ObjectiveTo study of the impact on dose distribution by electron width of energy spectrum and angular distribution using Monte Carlo simulation.MethodsThe simulated electron energy spectrum and angular distributions was as the input parameters and percentage depth dose (PDD) and offaxis curves were simulated by a modified PENELOPE code package. Results PDD and off-axis dose distribution curves are almost the same and are not sensitive to energy spectrum width and angular distribution with the exception of energy spectrum width of 2.5 MeV with obviously different curves.ConclusionsIn the situation of clinical treatment,spectrum and angular distributions can be ignored when their width are not very large.It is helpful to save about 9％ time by using monoenergy beams in treatment planning system development.

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.

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.

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.

ObjectiveTo analyze the role of postmastectomy radiotherapy in different molecular subtypes of breast cancer patients with Stage T1 -T2 and one to three positive axillary nodes. MethodsA total of 436 breast cancer patients with T1 -T2 and one to three positive axillary lymph nodes treated with mastectomy and axillary dissection were retrospectively analyzed. Patients were grouped as the following four subtypes:Luminal A, Luminal B, Her2+ and triple-negative. The local recurrence (LR), distant metastasis ( DM ), disease free survival (DFS) and overall survival (OS) rates were compared between paitents with or without radiotherapy in univariate analyses. Multivariate analyses for LR were performed. Results The follow-up rate was 86. 0％. In patients with Luminal A subtype, radiotherapy decreased the 5-year LR rate (4.6％ vs 15.8％ ,x2 =5.74,P=0.017) but had no influences on DM, DFS or OS rates (17.2％ vs 19.7％,x2 =0. 17,P=0.682;77.0％ vs 67. 1％ ,x2 =1.99,P=0. 158 or87.4％:85. 5％ ,x2 =0. 12,P=0. 733 ). In patients with Luminal B subtype, radiotherapy decreased the 5-year LR rate (3.7％ vs 12. 1％,x2 =4. 13, P =0. 042), increased DFS and OS ( 84. 0％ vs 57.6％ ( x2 =14.61, P =0. 000) and 91.4％ vs 70. 7％ ( x2 =11.87, P =0. 001 ), but had no influence on DM ( 12. 3％ vs 22. 2％, x2 =2. 97, P =0. 085).In patients with Her2+ subtype, radiotherapy decreased the 5-year LR rate (5. 6％ vs 31.0％ ,x2 =4. 31,P=0. 035) , increased DFS (61. 1％ vs 13. 8％ ,x2 =11.44,P=0.001 ) ,but had no influence on DM and OS (27.8％ vs 41.4％, x2 =0. 89, P =0. 345 and 66. 7％ vs 48. 3％, x2 =1.52,P =0. 218 ). In patients with triple-negative subtype, radiotherapy had no influence in LR, DM, DFS or OS (8. 7％ vs 26. 1％ ,x2 =2.42,P=0.120;39.1％ vs47.8％,x2=0.35,P=0.552;52.2％ vs 26.1％ , x2 =3. 29, P =0. 070 or 65.2％ vs 56. 5％ ,x2 =0. 37 ,P =0. 546). Tumor size and radiotherapy were independent prognostic factors for LR rate in multivariate analyses ( x2 =4. 76, P =0. 029 and x2 =8.06, P =0. 005 ). ConclusionsFor patients with stage T1 -T2 and one to three positive axillary nodes, patients with all molecular subtypes except triple-negative can benefit from postmasteetomy radiotherapy.

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.

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.

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.

Objective To calculate the effects of thermoplastic mask on X-ray surface dose.Methods The BEAMnrc Monte Carlo Code system, designed especially for computer simulation of radioactive sources, was performed to evaluate the effects of thermoplastic mask on X-ray surface dose.Thermoplastic mask came from our center with a material density of 1.12 g/cm2. The masks without holes,with holes size of 0. 1 cm× 0. 1 cm, and with holes size of 0. 1 cm × 0. 2 cm, and masks with different depth (0.12 cm and 0.24 cm) were evaluated separately. For those with holes, the material width between adjacent holes was 0. 1 cm. Virtual masks with a material density of 1.38 g/cm3 without holes with two different depths were also evaluated. Results Thermoplastic mask affected X-rays surface dose. When using a thermoplastic mask with the depth of 0. 24 cm without holes, the surface dose was 74. 9% and 57.0% for those with the density of 1.38 g/cm3 and 1.12 g/cm3 respectively. When focusing on the masks with the density of 1.12 g/cm3, the surface dose was 41.2% for those with 0.12 cm depth without holes;57.0% for those with 0. 24 cm depth without holes;44. 5% for those with 0. 24 cm depth with holes size of 0.1 cm ×0.2 cm;and 54.1% for those with 0.24 cm depths with holes size of 0.1 cm ×0.1 cm.Conclusions Using thermoplastic mask during the radiation increases patient surface dose. The severity is relative to the hole size and the depth of thermoplastic mask. The surface dose change should be considered in radiation planning to avoid severe skin reaction.

OBJECTIVE To study the radiose-nsitization by Topotecan on human nasopharyngeal carcinoma in nude mice. METHODS ①To study the maximum tolerance dose of TPT and detect the effective rate of TPT and RT on nude mice. ② Plan of radiosensitization practice:53 nude mice xenografts were distributed to 5 groups:RT 20 Gy group,RT 40 Gy group,TPT 12.5 mg/kg group,TPT 12.5 mg/kg+RT 20 Gy group and the controlgroup. After treatment,the volume of tumors were measured every 3 days in order to value the effective rate [complete remission(CR) + partial remission(PR) ]and regrowth delay time(TGD) and to fit the growth curve. RESULTS This study showed that the effective rates had significant difference among RT20 Gy+TPT 12.5 mg/kg group,RT20 Gy group and TPT12.5 mg/kg group,while that of RT20 Gy +TPT 12.5 mg/kg group and RT40 Gy group had no statistical difference. SER reached to 1.34. CONCLUSION Topotecan has been shown a radiosensitizing effect on human nasopharyngeal carcinoma in vivo.