Analysis of Individualized Silicone Rubber Bolus Using Fan Beam Computed Tomography in Postmastectomy Radiotherapy: A Dosimetric Evaluation and Skin Acute Radiation Dermatitis Survey.

Objective: To investigate the dosimetric effects of using individualized silicone rubber (SR) bolus on the target area and organs at risk (OARs) during postmastectomy radiotherapy (PMRT), as well as evaluate skin acute radiation dermatitis (ARD). Methods: A retrospective study was performed on 30 patients with breast cancer. Each patient was prepared with an individualized SR bolus of 3 mm thickness. Fan-beam computed tomography (FBCT) was performed at the first and second fractions, and then once a week for a total of 5 times. Dosimetric metrics such as homogeneity index (HI), conformity index (CI), skin dose (SD), and OARs including the heart, lungs, and spinal cord were compared between the original plan and the FBCTs. The acute side effects were recorded. Results: In targets' dosimetric metrics, there were no significant differences in Dmean and V105% between planning computed tomography (CT) and actual treatments (P > .05), while the differences in D95%, V95%, HI, and CI were statistically significant (P < .05). In OARs, there were no significant differences between the Dmean, V5, and V20 of the affected lung, V5 of the heart and Dmax of the spinal cord (P > .05) except the V30 of affected lung, which was slightly lower than the planning CT (P < .05). In SD, both Dmax and Dmean in actual treatments were increased than plan A, and the difference was statistically significant (P < .05), while the skin-V20 and skin-V30 has no difference. Among the 30 patients, only one patient had no skin ARD, and 5 patients developed ARD of grade 2, while the remaining 24 patients were grade 1. Conclusion: The OR bolus showed good anastomoses and high interfraction reproducibility with the chest wall, and did not cause deformation during irradiation. It ensured accurate dose delivery of the target and OARs during the treatment, which may increase SD by over 101%. In this study, no cases of grade 3 skin ARD were observed. However, the potential of using OR bolus to reduce grade 1 and 2 skin ARD warrants further investigation with a larger sample size.

Myeloid differentiation protein 1 protected myocardial function against high-fat stimulation induced pathological remodelling.

Myeloid differentiation 1 (MD-1) is a secreted protein that regulates the immune response of B cell through interacting with radioprotective 105 (RP105). Disrupted immune response may contribute to the development of cardiac diseases, while the roles of MD-1 remain elusive. Our studies aimed to explore the functions and molecular mechanisms of MD-1 in obesity-induced cardiomyopathy. H9C2 myocardial cells were treated with free fatty acid (FFA) containing palmitic acid and oleic acid to challenge high-fat stimulation and adenoviruses harbouring human MD-1 coding sequences or shRNA for MD-1 overexpression or knockdown in vitro. MD-1 overexpression or knockdown transgenic mice were generated to assess the effects of MD-1 on high-fat diet (HD) induced cardiomyopathy in vivo. Our results showed that MD-1 was down-regulated in H9C2 cells exposed to FFA stimulation for 48 hours and in obesity mice induced by HD for 20 weeks. Both in vivo and in vitro, silencing of MD-1 accelerated myocardial function injury induced by HD stimulation through increased cardiac hypertrophy and fibrosis, while overexpression of MD-1 alleviated the effects of HD by inhibiting the process of cardiac remodelling. Moreover, the MAPK and NF-κB pathways were overactivated in MD-1 deficient mice and H9C2 cells after high-fat treatment. Inhibition of MAPK and NF-κB pathways played a cardioprotective role against the adverse effects of MD-1 silencing on high-fat stimulation induced pathological remodelling. In conclusion, MD-1 protected myocardial function against high-fat stimulation induced cardiac pathological remodelling through negative regulation for MAPK/NF-κB signalling pathways, providing feasible strategies for obesity cardiomyopathy.

A novel supine isocentric approach for craniospinal irradiation and its clinical outcome.

OBJECTIVE: To report a novel approach for craniospinal irradiation (CSI) using a supine isocentric technique. METHODS: Patients were treated in the supine position using CT simulation. Half-beam-blocked lateral cranial fields and superior spinal fields have the same isocentre, and their beam divergences match. Tangential irradiation provides a non-divergent junction for the other two full-beam spinal fields. Shielding for cranial fields was generated, and dose distribution was calculated using a three-dimensional planning system. When sacral spinal fields were required, two lateral opposite fields were designed to protect the urogenital organs. All treatment portals were filmed once per week. RESULTS: At a median follow-up of 49.8 months, 5 relapses and no cases of radiation myelitis developed in 26 consecutive patients. In the junctions of the brain-spine or spine-spine field, no failure occurred. Three failures occurred in the primary site alone, two in the spinal axis alone. CONCLUSION: The results of our study have shown that our novel approach for CSI was not associated with increased failures at the field junction and deaths. In addition, no radiation myelitis, pneumonia, severe damage to the heart and gastrointestinal tract, and second cancers occurred in our study. ADVANCES IN KNOWLEDGE: This new approach is an optimal alternative in cancer centre without tomotherapy because of its convenience for immobilization, repeatability, optimal dose distribution and satisfactory clinical outcome.