Intensity-modulated radiation therapy(IMRT) is currently the main treatment method for nasopharyngeal carcinoma. During radiotherapy for nasopharyngeal carcinoma, factors such as body mass reduction, tumor regression, and organ displacement at risk can affect the precise implementation of radiation therapy. Applying adaptive radiotherapy (ART) technology to optimize the treatment plan at the appropriate timing can reduce the adverse effects caused by the above factors and enhance the accuracy of radiotherapy. There are no uniform standards for the necessity, timing, and case selection of ART. In this review, the research progress of ART in the radiotherapy of nasopharyngeal carcinoma in recent years was reviewed to provide a reference for further clinical application of ART in nasopharyngeal carcinoma.

OBJECTIVE: To investigate the effects of on the acoustic characteristics of tumor tissue and how such acoustic changes affect the efficacy of high-intensity focused ultrasound (HIFU) ablation in nude mice. METHODS: Forty mice bearing human breast cancer cell (MDA-MB-231) xenograft were randomized into experimental group (=20) and control group (=20) for intravenous injection of suspension (200 μL, 4 × 10 cfu/mL) and PBS (200 μL) for 3 consecutive days, respectively. Before and at 3 and 7 days after the first injection, shear wave elastography was used to evaluate the hardness of the tumor tissue. On day 7 after the first injection, 10 mice from each group were sacrificed and the sound velocity and sound attenuation of the tumor tissues were measured. The changes in the collagen fibers in the tumors were evaluated using Masson staining, and neovascularization in the tumor was assessed with immunohistochemistry for platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31). The remaining 10 tumor-bearing mice in each group were subjected to HIFU ablation, and the ablation efficiency was evaluated by assessing the changes in irradiation gray values, coagulative necrosis volume, energy efficiency factor (EEF) and irradiation area and by pathological examination with HE staining. RESULTS: In the experimental group, the collagen fibers in the tumor tissues were strong and densely aligned, and the tumors contained fewer new blood vessels showing strip-or spot-like morphologies. In the control group, the collagen fibers in the tumors were thin and loosely arranged, and the tumors showed abundant elongated or round new blood vessels. colonized in the tumor 7 days after the injection, and the tumor hardness was significantly greater in the experimental group than in the control group (=0.01); the acoustic velocity (=0.001) and the acoustic attenuation (=0.000) of the tumor tissues were also greater in the experimental group. HIFU irradiation resulted in significantly greater changes in the gray scale of tumor (=0.0006) and larger coagulative necrosis volume (=0.0045) in the experimental group than in the control group, and the EEF was significantly smaller in the experimental group (=0.0134). CONCLUSIONS can cause changes in collagen fiber content, acoustic velocity and attenuation in the tumor tissue and reduce the EEF of HIFU irradiation, thereby improving the efficacy of HIFU irradiation.
Acoustics ; Animals ; Bifidobacterium ; pathogenicity ; Breast Neoplasms ; pathology ; Collagen ; Elasticity Imaging Techniques ; High-Intensity Focused Ultrasound Ablation ; Humans ; Mice ; Mice, Nude ; Neoplasm Transplantation ; Random Allocation