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Objective:To systematically compare the efficacy and safety of chrono-chemotherapy combined with radiotherapy in patients with locally advanced nasopharyngeal carcinoma.Methods:Seven databases were searched, including the Cochrane Library (Issue 5, 2021), PubMed, Embase, CBM, CNKI, VIP and Wanfang Database. The method ological quality of the eligible studies was evaluated. The Meta-analysis was performed by the Revman 5.3 software.Results:Sixteen studies consisting of 1275 patients were finally included. Among them, 642 patients were treated with chrono-chemotherapy combined with radiotherapy and 633 patients received conventional chemotherapy combined with radiotherapy. Results showed that compared with conventional chemotherapy group, the effective rate was significantly elevated ( OR=1.66, 95% CI: 1.17-2.34, P=0.004), the incidence of leucopenia, thrombocytopenia, gastrointestinal reaction, grade 3-4 oral mucosal reaction and grade 3-4 radiothermitis was significantly reduced (all P<0.001), and the quantity of CD3, CD4 and CD4/CD8 was significantly increased in the chrono-chemotherapy group. Conclusion:Current evidence shows that compared with conventional chemotherapy, chrono-chemotherapy combined with radiotherapy could improve the effective rate, reduce adverse reactions and mitigate the destruction of immune function simultaneously.
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Nasopharyngeal carcinoma (NPC) is a common head and neck malignant tumor with high incidence in southern China. Local recurrence is one of the main failure modes of locally advanced NPC. The dose-escalation after radical radiotherapy for locally advanced NPC remains controversial. In the era of modern radiotherapy, the mainstream treatment mode of locally advanced NPC is neoadjuvant chemotherapy plus concurrent chemoradiotherapy. There is no consensus on whether to prescribe dose-escalation, how and when to conduct dose-escalation, how much dose to prescribe for patients with residual lesion proved by MRI or pathology. How to accurately determine the target volume and dose / fraction to maximize the local control of the tumor are the directions of clinical practice for locally advanced NPC, which remain to be further studied.
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Objective:To evaluate the efficacy of concurrent radiotherapy combined with S-1 (CCRT) versus radiotherapy (RT) alone in elderly patients with esophageal cancer by Meta-analysis.Methods:The Cochrane Library, PubMed, Web of science, EMbase, CBM, CNKI, VIP and Wanfang database were searched. The eligible studies were subject to evaluation of methodological quality. The Meta-analysis was performed by the Revman 5.3 software.Results:A total of 1693 patients were enrolled in 23 studies. The results showed that CCRT increased the incidence of CR [ OR=2.08,95% CI (1.66-2.61), P<0.001] and PR [ OR=1.31,95% CI (1.08-1.60), P=0.007] and total response rate [ OR=2.99,95% CI (2.37-3.77), P<0.001]. Furthermore, CCRT improved the 1-year survival rate [ OR=2.56, 95% CI (1.94-3.38), P<0.001] and 2-year survival rate [ OR=2.33, 95% CI (1.77-3.08), P<0.001]. Meanwhile, CCRT reduced the incidence of leucopenia, thrombocytopenia, radioactive esophagitis, nausea and vomiting (all P<0.05), but there was no significant difference in the incidence of anemia and radiation pneumonia between two groups (both P>0.05). Conclusions:Available evidence suggests that CCRT combined with S-1 can improve therapeutic efficacy and prolong survival time in elderly patients with esophageal cancer, but CCRT may increase the incidence of treatment-related side effects. Due to the limitations of the number and quality of the included studies, the above conclusions need to be verified by more high-quality studies.
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Objective:To retrospectively analyze the long-term survival (10-15 years) and late toxicity of nasopharyngeal carcinoma (NPC) patients after intensity-modulated radiotherapy (IMRT), aiming to provide reference for the optimal treatment of NPC.Methods:132 patients with NPC who were treated with IMRT in Sichuan Cancer Hospital from 2003 to 2009 were recruited. Among them, 3 patients were classified as stage Ⅰ, 22 cases of grade Ⅱ, 61 cases of grade Ⅲ, 43 cases of Ⅳ A and 3 cases of Ⅳ B, respectively. The median dose was 73.37Gy (66 to 85Gy), divided into 33 times. Twenty patients received radiotherapy alone, 112 cases of concurrent radiochemotherapy. The survival rate was calculated by Kaplan-Meier method and log- rank test. Univariate prognostic analysis was performed. Cox model was used to conduct multivariate prognostic analysis. The late radiation toxicity was evaluated by RTOG/EORTC criteria. Results:The median follow-up duration was 128 months (range, 3 to 191 months). The 10-and 15-year local control rates of NPC patients were 86.0% and 79.9%. The disease-free survival rates were 72.5% and 63.2%, and the overall survival (OS) rates were 65.2% and 57.1%. The local recurrence rate was 12.1%, and the distant metastasis rate was 16.7%. A total of 53 patients died, of whom 15 patients died of local recurrence, 20 patients died of distant metastasis and 18 patients died of other diseases (pneumonia, intracranial hemorrhage and accident, etc.). The 10-and 15-year non-tumor-related mortality rates were 11.3% and 13.6%. Univariate analysis showed that age, smoking habit, lactate dehydrogenase (LDH), T stage and clinical stage were the independent prognostic factors of OS in NPC patients. Multivariate analysis demonstrated that LDH, T stage and synchronous chemotherapy were the prognostic factors of OS in NPC patients. The incidence of gradeⅠ-Ⅱ late radiation injury (hearing impairment, dysphagia, dental caries and xerostomia) was 90.4%, and 8.5% for grade Ⅲ-Ⅳ late radiation injury (skin fibrosis, hearing impairment and radiation brain injury).Conclusions:The 10-and 15-year OS of NPC patients treated with IMRT is relatively high. With the prolongation of survival, the non-tumor-related mortality rate is increased. Distant metastasis is the main cause of treatment failure. The main late injuries include grade Ⅰ/Ⅱ hearing impairment, dysphagia, dental caries and xerostomia.
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Objective To explore the correlation between EBV DNA load and peripheral immune cells (including lymphocyte supsets and natural killer cells) before treatment in patients with NPC, and analyze the influence of circulating immune cell supsets related to EBV on the prognosis of NPC patients. Methods We retrospectively analyzed the general data of 203 NPC patients without distant metastasis at the first treatment, as well as the data of peripheral blood EBV DNA and circulating immune cell supset. The ROC curve analysis was used to determine the cutoff value of each circulating immune cell supset. Kaplan-Meier method was used for survival analysis, and Cox regression model was used for multi-factor prognostic correlation analysis. Results The 3-year OS, PFS, DMFS and LRFS of EBV DNA < 400 copies/ml group and EBV DNA≥400 copies/ml group were 99.2% vs. 90.1% (P=0.001), 96.7% vs. 90.1% (P=0.028), 98.4% vs. 90.1% (P=0.005) and 98.4% vs. 100% (P > 0.05), respectively. EBV DNA is negatively correlated with the ratio of CD19+ B cells before treatment (r=-0.138, P=0.040), and there was no significant correlation between EBV DNA and other circulating immune supgroups (P > 0.05). ROC analysis showed that the cut-off value of CD19+B cell ratio before treatment related to the 3-year OS was 8.33% (P=0.02). The 3-year OS, PFS, DMFS and LRFS of patients with CD19+B cells ratio ≤8.33% and CD19+B cells ratio > 8.33% were respectively 90.4% vs. 99.2% (P=0.003), 89.2% vs. 97.5% (P=0.008), 90.4% vs. 98.3% (P=0.008) and 98.8% vs. 99.2% (P > 0.05). However, ROC analysis showed that there was no significant correlation between OS and other peripheral immune cells (including the proportion of CD3+T, CD3+CD4+T, CD3+CD8+T and CD56+NK cells and CD4+/CD8+ ratio). Multivariate analysis showed that EBV DNA load was an independent prognostic factor of 3-year PFS of NPC patients, and the ratio of CD19+B cells was an independent prognostic factor of 3-year PFS, MFS and OS of NPC patients. Conclusion Before treatment, there is a negative correlation between plasma EBV DNA and the proportion of CD19+B cells in peripheral blood. Both can be used as the predictors of 3-year OS, PFS and DMFS of NPC patients.
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The purpose of tumor staging is to guide treatment, and the treatment for a certain stage should be adjusted based on the changes in disease condition, in order to facilitate better control of tumor. Therefore, the treatment of liver cancer requires follow-up and re-staging to develop better treatment regimens for patients, especially the opportunity for cure. Surgical resection is not suitable for large hepatocellular carcinoma confined to the liver, and after embolization chemotherapy combined with radiotherapy for tumor regression and downstaging, some patients may undergo surgical resection, and the incurable tumor can thus be cured. For liver cancer patients with portal vein tumor thrombus, surgical resection can be performed after tumor thrombus is reduced by neoadjuvant radiotherapy, and the patients undergoing neoadjuvant radiotherapy have a significant increase in survival time than those not undergoing neoadjuvant radiotherapy. Large hepatocellular carcinoma can be downstaged to small hepatocellular carcinoma after multimodality therapy, and then stereotactic radiotherapy or radiofrequency ablation can help to achieve radical treatment. There is an increasing number of clinical reports of radiotherapy for liver cancer downstaging, with a gradual increase in evidence-based level, and thus it holds promise for clinical application.
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Objective@#To investigate the radiotherapy (RT)-induced changes in the brain structural network in patients with nasopharyngeal carcinoma (NPC).@*Methods@#Three-dimensional structural magnetic resonance data (3D-T1W) was adopted to investigate the structural network in 103 patients with NPC before and after receiving RT. The structural networks were then reconstructed using 3D-T1W. The radiation-induced changes in topology properties of small world network were analyzed by using graph theoretical analysis.@*Results@#Patients showed small world properties before and after RT. Compared with the pre-RT group, the global and local efficiency were lower, the shortest path length was longer and the clustering coefficient was less in the post-RT group. In addition, the hub regions in the post-RT group were significantly different from those in the pre-RT group, mainly located in the left rolandic operculum, right inferior frontal gyrus, right parahippocampal gyrus, right lingual gyrus, bilateral supramarginal gyrus, left superior temporal gyrus and temporal pole of the right middle temporal gyrus.@*Conclusion@#It is speculated that RT leads to high efficiency of network topology and information transmission, which provides a novel perspective for exploring the RT-induced brain changes, diagnosis of RT-induced injury and evaluation of RT efficacy.
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Objective To investigate the clinical outcomes of patients with locally advanced uterine cervical cancer (UCC) treated by 3-dimensional high dose rate-intracavitary brachytherapy (3D HDR-ICBT) combined with complementary applicator-guided external beam radiotherapy (EBRT).Methods A total of 120 patients pathologically diagnosed with locally advanced UCC (tumors with a maximum diameter≥6 cm or ≥5 cm complicated with eccentric tumor growth) treated with concurrent chemoradiotherapy (CCRT) from June 2010 to June 2015 were recruited.Five fractions of 3D HDR-ICBT combined with complementary applicator-guided external beam radiotherapy were performed.The prescribed dose for HR-CTV and IR-CTV was 7 Gy (D9o) and 5-6 Gy (D90).The rectum,sigmoid colon,bladder and adjacent small intestine were delineated as the organs at risk.Intensity-modulated radiation therapy (IMRT) was used for EBRT (45 Gy/ 25f) combined with cisplatin-based chemotherapy every three weeks (75 mg/m2).Results The median follow-up time was 46 months (14-96 months).The 5-year local control rate (LCR),disease-free survival (DFS),and overall survival (OS) were 92.8％,76.6％ and 81.0％,respectively.The incidence rate of grade Ⅰ-Ⅱ genitourinary and gastrointestinal acute toxicities were 57.8％ and 14.6％,whereas 8.1％ and 2.9％ for grade Ⅲ toxicities.The incidence rate of later grade Ⅰ-Ⅱ genitourinary and gastrointestinal toxicities were 8.4％ and 5.3％,and 0.97％ and 1.3％ for grade Ⅲ late toxicities.Conclusions The combination of HDR-ICBT with an applicator-guided IMRT (ICBT+IMRT) yields low incidence of severe adverse events,relatively high LC and OS rate for locally advanced UCC.It is an efficacious comprehensive treatment of locally advanced bulky UCC.
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Artificial Intelligence are emerging as poweful tools for many field including medicine.It has be applied to radiation therapy in different degree,such as automatic OAR or tumor volume segmentation,automatic radiotherapy planning,prediction of toxicity and prognostic,etc.In this article,the research progress on Artificial Intelligence in the radiotherapy for malignant tumor was reviewed.
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New developments in radiomics and bio-omics, blockchain, digital twins, cloud-to-edge computing, big data, and artificial intelligence are revolutionizing cancer radiotherapy, with breakthroughs in treatment accuracy and efficacy. Smart omics-guided radio-therapy will eventually resolve the problem of radiotherapy. In the radiotherapy decision-making, the whole genetic information and biological characteristics of tumors and individuals can be obtained through the methods of omics technology. For the determination of radiotherapy targets, through the image technique it provides the full genetics and microenvironmental information of the cancer lesion. For treatment response evaluation and follow-up, it can timely optimize the radiotherapy plan and monitor the tumor by real-time dynamic observation of changes in various histological information throughout the treatment process. The advantages of the treatment model are reflected in accurate decision-making, avoiding "blind people's touch" and partial errors. Holographic target iden-tification avoids the uncertainty caused by manual delineation of targets, and full and dynamic histological evaluation can promote the early detection of tumor recurrence.
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Objective To investigate the clinical efficacy and safety of preoperative hypofractionated and conventionally-fractionated chemoradiotherapy for thoracic esophageal cancer. Methods A total of 86 patients with thoracic esophageal cancer receiving chemoradiotherpy in Sichuan Cancer Hospital between 2002 and 2011 were enrolled and randomized into the preoperative hypofractionated chemoradiotherapy group ( group A, n=41, 30 Gy in 10 fractions for 2 weeks ) and conventionally-fractionated chemoradiotherapy group ( group B, n=45, 40 Gy in 20 fractions for 4 weeks ) . Surgery was performed at 2-6 weeks after chemoradiotherapy. The probability of patients' survival was estimated by Kaplan-Meier method and analyzed by log-rank test. Results In groups A and B, the pathological downstaging rates were 68％ and 56％( P=0. 270) , the R0 resection rates were 95％ and 89％( P=0. 437) and the pCR rates of 32％ and 24％( P=0. 480).The 1-,3-and 5-year overall survival (OS) rates were 78％ and 69％,44％ and 44％,29％ and 33％(P=0. 114,0. 223,0. 289), and the progression-free survival (PFS) rates were 71％ and 62％,39％ and 38％,24％ and 29％(P=0. 211,0. 689,0. 331), respectively. The incidence rate of chemoradiothery-and surgery-related adverse events did not differ between two groups (P=0. 089-0. 872).The average length of hospital stay, radiotherapy cost and preoperative treatment costs in group A were significantly less compared with those in group B (P=0. 000,0. 000,0. 000). Conclusions Both preoperative hypofractionated and conventionally-fractionated chemoradiotherapy can be used as the regimen of preoperative chemoradiotherapy in patients with resectable thoracic esophageal carcinoma. Compared with conventionally-fractionated chemoradiotherapy, preoperative hypofractionated chemoradiotherapy has shorter treatment cycle, shorter length of hospital stay and lower radiotherapy cost, which is more easily accepted by patients.
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In recent years,exosomes has gradually captivated widespread attention.It plays a crucial role in the proliferation,differentiation and metastasis of malignant tumors.As nanosized vesicles,exosomes can penetrate through the blood-brain barrier.Thus,exosomes may be a novel tool for the diagnosis and treatment of malignant glioma.In this paper,57 relevant literatures were reviewed to summarize the research status and progress on the role of exosomes in the incidence,progression,liquid biopsy,prognosis evaluation and clinical therapy of malignant glioma.
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Objective This study was conducted to evaluate treatment-related toxicities,the patterns of failure,overall survival(OS)and progression-free survival(PFS)by comparing IFI with ENI in combination with chemotherapy. Methods Eligible patients were treated with concurrent chemoradiotherapy and randomized into either an IFI or ENI arm. The primary end points wereacute treatment-related toxicities. The secondary end points were patterns of failure,OS and PFS. Kaplan?Meier survival rate of the method for calculating the Logrank test difference method. Results Between April 2012 and October 2016,a total of 228 patients were enrolled from nine centers in china. Grade≥3,Grade≥2 radiation esophagitis and pneumonitis in the IFI arm were significantly lower than that of the ENI arm(P=0.018,0.027).No significant differences were observed in overall failure rates,loco-regional failure,distant failure rates,in-field and out-field lymph node failure between the two arms(P=0.401,0.561,0.510,0.561,0.681).The 1-,2-, 3-,4-yearand median OS in the ENI arm and IFI arm were 84.1%,57.3%,39.4%,31.6%,28 months and 83.6%,62.1%,44.5%,31.5%,32 months(P=0.654),respectively. The 1-,2-,3-yearand median PFS in the ENI arm and IFI arm were 71.9%,42.3%,32.7%,20 months and 70.1%,45.0%,35.9%,22 months (P=0.885),respectively. Conclusions Compared to ENI,IFI resulted in decreased radiation pneumonitis and esophagitis without sacrificing loco-regional lymph nodal control,PFS and OS in thoracic ESCC. Clinical Trial Registry Chinese Clinical trail registry,registration number:NCT01551589.
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The application of precision medicine in cancer treatment is becoming increasingly common as a result of the continuous advancement in basic research and physical techniques.The revolution of radiotherapy techniques, development of multimodal imaging technology, application of biological target dose carving and adaptive radiotherapy, availability of big data-based radiotherapy planning systems, and selection of chemotherapy regimen have all made the treatment of nasopharyngeal carcinoma increasingly precise.The growing interaction between laboratory research and clinical practice not only underscores the importance of translational medicine, but also prompts the development of biological immunotherapy and screening of prognostic factors.As a result, these changes mark the beginning of a new era for the diagnosis and treatment of nasopharyngeal carcinoma.This review provides a summary from 61 articles on the current progress in translational study and clinical application of precision medicine in nasopharyngeal carcinoma.
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Objective To conduct the 7th investigation by Chinese Society of Radiation Oncology,Chinese Medical Association,and to further investigate the current situation of radiotherapy in mainland China,reasonably allocate personnel and equipment resources,and promote the development of radiotherapy in China.Methods From October 8,2015 to December 2015,the office for investigation of radiotherapy information was established,the list and contact information of radiotherapy units were provided by each province,and a special data submission system was used for a complete,rapid,and efficient investigation through the Internet.Results As of January 20,2016,there were 1 413 radiotherapy units in the mainland China with 52,496 employees in total,among which there were 15 839 radiotherapy physicians (4824 with senior professional titles),8 452 technical therapists (260 with senior professional titles),3 292 physicists (562 with senior professional titles),and 938 maintenance engineers (120 with senior professional titles).In the aspect of radiotherapy equipment,there were 1930 linear accelerators,96 Co-60 teletherapy units,173 X-knife units,212 γ-knife units,382 Ir-192 brachytherapy units,436 Co-60 brachytherapy units,1 051 X-ray simulators,1 353 CT simulators,642 MRI simulators,978 sets of multileaf collimators,1922 sets of treatment planning systems,and 974 sets of radiotherapy network systems.As for quality control devices,there were 1 792 dosimeters,2 143 ionization chambers,935 two-dimensional array dosimeters,540 threedimensional dosimetric verification systems,596 three-dimensional water tanks,844 anthropomorphic phantoms,and 1 168 water equivalent phantoms.In the aspect of therapeutic situation,there were 102,170 beds (including beds in departments of oncology in general hospitals),76612 episodes per day,and 919339 episodes per year.Conclusions The results of this investigation show significant increases in radiotherapy units,personnel,and equipment in recent years in mainland China.The distribution of radiotherapy units and equipment and the structure of radiotherapy personnel are becoming more reasonable,but there are still some problems.In some regions,current radiotherapy equipment cannot meet the medical needs,and there is a lack of professional technical personnel.
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Objective To investigate the dose and mechanical properties of medical electron linear accelerators in grass-roots radiotherapy units in Sichuan Province,China via sampling and inspection.Methods A total of eight radiotherapy units in Sichuan Province were selected by sampling,and the tests were performed for the dose and mechanical properties of the medical electron linear accelerators in use.Among these accelerators,there were 5 imported accelerators and 3 domestic accelerators.The test items and methods were determined according to the requirements in GB15213-94.Results Among the 14 test items,the items related to the flatness,symmetry,and overlap of radiation field.The other tests of dose accuracy and mechanical precision achieved good results.Conclusions There is a need to strengthen the daily quality control work for dose and mechanical accuracy of medical electron linear accelerators in grass-roots radiotherapy units in Sichuan Province and perfect the allocation of professional equipment and personnel and training of related personnel.With the support of Sichuan Radiotherapy Quality Control Center,quality control supervision and guidance should cover the whole province.
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Objective To investigate the possibility of chloroquine radiosensitization of esophageal cancer cell line TE-1 and its further mechanism.Methods Effect of chloroquine on cell viability of TE-1 cells was determined by MTT method.Expression of LC3,Beclin-1 and formation of acidic vesicular organelles (AVOs) were determined by Western blot,and fluorescence staining with Lyso-Tracker Red DND-99,respectively.Clonogenic survival of TE-1 cells was examined by clonogenic forming assay.Results Chloroquine showed dose-dependent inhibition of TE-1 cell growth,and its values of IC50 and IC10 were (72.33 ± 5.28) and (15.42 ± 3.33) μmol/L,respectively.The expression of Beclin-1 and LC3-Ⅱ/Ⅰ markedly increased in irradiated TE-1 cells.The addition of chloroquine with IC10concentration significantly reduced the fluorescence and intensity of AVOs accumulation in the cytoplasm of TE-1 cells.Clonogenic survival fraction decreased obviously,in TE-1 cells with addition of chloroquine after radiation and the value of SERD0 was 1.439.Conclusions Chloroquine could radiosensitize esophageal cancer cells by blocking autophagy-lysosomal pathway and be used as a potential radiosensitizing strategy.
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ObjectiveTo study the using of cerrobase as the compensation material in the intensitymodulated radiation therapy (IMRT) implementation and impact factors.MethodsWith therapy planning system (TPS) exported the radiation field intensity file (Dicom RT),through measuring the attenuation coefficient of cerrobase,to calculate the processing depth of AUTIMO 3D CNC corresponding for Dicom RT files at each pixel,then using the processed foam casting of Cerrobase,produced the required IMRT compensator.Through the MATRIXX testing the IMRT compensator in clinical implementation.At the same time we compared the MU of using multi-leaf collimator (MLC) and Cerrobase IMRT compensator for 10patients.ResultsWith cerrobase compensation IMRT can get similar dose or dose distribution to dose produced by TPS for point or plane dose,error is within 5％.To comparison with MLC,using cerrobase compensator has fewer treatment times ( (4.44±0.39) min:(5.71±0.57) min (t =10.82,P =0.000) )and fewer MU (462.5 ± 65.8) MU:(524.5±99.6) MU(t=3.14,P=0.012) ).Conclusions Comparison with MLC IMRT,the cerrobase compensation technique has an important application value with its unique advantages.This research provides an implemented method of IMRT radiotherapy for the primaryhospital.
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Objective To evaluate the safety of cetuximab combined with intensity-modulated radiotherapy (IMRT) plus concurrent cisplatin chemotherapy in locoregionally advanced nasopharyngeal carcinoma (NPC) in a Chinese multicenter clinical study.MethodsFrom July 2008 to April 2009,100Patients with primary stage Ⅲ- Ⅳb non-keratinizing NPC were enrolled.The planned dose of IMRT to gross tumor volume and positive cervical lymph nodes was 66.0-75.9 Gy and 60-70 Gy in 30-33 fractions.Cisplatin (80 mg/m2,q3 week (w)) and cetuximab (400 mg/m2 one w before radiation,and then 250mg/m2 per w) were given concurrently.The adverse events (AEs) were graded according to common terminology criteria for adverse events v3.0.ResultsThe compliance of the entire group of patient was satisfactory.Actual median dose to gross tumor volume was 69.96 Gy,and the median dose to positive cervical lymph nodes was 68 Gy.Median dose of cisplatin was 133 mg,median first-dose of cetuximab was 690 mg,and median weekly dose was 410 mg.AEs were well tolerated and manageable,mainly consisting of acneiform skin eruptions,dermatitis and mucositis.Grade 4 mucositis was observed in 2％ of the patients and no other grade 4 AEs were observed.ConclusionsThe combined treatment modality of IMRT +concurrent chemotherapy + cetuximab in loco-regionally advanced NPC is well tolerated.
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ObjectiveTo compare the calculation precision of the collapsed cone convolution (CCC) algorithm and pencil beam convolution (PBC) algorithm in TPS in heterogeneous tissue.Methods We made two virtual lung phantoms,one is single field phantom,In this case the photon beam incident into the phantom,the other is the two fields phantom and a cubic'tumor' was placed in the centre of the phantom.two opposite photon beams incident into the phantom.We calculated the dose of the'tumor' and the lung with the CCC and PBC algorithm.We compared the results in both case with if obtained from Monte Carlo (MC) method.ResultsIn the single field phantom,the photon beam incident from the high-density tissue to the low-density lung equivalent tissue,compared with the result of MC algorithm PBC algorithm overestimated the lung equivalent tissue dose (t =3.90,P =0.012) and the result of CCC algorithm is close to it ( t =2.25,P =0.087 ).In the two fields phantom,tumor boundary dose calculated by CCC algorithm and the MC algorithm are lower than that of the PBC algorithm (t =2.43,3.18,P =0.038,0.011 ),and the difference increase when the field size decrease, the beam energy increase and the density of the inhomogeneity decrease.ConclusionsWe had better use the CCC algorithm when calculating the dose of the tumor surrounded by low-density tissue or the tumor behind the low-density tissue,such as the lung cancer,esophageal cancer etc.