Calculation of set-up margin in frameless stereotactic radiotherapy accounting for translational and rotational patient positing error.

Context: Rotation corrected set-up margins in stereotactic radiotherapy (SRT). Aims: This study aimed to calculate the rotational positional error corrected set-up margin in frameless SRT. Settings and Design: 6D setup errors for the steriotactic radiotherapy patients were converted to 3D translational only error mathematically. Setup margins were calculated with and without considering the rotational error and compared. Materials and Methods: A total of 79 patients of SRT each received >1 fraction (3-6 fractions) incorporated in this study. Two cone-beam computed tomography (CBCT) scans were acquired for each session of treatment, before and after the robotic couch-aided patient position correction using a CBCT. The postpositional correction set-up margin was calculated using the van Herk formula. Further, a planning target volume_R (PTV_R) (with rotational correction) and PTV_NR (without rotational correction) were calculated by applying the rotation corrected and uncorrected set-up margins on the gross tumor volumes (GTVs). Statistical Analysis Used: General. Results: A total of 380 sessions of pre- (190) and post (190) table positional correction CBCT was analyzed. Posttable position correction mean positional error for lateral, longitudinal, and vertical translational and rotational shifts was (x)-0.01 ± 0.05 cm, (y)-0.02 ± 0.05 cm, (z) 0.00 ± 0.05 cm, and (θ) 0.04° ± 0.3°, (Φ) 0.1° ± 0.4°, (Ψ) 0.0° ± 0.4°, respectively. The GTV volumes show a range of 0.13 cc-39.56 cc, with a mean volume of 6.35 ± 8.65 cc. Rotational correction incorporated postpositional correction set-up margin the in lateral (x), longitudinal (y) and vertical (z) directions were 0.05 cm, 0.12 cm, and 0.1 cm, respectively. PTV_R ranges from 0.27 cc to 44.7 cc, with a mean volume of 7.7 ± 9.8 cc. PTV_NR ranges from 0.32 cc to 46.0 cc, with a mean volume of 8.1 ± 10.1 cc. Conclusions: The postcorrection linear set-up margin matches well with the conventional set-up margin of 1 mm. Beyond a GTV radius of 2 cm, the difference between PTV_NR and PTV_R is ≤2.5%, hence not significant.

Dynamics of the COVID -19 Related Publications

BackgroundThis study aims to analyze the dynamics of the published articles and preprints of Covid-19 related literature from different scientific databases and sharing platforms. MethodsThe PubMed, Elsevier, and Research Gate (RG) databases were under consideration in this study over a specific time. Analyses were carried out on the number of publications as (a) function of time (day), (b) journals and (c) authors. Doubling time of the number of publications was analyzed for PubMed "all articles" and Elsevier published articles. Analyzed databases were (1A) PubMed "all articles" (01/12/2019-12/06/2020) (1B) PubMed Review articles (01/12/2019-2/5/2020) and (1C) PubMed Clinical Trials (01/01/2020-30/06/2020) (2) Elsevier all publications (01/12/2019-25/05/2020) (3) RG (Article, Pre Print, Technical Report) (15/04/2020-30/4/2020). FindingsTotal publications in the observation period for PubMed, Elsevier, and RG were 23000, 5898 and 5393 respectively. The average number of publications/day for PubMed, Elsevier and RG were 70.0 {+/-}128.6, 77.6{+/-}125.3 and 255.6{+/-}205.8 respectively. PubMed shows an avalanche in the number of publication around May 10, number of publications jumped from 6.0{+/-}8.4/day to 282.5{+/-}110.3/day. The average doubling time for PubMed, Elsevier, and RG was 10.3{+/-}4 days, 20.6 days, and 2.3{+/-}2.0 days respectively. In PubMed average articles/journal was 5.2{+/-}10.3 and top 20 authors representing 935 articles are of Chinese descent. The average number of publications per author for PubMed, Elsevier, and RG was 1.2{+/-}1.4, 1.3{+/-}0.9, and 1.1{+/-}0.4 respectively. Subgroup analysis, PubMed review articles mean and median review time for each article were <0|17{+/-}17|77> and 13.9 days respectively; and reducing at a rate of-0.21 days (count)/day. InterpretationAlthough the disease has been known for around 6 months, the number of publications related to the Covid-19 until now is huge and growing very fast with time. It is essential to rationalize the publications scientifically by the researchers, authors, reviewers, and publishing houses. FundingNone