[en] Objective: To evaluate the effect of radiotherapy combined with inductive chemotherapy for patients with upper and middle esophageal cancer. Methods: 162 patients with upper and middle esophageal cancer were randomized into two groups, with 82 treated by inductive chemotherapy combined with radiotherapy (C + R) and 80 by radiotherapy alone (R). The chemotherapy regimen included 5-fluorouracil 500 mg/m² on d1-d5 by continuous infusion for 120 hours, cisplatin 60 mg/m² on dl and bleomycin A5 8 mg on d1, d3, d5 intravenously. Three to seven days after chemotherapy, the patients were irradiated with anteroposterior (AP) and posteroanterior (PA) fields to a dose of 40-44 Gy in 4.0-4.4 weeks followed by a boost of 24-28 Gy in 2.4-2.8 weeks through oblique fields. Results: The 5- and 10-year survival rates were 22.0%, 15.9% for the C + R group and 13.8%, 8.8% for the R group. The difference was statistically significant (P = 0.034). The toxic and side effects were tolerable and similar in the two groups. Nineteen patients (23%) in the C + R group and thirty-one (39%) in the R group died from distant metastasis and/or lymph node metastasis, even though the difference was not statistically significant (x² = 3.47, P > 0.05). Conclusions: Inductive chemotherapy with 5-fluorouracil, cisplatin, bleomycin A5 plus radiotherapy may improve the outcome of esophageal cancer, with the toxic and side effects of the combined modality severer than radiation along, but they are well tolerated

[en] Purpose: To calculate vaginal doses during image guided brachytherapy with volume-based metrics and correlate with long-term vaginal toxicity. Methods and Materials: In this institutional review board–approved study, institutional databases were searched to identify women undergoing computed tomography and/or magnetic resonance–guided brachytherapy at the Duke Cancer Center from 2009 to 2015. All insertions were contoured to include the vagina as a 3-dimensional structure. All contouring was performed on computed tomography or magnetic resonance imaging and used a 0.4-cm fixed brush to outline the applicator and/or packing, expanded to include any grossly visible vagina. The surface of the cervix was specifically excluded from the contour. High-dose-rate (HDR) and low-dose-rate (LDR) doses were converted to the equivalent dose in 2-Gy fractions using an α/β of 3 for late effects. The parameters D0.1cc, D1cc, and D2cc were calculated for all insertions and summed with prior external beam therapy. Late and subacute toxicity to the vagina were determined by the Common Terminology Criteria for Adverse Events version 4.0 and compared by the median and 4th quartile doses, via the log-rank test. Univariate and multivariate hazard ratios were calculated via Cox regression. Results: A total of 258 insertions in 62 women who underwent definitive radiation therapy including brachytherapy for cervical (n=48) and uterine cancer (n=14) were identified. Twenty HDR tandem and ovoid, 32 HDR tandem and ring, and 10 LDR tandem and ovoid insertions were contoured. The median values (interquartile ranges) for vaginal D0.1cc, D1cc, and D2cc were 157.9 (134.4-196.53) Gy, 112.6 (96.7-124.6) Gy, and 100.5 (86.8-108.4) Gy, respectively. At the 4th quartile cutoff of 108 Gy for D2cc, the rate of late grade 1 toxicity at 2 years was 61.2% (95% confidence interval [CI] 43.0%-79.4%) below 108 Gy and 83.9% (63.9%-100%) above (P=.018); grade 2 or greater toxicity was 36.2% (95% CI 15.8%-56.6%) below 108 Gy and 70.7% (95% CI 45.2%-96.2%) above (P=.004); and grade 3 or worse toxicity was 9.9% (95% CI 0.0%-23.6%) below 108 Gy and 30.0% (95% CI 4.7%-55.3%) above (P=.025). This association was maintained on multivariate analysis, independent of covariates such as applicator type, age, and dose rate. Conclusions: Vaginal dose was associated with all grades of vaginal toxicity. Confirmation at other sites using this methodology will be necessary to establish reproducibility; however, the integration of routine calculation of vaginal dose may be warranted.

[en] Objective: To study the outcome of locally advanced or recurrent rectal cancer treated by three dimensional conformal radiotherapy (3D-CRT) combined with chemotherapy (CT). Methods: Twenty-four patients with locally advanced or recurrent rectal cancer were irradiated by external beam radiotherapy to a total dose of 44 Gy, then randomized to receive 3D-CRT plus CT (combined group) or 3D-CRT alone (control group), with 11 patients in the former and 13 in the latter. The chemotherapy regimen included 5-Fu and CF. Results: The pain-alleviation rates were 90.9% and 84.6%, while the overall response (CR+PR) rates were 90.9% and 69.2% in the combined and control group, with the difference insignificant (P>0.05). Yet, for the combined and control groups, the 2-year survival rates were 63.6% and 38.5%, with the difference significant (P=0.013). The 2-year local control rates were 72.7% and 61.5%, with the difference insignificant (P=0.053). The 2-year distant metastasis rates were 36.3% and 61.5%, with the difference significant (P=0.007). The side effects were similar in the two groups (P>0.05). Conclusions: Conventional radiotherapy plus three dimensional conformal radiotherapy combined with chemotherapy may significantly improve the survival rate and reduce the distant metastasis rate of locally advanced or recurrent rectal cancer

[en] To quantitatively evaluate dosimetric effects of rotational offsets in stereotactic body radiation therapy (SBRT) for lung cancer. Overall, 11 lung SBRT patients (8 female and 3 male; mean age: 75.0 years) with medially located tumors were included. Treatment plans with simulated rotational offsets of 1°, 3°, and 5° in roll, yaw, and pitch were generated and compared with the original plans. Both clockwise and counterclockwise rotations were investigated. The following dosimetric metrics were quantitatively evaluated: planning target volume coverage (PTV V_100%), max PTV dose (PTV D_max), percentage prescription dose to 0.35 cc of cord (cord D_0.35cc), percentage prescription dose to 0.35 cc and 5 cc of esophagus (esophagus D_0.35cc and D_5cc), and volume of the lungs receiving at least 20 Gy (lung V₂₀). Statistical significance was tested using Wilcoxon signed rank test at the significance level of 0.05. Overall, small differences were found in all dosimetric matrices at all rotational offsets: 95.6% of differences were < 1% or < 1 Gy. Of all rotational offsets, largest change in PTV V_100%, PTV D_max, cord D_0.35cc, esophagus D_0.35cc, esophagus D_5cc, and lung V₂₀ was − 8.36%, − 6.06%, 11.96%, 8.66%, 6.02%, and − 0.69%, respectively. No significant correlation was found between any dosimetric change and tumor-to-cord/esophagus distances (R² range: 0 to 0.44). Larger dosimetric changes and intersubject variations were observed at larger rotational offsets. Small dosimetric differences were found owing to rotational offsets up to 5° in lung SBRT for medially located tumors. Larger intersubject variations were observed at larger rotational offsets

[en] Objective: To explore the radiosensitivity of berberine on esophageal cancer cells under hypoxia condition. Methods: MTT assay and clonogenic survival assay were used to evaluate the effect of berberine on proliferation inhibition and radiosensitivity of esophageal cancer cells, respectively. Immunofluorescence was employed to examine the expression of HIF-1. The change of cell cycle distribution and cell apoptosis was assayed by flow cytometry. The expression of HIF-1 was measured by Western blot. DNA damage was detected by γ-H2AX Foci counting. Results: With a clear dose and time effect, berberine inhibited cell proliferation and enhanced cell radiosensitivity (t = 3.69, P < 0.05) with a sensitizing enhancement ratio (SER) of 1.42. Berberine caused a dose-dependent decrease in HIF-1 protein expression and also significantly increased the cell apoptosis in ECA-109 population (t = 4.74, P < 0.05). Compared with the radiation alone group, berberine enhanced X-ray induced DNA double chain breaks (DSB). Conclusions: Berberine can increase the radiosensitivity of esophageal cell line ECA-109, which may be associated with decrease of HIF-1 expression and induction of apoptosis in ECA-109 cells. (authors)

[en] Objective: To study expression of transforming growth factor-β₁ (TGF-β₁) and tumor necrosis factor-α(TNF-α) in C57/BL mice after lung radiation and relation between them and radiation injury of lung. Methods: Using male C57/BL mice, authors observed the histological changes of their lungs stained with HE up to 40 days after right thorax radiation. Expression of TGF-β₁ and TNF-α was evaluated by ELISA technique. Results: The average serum TGF-β₁ level in mice which were radiated with 10 Gy was higher than that in those being radiated with 6 Gy and in the control group (P<0.05); The average serum TGF-β₁ level in mice which were radiated with 6 Gy was not higher than the level in the control group (P>0.05). The condition of TNF-α was just like that of TGF-β₁. Acute inflammatory changes of the lung was able to be seen in the group of 10 Gy with HE stained from 36 h-40 d after radiation. But it was not very serious. Conclusion: The reason of radiation-induced injury of the normal lung has many factors. And there was some relation between TGF-β₁, TNF-α and radiation dose

[en] A detailed analysis of self-consistent potentials, electric fields, electron distributions, and transport properties of dual-channel (DC) n-Al${}_{0.3}$Ga${}_{0.7}$N/GaN/i-Al${}_x$Ga${}_{1-<!--\; ???\; -->x}$N/GaN high-electron-mobility transistors (HEMTs) is performed in this article. The 2D electron gas (2DEG) densities and mobility states limited by different scattering mechanisms in channel 1 and channel 2 are obtained, with varying values of doping concentrations, ambient temperatures, Al components, and thicknesses of the back barrier layer. The reduced and increased 2DEG densities are respectively observed in channel 1 and channel 2 with growing Al fractions and thicknesses of the Al${}_x$Ga${}_{1-<!--\; ???\; -->x}$N layer. Alloy disorder scattering exhibits a superior effect on carriers in channel 2 due to the lower barrier height and higher permeable electrons, which together with the interface roughness scattering severely depends on the thicknesses and Al fractions of the back barrier layer. Polar optical phonon scattering becomes important at higher temperatures. The trend of individual mobility in channel 1 is exactly opposite to that in channel 2. The parameter variation of the back barrier layer can effectively change the scattering characteristics of the main channel. Low-temperature mobilities of n-Al${}_{0.3}$Ga${}_{0.7}$N/GaN/i-Al${}_x$Ga${}_{1-<!--\; ???\; -->x}$N/GaN HEMTs under varied doping concentrations are also obtained. Finally, the results are verified by comparison with the technology computer-aided design simulations for DC HEMTs. (© 2024 Wiley‐VCH GmbH)

[en] In this paper, a gradient-based iterative algorithm is proposed for finding the least-squares solutions of the following constrained generalized inverse eigenvalue problem: given $X\in <!--\; ???\; -->C^{n\times <!--\; ??\; -->m}$, $\mathrm{\Lambda <!--\; ??\; -->}=\mathrm{d}\mathrm{i}\mathrm{a}\mathrm{g}({\mathrm{\lambda <!--\; ??\; -->}}_1,{\mathrm{\lambda <!--\; ??\; -->}}_2,\dots <!--\; ???\; -->,{\mathrm{\lambda <!--\; ??\; -->}}_m)\in <!--\; ???\; -->C^{m\times <!--\; ??\; -->m}$, find $A^{\ast <!--\; ???\; -->},B^{\ast <!--\; ???\; -->}\in <!--\; ???\; -->C^{n\times <!--\; ??\; -->n}$, such that $\parallel <!--\; ???\; -->AX-<!--\; ???\; -->BX\mathrm{\Lambda <!--\; ??\; -->}\parallel <!--\; ???\; -->$ is minimized, where $A^{\ast <!--\; ???\; -->},B^{\ast <!--\; ???\; -->}$ are Hermitian–Hamiltonian except for a special submatrix. For any initial constrained matrices, a solution pair $(A^{\ast <!--\; ???\; -->},B^{\ast <!--\; ???\; -->})$ can be obtained in finite iteration steps by this iterative algorithm in the absence of roundoff errors. The least-norm solution can be obtained by choosing a special kind of initial matrix pencil. In addition, the unique optimal approximation solution to a given matrix pencil in the solution set of the above problem can also be obtained. A numerical example is given to show the efficiency of the proposed algorithm.

[en] A physics-based threshold voltage and drain-source current model based on double-channel Al${}_x$Ga${}_{1-<!--\; ???\; -->x}$N/GaN/Al${}_y$Ga${}_{1-<!--\; ???\; -->y}$N/GaN high-electron-mobility transistors (HEMTs) is proposed in this article. Electrons limited in the potential well are derived from ionized donor-like surface states of the Al${}_x$Ga${}_{1-<!--\; ???\; -->x}$N layer. Accumulated 2D electron gases (2DEGs) and positive charges left are equivalent to planar plate capacitors and further form electric fields, weakening the polarization fields in barrier layers. The physical properties of the dual-channel HEMT are considered holistically rather than two separate and independent single heterojunctions. The effect of the charges and 2DEGs distributed in lower layers on the upper channel is contained in our model as well. Subsequently, a drain-source current model is proposed through coupling the critical electric field with the threshold voltage (V${}_{TH}$). The influence of channel length modulation, short channel effect, self-heating effect, and kink effect is involved in this model. The accuracy of the proposed models is verified by comparison with technology computer-aided design simulations and the experimental results. Proposed models can greatly describe the output characteristics, the transmission characteristics, and the relationship between V${}_{TH}$ and device parameters of double-channel AlGaN/GaN HEMTs. (© 2023 Wiley‐VCH GmbH)

[en] During the last 10 years, radiation therapy technologies have gone through major changes, mainly related introduction of sophisticated delivery and imaging techniques to improve the target localization accuracy and dose conformity. While implementation of these emerging technologies such as image-guided SRS/SBRT, IMRT/IMAT, IGRT, 4D motion management, and special delivery technologies showed substantial clinical gains for patient care, many other factors, such as training/quality, efficiency/efficacy, and cost/effectiveness etc. remain to be challenging. This talk will address technical challenges for dosimetry verification of implementing these emerging technologies in radiation therapy.