Résumé
Background: the dynamic phantom is one of the best tools to study the impact of motion on tumor target delineation and absorbed dose verification during dose delivery
Materials and Methods: this study, a 6-DOF [degrees of freedom] phantom was designed following the stacked serial kinematics and assembled by six commercial motion stages to generate 6-DOF motion, which were RotX [pitch, around X], RotY [roll, around Y], TransZ [anterior-posterior], RotZ [yaw, around Z], TransY [superior-inferior] and TransX [left-right]. Tumor targets were designed by six plastic spheres for the delineation test. Also, an ionization chamber array detector and RW3 solid water were combined to measure the absorbed dose for dose verification tests
Results: the maximum translation speeds for LineX and LineY were 50mm/s and 35mm/s for LineZ, while the maximum rotation speeds for RotX, RotY, RotZ were 5.33° per second, 6degree per second and 15degree per second respectively. Spiral-CT and 4D-CT images acquired in the static and dynamic states successfully showed the influences of tumor motion on target delineation. In the absorbed dose verification, all cases did not pass the gamma test; the pass rate for the 6-DOF motion case was only 34.2% and the pass rates of all other cases were less than 90%
Conclusion: the phantom designed in this study is able to simulate complex tumor motion and can be used to study the influence of tumor motion in radiotherapy
Résumé
Background: To investigate the expression of TNF-alpha, IL-6, IL-10 in the plasma of patients with lung cancer who received radiation therapy [RT], and to analyze the correlation between these cytokines and radiation pneumonitis [RP]. Materials and Methods: Patients with lung cancer who received 3D-CRT in our hospital were prospectively evaluated. Circulating cytokine levels were measured with ELISA before RT and at the end of RT. Regular follow-up was undertaken 3 months after RT. Statistical analysis was applied to determine the relevance of cytokines to radiation-induced lung injury. Results: Of 104 patients, 29 [27.9%] developed RP. The levels of TNF-alpha and IL-6 levels in the plasma after RT were significantly higher than before RT [p<0.05], whereas IL -10 levels were significantly lower after RT than before RT [p<0.05]. Before RT, TNF-alpha levels were higher in RP group [p<0.05],but there were no differences in TNF-alpha levels after RT. No association was observed between IL-6 and IL-10 levels and the risk of RP. Univariate analysis showed that baseline pulmonary function, smoking history, histopathology, lung volume receiving >/=20 Gy [V20], Mean lung dose [MLD] and total radiation dose were related to RP, but only MLD was an independent risk factor for RP in lung cancer patients [OR>1]. Conclusion: TNF-alpha levels in plasma were closely related to RP but still cannot be used as predictors for RP