Objective:To investigate the effectiveness and feasibility of a 3D U-Net in conjunction with a three-phase CT image segmentation model in the automatic segmentation of GTVnx and GTVnd in nasopharyngeal carcinoma.Methods:A total of 645 sets of computed tomography (CT) images were retrospectively collected from 215 nasopharyngeal carcinoma cases, including three phases: plain scan (CT), contrast-enhanced CT (CTC), and delayed CT (CTD). The dataset was grouped into a training set consisting of 172 cases and a test set comprising 43 cases using the random number table method. Meanwhile, six experimental groups, A1, A2, A3, A4, B1, and B2, were established. Among them, the former four groups used only CT, only CTC, only CTD, and all three phases, respectively. The B1 and B2 groups used phase fine-tuning CTC models. The Dice similarity coefficient (DSC) and 95% Hausdorff distance (HD95) served as quantitative evaluation indicators.Results:Compared to only monophasic CT (group A1/A2/A3), triphasic CT (group A4) yielded better result in the automatic segmentation of GTVnd (DSC: 0.67 vs. 0.61, 0.64, 0.64; t = 7.48, 3.27, 4.84, P < 0.01; HD95: 36.45 vs. 79.23, 59.55, 65.17; t = 5.24, 2.99, 3.89, P < 0.01), with statistically significant differences ( P < 0.01). However, triphasic CT (group A4) showed no significant enhancement in the automatic segmentation of GTVnx compared to monophasic CT (group A1/A2/A3) (DSC: 0.73 vs. 0.74, 0.74, 0.73; HD95: 14.17 mm vs. 8.06, 8.11, 8.10 mm), with no statistically significant difference ( P > 0.05). For the automatic segmentation of GTVnd, group B1/B2 showed higher automatic segmentation accuracy compared to group A1 (DSC: 0.63, 0.63 vs. 0.61, t = 4.10, 3.03, P<0.01; HD95: 58.11, 50.31 mm vs. 79.23 mm, t = 2.75, 3.10, P < 0.01). Conclusions:Triphasic CT scanning can improve the automatic segmentation of the GTVnd in nasopharyngeal carcinoma. Additionally, phase fine-tuning models can enhance the automatic segmentation accuracy of the GTVnd on plain CT images.

Artificial intelligence is the use of computer algorithms to copy or simulate human behavior, giving machines human-like ability. With the rapid development of radiotherapy technology, artificial intelligence has great potential value in all stages of radiotherapy. Image segmentation is the premise of target delineation using artificial intelligence. The commonly used methods in clinic mainly include automatic segmentation based on deep learning and atlas library. The technology of artificial intelligence in organs at risk delineation is relatively mature, which can significantly shorten the delineation time and improve the efficiency. The delineation of tumor targets has achieved some success, the accuracy still needs to be further improved. Artificial intelligence technology makes the target delineation more and more efficient, and the consistency and repeatability have been significantly improved. It is expected to provide more accurate and individualized treatment for patients.

Objective: To compare the accuracy of two automatic segmentation softwares (Smart Segmentation and MIM Atlas) in organs at risk (OARs) contouring for nasopharyngeal carcinoma (NPC). Methods: Totally 55 NPC patients were retrospectively reviewed with manually contoured OARs on CT images, in which 30 cases were randomly selected to create a data base in the Smart Segmentation and MIM Atlas. The remaining 25 cases were automatically contoured with Smart Segmentation and MIM as test cases. The automatic contouring accuracies of two softwares were evaluated with Dice coefficient(DSC), Hausdorff distance(HD), and absolute volume difference(△V) using manual contours as a golden standard. Results: The overall DSC, HD and △V of all organs contoured by MIM Atlas and Smart Segmentation were (0.79±0.13) vs. (0.62±0.24) (t=14.06, P<0.05), (5.50±3.84)mm vs.(8.38±4.88)mm (t=-11.40, P<0.05), and (1.52±2.46) cm³ vs. (2.38±3.57) cm³ (t=-4.70, P<0.05), respectively. The average DSC of 11 organs (brain stem, optic chiasm, bilateral lens, bilateral optic nerve, bilateral eyeballs, bilateral parotid gland, spinal cord) delineated by MIM Atlas was statistically greater than that of Smart Segmentation (t=5.27, 4.41, 6.34, 5.70, 10.62, 7.45, 3.96, 4.26, 6.25, 5.42, 7.23, P<0.05). The average HD of 10 organs (brain stem, optic chiasm, bilateral lens, bilateral optic nerve, bilateral eyeballs, left parotid gland, spinal cord) delineated by MIM Atlas was statistically less than that of Smart Segmentation (t=-4.51, -4.49, -3.92, -3.45, -5.36, -5.56, -3.89, -3.90, -3.60, -3.68, P<0.05). The average △V of 6 organs (brain stem, optic chiasm, left len, bilateral optic nerve, right eyeball) delineated by MIM Atlas was statistically less than that of Smart Segmentation (t=-2.83, -3.39, -2.56, -2.27, -2.43, -2.51, P<0.05). Conclusions Both softwares have reasonable contouring accuracy for larger organs. The accuracy decreased with the decrease of organ volumes and blurred boundary. Generally, MIM Atlas′s performs better than Smart Segmentation does.

Diffusion tensor imaging (DTI) uses the diffusion motion of water molecules to describe the spatial structure of brain.DTI,which can obtain the infiltration of brain tumors into normal physiological structures,makes the diagnosis of diseases change from macroscopic to microscopic,from morphology to both morphology and metabolism,bringing new opportunities for the diagnosis and treatment of brain tumors.In this review,we outlined the theoretical basis and current technical limitations of DTI,and comprehensively discussed its research values in brain tumors radiotherapy treatment and its prognostic value.We believe that DTI can provide important imaging information for radiotherapy planning of brain tumors.

Objective To compare the dose distribution and setup error of angled breast board position ( ABB) with plain breast board position ( PBB) in breast cancer radiotherapy. Methods Twenty consecutive postoperative left breast cancer patients in the First Affiliated Hospital, Zhejiang University were enrolled from March 2017 to January 2018. All cases were assigned into the ABB and PBB groups according to positions and there were 10 cases in each groups respectively. The target volume, heart and lung structures were defined on the CT images of the localized scan. The plan was designed using the field in field ( FIF) technique to compare the dosimetric parameters of the PTV, lung, and heart treatments, and the setup errors for the two different positions. Results The ipsilateral lung V20[ABB:(11.2 ±3.2)％, PBB:(15.9 ±5.3)％, t= -2.47,P< 0.05], and V30[ABB:(9.8 ±1.5)％, PBB:(12.9 ±2.2)％, t= -4.46,P<0.05] were both statistically significant for the two different position and immobilization. Heart dose V25[ABB: (1.9 ± 0.2)％, PBB: (2.8 ± 0.4)％, t = -8.28, P <0.05], V30 [ABB:(1.8 ±0.1)％, PBB: (2.7 ± 0.3)％, t = -8.34,P < 0.05], and Dmean of heart [ABB: (3.0 ±0.5)Gy, PBB:(5.3 ± 1.2)Gy, t=5.58,P<0.05] were all statistically significant for the two different positions. The translational errors of ABB and PBB on LR, SI, and AP were ( 3.23 ± 2.63 ) , ( 5.42 ± 3.22), (4.58 ± 2.30) mm, and (2.35 ± 1.22), (2.17 ± 1.29), (2.27 ± 1.58) mm, respectively. The rotation errors of pitch(θ), yaw(Φ) and roll(ψ) for ABB and PBB were (1.60 ± 0.56)°, (3.40 ± 1.65)°, (2.50 ± 1.72)°, and (1.37 ± 0.43)°, (1.79 ± 0.71)°, (2.06 ± 0.63)°, respectively. Meanwhile, the in-and out-SI, anterior and posterior AP, yaw rotation error (Φ) were also statistically significant(t=3.06, 2.80, 3.33,P<0.05). Conclusions There is no statistically significant difference in the tumor target between the two position and immobilization techniques. However, the ABB is better than the PBB in normal tissue sparing while the setup accuracy of PBB is better than the ABB.

Objective To investigate the dosimetric differences among three types of breath hold mode ( free breath:FB, thoracic deep inspiration breath hold: T-DIBH, abdomen deep inspiration breath hold:A-DIBH) and to explore the optimal breath hold method in the postoperative radiotherapy of left-side breast cancer patients with minimum dose to normal tissues and organs at risk. Methods A total of eighteen patients with left-side breast cancer patients who underwent postoperative radiotherapy were enrolled in this study. Three CT simulation scans with three different breath hold method ( FB, T-DIBH, and A-DIBH ) were performed for each patient. Dosimetric differences were compared among plans generated on these three different CT image sets. Results There was no significant difference in the volume, mean dose, and homogeneity of planning target volume ( PTV) among plans generated from three different image sets (P>0. 05). The mean heart dose, mean LAD dose and mean ipsilateral lung dose in plans generated from CT image sets with FB, T-DIBH and A-DIBH were (3. 21 ± 1. 02), (1. 74 ± 0. 51), (1. 31 ±0. 41) Gy (W =171, P <0. 05), (34. 61 ± 13. 51), (14. 38 ±10. 20), (9. 21 ± 6. 53) Gy (W=171, P<0. 05), and (8. 31 ±2. 75), (7. 46 ±1. 96), (6. 89 ±1. 79) Gy (W=171, P<0. 05), respectively. Conclusions Compared with plans with FB, plans with DIBH ( T-DIBH and A-DIBH ) achieved lower cardiac, LAD and pulmonary doses. A-DIBH achieved a better normal dose reduction than T-DIBH.

Objective To compare the dosimetric results of postoperative intensity modulated radiation therapy (IMRT) using single-energy or mixed-energy photons in invasive thymoma patients.Methods Simulation CT images were acquired and clinical target volume (CTV),planning target volume (PTV) and organs at risk (OARs) were defined.Three sets of fixed-field IMRT planning were generated using 6 MV,10 MV and mixed 6/10 MV photons for each case.Monitor Units (MUs) for each plan were recorded after optimization,and parameters of PTV such as conformity index (CI),homogeneity index (HI) and dose to OARs were evaluated on dose-volume histograms.Results Near-Maximal dose (D2％) received by PTV was better in mixed-energy IMRT as compared with 6 MV(t =3.107,P ＜0.05).HI was better in mixed-energy than in 6 MV(t =2.924,P ＜0.05).There were statistically significant differences in CI among three IMRT plans.MU was higher in 6 MV than in both 10 MV and mixed-energy IMRT.The percentages of lung volumes receiving 5 Gy (V5),10 Gy(V10),20 Gy (V20),30 Gy (V30) and the mean lung dose (D) were also significantly different in most plans.V30 and V40 of the heart were comparable between 6 MV and mixed energy plans but better than in 10 MV plan.Conclusions If the reasonable choice of beam angles and number,and capability of energy selection according to beam directions,with combined advantages of low and high energy photons,mixed IMRT plans can improve the quality of IMRT plans in general and has clinical potential for postoperative radiotherapy of invasive thymomas.

Objective To assess the outcomes of involved field irradiation (IFI) and elective nodal irradiation (ENI) in patients older than 70 years with esophageal squamous-cell carcinoma(SCC) receiving radical IMRT,and to determine whether IFI is feasible in these patients.Methods Totally 79 patients older than 70 years diagnosed with SCC of esophagus without distant metastases were collected.48 patients were received IFI,and the other 31 patients were treated with ENI.With a median follow-up time of 24 months,disease-free survival,overall survival,patterns of failure,irradiated lung dose and radiation pneumonitis were observed and compared between IFI and ENI groups.Results In IFI and ENI arm,the disease-free survival rates of 1,2,3 years were 60.4％,34.9％,29.7％ and 64.5％,54.0％,35.0％,respectively(P ＞0.05).The 1-,2-,and 3-year survival rates were 72.9％,43.4％,31.5％ for the IFI arm,and 73.0％,53.0％,38.3％ for the ENI arm(P ＞ 0.05).The ENI arm had a tendency to expand survival,but the two arms had no significant difference (P ＞ 0.05).The patterns of failure also had no difference between the two arms.Distant failure,local failure,uninvolved nodal failure in IFI arm were 22.9％,27.0％,4.2％,while in ENI arm were 25.8％,0,19.4％,all of them had no significant difference (P ＞ 0.05).However,the lung V5,V20,mean lung dose in ENI arm were higher than that in IFI and all of them had a significantly difference (t =4.66,29.90,15.63,P ＜ 0.05).The radiation pneumonitis rates were higher in ENI than in IFI arm.The rates of degree 1-2 and degree 3 were 22％,19％,and 13％ and 4％ in the two arms,respectively,with a significantly difference(x2 =4.55,4.77,P ＜ 0.05).Conclusions It is feasible that IFI for definitive IMRT in the elderly patients older than 70 years with SCC,because it got similar disease-free survival and overall survival but with less lung doses along with decreased radio-pulmonary lesion when compared with ENI.

The oligometastasic stage is an intermediate state with mild biological invasion,in which spread may be limited to specific organs and polymetastases do not occour.The number of metastatic tumors is limited less than five.Local therapy such as radiotherapy,surgery and radiofrequency ablation for the relapsed sites could thus improve patients survival.The expression of miR-200 family characterizes oligometastasis(es).Correct understanding and familiarization with treatment of oligometastasis may change the traditional therapeutic strategy of advanced tumors,and some advanced cancer patients may achieve curable results.

Objective To investigate the value of diffusion-weighted magnetic resonance imaging (DWI) and apparent diffusion coefficients (ADC) in detecting metastatic lymph nodes from nasopharyngeal carcinoma (NPC),and predicting the response of these nodes to concurrent chemoradiation (CRT).Methods Eighteen patients with pathologically proven NPC received conventional magnetic resonance imaging (MRI) and DWI before treatment,weekly during treatment,and one month after treatment.DWI was performed using a single-shot echo-planar (SSEPI) MR imaging sequence with b values of 0 and 1500 s/mm2.ADC maps were reconstructed for all patients and ADC values were calculated for each lymph node and tongue muscle.Totally fifty-two morphologically abnormal lymph nodes were analyzed.The ADC values of the metastatic lymph nodes before treatment were compared between those with the short axis≥10 mm (n=32) and those with the short axis<10 mm (n=20),and the dynamic changes in ADC values of the lymph nodes before,during,and after therapy were observed and recorded.Results The average ADC of the 32 lymph nodes with the short axis ≥ 10 mm was (0.71±0.12) x 10-3mm/s,not significantly different from that of the 20 lymph nodes with the short axis < 10 mm [(0.73±0.16) x 10-3mm/s,t = 1.11 ,P =0.27].The average ADC values of these lymph nodes before treatment was significantly lower than that of the tongue muscle (t = 19.35,P < 0.0001).During CRT,the ADC values of the lymph nodes increased gradually,with the most evident change in the first two weeks before reaching a relatively flat plateau thereafter.The ADC value of the residual lymph nodes after CRT was significantly higher than that before treatment (t = 12.72,P < 0.0001),however,not statistically significant different from that of the normal tongue muscle (t = 0.34,P = 0.73).Conclusions DWI plays an important role in diagnosing the metastatic lymph nodes from NPC and is feasible for observation of the early response of the lymph nodes to IMRT,thus helping the clinicians make appropriate treatment planning and replanning in the course of radiotherapy.