Evaluation of skin dose associated with different frequencies of bolus applications in post-mastectomy three-dimensional conformal radiotherapy

<p>Abstract</p> <p>Background</p> <p>The study aimed to calculate chest-wall skin dose associated with different frequencies of bolus applications in post-mastectomy three-dimensional conformal radiotherapy (3D-CRT) and to provide detailed information in the selection of an appropriate bolus regimen in this clinical setting.</p> <p>Methods</p> <p>CT-Simulation scans of 22 post-mastectomy patients were used. Chest wall for clinical target volume (CTV) and a volume including 2-mm surface thickness of the chest wall for skin structures were delineated. Precise PLAN 2.11 treatment planning system (TPS) was used for 3D-CRT planning. 50 Gy in 25 fractions were prescribed using tangential fields and 6-MV photons. Six different frequencies of bolus applications (0, 5, 10, 15, 20, and 25) were administered. Cumulative dose-volume histograms were generated for each bolus regimen. The minimum, maximum and mean skin doses associated with the bolus regimens were compared. To test the accuracy of TPS dose calculations, experimental measurements were performed using EBT gafchromic films.</p> <p>Results</p> <p>The mean, minimum and maximum skin doses were significantly increased with increasing days of bolus applications (p < 0.001). The minimum skin doses for 0, 5, 10, 15, 20, and 25 days of bolus applications were 73.0% ± 2.0%, 78.2% ± 2.0%, 83.3% ± 1.7%, 88.3% ± 1.6%, 92.2% ± 1.7%, and 93.8% ± 1.8%, respectively. The minimum skin dose increments between 20 and 25 (1.6% ± 1.0%), and 15 and 20 (4.0% ± 1.0%) days of bolus applications were significantly lower than the dose increments between 0 and 5 (5.2% ± 0.6%), 5 and 10 (5.1% ± 0.8%), and 10 and 15 (4.9% ± 0.8%) days of bolus applications (p < 0.001). The maximum skin doses for 0, 5, 10, 15, 20, and 25 days of bolus applications were 110.1% ± 1.1%, 110.3% ± 1.1%, 110.5% ± 1.2%, 110.8% ± 1.3%, 111.2% ± 1.5%, and 112.2% ± 1.7%, respectively. The maximum skin dose increments between 20 and 25 (1.0% ± 0.6%), and 15 and 20 (0.4% ± 0.3%) days of bolus applications were significantly higher than the dose increments between 0 and 5 (0.2% ± 0.2%), 5 and 10 (0.2% ± 0.2%), and 10 and 15 (0.2% ± 0.2%) days of bolus applications (p ≤ 0.003). The TPS overestimated the near-surface dose 10.8% at 2-mm below the skin surface.</p> <p>Conclusion</p> <p>In post-mastectomy 3D-CRT, using a 1-cm thick bolus in up to 15 of the total 25 fractions increased minimum skin doses with a tolerable increase in maximum doses.</p

ACE I/D gene polymorphism in primary FSGS and steroid-sensitive nephrotic syndrome

The role of angiotensin-converting enzyme (ACE) insertion/deletion (I/D) gene polymorphism in various renal disorders has been investigated. We evaluated the association between the clinical characteristics and ACE genotypes of Turkish children with primary focal segmental glomerulosclerosis (FSGS) and steroid-sensitive nephrotic syndrome (SSNS). Patients with FSGS (n=30) were classified into two groups: one with remission together with stable renal function (n=22) and the other without remission and with impaired renal function (n=8). We classified children with SSNS (n=43) that were followed for at least 4 years into two subgroups as having more frequent (n=19) and less frequent relapses (n=11). The DD genotype was more frequent in the SSNS group than that in controls (37% vs. 17%, chi(2)=4.98, P=0.025). However, among SSNS subgroups, the frequency of the DD genotype was not different. The distribution of ACE genotype was similar among patients with FSGS and SSNS. There was no difference in the ACE I/D distribution between children with FSGS and normal controls (II 10%, ID 60%, DD 30% vs. II 13%, ID 70%, DD 17%). The frequency of the DD genotype was higher in FSGS patients with declining renal function (63%) than in those with stable renal function (18%) (P=0.031). Progressive renal impairment was significantly more frequent in patients with FSGS with the homozygous D allele compared with FSGS patients with ID and II genotypes. Our results indicate that the DD genotype may be a risk factor for the development of progressive renal impairment in children with FSGS; however, larger studies are required to confirm this

External jacketing of unreinforced historical masonry piers with open-grid basalt-reinforced mortar

Existing unreinforced masonry buildings in seismically active regions are in urgent need of consolidation and preservation against seismic action to prevent damage and loss of financial resources. In this research, an experimental study of externally confined brick masonry piers, which are frequently preferred as load-bearing elements in historical buildings, was conducted. The confinement system included a combination of open-grid basalt textile and mortar. Eighteen masonry pier specimens were produced using solid bricks collected from a historical building constructed in approximately the 1930s and a local mortar with substandard mechanical characteristics to simulate mortar properties in existing heritage buildings. All the square/rectangular pier specimens were tested under concentric compressive loads. In general, confinement of the tested textile-reinforced mortar (TRM) improved the energy dissipation of the masonry piers significantly. A comparison was made between the experimental results and theoretical predictions using the available analytical models. The compressive strengths predicted by the models are satisfactory