Objective: This study explored the application of four-dimensional cone beam computed tomography (4D CBCT) in lung cancer patients, seeking to improve the accuracy of radiotherapy and to establish a uniform protocol for the application of 4D CBCT in radiotherapy for lung cancer. Methods: 4D CBCT was applied to evaluate tumor volume response (TVR), motion, and center coordinates during radiotherapy in 67 eligible individuals with lung cancer diagnoses. The differences between 4D CBCT and 3D CBCT in different registration methods were compared. Results: TVR was observed during treatment in 41% of patients (28/67), with a mean volume reduction of 41.7% and a median time to TVR of 19 days. Tumor motion was obvious in 16 patients, with a mean value of 0.52 cm (0.22 to 1.34 cm), and in 3 of 6 tumors close to the diaphragm (0.28 to 0.66 cm). Gray value registration based on mean density projection could still achieve close results to the 4D gray value registration. However, when the registration was based on bone alone, partial off-targeting occurred in the treatment in 41.8% of cases. The off-target rate was 19.0% when the tumor motion was ≤ 0.5 cm and 52.2% when the motion was > 0.5 cm. Conclusion: Tumor volume and motion of intrapulmonary lesions in individuals diagnosed with lung cancer varied significantly in the third week of radiotherapy. 4D CBCT may be more advantageous for isolated lesions without reference to relative anatomical structures or those near the diaphragm. Grayscale registration based on mean density projection is feasible.

This study investigated the evolving trends, current research hotspots, and future directions of radiotherapy combined with nanobiomaterials through a bibliometric analysis. Publications related to nanobiomaterials used in radiotherapy between 2004 and 2024 were retrieved from the Web of Science Core Collection database and analyzed using VOSviewer, R, and CiteSpace. China emerged as the leading contributor, accounting for 1051 publications (50.41%), followed by the USA. Liu Zhuang is the most productive author in this field. American Chemical Society (ACS) Nano published the most influential articles and accumulated the highest number of citations. Advanced Targeted Therapies in Cancer: Drug Nanocarriers, the Future of Chemotherapy was the most cited, with 1255 citations. Citation bursts have revealed emerging research trends in targeted delivery, cellular studies, co-delivery strategies, immunogenic cell death, polymeric nanoparticles, tumor research, and drug delivery systems, indicating potential avenues for future research. Over the past two decades, nanomaterials for radiotherapy have gained substantial attention. Key areas of focus include enhancing the efficacy of radiotherapy, achieving targeted drug delivery, minimizing adverse effects, and integrating nanomaterials with other therapeutic modalities. Future investigations are expected to improve the precision of radiotherapy, augment radiation effects, and optimize the tumor microenvironment.