Publications (67) View all
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Article: Balancing radiation pneumonitis versus locoregional tumor control in non-small-cell lung cancer.
Journal of thoracic oncology: official publication of the International Association for the Study of Lung Cancer 05/2013; 8(5):e47-8. · 4.55 Impact Factor -
Article: Use of 4-Dimensional Computed Tomography-Based Ventilation Imaging to Correlate Lung Dose and Function With Clinical Outcomes.
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ABSTRACT: PURPOSE: Four-dimensional computed tomography (4DCT)-based ventilation is an emerging imaging modality that can be used in the thoracic treatment planning process. The clinical benefit of using ventilation images in radiation treatment plans remains to be tested. The purpose of the current work was to test the potential benefit of using ventilation in treatment planning by evaluating whether dose to highly ventilated regions of the lung resulted in increased incidence of clinical toxicity. METHODS AND MATERIALS: Pretreatment 4DCT data were used to compute pretreatment ventilation images for 96 lung cancer patients. Ventilation images were calculated using 4DCT data, deformable image registration, and a density-change based algorithm. Dose-volume and ventilation-based dose function metrics were computed for each patient. The ability of the dose-volume and ventilation-based dose-function metrics to predict for severe (grade 3+) radiation pneumonitis was assessed using logistic regression analysis, area under the curve (AUC) metrics, and bootstrap methods. RESULTS: A specific patient example is presented that demonstrates how incorporating ventilation-based functional information can help separate patients with and without toxicity. The logistic regression significance values were all lower for the dose-function metrics (range P=.093-.250) than for their dose-volume equivalents (range, P=.331-.580). The AUC values were all greater for the dose-function metrics (range, 0.569-0.620) than for their dose-volume equivalents (range, 0.500-0.544). Bootstrap results revealed an improvement in model fit using dose-function metrics compared to dose-volume metrics that approached significance (range, P=.118-.155). CONCLUSIONS: To our knowledge, this is the first study that attempts to correlate lung dose and 4DCT ventilation-based function to thoracic toxicity after radiation therapy. Although the results were not significant at the .05 level, our data suggests that incorporating ventilation-based functional imaging can improve prediction for radiation pneumonitis. We present an important first step toward validating the use of 4DCT-based ventilation imaging in thoracic treatment planning.International journal of radiation oncology, biology, physics 03/2013; · 4.59 Impact Factor -
Article: Aortic dose constraints when reirradiating thoracic tumors.
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ABSTRACT: BACKGROUND AND PURPOSE: Improved radiation delivery and planning has allowed, in some instances, for the retreatment of thoracic tumors. We investigated the dose limits of the aorta wherein grade 5 aortic toxicity was observed after reirradiation of lung tumors. MATERIAL AND METHODS: In a retrospective analysis, 35 patients were identified, between 1993 and 2008, who received two rounds of external beam irradiation that included the aorta in the radiation fields of both the initial and retreatment plans. We determined the maximum cumulative dose to 1 cm3 of the aorta (the composite dose) for each patient, normalized these doses to 1.8Gy/fraction, and corrected them for long-term tissue recovery between treatments (NIDR). RESULTS: The median time interval between treatments was 30months (range, 1-185months). The median follow-up of patients alive at analysis was 42months (range, 14-70months). Two of the 35 patients (6%) were identified as having grade 5 aortic toxicities. There was a 25% rate of grade 5 aortic toxicity for patients receiving composite doses ⩾120.0Gy (vs. 0% for patients receiving <120.0Gy) (P=0.047). CONCLUSIONS: Grade 5 aortic toxicities were observed with composite doses ⩾120.0Gy (NIDR ⩾90.0Gy) to 1cm3 of the aorta.Radiotherapy and Oncology 02/2013; · 5.58 Impact Factor -
Article: A technique to use CT images for in vivo detection and quantification of the spatial distribution of radiation-induced esophagitis.
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ABSTRACT: The purpose of the study was to examine whether CT imaging can be used to quantify radiation-induced injury to the esophagus. Weekly CT images for 14 patients receiving proton therapy for thoracic tumors were retrospectively reviewed. The images were registered with the original treatment planning CT image using deformable registration techniques, and the esophageal contours from the treatment plan were automatically mapped to the weekly images. The relative change in the size of the esophagus was calculated for each CT slice as the ratio of the cross-sectional area of the esophagus (minus air) in the weekly CT image to the same area in the planning CT image. The maximum relative change in cross sectional area for each CT image was calculated and examined for correlation with the clinical toxicity score for all the patients. The average maximum relative expansion of the esophagus at the end of treatment was 1.41 ± 0.26, 1.68 ± 0.36, and 2.10 ± 0.18 for patients with grade 0, 2, and 3 esophagitis, respectively. An unpaired t-test, with the level of significance corrected with a Bonferroni correction, showed that the difference between grade 3 and 0 was significant, but the differences between grade 0 and 2, and 2 and 3 were not. The timing of changes in esophageal expansion closely matched that of clinically noted changes in patient symptoms. Expansion of the esophagus on CT images has potential as an objective measure of toxicity. The ability to quantify objectively the spatial distribution of radiation-induced injury will be a useful tool in understanding the impact of partial esophageal sparing on the probability of esophagitis.Journal of Applied Clinical Medical Physics 01/2013; 14(3):4195. · 1.29 Impact Factor -
Article: Prescribing radiation dose to lung cancer patients based on personalized toxicity estimates.
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ABSTRACT: : The lung radiosensitivity of the most sensitive patients limits doses that can be given to the majority of lung cancer patients. The purpose of the current study was to illustrate the concept of personalizing prescription dose by performing a retrospective study in which the prescription is determined using an individualized dose-volume constraint that is calculated from a toxicity prediction model. We test whether using a model-generated personalized lung-dose limit results in a clinically significant change to the prescription. : A model consisting of a dose-volume component and a genetic component (single-nucleotide polymorphism information) was used to determine iso-risk mean lung-dose (MLD) limits for each patient. The prescription dose for each patient was scaled according to the individualized MLD constraint and population-based constraints for the cord, esophagus, and heart. The difference between the model-determined prescription dose and the prescription the patient was originally treated with was evaluated. : For 59% of the patients the change in prescription using the model-determined limit was greater than 5 Gy (either dose escalation or de-escalation). For 96% of the patients who developed radiation pneumonitis the model predicted that the prescription should have been lowered. : Our results indicate that using a model-generated personalized MLD results in a clinically different (≥ 5 Gy) prescription. A model used in the manner described by the study can help physicians further personalize radiation therapy and aid them in determining how much dose can safely be delivered to the tumor and normal tissues.Journal of thoracic oncology: official publication of the International Association for the Study of Lung Cancer 10/2012; 7(11):1676-82. · 4.55 Impact Factor
