov, NCT01530997) assessing the efficacy of de-intensified chemoradiotherapy in patients with favorable risk, HPV-associated oropharyngeal squamous cell carcinoma. All patients received 60Gy intensity modulated radiotherapy with concurrent weekly intravenous cisplatinum. All patients reported severity of their xerostomia and dysphagia (pre- and post-treatment) using the patient reported outcome version of the CTCAE (PRO-CTCAE). A change in severity (from baseline) of ≥2 was considered clinically meaningful. The Lyman-Kutcher-Burman (LKB), Relative Seriality (RS), Logit, and Relative Seriality Logit (RSL) NTCP models were used to fit the patients' dose/volume data to changes in PRO-CTCAE severity of xerostomia and dysphagia (from baseline to 6 and 12months post-treatment). The correlation of the models with the patient outcomes was performed for different combinations of salivary glands and different sections of pharyngeal constrictors. The goodness-of-fit of the different models was assessed through the area under the receiver operating characteristic curve (AUC), maximum of the log-likelihood function, normal error distribution and Akaike information criterion (AIC).

Results: The dose/volume metrics of the combined contralateral (parotid+submandibular) glands appear to correlate best with xerostomia, at both 6- and 12-months. Among the different sections of pharyngeal constrictors, the dose/volume metrics of the superior pharyngeal constrictors appear to correlate best with dysphagia at 6months. The AUC values ranged from 0.72 to 0.85 in the case of xerostomia and 0.73 to 0.74 in the case of dysphagia over the different models. The four NTCP models showed similar goodness-of-fit. The differences in AIC between the different models were less than 2 and ranged within 0.7 and 0.8 in the cases of xerostomia and dysphagia, respectively. The calculated parameters of the LKB model were D=26.9Gy, m=0.63, n=1.0 for the combined contralateral glands at 12months and D=62.0Gy, m=0.10, n=0.49 for the superior pharyngeal constrictors at 6months.

Conclusions: The values of the parameters of four NTCP models were determined for salivary glands and pharyngeal constrictors. All four models could fit the clinical data equally well. The NTCP predictions of the combined contralateral glands and superior pharyngeal constrictors showed the best correlation with the patient reported outcomes of xerostomia and dysphagia, respectively.
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http://dx.doi.org/10.1016/j.radonc.2017.06.020DOI Listing
August 2017

Toward a standard for the evaluation of PET-Auto-Segmentation methods following the recommendations of AAPM task group No. 211: Requirements and implementation.

Med Phys 2017 Aug 2;44(8):4098-4111. Epub 2017 Jul 2.

Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA.

Purpose: The aim of this paper is to define the requirements and describe the design and implementation of a standard benchmark tool for evaluation and validation of PET-auto-segmentation (PET-AS) algorithms. This work follows the recommendations of Task Group 211 (TG211) appointed by the American Association of Physicists in Medicine (AAPM).

Methods: The recommendations published in the AAPM TG211 report were used to derive a set of required features and to guide the design and structure of a benchmarking software tool. These items included the selection of appropriate representative data and reference contours obtained from established approaches and the description of available metrics. The benchmark was designed in a way that it could be extendable by inclusion of bespoke segmentation methods, while maintaining its main purpose of being a standard testing platform for newly developed PET-AS methods. An example of implementation of the proposed framework, named PETASset, was built. In this work, a selection of PET-AS methods representing common approaches to PET image segmentation was evaluated within PETASset for the purpose of testing and demonstrating the capabilities of the software as a benchmark platform.

Results: A selection of clinical, physical, and simulated phantom data, including "best estimates" reference contours from macroscopic specimens, simulation template, and CT scans was built into the PETASset application database. Specific metrics such as Dice Similarity Coefficient (DSC), Positive Predictive Value (PPV), and Sensitivity (S), were included to allow the user to compare the results of any given PET-AS algorithm to the reference contours. In addition, a tool to generate structured reports on the evaluation of the performance of PET-AS algorithms against the reference contours was built. The variation of the metric agreement values with the reference contours across the PET-AS methods evaluated for demonstration were between 0.51 and 0.83, 0.44 and 0.86, and 0.61 and 1.00 for DSC, PPV, and the S metric, respectively. Examples of agreement limits were provided to show how the software could be used to evaluate a new algorithm against the existing state-of-the art.

Conclusions: PETASset provides a platform that allows standardizing the evaluation and comparison of different PET-AS methods on a wide range of PET datasets. The developed platform will be available to users willing to evaluate their PET-AS methods and contribute with more evaluation datasets.
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http://dx.doi.org/10.1002/mp.12312DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5575543PMC
August 2017

Early cardiac perfusion defects after left-sided radiation therapy for breast cancer: is there a volume response?

Breast Cancer Res Treat 2017 Jul 21;164(2):253-262. Epub 2017 Apr 21.

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

Purpose: Cardiac single-photon emission computed tomography (SPECT) is often used to identify defects in myocardial perfusion due to atherosclerotic coronary artery disease. It was also used in studies to evaluate radiation therapy (RT)-associated cardiac abnormalities. In the current review, we aim to evaluate the rates of post-RT cardiac SPECT early perfusion abnormalities and relate this to the irradiated left ventricular volume.

Methods: The studies cited in this systematic review were identified using the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines.

Results: Six studies between 1996 and 2016 fulfilled the inclusion criteria. The reported perfusion defects in these studies were seen in the apical and anterolateral aspects of the left ventricle. Three studies show correlation between the percent of the left ventricle within the RT-field and percent of patients with early perfusion defects on cardiac SPECT. In two studies that used cardiac sparing techniques (such as deep inspiration), that resulted in a low mean heart dose, no perfusion defects were noted.

Conclusions: Data suggest that incidental irradiation of the heart in cases of left breast/chest wall RT can result in early post-RT perfusion defects on cardiac SPECT. There appears to be strong dose/volume dependence to the risk, and hence techniques to reduce cardiac exposure are recommended.
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http://dx.doi.org/10.1007/s10549-017-4248-yDOI Listing
July 2017

Integration of PET/MR Hybrid Imaging into Radiation Therapy Treatment.

Magn Reson Imaging Clin N Am 2017 May;25(2):377-430

Department of Radiology, University of North Carolina at Chapel Hill, 101 Manning Drive, Chapel Hill, NC 27599, USA. Electronic address:

Hybrid PET/MR imaging is in early development for treatment planning. This article briefly reviews research and clinical applications of PET/MR imaging in radiation oncology. With improvements in workflow, more specific tracers, and fast and robust acquisition protocols, PET/MR imaging will play an increasingly important role in better target delineation for treatment planning and have clear advantages in the evaluation of tumor response and in a better understanding of tumor heterogeneity. With advances in treatment delivery and the potential of integrating PET/MR imaging with research on radiomics for radiation oncology, quantitative and physiologic information could lead to more precise and personalized RT.
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http://dx.doi.org/10.1016/j.mric.2017.01.001DOI Listing
May 2017

Utility of Deep Inspiration Breath Hold for Left-Sided Breast Radiation Therapy in Preventing Early Cardiac Perfusion Defects: A Prospective Study.

Int J Radiat Oncol Biol Phys 2017 04 18;97(5):903-909. Epub 2016 Dec 18.

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

Purpose: To evaluate early cardiac single photon computed tomography (SPECT) findings after left breast/chest wall postoperative radiation therapy (RT) in the setting of deep inspiration breath hold (DIBH).

Methods And Materials: We performed a prospective single-institution single-arm study of patients who were planned for tangential RT with DIBH to the left breast/chest wall (± internal mammary nodes). The DIBH was done by use of a controlled surface monitoring technique (AlignRT, Vision RT Ltd, London, UK). The RT was given with tangential fields and a heart block. Radiation-induced cardiac perfusion and wall motion changes were assessed by pre-RT and 6-month post-RT SPECT scans. A cumulative SPECT summed-rest score was used to quantify perfusion in predefined left ventricle segments. The incidence of wall motion abnormalities was assessed in each of these same segments.

Results: A total of 20 patients with normal pre-RT scans were studied; their median age was 56 years (range, 39-72 years). Seven (35%) patients also received irradiation to the left internal mammary chain, and 5 (25%) received an additional RT field to supraclavicular nodes. The median heart dose was 94 cGy (range, 56-200 cGy), and the median V25 was zero (range, 0-0.1). None of the patients had post-RT perfusion or wall motion abnormalities.

Conclusions: Our results suggest that DIBH and conformal cardiac blocking for patients receiving tangential RT for left-sided breast cancer is an effective means to avoid early RT-associated cardiac perfusion defects.
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http://dx.doi.org/10.1016/j.ijrobp.2016.12.017DOI Listing
April 2017