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IntroductionDynamic chest radiography (DCR) is a novel, low-dose, real-time digital imaging system where software identifies moving thoracic structures and can automatically calculate lung areas. In an observational, prospective, non-controlled, single-centre pilot study, we compared it with whole-body plethysmography (WBP) in the measurement of lung volume subdivisions in people with cystic fibrosis (pwCF).MethodsLung volume subdivisions were estimated by DCR using projected lung area (PLA) during deep inspiration, tidal breathing and full expiration, and compared with same-day WBP in 20 adult pwCF attending routine review. Linear regression models to predict lung volumes from PLA were developed.ResultsTotal lung area (PLA at maximum inspiration) correlated with total lung capacity (TLC) (r=0.78, pConclusionDCR is a promising new technology that can be used to estimate lung volume subdivisions. Plausible correlations between plethysmographic lung volumes and DCR lung areas were identified. Further studies are needed to build on this exploratory work in both pwCF and individuals without CF.Trial registration numberISRCTN64994816.

Sea salt aerosols play an important role in the radiation budget and atmospheric composition over the Arctic, where the climate is rapidly changing. Previous observational studies have shown Arctic sea ice leads to be an important source of sea salt aerosols, and modeling efforts have also proposed blowing snow sublimation as a source. In this study, size-resolved atmospheric particle number concentrations and chemical composition were measured at the Arctic coastal tundra site of Utqiaġvik, Alaska during spring (April 3 – May 7, 2016). Blowing snow conditions were observed during 25 % of the five-week study period and were over-predicted by a commonly used blowing snow parameterization based solely on wind speed and temperature. Throughout the study, open leads were present locally. During periods when blowing snow was observed, significant increases in the number concentrations of 0.01–0.06 μm particles (factor of six, on average) and 0.06–0.3 μm particles (67 %, on average), and a significant decrease (82 %, on average) in 1–4 μm particles, were observed, compared to low wind speed periods. These size distribution changes were likely caused by the generation of ultrafine particles from leads and/or blowing snow, with scavenging of supermicron particles by blowing snow. At elevated wind speeds, both submicron and supermicron sodium and chloride mass concentrations were enhanced, consistent with wind-dependent local sea salt aerosol production. At moderate wind speeds below the threshold for blowing snow, as well as during observed blowing snow, individual sea spray aerosol particles were measured. These individual salt particles were enriched in calcium relative to sodium in seawater, due to the binding of this divalent cation with organic matter in the sea surface microlayer and subsequent enrichment during seawater bubble bursting. The chemical composition of the surface snowpack also showed contributions from sea spray aerosol deposition. Overall, these results show the contribution of sea spray aerosol production from leads on both aerosols and the surface snowpack. Therefore, if blowing snow sublimation contributed to the observed sea salt aerosol, the snow being sublimed must have been impacted by sea spray aerosol deposition, rather than upward brine migration through the snowpack. Sea spray aerosol production from leads is expected to increase, with thinning and fracturing of sea ice in the rapidly warming Arctic.

This study aimed to correlate planned dose to the nausea center (NC)—area postrema (AP) and dorsal vagal complex (DVC)—with nausea and vomiting symptoms in oropharyngeal cancer (OPC) patients treated with intensity-modulated radiation therapy (IMRT) without chemotherapy. We also investigated whether it was possible to reduce doses to the NC without significant degradation of the clinically accepted treatment plan. From November 2004 to April 2009, 37 OPC patients were treated with definitive or adjuvant IMRT without chemotherapy. Of these, only 23 patients had restorable plans and were included in this analysis. We contoured the NC with the assistance of an expert, board-certified neuroradiologist. We searched for correlation between the delivered dose to the NC and patient-reported nausea and vomiting during IMRT. We used one-paired two-sample t test assuming equal variances to compare differences in dose to NC between symptomatic and asymptomatic patients. We then replanned each case to determine if reduced dose to the NC could be achieved without compromising coverage to target volumes, increasing unwarranted hotspots, or increasing dose to surrounding critical normal tissues. Acute symptoms of nausea were as follows: grade 0 (n = 6), grade 1 (n = 13), grade 2 (n = 3), and grade 3 (n = 1). Patients with no complaints of nausea had a median dose to the DVC of 34.2 Gy (range 4.6–46.6 Gy) and AP of 32.6 Gy (range 7.0–41.4 Gy), whereas those with any complaints of nausea had a median DVC dose of 40.4 Gy (range 19.3–49.4 Gy) and AP dose of 38.7 Gy (range 16.7–46.8 Gy) (p = 0.04). Acute vomiting was as follows: grade 0 (n = 17), grade 1 (n = 4), grade 2 (n = 1), and grade 3 (n = 1). There was no significant difference in DVC or AP dose among those with and without vomiting symptoms (p = 0.28). Upon replanning of each case to minimize dose to the NC, we were, on average, able to reduce the radiation dose to AP by 18 % and DVC by 17 %, while the average dose variations to the planning target volume (PTV) coverage, brainstem, cord, temporal lobes, and cochlea were never greater than 3 %. Hotspots increased by 2 % for three patients while hotspots for the remaining patients were less than 2 % variation. For OPC cancer patients treated with IMRT without chemotherapy, dose to AP and DVC may be associated with development of nausea. We were able to show that reducing doses substantially to the NC is achievable without significant alteration of the clinically accepted plan and may reduce the incidence and grade of nausea. As symptoms of nausea can be devastating to patients, one can consider routine contouring and constraining of the NC to minimize chances of having this complication.

• Best practice molecular diagnostic reference standards require international collaboration.