Effects of tumor-treating field arrays on the radiation position and dose of glioblastoma / 中华放射医学与防护杂志

Objective:To preliminarily investigate the effects of tumor treating field (TTF) arrays on the positioning accuracy of radiotherapy setup in the treatment of glioblastoma.Methods:The kilovolt cone-beam CT (CBCT) and an X-ray volumetric imaging (XVI) system were used to verify the radiotherapy setup of 29 patients treated with conventional radiotherapy and 12 patients treated with TTF concurrent radiotherapy, respectively. The errors of radiotherapy position isocenter and treatment plan isocenter were evaluated in six directions, namely lateral (Lat), head pin (Lng), dorsoventral (Vrt), roll, pitch, and rotation (Rtn). Then, the plan isocenter was redetermined according to the setup error data. Moreover, the dose distribution was recalculated without changing the radiation field parameters. Finally, the V40, Dmean, D98% and D2% of both PTV and CTV and the Dmean, D20 cm 3, and D30 cm 3 of scalp tissue were evaluated. Results:When patients were treated with TTF concurrent radiotherapy wearing TTF arrays, the setup errors increased by 2 mm and 1.3 mm on average (maximum: 3.5 mm and 2.7 mm) toward the foot and dorsal directions, respectively. In addition, the setup errors in both Roll and Rtn directions increased by about 1.1° toward one side. The V40 and D98% of PTV decreased by up to 4.78% and 6%, respectively. The Dmean, D20 cm 3, and D30 cm 3 to scalp tissue increased by up to 2.6%, 3.2%, and 3.5%, respectively. The errors of other dose parameters for both CTV and PTV were within 2%. Conclusions:TTF arrays have significant effects on the setup errors of patients in the Lng and Vrt directions and increase the setup difficulty in the Roll and Rtn directions, while there is no significant error in the Lat and Pitch directions. Moreover, too large setup errors can significantly reduce the dose to PTV.

Automatic delineation of craniospinal clinical target volume based on hybrid attention U-net / 中华放射肿瘤学杂志

Objective:Hybrid attention U-net (HA-U-net) neural network was designed based on U-net for automatic delineation of craniospinal clinical target volume (CTV) and the segmentation results were compared with those of U-net automatic segmentation model.Methods:The data of 110 craniospinal patients were reviewed, Among them, 80 cases were selected for the training set, 10 cases for the validation set and 20 cases for the test set. HA-U-net took U-net as the basic network architecture, double attention module was added at the input of U-net network, and attention gate module was combined in skip-connection to establish the craniospinal automatic delineation network model. The evaluation parameters included Dice similarity coefficient (DSC), Hausdorff distance (HD) and precision.Results:The DSC, HD and precision of HA-U-net network were 0.901±0.041, 2.77±0.29 mm and 0.903±0.038, respectively, which were better than those of U-net (all P<0.05). Conclusion:The results show that HA-U-net convolutional neural network can effectively improve the accuracy of automatic segmentation of craniospinal CTV, and help doctors to improve the work efficiency and the consistent delineation of CTV.

Effects of tumor treating fields (TTF) arrays on the radiation doses to glioblastoma / 中华放射医学与防护杂志

Objective:To preliminarily explore the effects of tumor treating fields (TTF) arrays on the dose distribution in the treatment of Glioblastoma (GBM) using combined radiotherapy and concurrent TTF.Methods:EDR2 and MatriXX plate ionization chamber were employed to measure the absorbed doses of tissues at different depths (< 1 mm, 3 mm, 5 mm, 1 cm, 1.5 cm, 3 cm, 5 cm, 10 cm, and 15 cm) in the case that TTF arrays and latex-free foam were attached and not attached on the surface. Then the absorbed doses were calculated, compared, and analyzed. For the volumetric arc therapy (VMAT) of 10 GBM patients, deep dose verification was performed using the Sun Nuclear ArcCheck 3D dose verification system and the D99%, Dmean, and D1% of tumors and OARs were assessed. Results:The surface dose increased by 173% in the case that TTF arrays and latex-free foam were attached to the surface compared with the case of the surface with nothing attached. The surface dose increased by 61.7% due to the attachment of low-density latex-free foam. The dose deviation gradually decreased with an increase in the depth and stabilized (about 4%) at a depth of greater than 1.5 cm. As indicated by the VMAT verification result, the D99%, Dmean, and D1% of PTV and CTV decreased by 1.1%-1.2% and the Dmean and D1% of OARs (i.e., brainstem, pituitary gland, optic chiasma, optic nerve, eyeball, and eye crystal) decreased by 0.7%-1.5% in the case that TTF array and latex-free foam were attached on the surface compared with the case the surface with nothing attached. Conclusions:The combined radiotherapy and concurrent TTF in the GBM treatment will lead to a slight reduction of the absorbed doses of targets and OARs but a significant increase in the absorbed doses of the scalp. Therefore, it is recommended that the scalp doses should be reduced as far as possible in the design of the radiation treatment plan to reduce the adverse reactions on the scalp of GBM patients.

DWI in survival prediction for patients with glioblastoma receiving chemoradiotherapy / 肿瘤

Objective: To explore the value of diffusion-weighted imaging (DWI) in predicting the prognosis of patients with glioblastoma (GBM) receiving chemoradiotherapy. Methods: The GBM patients undergoing complete resection were included in this prospective study. All patients received diffusionweighted imaging (DWI) followed by standard radiation and chemotherapy. The apparent diffusion coefficient (ADC) values of proximal area, middle area and distal area were measured. The patients were classified according to the median and minimum ADC values. The overall survival (OS) and the progression-free survival (PFS) were evaluated. Results: The 6-month and 12-month OS rates of 83 patients included in this study were 99% and 82%, respectively, and the 6-month and 12-month PFS rates were 84% and 66%, respectively. The OS and PFS of the patients with the average ADC values>0.979×10-3 mm2/sin the proximal area were superior to those of the patients with the average ADC values ≤ 0.979×10-3 mm2/s (OS: P = 0.019; PFS: P = 0.005). The PFS of the patients with the minimum ADC value>0.894×10-3 mm2/s in the proximal area was superior to that of the patients with the minimum ADC value ≤ 0.894×10-3 mm2/s (P = 0.018). The differences in OS and PFS were not statistically significant with respect to the middle area and the distal area (all P>0.05). Conclusion: DWI can provide additional useful information in predicting the efficacy of chemoradiotherapy in the patients with GBM.