Uncertainties in ocular proton planning and their impact on required margins.

PURPOSE: To review required margins in ocular proton therapy (OPT) based on an uncertainty estimation and to compare them with widely used values. Further, uncertainties when using registered funduscopy images in the 3D model is investigated. METHODS: An uncertainty budget in planning and delivery was defined to determine required aperture and range margins. Setup uncertainties were considered for a cohort of treated patients and tested in a worst-case estimation. Other uncertainties were based on a best-guess and knowledge of institutional specifics, e.g. range reproducibility. Margins for funduscopy registration were defined resulting from scaling, rotation and translation of the image. Image formation for a wide-field fundus camera was reviewed and compared to the projection employed in treatment planning systems. RESULTS: Values for aperture and range with margins of 2.5 mm as reported in literature could be determined. Aperture margins appear appropriate for setup uncertainties below 0.5 mm, but depend on lateral penumbra. Range margins depend on depth and associated density uncertainty in tissue. Registration of funduscopy images may require margins of >2 mm, increasing towards the equator. Difference in the projection may lead to discrepancies of several mm. CONCLUSIONS: The commonly used 2.5 mm aperture margin was validated as an appropriate choice, while range margins could be reduced for lower ranges. Margins may however not include uncertainties in contouring and possible microscopic spread. If a target base is contoured on registered funduscopy images care must be taken as they are subject to larger uncertainties. Multimodal imaging approach in OPT remains advisable.

10 kHz cervical SCS for chronic neck and upper limb pain: 12 months' results.

OBJECTIVE: Spinal Cord Stimulation (SCS) overlaps painful areas with paresthesia to alleviate pain. Ten kHz High-Frequency SCS (HF10 cSCS) constitutes a treatment option that can provide pain relief without inducing paresthesia. In this retrospective, open-label study, we evaluated the efficacy of HF10 cSCS in chronic neck and/or upper limb pain. METHODS: Between May 2015 and August 2017, 24 consecutive patients with neck and/or upper limb pain were treated with HF10 cSCS. The patients' mean age was 61.4 years (range: 40.1-82.6 years). The mean neck and upper limb pain at baseline was 8.8 (range: 7.0-10) and 7.5 (range: 6.0-9.0) according to the visual analog scale (VAS). Functionality was evaluated using the Oswestry Disability Index (ODI). To assess health-related psychological impairment, we used the Global Assessment of Functioning questionnaire. RESULTS: Twenty-three patients responded to treatment. Pain intensity reduced significantly to a mean score of VAS 2.5 (range: 2.0-4.0) for neck and 2.0 (range: 1.0-3.0) for upper limb pain after 6 months. At 12 months, VAS scores for neck and upper limb pain reduced to 2.2 (range: 1.0-3.0) and 1.7 (range: 1.0-3.0), respectively. Mean ODI scores decreased from 31 (range: 21-42) at baseline to 19.9 (range: 8-26) after 12 months. In three patients, infection of the IPG pocket occurred r and 8.7 months after surgery. One patient has had lead migration resulting in a surgical revision. INTERPRETATION: HF10 cSCS therapy has proven to be effective in reducing neck and upper limb pain significantly and increasing functional capacity. These results warrant further studies with larger patient series and longer follow-ups.

Patterns of proton therapy use in pediatric cancer management in 2016: An international survey.

PURPOSE: To facilitate the initiation of observational studies on late effects of proton therapy in pediatric patients, we report on current patterns of proton therapy use worldwide in patients aged less than 22 years. MATERIALS & METHODS: Fifty-four proton centers treating pediatric patients in 2016 in 11 countries were invited to respond to a survey about the number of patients treated during that year by age group, intent of treatment, delivery technique and tumor types. RESULTS: Among the 40 participating centers (participation rate: 74%), a total of 1,860 patients were treated in 2016 (North America: 1205, Europe: 432, Asia: 223). The numbers of patients per center ranged from 1 to 206 (median: 29). Twenty-four percent of the patients were <5 years of age, and 50% <10 years. More than 30 pediatric tumor types were identified, mainly treated with curative intent: 48% were CNS, 25% extra-cranial sarcomas, 7% neuroblastoma, and 5% hematopoietic tumors. About half of the patients were treated with pencil beam scanning. Treatment patterns were broadly similar across the three continents. CONCLUSION: To our knowledge, this survey provides the first worldwide assessment of proton therapy use for pediatric cancer management. Since previous estimates in the United States and Europe, CNS tumors remain the cancer types most commonly treated with protons in 2016. However, the proportion of extra-cranial tumors is growing worldwide. The typically low numbers of patients treated in each center indicate the need for international research collaborations to assess long-term outcomes of proton therapy in pediatric patients.

The delineation of target volumes for radiotherapy of lung cancer patients.

PURPOSE: Differences in the delineation of the gross target volume (GTV) and planning target volume (PTV) in patients with non-small-cell lung cancer are considerable. The focus of this work is on the analysis of observer-related reasons while controlling for other variables. METHODS: In three consecutive patients, eighteen physicians from fourteen different departments delineated the GTV and PTV in CT-slices using a detailed instruction for target delineation. Differences in the volumes, the delineated anatomic lymph node compartments and differences in every delineated pixel of the contoured volumes in the CT-slices (pixel-by-pixel-analysis) were evaluated for different groups: ten radiation oncologists from ten departments (ROs), four haematologic oncologists and chest physicians from four departments (HOs) and five radiation oncologists from one department (RO1D). RESULTS: Agreement (overlap > or = 70% of the contoured pixels) for the GTV and PTV delineation was found in 16.3% and 23.7% (ROs), 30.4% and 38.6% (HOs) and 32.8% and 35.9% (RO1D), respectively. CONCLUSION: A large interobserver variability in the PTV and much more in the GTV delineation were observed in spite of a detailed instruction for delineation. The variability was smallest for group ROID where due to repeated discussions and uniform teaching a better agreement was achieved.

Scanning tropospheric ozone and aerosol lidar with double-gated photomultipliers.

The Ozone Profiling Atmospheric Lidar is a scanning four-wavelength ultraviolet differential absorption lidar that measures tropospheric ozone and aerosols. Derived profiles from the lidar data include ozone concentration, aerosol extinction, and calibrated aerosol backscatter. Aerosol calibrations assume a clear air region aloft. Other products include cloud base heights, aerosol layer heights, and scans of particulate plumes from aircraft. The aerosol data range from 280 m to 12 km with 5 m range resolution, while the ozone data ranges from 280 m to about 1.2 km with 100 m resolution. In horizontally homogeneous atmospheres, data from multiple-elevation angles is combined to reduce the minimum altitude of the aerosol and ozone profiles to about 20 m. The lidar design, the characterization of the photomultiplier tubes, ozone and aerosol analysis techniques, and sample data are described. Also discussed is a double-gating technique to shorten the gated turn-on time of the photomultiplier tubes, and thereby reduce the detection of background light and the outgoing laser pulse.

Relationship of Somatic Cell Count and Total Sulfhydryls in Milk.

Individual milk samples from 32 cows were analyzed to determine the relationship between somatic cell concentration and total sulfhydryl concentration (cysteine plus reduced cystine). A significant relationship was detected between somatic cell count, which ranged from 1.7 × 104 to 1.0 × 107 cells/ml, and total sulfhydryls per gram of milk protein. The regression equation, total sulfhydryls/g of milk protein = 31.96 + 7.99 (log10 somatic cell count) with r2 = 0.19, was calculated. The mean total sulfhydryl concentration was 73.1 µmol/g of protein. The minimal effect of somatic cell concentration on total sulfhydryl concentration indicates that somatic cell concentration should have little influence on chemical parameters of milk protein determined by sulfhydryl analysis when proper experimental controls are used.