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Purpose Methods Automated techniques for estimating the contours of organs and structures in medical images have become more widespread and a variety of measures are available for assessing their quality. Quantitative measures of geometric agreement, for example, overlap with a gold-standard delineation, are popular but may not predict the level of clinical acceptance for the contouring method. Therefore, surrogate measures that relate more directly to the clinical judgment of contours, and to the way they are used in routine workflows, need to be developed. The purpose of this study is to propose a method (inspired by the Turing Test) for providing contour quality measures that directly draw upon practitioners' assessments of manual and automatic contours. This approach assumes that an inability to distinguish automatically produced contours from those of clinical experts would indicate that the contours are of sufficient quality for clinical use. In turn, it is anticipated that such contours would receive less manual editing prior to being accepted for clinical use. In this study, an initial assessment of this approach is performed with radiation oncologists and therapists. Eight clinical observers were presented with thoracic organ-at-risk contours through a web interface and were asked to determine if they were automatically generated or manually delineated. The accuracy of the visual determination was assessed, and the proportion of contours for which the source was misclassified recorded. Contours of six different organs in a clinical workflow were for 20 patient cases. The time required to edit autocontours to a clinically acceptable standard was also measured, as a gold standard of clinical utility. Established quantitative measures of autocontouring performance, such as Dice similarity coefficient with respect to the original clinical contour and the misclassification rate accessed with the proposed framework, were evaluated as surrogates of the editing

Background and purpose: Isolated nodal failures (INF) are rare after 3D-conformal radiotherapy (3D-CRT) for stage III non-small cell lung cancer (NSCLC). Since incidental nodal irradiation doses are lower with Intensity Modulated Radiation Therapy (IMRT) than with 3D-CRT, INF may be higher after IMRT. We therefore investigated the incidence of INF after IMRT in stage III NSCLC patients. Materials and methods: Stage III NSCLC patients undergoing radical radiotherapy using IMRT in the period January 2010 till March 2012 were included. The primary endpoint was the rate of INF, secondary endpoints included patterns of failure, progression free survival (PFS), overall survival (OS) and toxicity. Results: 183 stage III NSCLC patients were enrolled. With a median follow-up of 58.0 months 2.2% of patients had an INF. The median PFS was 15.0 months, the median OS 19.5 months. Patterns of recurrence: 2.2% INF, 11.5% local and 2.7% loco-regional recurrence, 26.8% distant metastases only, 18.0% a combination of local/loco-regional and distant metastases, and 38.3% patients without recurrence. One INF was out of field, in adjacent lymph nodes. Acute toxicity was limited. Discussion: Selective nodal irradiation using IMRT in stage III NSCLC patients results in a low in-field incidence of INF (2.2%), similar to 3D-CRT, and may thus be considered safe.

BACKGROUND AND PURPOSE: [(18)F]HX4 is a promising hypoxia PET-tracer. Uptake, spatio-temporal stability and optimal acquisition parameters for [(18)F]HX4 PET imaging were evaluated in non-small cell lung cancer (NSCLC) patients. MATERIALS AND METHODS: [(18)F]HX4 PET/CT images of 15 NSCLC patients were acquired 2h and 4h after injection (p.i.). Maximum standardized-uptake-value (SUVmax), tumor-to-blood-ratio (TBRmax), hypoxic fraction (HF) and contrast-to-noise-ratio (CNR) were determined for all lesions. To evaluate spatio-temporal stability, DICE-similarity and Pearson correlation coefficients were calculated. Optimal acquisition-duration was assessed by comparing 30, 20, 10 and 5min acquisitions. RESULTS: Considerable uptake (TBR >1.4) was observed in 18/25 target lesions. TBRmax increased significantly from 2h (1.6±0.3) to 4h p.i. (2.0±0.6). Uptake patterns at 2h and 4h p.i. showed a strong correlation (R=0.77±0.10) with a DICE similarity coefficient of 0.69±0.08 for the 30% highest uptake volume. Reducing acquisition-time resulted in significant changes in SUVmax and CNR. TBRmax and HF were only affected for scan-times of 5min. CONCLUSIONS: The majority of NSCLC lesions showed considerable [(18)F]HX4 uptake. The heterogeneous uptake pattern was stable between 2h and 4h p.i. [(18)F]HX4 PET imaging at 4h p.i. is superior to 2h p.i. to reach highest contrast. Acquisition time may be reduced to 10min without significant effects on TBRmax and HF.

PURPOSE: To evaluate the results of selective nodal irradiation on basis of (18)F-deoxyglucose positron emission tomography (PET) scans in patients with limited-disease small-cell lung cancer (LD-SCLC) on isolated nodal failure.METHODS AND MATERIALS: A prospective study was performed of 60 patients with LD-SCLC. Radiotherapy was given to a dose of 45 Gy in twice-daily fractions of 1.5 Gy, concurrent with carboplatin and etoposide chemotherapy. Only the primary tumor and the mediastinal lymph nodes involved on the pretreatment PET scan were irradiated. A chest computed tomography (CT) scan was performed 3 months after radiotherapy completion and every 6 months thereafter.RESULTS: A difference was seen in the involved nodal stations between the pretreatment (18)F-deoxyglucose PET scans and computed tomography scans in 30% of patients (95% confidence interval, 20-43%). Of the 60 patients, 39 (65%; 95% confidence interval [CI], 52-76%) developed a recurrence; 2 patients (3%, 95% CI, 1-11%) experienced isolated regional failure. The median actuarial overall survival was 19 months (95% CI, 17-21). The median actuarial progression-free survival was 14 months (95% CI, 12-16). 12% (95% CI, 6-22%) of patients experienced acute Grade 3 (Common Terminology Criteria for Adverse Events, version 3.0) esophagitis.CONCLUSION: PET-based selective nodal irradiation for LD-SCLC resulted in a low rate of isolated nodal failures (3%), with a low percentage of acute esophagitis. These findings are in contrast to those from our prospective study of CT-based selective nodal irradiation, which resulted in an unexpectedly high percentage of isolated nodal failures (11%). Because of the low rate of isolated nodal failures and toxicity, we believe that our data support the use of PET-based SNI for LD-SCLC.