Iodine quantification with DECT may help in differentiating benign periablational reactive tissue from residual tumour in VX2 carcinoma in rabbits after RFA.
Results of superconducting transition temperature measurements are presented for the bulk metallic glass Zr 46.75 Ti 8.25 Cu 7.5 Ni 10 Be 27.5 before and after annealing. The superconducting critical temperature T c is 1.84 K for the asprepared metallic glassy sample and 3.76 K for the annealed sample at zero magnetic field, respectively. The temperature gradient (−d H c2 /dT ) T c of the upper critical field H c2 near the critical temperature T c of the bulk metallic glass Zr 46.75 Ti 8.25 Cu 7.5 Ni 10 Be 27.5 is about 2.5 T K −1 . Annealing of the metallic glass leads to a decrease of (−d H c2 /dT ) T c to 1.2 T K −1 . The origin of the reduction of the critical temperature T c in the amorphous Zr 46.75 Ti 8.25 Cu 7.5 Ni 10 Be 27.5 is ascribed to a smearing of the density of states by the disordered atomic structure.
Purpose: To measure the setup errors by using cone beam computed tomography (CBCT) and to analyze the effect of the setup errors on the physics dose of targets and peripheral organs at risk (OARs) for cervical Cancer undergoing the intensity modu1ated radiation therapy (IMRT). Methods: Ten cervical Cancer cases were chosen at random. CBCT was performed before radiotherapy.The acquired CBCT were co‐ registered with the planning CT for online set‐up correction and errors of isocenter positions on x、y、z axes were obtained .Those were simulated in actual therapy on the treatment planning system (TPS),and recalculated their dose distribution.A series of relative targets and OAR dose parameters were analyzed,and obtained the impact of the setup errors on the physics dose. Results: (1)A total of 126 CBCT scans were performed on 10 patients.The detection rates of deviation of ≤0.3cm were 92.86% in left‐ to‐right (X) direction,83.33% in superior‐to‐inferior (Y) direction, and 91.26% in anterior‐to ‐posterior (Z)direction;The setup errors on X,Y and Z axes direction were(0.24±0.21)cm 2289;(0.28±0.32)cm 2289;(0.10士0.23)c m. (2) Dose and volumes index of CTV were no significant difference between simulated plans and actual plans. (3) V45、V50 of bladder and V30、V40、V45、V50 of rectum in simulated plans were significantly larger than those in actual plans,especially V45、V50 of rectum(P<0.005). Conclusions: The CBCT plays key ro1e in the guarantee of accurate delivery of IMRT for cervical Cancer,especially peripheral OARs.
lungV30 is risk factor to affect PFTs changes in patients with NSCLC excluding those who have had pretreatment atelectasis. Our funding support received from National Natural Science Foundation of China (30870743).
Purpose:
To present a technique to automatically determine beam angle configurations for lung IMRT planning based on the patient‐specific anatomy and tumor geometry.
Methods:
The relationship between individual patient anatomy and proper beam configurations was learned from high quality clinical plans in three steps. First, a beam configuration atlas was obtained by classifying 60 lung IMRT plans into 6 beam configuration clusters based on a dissimilarity measure defined between different beam configurations. A beam configuration template was extracted from each cluster to form an atlas. Second, a beam efficiency index map (EI map) was constructed to characterize the geometry of the tumor relative to the lungs, the body and other OARs along each candidate beam direction. Finally, the EI maps of the clinical cases and the cluster assignments of their beam configurations were paired to train a Bayesian classification model. This technique was validated by leave‐one‐out cross validation with 16 cases randomly selected from the original dataset. An IMRT plan (autobeam plan) for each test case was generated using the beam configuration template according to the cluster assignment given by the model and was compared with the corresponding clinical plan.
Results:
The dosimetric parameters (mean±S.D. in percentage of prescription dose) in the auto‐beam plans and in the clinical plans, respectively, and the p‐values by a paired ttest (in parenthesis) are: lung Dmean: 16.3±9.3, 18.6±7.4 (0.48), esophagus Dmean: 28.4±18, 30.7±19.3 (0.02), Heart Dmean: 21.5±17.5,21.1±17.2 (0.76), Spinal Cord D2%: 48±23, 51.2±21.8 (0.01), PTV dose homogeneity (D2%–D99%): 22±27.4, 20.4±12.8 (0.10). The dose reductions by the autobeam plans in esophagus Dmean and cord D02 are statistically significant but the differences (<4%) may not be clinically significant. The other dosimetric parameters are not statistically different.
Conclusion:
Plans generated by the automatic beam angle determination method can achieve dosimetric quality equivalent to that of clinical plans.
Partially supported by NIH/NCI under grant #R21CA161389 and a master research grant by Varian Medical System.
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