As a new therapeutic strategy for esophageal cancer, immunotherapy has attracted more and more attention. The completed and ongoing clinical trials of immunotherapy for esophageal cancer confirm the great potential of immune checkpoint inhibitors in esophageal cancer. Future research will focus on the combination of immunotherapy with existing or new therapeutic modalities and the identification of populations likely to benefit from immunotherapy.

Objective To explore the effect of pitch in three-dimensional computed tomography (3DCT)on the gross tumor volume(GTV)and spatial position of solitary pulmonary lesion(SPL), and to evaluate the feasibility of high-pitch 3DCT simulation for SPL. Methods Twenty-two patients with peripheral lung cancer or metastatic SPL were divided into groups A and B according to the tumor location. All patients underwent spiral CT scans at different pitches(pitchCON=0.938, pitchS=0.438, and pitchB=1.188)during free breathing. All GTVSwere delineated by the same radiation oncologist using the same contouring protocol. GTVCONgenerated at pitchCON, GTVSgenerated at pitches, and GTVBgenerated at pitchB were compared in terms of volume and geometric position, and GTVSand GTVBwere registered to GTVCONgained at the conventional pitch. The Friedman M and Wilcoxon rank-rum test were used for comparison. Results The volumes of GTVCON, GTVS, and GTVBwere 11.58± 16.42 cm3, 11.63± 17.73 cm3, and 12.09± 17.46 cm3, respectively(P=0.11). There were no significant differences in the centroid position in x,y,and z directions between GTVCON,GTVS,and GTVB(Px=0.33,Py=0.81, Pz=0.39). The same result was found in group B (Px=0.92,Py=0.05, Pz=0.37). The matching index(MI)between GTVSand GTVCONwas related to the tumor location,so was the MI between GTVBand GTVCON. Conclusions The pitch in 3DCT simulation has no significant effect on the GTV and spatial position of SPL. Increasing CT pitch appropriately can improve the scanning speed and shorten the duration of 3DCT simulation,so high-pitch 3DCT simulation is feasible for SPL.

Modern medical imaging techniques,such as computed tomorgraphy (CT),magnetic resonance imaging (MRI) and position emission tomorgraphy/computed tomorgraphy (PET-CT) can accurately delineate the gross target volume (GTV) of hepatocellular carcinoma (HCC).Comparison of postoperative pathological subclinical lesions,imaging and clinical parameters contributes to the precise delineation of clinical target volume (CTV).Moreover,radiotherapy-assisted techniques,such as fourdimensional computed tomography (4DCT),compression of abdomen,active breathing control and respiratory gating,can minimize the internal target volume (ITV).In addition,immobilization with vacuum cushion and body membrane can reduce the set-up error,minimize the planning target volume (PTV) and avoid or decrease the irradiation error or missing irradiation.All these approach can minimize the target volume,elevate the dose and reduce the complications during radiotherapy for HCC.In this article,the research progress on the target delineation for external beam radiotherapy in HCC patients was reviewed.

Objective To explore the dosimetric variance in incidental irradiation to the internal mammary nodes among inverse intensity-modulated radiotherapy (I-IMRT), forward intensity-modulated radiotherapy (F-IMRT),and three-dimensional conformal radiotherapy (3DCRT) after breast-conserving surgery,and to provide a basis for deciding whether to spare the internal mammary nodes in clinical treatment. Methods A total of 84 patients undergoing breast-conserving surgery were enrolled as subjects. The internal mammary nodes in the first three intercostal spaces were contoured. Three radiotherapy plans were designed for each patient. The internal mammary nodes were not included in the planning target volume. Comparison was made among the three plans. The results were compared using Wilcoxon signed rank test. Results The I-IMRT, F-IMRT,and 3DCRT plans had similar median Dmeanvalues for the internal mammary nodes,which were 2 740.2,2973.9,and 2951.4 cGy,respectively. The analyses of the three individual intercostal spaces showed that there was no difference in Dmeanfor the first intercostal space or the second intercostal space between the three plans;For the third intercostal space,however,I-IMRT had a significantly higher Dmeanthan 3DCRT and F-IMRT. The analyses of the three individual plans showed that for each plan,the Dmeanwas the highest in the third intercostal space,followed by the second intercostal space and the first intercostal space. Conclusions All the three plans fail to attain an adequate prescribed dose to cure subclinical disease,and there is no significant difference among the three plans. Therefore,it is risky to exclude the internal mammary nodes using any one of the three radiotherapy techniques for patients with clinical indications for internal mammary nodes radiation. In the combination therapy including chemotherapy,endocrine therapy,and targeted therapy,however,further follow-up is needed to determine whether the incidental irradiation dose to the internal mammary nodes could meet clinical requirement.

Neoadjuvant chemoradiotherapy is the preferred treatment mode for the diagnosis and treatment of locally advanced operable esophageal carcinoma recommended by many guidelines. However, some problems remain to be further explored. In this article, current problems perplexing clinical practice were sorted out, aiming to provide constructive suggestions for the smooth development of neoadjuvant chemoradiotherapy for esophageal carcinoma in the future.

Objective:To compare positional and volumetric differences between the gross target volumes (GTV) delineated on three-dimensional CT (3D-CT) referencing 18F-FDG PET/CT and the GTV on the deformed image derived from 3D-CT and 18F-FDG PET/CT for primary thoracic esophageal cancer (EC). Methods:Seventy-two patients underwent chemoradiotherapy were enrolled. All the patients sequentially underwent 18F-FDG PET/CT scans for diagnosis and 3D-CT scans for simulation. The GTV 3D was delineated on 3D-CT without referencing 18F-FDG PET/CT. The GTV PET-ref was delineated on 3D-CT referencing 18F-FDG PET/CT. The GTV PET-regwas delineated on the deformed image derived from 3D-CT and 18F-FDG PET/CT by MIM deformable registration software. The differences in position, volume, length, conformity index (CI), and degree of inclusion (DI) of target volumes were compared, respectively. Results:The median volume of GTV 3D, GTV PET-ref, GTV PET-reg were 44.90, 40.36 and 41.15 cm 3, respectively. There was no statistical difference between the volumes of any two targets. The mean lengths of GTV 3D, GTV PET-ref, GTV PET-reg were 8.54, 9.29 and 8.38 cm, respectively. The length of GTV PET-ref was longer than that of GTV 3D ( t=2.134, P<0.05). The median DIs of GTV PET-ref, GTV PET-regin GTV 3D were 0.86, 0.82( Z=-2.741, P<0.05), and that of GTV 3D in GTV PET-ref, GTV PET-reg were 0.87, 0.84 ( Z=-1.429, P<0.05). The median CIs of GTV 3D in GTV PET-ref and GTV PET-reg were 0.72, 0.68 ( Z=2.756, P<0.05), and the difference was significant. The CIs of GTV 3D and GTV PET-ref, GTV 3D and GTV PET-reg, GTV PET-ref and GTV PET-reg had significant negative correlation with the distance of target centers. Conclusions:There was no significant difference between GTV contoured on three-dimensional CT (3D-CT) referencing 18F-FDG PET/CT and the GTV on the deformed image derived from 3D-CT and 18F-FDG PET/CT either in volume size or in spatial position. Therefore, it is recommended that radiation oncologists can refer to the recent diagnostic PET/CT when delineating the gross target volume for primary thoracic esophageal cancer.

Objective To study the dose volume histogram ( DVH ) difference of target and organs at risk in intensity-modulated radiation therapy ( IMRT ) planning of cervical cancer based on the interquartile range. Methods A total of 22 cervical cancer patients′ IMRT plans were retrospectively analyzed. Five groups of DVH curves of PTV and OARs ( bladder, rectum, left and right femoral heads) were derived from the Pinnacle3 planning system. The mean DVH curves and interquartile range of volume ( IQRvol ) as a function of dose were calculated from each group′s DVH curve. Results The maximum volume variation for PTV reached at IQRvol(54. 03 Gy) =6. 95%, the volume of the target reached by the prescription dose was ( 96. 43 ± 1. 63 )%. The maximum volume variation for bladder reached at IQRvol (17. 24 Gy) = 14. 62%. V40 and V30 for bladder were ( 32. 79 ± 7. 06 )% and ( 56. 47 ± 9. 94 )%, respectively. Rectal DVH showed the largest difference at 35. 92 Gy, with the quartile of 19. 94%, the V40 and V30 for rectum were (30. 17 ± 10. 80)% and (58. 16 ± 11. 99)%, respectively. The difference in the bladder and the rectum was statistically significant (z = -6. 59, P < 0. 05). The maximum volume variation of left femoral head reached at IQRvol(16. 06 Gy) =31. 47%. The maximum volume variation of right femoral head was reached at IQRvol (17. 47 Gy) =32. 82%. There was no significant difference in IQRvol between right and left femoral head (P>0. 05). Conclusions Quartile range curve of DVHs can be used to analyze the deviations of DVH curves of PTV and OARs, and provide guidance for automatic planning optimization parameter setting.

Objective To compare the dosimetric and delivery efficiency between intensity-modulated radiation therapy (IMRT) plans based on Halcyon and Trilogy accelerator.Methods Clinical data of 12 patients with cervical cancer receiving Trilogy platform-based IMRT were retrospectively analyzed.The target area and organ at risk were introduced into the Eclipse version 15.1 TPS.The Halcyon-based IMRT was re-designed.The dose coverage of target area and organs at risk,monitor unit (MU) efficiency,delivery time and segment area and the differences between the proximal and distal segment area were statistically compared between two IMRT plans.Results The Halcyon treatment platform could meet the clinical objectives.Dose distribution of the target area was similar to that of the Trilogy plan (P＞O.05).The volumes in the bladder and rectum receiving 30 Gy and the volumes in the left femoral head receiving 20 Gy of Halcyon plan and the mean dose (D) of bladder,rectum and left femoral head were significantly lower compared with those of the Trilogy plan (P=0.001-0.043).The MUs of the Halcyon plan was 2 316.7± 209.7,significantly higher than 1 692.5± 259.5 of the Trilogy plan (P=0.000).The delivery time significantly differed between the Halcyon [(3.01±0.28) min] and Trilogy [(12.38± 1.49) min] (P=0.000).The average segment area of Halcyon plan for proximal and distal MLC was (43.7±32.5) cm2 and (28.8±25.4) cm2,the average segment area of Trilogy plan was (25.7±16.8) cm2,the ratio of the proximal and distal segment area was 1.73±0.43,ranging from 0.71 to 6.28.Conclusions Halcyon treatment platform can meet the clinical requirements and reduce the dosage coverage of normal tissues with better delivery efficiency.The ratio of proximal and distal segment areas should be considered during the plan design.

Objective To analyze the dosimetric and delivery efficiency differences between IMRT plans based on Halcyon and Trilogy Accelerator for left side breast cancer.Methods A total of 10 patients with left side breast cancer based on the Trilogy platform were retrospectively analyzed.For each patient,plan based on Halcyon was redesigned using Eclipse Version 15.1 TPS.In order to evaluate plan quality,dose coverage of target and dose to organs at risk,monitor unit efficiency,segment size and delivery time were compared.Results Halcyon treatment platform could meet the clinical objective.Dose distribution of the target volume had no significant difference with the Trilogy plans (P＞0.05).Volumes receiving 10 Gy,20 Gy and D of the left lung were significantly reduced(Z=-2.22--1.78,P＜0.05).V5 of heart for Halcyon and Trilogy was(27.80±7.66)％ and (23.18±8.19)％,respectively(Z=-0.71,P＜0.05),while D was (7.03± 1.8)Gy and(7.11±2.40)Gy,respectively(P＞0.05).Halcyon increased the monitor unit from 1 526.2±227.7 by Trilogy to 1 770.5±383.9(Z=-0.71,P＜0.05),but decreased the delivery time from (12.38± 1.49) min by Trilogy to (3.01 ±0.28) min (Z =-3.42,P＜ 0.05).Conclusion Halcyon treatment platform can meet the clinical requirements,reduce dose to normal tissue with high delivery efficiency.

Radiotherapy is one of the important cancer therapy methods that can lead to tissue damage including radiation lung injury,radiation esophageal injury,radiation skin damage and abnormal changes in hemopoietic system and immune system.Epigallocatechin-3-gallate (EGCG) is the most abundant catechin in green tea.It has been demonstrated that EGCG has biological effects of antiinflammatory,antioxidant,anti-apoptosis and regulating immunity.Recently some studies of cell and animal models suggest that EGCG has radioprotective effect,but few clinical research was reported.In this review,the studies about EGCG in preventing and treating radiation injury were summarized from antiradiation mechanism in order to enhance the understanding of the potential clinical application of EGCG.