Objective:In this paper, based on the 4D dose distribution of the treatment plan, the effects of respiratory movement on the dose distribution of three-dimensional conformal radiation therapy (3DCRT) and sliding window intensity-modulated radiation therapy (SW-IMRT) techniques were analyzed, and the dose errors caused by respiratory movement based on the 4D dose distribution were evaluated.Methods:In this study, the dynamic thoracic phantom (CIRS-008A) was used to simulate the patient with a 3 cm spherical insert as the tumor. Four motion patterns were simulated with cos 4( x) and sin ( x) wave forms of 10 mm and 5 mm amplitudes. The 4DCT scans with the phantom were performed in different breathing modes, and the maximum intensity projection (MIP), average intensity projection (AIP) and 10 separate 4DCT phase images were transferred to the Eclipse treatment planning system. The targets were contoured on MIP, with corresponding 3DCRT and SW-IMRT plans designed and dose calculated on AIP. By copying the plan designed on the AIP to each phase image of the 4DCT set, the MATLAB software package was employed to register and superimpose all the phase-specific doses onto one of the reference phase to create a 4D-accumulated dose distribution. Both films (EBT2) and optically stimulated luminescence (OSLD) detectors were inserted in and around the target area of the phantom to measure the delivered doses. The calculated 4D-accumulated doses were compared to the measured doses and their differences were evaluated using Gamma analysis. Results:Under different respiration modes, the average Gamma index (3%/3 mm) passing rates between the 4D-accumulated doses and EBT2-measured doses for 3DCRT and SW-IMRT plans were (98.8±0.78)% and (96.4±1.89)%, respectively. The absolute measurements of OSLDs both inside and outside of the target area well matched the 4D-accumulated doses.Conclusions:4DCT can be effectively applied to evaluate the treatment plan dose distribution through 4D dose accumulation, which can potentially avoid cold spots and target under-coverage. Under different respiration modes, both 3DCRT and SW-IMRT plans provide dose measurements consistent with those predicted by the 4D-accumulated dose of treatment plan.

Objective:To simulate the biomechanical characteristics of the real human thoracic cavity with a multi-spring group variable damping structure, and to design a new cardiopulmonary resuscitation training manikin based on the simulated thoracic biomechanical characteristics combined with the original electronic feedback system, and to test its application effect in cardiopulmonary resuscitation (CPR) teaching.Methods:A total of 60 undergraduate students majoring in five-year clinical medicine of Batch 2019 in Naval Medical University were selected as the research objects and were randomly divided into the experimental group and the control group, with 30 students in each group. The control group used the traditional manikin for CPR training, and the experimental group used the new type of manikin for CPR training based on the control group. After the training, the two groups of personnel were assessed for single skill. The single skill was mainly manual CPR operations, including artificial respiration and chest compressions. The theory and skill operation assessment of CPR and satisfaction for teaching method in the two groups were compared. SPSS 23.0 was used for statistical analysis.Results:The students in the experimental group scored (54.33±3.09) points in the single skill operation assessment, which were significantly better than that of the students in the control group [(52.33±3.08) points], and the difference was statistically significant ( P<0.05). The follow-up questionnaire showed that the students in the experimental group had a better evaluation of the teaching and training effect of the new type of manikin. Conclusion:Compared with the traditional manikin, the new CPR manikin can simulate the CPR emergency scene of the real human body, which can effectively improve the CPR teaching effect of standardized training for medical students, and help the standardization, normalization, and popularization of CPR technology in China.