To evaluate the dosimetric impact of titanium implants in spine SBRT using four dose calculation algorithms. Twenty patients with titanium implants in the spine treated with SBRT without density override (DO) were selected. The clinical plan for each patient was created in Pinnacle and subsequently imported into Eclipse (AAA and AcurosXB) and Raystation (CC) for dose evaluation with and without DO to the titanium implant. We renormalized all plans such that 90% of the tumor volume received the prescription dose and subsequently evaluated the following dose metrics: (1) the maximum dose to 0.03 cc (Dmax), dose to 99% (D99%) and 90% (D90%) of the tumor volume; (2) Dmax and volumetric metrics of the spinal cord. For the same algorithm, plans with and without DO had similar dose distributions. Differences in Dmax, D99% and D90% of the tumor were on average <2% with slightly larger variations up to 5.58% in Dmax using AcurosXB. Dmax of the spinal cord for plans calculated with DO increased but the differences were clinically insignificant for all algorithms (mean: 0.36% ± 0.7%). Comparing to the clinical plans, the relative differences for all algorithms had an average of 1.73% (−10.36%–13.21%) for the tumor metrics and −0.93% (−9.87%–10.95%) for Dmax of the spinal cord. A few cases with small tumor and spinal cord volumes, dose differences of >10% in both D99% and Dmax of the tumor, and Dmax of the spinal cord were observed. For all algorithms, the presence of titanium implants in the spine for most patients had minimal impact on dose distributions with and without DO. For the same plan calculated with different algorithms, larger differences in volumetric metrics of >10% could be observed, impacted by dose gradient at the plan normalization volume, tumor volumes, plan complexity, and partial voxel volume interpolation.

The purpose of this work is to objectively assess variability of intercampus plan quality for head‐and‐neck (HN) cancer and to test utility of a priori feasibility dose–volume histograms (FDVHs) as planning dose goals. In this study, 109 plans treated from 2017 to 2019 were selected, with 52 from the main campus and 57 from various regional centers. For each patient, the planning computed tomography images and contours were imported into a commercial program to generate FDVHs with a feasibility value ( f ‐value) ranging from 0.0 to 0.5. For 10 selected organs‐at‐risk (OARs), we used the Dice similarity coefficient (DSC) to quantify the overlaps between FDVH and clinically achieved DVH of each OAR and determined the f ‐value associated with the maximum DSC (labeled as f ‐max). Subsequently, 10 HN plans from the regional centers were replanned with planning dose goals guided by FDVHs. The clinical and feasibility‐guided auto‐planning (FgAP) plans were evaluated using our institutional criteria. Among plans from the main campus and regional centers, the median f ‐max values were statistically significantly different ( p < 0.05) for all OARs except for the left parotid ( p = 0.622), oral cavity ( p = 0.057), and mandible ( p = 0.237). For the 10 FgAP plans, the median values of f ‐max were 0.21, compared to 0.37 from the clinical plans. With comparable dose coverage to the tumor volumes, the significant differences ( p < 0.05) in the median f ‐max and corresponding dose reduction (shown in parenthesis) for the spinal cord, larynx, supraglottis, trachea, and esophagus were 0.27 (8.5 Gy), 0.3 (7.6 Gy), 0.19 (5.9 Gy), 0.19 (8.9 Gy), and 0.12 (4.0 Gy), respectively. In conclusion, the FDVH prediction is an objective quality assurance tool to evaluate the intercampus plan variability. This tool can also provide guideline in planning dose goals to further improve plan quality.

The histological distribution and ultrastructural findings were investigated in 52 amyloid-positive cases obtained from 80 F, mice (32 males and 48 females) receiving 126 to 502 daily intraperitoneal injections of ferric nitrilotriacetic acid (Fe-NTA) resulting from reciprocal crossing of 20 parental mice receiving daily intraperitoneal injections of Fe-NTA for 5 months. Of 52 amyloidotic F, mice 49 (94%) developed a moderate degree of amyloid deposits in the gastrointestinal tract. Moderate amounts of amyloid deposits were sporadically discernible in the lamina propria of the stomach pars glandularis, the duodenal mucosa, and to a lesser extent in that of the rectal mucosa. Electron microscopic observation revealed that macrophages adjacent to amyloid mass were radiating outward abundant bundles of non-branching amyloid fibrils from the cytoplasmic invaginations. In the cytoplasm of the macrophages there were occasionally acid phosphatase-positive lysosomes including amyloid fibrils measuring approximately 100 A in width. Moreover, it is discussed whether fibroblasts or fibroblast-like interstitial cells are involved in amyloid formation.