PurposeMaximum dose to the left anterior descending artery (LADmax) is an important physical constraint to reduce the risk of cardiovascular toxicity. We generated a simple algorithm to guide the positioning of the tangent fields to reliably maintain LADmax <10 Gy.Methods and materialsDosimetric plans from 146 consecutive women treated prone to the left breast enrolled in prospective protocols of accelerated whole breast radiation therapy, with a concomitant daily boost to the tumor bed (40.5 Gy/15 fraction to the whole breast and 48 Gy to the tumor bed), provided the training set for algorithm development. Scatter plots and correlation coefficients were used to describe the bivariate relationships between LADmax and several parameters: distance from the tumor cavity to the tangent field edge, cavity size, breast separation, field size, and distance from the tangent field. A logistic sigmoid curve was used to model the relationship of LADmax and the distance from the tangent field. Furthermore, we tested this prediction model on a validation data set of 53 consecutive similar patients.ResultsA lack of linear relationships between LADmax and distance from cavity to LAD (−0.47), cavity size (−0.18), breast separation (−0.02), or field size (−0.28) was observed. In contrast, distance from the tangent field was highly negatively correlated to LADmax (-0.84) and was used in the models to predict LADmax. From a logistic sigmoid model we selected a cut-point of 2.46 mm (95% confidence interval, 2.19-2.74 mm) greater than which LADmax is <10 Gy (95% confidence interval, 9.30-10.72 Gy) and LADmean is <3.3 Gy.ConclusionsPlacing the edge of the tangents at least 2.5 mm from the closest point of the contoured LAD is likely to assure LADmax is <10 Gy and LADmean is <3.3 Gy in patients treated with prone accelerated breast radiation therapy.

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Background: Contrast-enhanced lumbar spine magnetic resonance imaging (MRI) was used to predict the efficacy of conservative treatment of giant lumbar disc herniation.Methods: From June 2017 to June 2019, 30 patients with giant lumbar disc herniation with positive and negative bull’s eye signs on contrast-enhanced lumbar spine MRI were assessed to measure differences in the rate of intervertebral disc herniation, rate of protrusion absorption, treatment effect, protrusion rate, and curative effect according to the lumbar Japanese Orthopedic Association (JOA) score before and after treatment.Results: Thirty patients with positive and negative bull’s eye signs (36 men and 24 women) aged 19 to 58 years (mean, 36.37 ± 9.56 years) were included. All patients were followed up for more than 1 year, and at least one MRI review was conducted within 1 year of treatment. The results of the first and final MRI examinations were compared. The protrusion rate was 82.16% ± 14.58% before treatment and 32.20% ± 30.80% after treatment, and the absorptivity of the protrusion was 59.48% ± 38.62%. There was no statistically significant difference in the general data before treatment between the positive and negative groups (P > 0.05). After treatment, the protrusion rate in the positive and negative bull’s eye sign groups was 14.41% ± 14.37% and 49.99% ± 32.70%, respectively (P < 0.05). The absorptivity in the positive and negative bull’s eye sign groups was 83.09% ± 15.54% and 35.87% ± 40.49%, respectively (P < 0.05). There was no statistically significant difference in the JOA score between the two groups before treatment (P > 0.05); however, there was a statistically significant difference in the JOA score between the two groups at 3 months (P < 0.05) and 1 year (P < 0.05) after treatment.Conclusions: Conservative treatment of giant lumbar disc herniation has a satisfactory clinical effect. Contrast-enhanced MRI can be used to predict the resorption of giant lumbar disc herniation. Protrusion resorption is more likely to occur in patients with than without a bull’s eye sign.Trial registration: Chinese Clinical Trial Registry (No. ChiCTR1900022377). Retrospectively registered 08 April 2019.