Objective To investigate the relationship of radiation dose with the volume and late toxicity of the sternocleidomastoid muscle (SM) in patients with nasopharyngeal carcinoma. Methods SM was divided into upper part and lower part based on the lower edge of cricoid cartilage. Patients were divided into three groups according to the prescribed dose for clinical target volume at the lower neck (CTV₂)(0,54,60 Gy). The dosimetric parameters included D_mean, V₆₆, and V₆₀ for the upper, lower, and whole SM. SM was delineated and the volume was calculated on computed tomography images in the treatment planning system before and at 6, 12, and 18 months after treatment. The anteroposterior and transversal diameters of SM at C₃-C₄, C₄-C₅, C₅-C₆, and C₆-C₇ levels were measured and recorded. Late toxicity of neck skin and SM was evaluated according to the Common Terminology Criteria for Adverse Events V₄.0 criteria. Between-group comparison was made by t-test or Kruskal-Wallis non-parametric test. Between-group comparison of the sample rate was made by one-way analysis of variance. The correlation analysis was made by Spearman correlation. Results There were significant difference in SM volume between the three time points after treatment (P=0.000). At 12 or 18 months after treatment, the volume of SM wasignificantly reduced (P=0.000,0.000);the reduction in SM volume was significantly correlated with V₆₆ of the SM and the upper SM (P=0.015,0.020). At 18 months after treatment, SM fibrosis was significantly correlated with V₆₀ of the upper SM (P=0.030);the fibrosis of neck skin was significantly correlated with the D_mean and V₆₀ of the upper SM (P=0.029,0.005). Conclusions In order to prevent the incidence of the fibrosis of neck skin and SM, the dose homogeneity should be as high as possible, while the number of hot spots should be as small as possible.

Objective To investigate the effects of hippocampal-sparing intensity-modulated radiotherapy (IMRT) on dose distribution of target volume and organs at risk (OARs) in locally advanced nasopharyngeal carcinoma. Methods A retrospective dosimetric analysis was performed among 11 patients with locally advanced nasopharyngeal carcinoma. The MONACOv5.10 Treatment Planning System was used to design three treatment plans:routine volumetric modulated arc therapy (VMAT),hippocampal-sparing VMAT,and nine fixed-fields IMRT.The D_98%,D_50%,D_2%,D_mean,conformity index (CI),and homogeneity index (HI) of planning target volume (PTV) and PTV_nx as well as dose distribution of the hippocampus and OARs were evaluated. Using single factor analysis of variance,two group comparative was LSD or paired t-test. Results For the above three plans,the D_2% values of PTV_nx were ,7513,and 7462 cGy,respectively (P=0.016);the D_98% values of PTV were 5837,5812,and 5914 cGy,respectively (P=0.029);the average D_2% values of PTV were 7399,7380,and 7333 cGy,respectively (P=0.047);the HI values of PTV were 0.239,0.241,and 0.220,respectively (P=0.016);the V₁₀ values of the brain stem were 97.2%,88.1%,and 90.3%,respectively (P=0.001);the V₂₀ values of the brain stem were 74.2%,62.3%,and 67.1%,respectively (P=0.032);the V₃₀ values of the brain stem were 50.9%,35.8%,and 45.5%,respectively (P=0.020);the V₄₀ values of brain stem were 24.4%,14.4%,and 23.3%,respectively (P=0.018);the D_mean values of hippocampus were 1518,899,and 896 cGy,respectively (P=0.000);the D_40% values of hippocampus were 1379,642,and 639 cGy,respectively (P=0.000);the V₁₀ values of the hippocampus were 54.1%,25.1%,and 3.8%,respectively (P=0.000);the V₂₀ values of the hippocampus were 26.2%,12.6%,and 12.0%,respectively (P=0.001). Conclusions Hippocampal-sparing VMAT and nine fixed-fields IMRT can significantly reduce the dose to the hippocampus without affecting dose distribution of target volume and OARs. VMAT may be superior to IMRT because VMAT can simultaneously reduce the dose to the brain stem.

Objective To retrospectively analyze the treatment outcomes and failure patterns in patients with head-and-neck cancer of unknown primary head-and-neck cancer of unknown primary, and to compare the efficacy between elective mucosal irradiation and ipsilateral neck treatment. Methods The clinical data of patients with head-and-neck cancer of unknown primary who were admitted from January 2007 to December 2013 were retrospectively collected. Thirty-one patients received elective pharyngeal mucosal irradiation and 61 patients only received ipsilateral neck treatment. The SPSS 19.0 software was used for comparison of the survival and local control between the two groups. Results In the 92 patients, the median age was 57 years;79.3% had metastasis to level Ⅱ lymph nodes;the median follow-up time was 36.5 months;the 3-year overall survival, mucosal control, and neck control rates were 89.0%,86.6%,and 82.4%,respectively. Primary sites were found in 15 patients, containing nasopharynx in 4 patients, oropharynx in 3 patients, oral cavity in 3 patients, throat and hypopharyngeal part in 3 patients, maxillary sinus in 1 patient, and esophagus in 1 patient. The patients undergoing elective pharyngeal mucosal irradiation had significantly higher 3-year mucosal control and neck control rates than those undergoing ipsilateral neck treatment (100% vs. 74.9%,P=0.040;87.5% vs. 62.2%,P=0.037).There was no difference in the 3-year overall survival rate between the two groups (83.5% vs. 88.7%,P=0.910). Conclusions For patients with head-and-neck cancer of unknown primary,elective pharyngeal mucosal irradiation can reduce the incidence of primary site and increase the neck control rate. A new standard for target volume delineation should be established as soon as possible for elective prophylactic pharyngeal mucosal irradiation.

Objective To investigate the effects of different metastatic sites on the prognosis of extensive-stage small cell lung cancer (SCLC). Methods A retrospective analysis was performed among 322 patients pathologically or cytologically diagnosed with extensive-stage SCLC (stage ⅠV defined by the seventh edition of the American Joint Committee on Cancer) who were admitted to our hospital from 2011 to 2015. In those patients, 246 had primary lesions with distant metastasis and 76 primary lesions with non-regional lymph node metastasis;261 had single-organ metastasis and 61 multi-organ metastases. Survival rates were calculated using the Kaplan-Meier method. Between-group comparison of the survival was made by the log-rank test. A multivariate prognostic analysis was made by the Cox proportional hazard model. Results In all the patients, the median survival time (MST) was 11.7 months;1-and 2-year overall survival (OS) rates were 47.9% and 19.5%, respectively. The patients with single-organ metastasis had significantly longer MST and significantly higher 1-and 2-year OS rates than the patients with multi-organ metastases (12.4 vs. 8.9 months;52.5% vs. 30.5%;21.9% vs. 11.2%;P=0.014). In the patients with single-organ metastasis, those with liver metastasis had the worst prognosis with a MST of 8.5 months, while those with non-regional lymph node metastasis had the best prognosis with a MST of 14.5 months (P=0.001);there was no significant difference in the prognosis between patients with metastasis to different organs other than the liver (P=0.139). In the patients with multi-organ metastases, those with liver metastasis and bone metastasis had the worst prognosis (P=0.016,0.006);there was no significant relationship between brain metastasis and the prognosis of extensive-stage SCLC with multi-organ metastases (P=0.995). There was no significant difference in the prognosis between those with liver metastasis only and multi-organ metastases (P=0.862). Conclusions Liver metastasis predicts the worst prognosis in patients initially diagnosed with extensive-stage SCLC and single-organ metastasis. Liver metastasis and bone metastasis predict the worst prognosis in patients with multi-organ metastases. Brain metastasis has no significant effect on the prognosis. There is no significant difference in the prognosis of extensive-stage SCLC between patients with single-and multi-organ metastases once liver metastasis occurs.

Objective To retrospectively analyze the value of postoperative adjuvant therapy in the treatment of stage Ⅲ thoracic esophageal squamous cell carcinoma (ESCC). Methods From 2008 to 2011,a total of 395 patients with stage Ⅲ thoracic ESCC undergoing radical resection were enrolled as subjects. In those patients.97 received surgery alone (S).212 postoperative adjuvant chemotherapy (POCT),and 86 postoperative radiotherapy (PORT).Comparison of categorical data was made by chi-square test. The survival rates were calculated by the Kaplan-Meier method. The log-rank test was used for between-group comparison and univariate analysis. Results All patients were followed up for at least 3 years.125 cases were followed up for at least 5 years. The 5-year overall survival (OS) rates in patients treated with S,POCT and PORT were 17.1%,29.2% and 36.4%,respectively (P=0.000).POCT and PORT could mainly increased OS in patients of males.upper-and middle-segment,severe ahhesion at surgery.well-or middle-differentiation,stage Ⅲ_aand Ⅲ_b(P=0.000-0.049);whenever ages.tumor lesion,two-/three field esophagectomy.and th e number of removal lymph nodes. PORT could improved OS also (P=0.001-0.047).POCT could also improve OS in patients of ages≤60,tumor lesion<6 cm and removal lymph nodes<10(P=0.002-0.049).The 5-year progression-free survival (PFS) were 19.0% with S,28.8% with POCT,36.4% with PORT,respectively (P=0.012).PORT could improve PFS (P=0.012);especially for patients of males,ages ≤60,upper-and middle segment ESCC,tumor lesion ≥6 cm,severe ahhesion at surgery,removal lymph node<10 and ≥10,well or middle differentiation,stage Ⅲ_a and Ⅲ_b(P=0.001-0.042).But POCT could not increased PFS (P=0.119). Conclusions In the treatment of patients with stage Ⅲ thoracic ESCC undergoing radical resection,both POCT and PORT can improve the OS rate,particularly in patients with stage Ⅲ_a or Ⅲ_b middle and upper thoracic ESCC,severe adhesion formation during surgery.and moderately or well differentiated squamous cell carcinoma. The DFS rate is improved in patients treated with PORT,but not in those treated with POCT.

Objective To observe the long-term survival and adverse reactions in patients with stage T₄N (+) Ⅲ middle and lower thoracic esophageal carcinoma undergoing intensity-modulated radiotherapy (IMRT). Methods From 2004 to 2010, 300 patients with stage T₄N (+) Ⅲ middle and lower thoracic esophageal carcinoma, consisting of 202 treated with three-dimensional conformal radiotherapy (3DCRT) and 98 treated with IMRT, were enrolled as subjects. All patients received conventionally fractionated radiotherapy with a prescribed dose of 60 Gy. The long-term survival and adverse reactions were compared between patients treated with the two different radiotherapy regimens. The survival rates were calculated by the Kaplan-Meier method and analyzed by the log-rank test. Results The 5-and 7-year sample sizes were 239 and 120, respectively. The 3DCRT group had significantly lower 1-, 3-, 5-, and 7-year local control (LC) and overall survival (OS) rates than the IMRT group (64.4% vs. 68.3%, 40.6% vs. 55.3%, 38.3% vs. 51.9%, 34.2% vs. 51.9%, P=0.048;54.5% vs. 63.3%, 19.8% vs. 34.7%, 14.7% vs. 24.4%, 10.9% vs. 20.3%, P=0.013). The stratified analysis showed that for patients older than 65 years, with the length of esophageal lesion>8.0 cm before radiotherapy, the largest diameter of esophageal lesion in computed tomography image>4.6 cm, gross tumor volume (GTV)>60 cm³, metastases to adjacent tissues or organs, stage N₂, and without chemotherapy, the IMRT group had a significantly higher OS rate than the 3DCRT group (P=0.022,0.003,0.022,0.034,0.016,0.044,0.047). The GTVD_min and GTVD₁₀₀ were significantly higher in the IMRT group than in the 3DCRT group (P=0.000,0.000), while the D_max of the spinal cord was significantly lower in the IMRT group than in the 3DCRT group (P=0.000). Compared with the 3DCRT group, the IMRT group had a significantly higher incidence of acute radiation-induced esophagitis, particularly grade 1-2 esophagitis (P=0.000). The mortality rate caused by local tumor was significantly higher in the 3DCRT group than in the IMRT group (P=0.039). Conclusions In the treatment of locally advanced middle and lower thoracic esophageal carcinoma, IMRT is safe and effective;it significantly improves the LC rate and long-term survival without severe toxicity to normal tissues. The results of this retrospective study need to be confirmed by prospective randomized controlled studies.

Objective To analyze the prognosis of advanced esophageal carcinoma treated with paclitaxel and different platinum-based chemotherapy regimens plus intensity-modulated radiotherapy (IMRT), and to explore an optimal chemotherapy regimen. Methods A total of 242 patients with advanced esophageal carcinoma who were admitted to our hospital and treated with paclitaxel and cisplatin (68 patients), nedaplatin (85 patients), lobaplatin (58 patients), or oxaliplatin (31 patients) plus IMRT from 2008 to 2014 were enrolled as subjects. The prognosis of the four groups was analyzed after 2, 3, and ≥4 cycles of chemotherapy. The survival rates were calculated by the Kaplan-Meier method and analyzed by the log-rank test. The Cox model was used for the multivariate prognostic analysis. Results The sample number of 3 years was 168 cases. In all the 242 patients, the medium survival time was 31.1 months and the 3-year overall survival (OS) rate was 47.4%. There was no significant difference in the 3-year OS rate between the cispaltin, nedaplatin, lobaplatin, and oxaliplatin groups (46.2% vs. 56.4% vs. 45.7% vs. 29.0%, P=0.090). The stratified analysis showed that the cisplatin, nedaplatin, and lobaplatin groups had a significantly higher OS rate than the oxaliplatin group (50.1% vs. 29.0%, P=0.021). There was no significant difference in the 3-year OS rate between patients receiving 2, 3, and ≥4 cycles of chemotherapy (40.1% vs. 49.5% vs. 50.8%, P=0.264). The multivariate analysis showed that esophageal tumor volume and the maximal size of metastatic lymph node were independent prognostic factors. Conclusions Combined with IMRT, paclitaxel plus cisplatin, nedaplatin, or lobaplatin-based chemotherapy achieves improved survival rates than paclitaxel plus oxaliplatin-based chemotherapy. Esophageal tumor volume and the maximal size of metastatic lymph node are independent prognostic factors.

Objective To compare the efficacy and resistance between S-1 combined with radiotherapy and S-1 alone in the treatment of elderly patients with locally advanced gastric cancer. Methods Fifty-eight elderly patients with unresectable locally advanced (stage Ⅲ) gastric cancer were randomly and equally divided into S-1 combined with concurrent radiotherapy group (experimental group) and S-1 alone group (control group). The experimental group received 4 cycles of S-1 treatment with each cycle containing two-week oral administration of S-1 at a dose of 40 mg/m² twice a day followed by one-week drug withdrawal. Gastric intensity-modulated radiotherapy was performed concurrently with a dose of 45 Gy (1.8 Gy per fraction). The control group received the same dose of S-1 alone. Short-term outcomes and adverse reactions were evaluated in the two groups. Comparison was made by chi-square test. Results All patients completed the planning treatment. The experimental group had significantly higher objective response, disease control, and symptom remission rates than the control group (52% vs. 24%, P=0.03;76% vs. 45%, P=0.016;86% vs. 48%, P=0.005). There were no significant differences in the incidence of nausea and vomiting, anorexia, leukopenia, diarrhea, or thrombocytopenia between the two groups (all P>0.05). Conclusions S-1 treatment combined with concurrent radiotherapy improves the short-term outcomes and causes tolerable toxicities in the treatment of elderly patients with locally advanced gastric cancer.

Objective To retrospectively analyze the prognostic factors for locoregionally recurrent early-stage extranodal nasal-type natural killer/T-cell lymphoma (NKTCL). Methods A total of 56 patients with early-stage extranodal nasal-type NKTCL, who had locoregional recurrence after initial treatment and then received salvage treatment from 1995 to 2014, were enrolled as subjects. The effects of salvage treatment on the overall survival (OS) rate were analyzed after initial treatment and recurrence. Univariate and multivariate prognostic analyses were performed on the OS rate after recurrence. Results The median follow-up time was 35.9 months after initial treatment and 14.8 months after recurrence. The 3-year OS rate was 73% after initial treatment and 58% after recurrence. Compared with chemotherapy alone, radiotherapy-containing salvage treatment significantly improved the OS rates after initial treatment and recurrence (P=0.040, 0.009), and re-irradiation also significantly improved the OS rates after initial treatment and recurrence (P=0.018, 0.019). Most (84%) of the acute and late adverse reactions after re-irradiation were grade 1-2 ones. The univariate and multivariate analyses showed that the Karnofsky Performance Status score, radiotherapy in initial treatment, and radiotherapy in salvage treatment were influencing factors for the OS rate after recurrence. Conclusions Radiotherapy achieves improved survival and tolerable toxicities, making it indispensable in the treatment of locoregionally recurrent extranodal nasal-type NKTCL.

Objective To investigate the difference in the pass rate of intensity-modulated radiation therapy (IMRT) planning in patients with different tumors and its value in determining pass rate thresholds. Methods A total of 35 verified IMRT plans for each of esophageal cancer, nasopharyngeal carcinoma, breast cancer, cervical cancer, and lung cancer were selected consecutively, and a one-way analysis of variance was used to investigate the difference in pass rate. A single pass rate threshold was used to test all IMRT plans, and the pass rate thresholds of IMRT plans for different tumors were calculated based on normal distribution law. Results There was a significant difference in the means between the 5 groups of data (F=35.83, P<0.01), and there was also a significant difference between any two groups (P=0.000).There were statistically significant differences between nasopharyngeal carcinoma group and other four groups (P=0.000). The difference was not only significant between the breast cancer group and the esophageal cancer group (P=0.001), but also between the breast cancer group and the lung cancer group (P=0.033). The calculated results of each threshold were 93.37%, 89.34%, 97.68%, 95.99%, and 95.42%, respectively. Conclusions Different thresholds should be used for IMRT plans for different tumors, and the normal distribution law can be used to calculate the threshold.

Objective To compare the dose distributions of the volumetric modulated arc therapy (VMAT) for early stage non-small cell lung cancer (NSCLC) using conventional flattening filter (FF) and the flattening filter free (FFF) beams and to verify the dose calculation accuracy of the FFF beam through a three-dimensional verification system. Methods The treatment plans of 20 patients (2015 years hospitalized) treated with SBRT for early stage NSCLC using a TrueBeam accelerator were retrospectively analyzed. The patients were scanned with 4DCT and the average density projection images were used for organ segmentation and treatment planning using an Eclipse plan system. Two volumetric modulated arc therapy (VMAT) plans with FF and FFF were designed with the same planning parameters for each patient. The dose distributions between the two plans were compared and their dose verifications were assessed with the ArcCheck device. Results With the same dose coverage for the target,there was no significant difference in the dose compatibility index 100%(CI_100%) between FF and FFF beams (P=0.82).CI_80% and CI_50% of FFF plan were lower than that of FF plan (P=0.02,0.01).The dose significantly decreased in the FFF plan comparing with the FF plan for the ipsilateral lung and the total lung (P<0.01 for both).There was no significant difference between monitor units of the FF and FFF plans (P=0.34),while the delivery time of FFF was significant shorter than that of FF (P<0.01).The DVH passing,γ pass rates and the absolute dose deviations of the FF and FFF plans at the central point were not significantly different (P=0.05,0.16,0.26). Conclusions FFF beams for NSCLC patients with VMAT planning can significantly improve the dose distribution compatibility and reduce radiation doses to lung. The beam delivery with FFF beams was also faster. Furthermore,the three-dimensional dose verification confirmed that the dose calculation in Eclipse plan system using FFF beams for VMAT plans were accurate and met the clinical need.

Objective To develop a practical image acquisition strategy using intermittent breath-hold cone beam computed tomography (CBCT). Methods A breathing phantom was used to simulate the movement of tumor near the diaphragm during free breathing and breath hold and scanned by conventional breath-hold CBCT and type Ⅰ/Ⅱ intermittent breath-hold CBCT. In the conventional breath-hold CBCT, scan paused and free breathing occurred at the break of breath hold and free breathing was not included in the scan. In the intermittent breath-hold CBCT, one scan covered several breath holds separated by free breathing in a ratio of 3 vs1. Image quality and three-dimensional registration accuracy were quantitatively compared between conventional breath-hold CBCT and type Ⅰ/Ⅱ intermittent breath-hold CBCT. Comparison of image quality parameters between conventional breath-hold CBCT and intermittent breath-hold CBCT was made by paired t test. Results Motion artifacts arose in type I and Ⅱ intermittent breath-hold CBCT scans. There were no significant differences in the reconstructed pixel value or uniformity between intermittent breath-hold CBCT and conventional breath-hold CBCT (P>0.05, and P=0.02,0.53). Compared with conventional breath-hold CBCT images, the signal-to-noise ratios of type I and Ⅱ intermittent breath-hold CBCT images were reduced by 30% and 60%, respectively (P<0.05). The registration errorwas up to 0.4 cm in the anterior-posterior direction and less than 0.1 cm in other directions. ConclusionsThe phantom study shows that intermittent breath-hold CBCT does not significantly reduce image quality or registration accuracy compared with conventional breath-hold CBCT. The feasibility of intermittent breath-hold CBCT in clinical application needs to be further validated among a large number of patients.

Objective To explore the dosimetric difference between different radiotherapytechnologies in the treatment of early peripheral stage non-small-cell lung cancer (NSCLC). Methods
Four-dimensional computed tomography scans and delineation of target volumes and organs at risk (OARs) were performed in 5 patients pathologically diagnosed with stage T₁/T₂ peripheral NSCLC who were admitted from 2014 to 2015. Target volumes contained gross tumor volume (GTV), internal target volume (ITV), and planning target volume (PTV). ITV was contoured on the maximum intensity projection images. PTV was defined as ITV plus a 5 mm margin. OARs contained the heart, lung, esophagus, and spinal cord. The Monaco 5.0 treatment planning system was used to design three plans. The three-dimensional conformal radiotherapy (3DCRT) plan had 11 fields in the diseased lung covering the PTV plus a 0.2 cm margin. The sliding window intensity-modulated radiotherapy (SW-IMRT) plan had 9 fields in the same areas as the 3DCRT plan. The volumetric modulated arc therapy (VMAT) plan had the gantry rotating 180° around the diseased lung. The evaluation criteria referred to the RTOG 0618 trial. Comparison was made by paired t test. Results The SW-IMRT plan had a significantly better homogeneity index than the 3DCRT plan (1.03 vs. 1.24,P=0.017). Compared with the VMAT plan, the mean monitor units in the 3DCRT plan was significantly reduced by 24.5%(P=0.022). The V₃₀ and V₄₀ of the 3DCRT plan were significantly reduced by 29.4% and 28.4%, respectively, compared with the SW-IMRT plan (P=0.003,0.006) and 56.7% and 59.7%, respectively, compared with the VMAT plan (P=0.041,0.019). Conclusions 3DCRT may be an appropriate radiotherapy method for early stage NSCLC.

Objective To compare the γ passing rate between measurements at actual degree gantry angle and zero degree gantry angle for dose verification of intensity-modulated radiotherapy (IMRT) in the treatment of nasopharyngeal carcinoma (NPC) and cervical carcinoma. Methods Thirty patients with NPC and thirty patients with cervical carcinoma were randomly chosen from 87 patients with NPC and 54 patients with cervical carcinoma, respectively. Using a gamma criterion of 3 mm/3%, the γ passing rates at actual gantry angle and zero degree gantry angle were measured using ArcCHECK and compared by paired t test. Results The γ passing rate was significantly lower at actual gantry angle than at zero degree gantry angle in patients with NPC or cervical carcinoma ((93.8±3.6)% vs. (97.8±1.1)%, P=0.00;(96.3±2.1)% vs. (98.2±1.0)%, P=0.00). Moreover, the variation range of the γ passing rate at actual gantry angle was larger than that at zero degree gantry angle. Both γ passing rates at actual gantryangle and zero degree gantryangle were lower in the patients with NPC than in the patients with cervical carcinoma. Conclusions
Compared with that at zero degree gantry angle, the γ passing rate at actual gantry angle is closer to reality. Therefore, the actual gantry angle is recommended for dose verification. In order to meet the clinical requirement, a higher standard of γ passing rate should be proposed when zero degree gantry angle is used for dose verification.

Objective To study the accuracy of collapsed cone convolution (CCC) and anisotropic analytical algorithm (AAA) in dosimetric calculation on the air cavity interface. Methods A BEAMnrc/EGSnrc Monte Carlo (MC) simulation was performed on a Varian Trilogy linear accelerator. The IBA Dosimetry “blue phantom” 3D scanning system was used to verify the accuracy and reliability of the MC simulation. Central axis depth dose distribution and lateral dose profile in a water-equivalent phantom with variously sized air cavities were calculated by CCC and AAA. The obtained depth dose distribution and lateral dose profile were compared with those by MC simulation and EBT₂ film, respectively. Results Both CCC and AAA overestimated the dose on the air cavity interface. In spite of some errors, CCC had a higher accuracy than AAA. The errors were mainly related to computational grid, field size, photon energy, cavity size, and the number of fields. Conclusion Electronic disequilibrium on the air cavity interface should be taken into account when CCC and AAA are used for dosimetric calculation in treatment planning system.

Objective To establish a Sprague-Dawley (SD) rat model of radiation-induced heart injury and myocardial fibrosis. Methods Using the small animal radiation research platform,18-Gy radiation was given to the heart of male SD rats in a single fraction. At six months after radiation,heart structure and function were assessed by color Doppler ultrasound;heart injury and collagen fiber deposition were evaluated using HE staining and picrosirius red staining,respectively;heart collagen content was analyzed by hydroxyproline measurement. Results According to the color Doppler ultrasound assessment,the left ventricular posterior wall thickness during systole was significantly smaller in the radiation group than in the control group (0.22±0.01 vs. 0.25±0.05 cm,P=0.037).The results of picrosirius red staining showed that the proportions of fibrosis area in the right ventricle,interventricular septum,and left ventricle were significantly higher in the radiation group than in the control group ((2.99±1.29)% vs. (2.21±0.87)%,P=0.025;(2.53±1.27)% vs. (0.91±0.70)%,P=0.000;(2.45±1.98)% vs. (0.54±0.31)%,P=0.000). According to the measurement of hydroxyproline concentration,the radiation group had a significantly higher level of hydroxyproline than the control group (0.56±0.02 vs. 0.49±0.05 ug/mg,P=0.010),indicating severe heart collagen deposition after radiation. Conclusions At the end of model establishment,SD rats have obvious myocardial fibrosis and reduced left ventricular posterior wall thickness during systole,suggesting that a SD rat model of radiation-induced heart injury and myocardial fibrosis is successfully established.

Objective This study is to investigate the changes in the NFATc4/3 signaling pathway in rat hippocampus after whole brain radiation. Methods A total of 120 one-month-old male Sprague-Dawley rats were randomly divided into four groups to receive whole brain radiation using 4-MeV electron beams with doses of 0(control),2,10,and 20 Gy,respectively,in a single fraction. At 6 hours,12 hours,1 day,3 days,1 week,and 2 weeks after radiation,Western blot and real-time PCR were used to evaluate the changes in expression levels of CaN,NFATc4/3,p-NFATc4/3,and GSK-3β. Results There were no significant changes in the expression of NFATc4/3 or p-NFATc4/3 at 6 and 12 hours after whole brain radiation. At 1 day after radiation,compared with the control group,the expression of p-NFATc4/3 in the radiation groups was significantly increased in a dose-dependent manner (2 Gy:P=0.014;10 Gy:P=0.011;20 Gy:P=0.000);however,there was no significant difference in the expression of NFATc4/3 between the radiation group and the control group. The expression of NFATc4/3 was significantly decreased in the radiation groups than in the control group at day 3(2 Gy:P=0.040;10 Gy:P=0.000;20 Gy:P=0.000),1 week (2 Gy:P=0.692;10 Gy:P=0.032;20 Gy:P=0.021),and 2 weeks (2 Gy:P=0.001;10 Gy:P=0.000;20 Gy:P=0.000) after radiation,while there was no significant difference in the expression of p-NFATc4/3 between any two groups. There were no time-or dose-dependent changes in expression of CaN or GSK-3β. Conclusions Ionization radiation has an inhibitory effect on the NFATc4/3 signaling pathway in rat hippocampus. Combined with our previous results,this study suggests that radiation-induced cognitive dysfunction is associated with the NFATc4/3 signaling pathway.

Objective To build two mathematical models, named LQB model and quantified LQB (qLQB) model, based on the LQ model, and to test their effectiveness in evaluation of radiation-induced lung injury using the Lyman-Kutcher-Burman (LKB) model. Methods Firstly, a qualitative LQB model was established. Forty-five patients with thoracic cancer were enrolled as subjects. For each patient, two plans were designed using ELEKTA Precise 2.12 treatment planning system. The plans preferred by the qualitative LQB model and the LKB model were compared. Secondly, a qLQB model was established based on the LQB model. The model was used to calculate the percentage of radiation pneumonitis (RP) for the 45 plans obtained in the first step. Comparison between the percentage of RP and normal tissue complication probability (NTCP) calculated by the LKB model was made by paired t test. Results In the plans for 45 patients, the coincidence rate of the qualitative LQB model with the LKB model was 96%(43/46). For the 45 plans preferred by the LKB model, there was no difference between the percentage of RP by the qLQB model and the NTCP by the LKB model (P=0.412). Conclusions The LQB model and the qLQB model are in good accordance with the LKB model in plan preference and evaluation of radiation-induced lung injury.