OBJECTIVETo evaluate the feasibility and accuracy of using Megavoltage CT(MVCT) for head and neck dose calculation.

METHODSThe cheese Phantom was imaged using MVCT scanner, and the MVCT value density calibration curve was established. Conventional CT and MVCT image of nasopharyngeal carcinoma was acquired respectively, and IMRT plan was designed on conventional CT image of NPC patient. The conventional CT plan was copied to MVCT image. The dose distribution was calculated for tumor and normal tissue using the MVCT value density calibration curve, and compared with that of conventional CT. Ten NPC patients were collected for dose verification of IMRT plan on MVCT images.

RESULTSThe MVCT numbers depended linearly on the electron density of the sample, and the stability of the MVCT numbers to electron density was good.The error between the measured dose and calculated dose in measured point was less than 3%.The isodose distribution was well agreement with that calculated by planning system.

CONCLUSIONSPerforming dose recalculation using MVCT of Tomotherapy in head and neck region was feasible.and the dose distributions on kVCT and MVCT were in excellent agreement.

Algorithms ; Head and Neck Neoplasms ; radiotherapy ; Humans ; Phantoms, Imaging ; Radiosurgery ; instrumentation ; methods ; Radiotherapy Dosage ; Tomography, Spiral Computed ; instrumentation

Objective To evaluate the variations of effective doges with the preset scanning parameters from linac-integrated kV cone beam CT( CBCT). Methods Weighted CT dose index(CTDIW) were measured with PTW TM30009 CT ion chamber in head phantom and body phantom, respectively, for different combinations of tube voltage, mAs, collimator and gantry rotation range. Dose length products(DLP) were derived from CTDIW and effective doses(E) were calculated by the DLP and EDLP. Results CTDIW and effective dose had the quadratical relationship with tube voltage, depending linearly on product of tube current and exposure time. Effective dose had close relationship with the collimator and the gantry rotation range. Both the DLP and ED for CBCT were lower than the reference dose level recommended for conventional CT. Conclusions Effective dose from CBCT has a close relationship with the scanning parameters. Optimal imaging parameters should be chosen according to the patient's anatomy to reduce patient dose.

Background: Radiation pneumonitis is one of the most common complications during radiotherapy of thoracic tumors. It impacts the quality of life of the patients and has life-threatening danger. However, there is a lack of drugs for prevention and treatment of this disease. Objective: To evaluate the efficacy of Liangxue Jiedu Huoxue Decoction, a compound traditional Chinese herbal medicine, in prevention of radiation pneumonitis. Design, setting, participants and interventions: A prospective randomized clinical study was conducted. A total of 100 patients diagnosed with lung cancer from Department of Radiotherapy, Chinese PLA General Hospital, who were planning to receive radiotherapy, were randomly assigned into treatment group and control group, with 50 patients in each group. In the treatment group 3 cases were lost to follow-up and one case was excluded, while in the control group 6 cases were lost to follow-up and 2 cases were excluded. Patients in the treatment group were treated with Liangxue Jiedu Huoxue Decoction in addition to radiotherapy, while patients in the control group were treated with radiotherapy alone. Main outcome measures: The incidence rates of radiation pneumonitis in the two groups were calculated. Acute radiation injury scoring criteria by Radiation Therapy Oncology Group (RTOG), clinical-radiographic-physiologic (CRP) score system, and Karnofsky Performance Status Scale (KPS) were used to evaluate the status of the patients. Results: The incidence rate of radiation pneumonitis was lower in the treatment group than in the control group (13.04% versus 33.33%, P<0.05). According to the RTOG scale, the extent of lung injury was improved in the treatment group as compared with that in the control group (P<0.05). The CRP score in the treatment group was significantly lower than that in the control group (P<0.05). The KPS score in the treatment group was significantly higher than that in the control group (P<0.05). Conclusion: Liangxue Jiedu Huoxue Decoction can decrease the incidence rate of radiation pneumonitis, reduce the extent of the lung injury, alleviate the symptoms of radiation pneumonitis, and improve life quality of the patients.

Object To explore the feasibility of breeding genetic modified (GM) medicine by expressing human cytokine in transgenic Chinese materia medica Methods Human interferon ? gene and RANTES gene available from the amplification in vitro were enzymatically excised, recoveried, and inserted into intermediate vectors The recombinants were identified by double enzyme digestion of EcoRⅠand HindⅢ The plasmids were extracted from Escherichia coli and introduced into A tumefaciens, and the transformants harboring binary vectors were screened by addition of antibiotics of kanamycin (Km) and rifampicin (Rif), and the explants of M charantia and P vulgaris were transformed by co cultivation of leaf disks with A tumefaciens strain Results RT PCR was applied to detect the transient expression of human interferon ? gene and RANTES gene in transformed medicinal herbal calli Conclusion The expression of recombinant human interferon ? gene and RANTES gene in transgenic M charantia and P vulgaris cells was firstly reported, which opens an alternative road to antivirus, especially anti AIDS virus, by using transgenic Chinese materia medica

Objective To evaluate the therapeutic effects and dose-effect relationships of different doses of the blood-cooling and blood flow-promoting drugs(凉血活血方) on radiation-induced lung injury of rat.Methods Seventy-two Wistar rats were randomly allocated into four groups: irradiation group(group A),small-dose group(group B,9 g?kg-1?d-1),middle-dose group(group C,18 g?kg-1?d-1) and high-dose group(group D,36 g?kg-1?d-1).All groups were repeatedly exposed to small dose of X-ray in the right hemi-thorax,and then the mice were sacrificed at different time points.The living animal features,the macro-changes of lung were observed,and pulmonary histopathological changes in all the groups were investigated,and the results of observation were compared.Results The symptoms of red patches around the nose and dry stool in groups C and D were less than those of groups A and B.After 26 weeks,lung coefficient in groups B,C and D was the same as that in group A,but right lung wet weights and lung coefficients at each time point in groups B,C and D were significantly lower than those in group A,and during 5th week,the right lung wet weights in groups C and D were obviously lower than the weight in group B(all P

Objective To evaluate the dosimetric characteristics of helical tomotherapy (HT),intensity-modulated radiation therapy (IMRT) and three-dimensional conformal radiation therapy (3D-CRT) for postoperative radiotherapy of rectal cancer.Methods Ten male patients with stage Ⅱ or Ⅲ middle or low position rectal cancer were selected retrospectively.All of the 10 patients underwent Dixon surgery and CT simulation orientation.The target volumes and normal organs were drawn in the CT images and the plans for HT,IMRT and 3D-CRT were designed.The prescribed dose was given 50 Gy in 25 fractions,covering at least 95％ of the planning target volume.Results All plans met the needs of the prescribed doses.The HT and IMRT plans met the needs of dose limit to organs at risk,however,the 3D-CRT plans failed to do that.The conformity indexes of HT,IMRT and 3D-CRT plans were 0.86,0.82 and 0.62,respectively (F =206.81,P ＜ 0.001),and the homogeneity indexes were 0.001,0.157,and 0.205,respectively (x2 =15.8,P ＜ 0.001).The 3D-CRT plans had larger volumes than the HT plans and IMRT plans in the high-dose regions such as pelvic V50,bladder V40,bowel V50 and femoral head D5 (P ＜ 0.05),but the differences between the HT plans and IMRT plans were not statistically significant (P ＞0.05).The V15 value of bowel of HT plans were higher than those of the IMRT and 3D-CRT plans (71.1％ vs.63.3％ and 67.7％,respectively).However,there was no significantly difference.Conclusions All of the HT,IMRT and 3D-CRT plans are able to meet the prescription dose requirement of the target regions of rectal cancer.The HT plans show the best dose homogeneity and target conformity,followed by the IMRT plans,and then the 3D-CRT plans.The HT plans meet the needs of all OARs slightly better than the IMRT plans.3D-CRT plans are simple and practical with poor protective ability toward the OARs.

Objective To evaluate the clinical outcome and the acute toxicity in nasopharyngeal carcinoma (NPC) treated with tomotherapy followed by the anti-EGFR monoclonal antibody.Methods Between March 2008 and November 2009,34 newly diagnosed NPC patients were treated with helical tomotherapy combined with nimotuzumab or cetuximab.All the patients underwent tomotherapy at the dose of 70 Gy/33F for the gross tumor volume (pGTVns) and positive lymphnodes (GTVnd) ,and 60 Gy/33F for the high risk clinical target volume (PTV1),and 56 Gy/33 F for the low risk clinical target volume (PTV2),respectively.17 patients in group N were given weekly injection of 200 mg for 6-7 times and 17 patients in group C were given initial dosage 400 mg/m2 followed by subsequent weekly dosage of 250 mg/m2 for 6-7 times.Acute lesions were evaluated with the RTOG/EORTC criteria.Result The median follow-up time was 22 months.The effective rates (CR + PR) in 3,6 and 12 months were 14/17,12/17,12/17 in group N and 15/17,14/17,14/17 in group C.The 1 year survival rate was 15/17 in group Nand 17/17 in group C.Nimotuzumab had less acute mucositis reaction (u = 2.25,P < 0.05),weight loss(t=2.56,P=0.02) and rash (u=4.36,P＜0.01) compared with cetuximab.Conclusions Helical tomotherapy combined with nimotuzumab or cetuximab was effective and made no difference in the shortterm efficacy and 1 year survival rate for the patients with NPC.Nimotuzumab has less acute reaction than cetuximab.More studies should be done to prove long-term effects.

Objective To study dosimetric characteristics of helical tomotherapy (HT) by comparing its treatment plans with linear accelerator-based step-and-shoot intensity modulated radiation therapy (IMRT) for nasopharyngeal carcinoma(NPC). Methods Targets on CT images of 10 NPC patients were delineated and transferred to HT and IMRT treatment plan systems. The prescription dose was 70 Gy/33 f for pGTV and GTVnd,60 Gy/33 f for FTV1 ,and 54 Gy/33 f for PTV2. The limit dose of organ at risk was parotid V35 ＜50% ,brain-stem＜54 Gy,spinal cord ＜45 Gy and lens ＜9 Gy. Data of the two groups were compared by paired t-test. Results The dose distribution, conformality and homogeneity were good in both groups.But the homogeneity index(HI) and Dmean of PTV1 in HT group were better than IMRT group( P ＜ 0.01 ).The Dmean of PTV1 in HT group(63.84 Gy)was lower than IMRT group(70.30 Gy). The Dmean, V35 and V30 of parotids,and the Dmax of larynx-esophagus were lower in HT group than IMRT group. Conclusions Helical tomotherapy treatment plan has a better homogeneity, steeper dose gradient, and a better protection for organs at risk.

Objective To develop a measurement method of dosimetric parameters for Hi-ART tomotherapy unit. Methods Percentage depth doses and beam profiles were measured using the dedicated mini water phantom, and compared to the results of 6 MV X-ray from Primus accelerator. Following the AAPM TG51 protocol, absolute dose calibration was carried out under SSD of 85 cm at depth of 1.5 cm for field of 5 cm ×40 cm. The output linearity and reproducibility were evaluated. The output variation with the gantry rotation was also investigated using 0.6 cm3 ion chamber in cylindrical perplex phantom and on-board MVCT detectors. Leaf fluence output factors were quantified for the leaf of interest and its adjacent leaves.Results The buildup depth was around 1.0 cm. The PDD values at 10 cm for Hi-ART and Primus were 59.7% and 64.7%, respectively. Varying with the field width, the lateral and longitudinal beam profiles were not so homogeneous as the Primus fields. The measured dose rate was 848.38 cGy/min. The fitted lint(sec) ,with a relative coefficient of 0. 999. The maximum deviation and standard deviation of output were 1.6% and less than 0.5% ; The maximum deviation and standard deviation of output changed by gantry angle were 1.1% and 0.5 % , respectively. Leaf fluence output factors did not increase significantly when leaves were opened beyond the two adjacent leaves. Conclusions Hi-ART Tomotherapy unit has a very high dose output and inhomogeneous beam profiles owing to its special design of the treatment head. This may be useful in dose calculation and treatment delivery.

Objective To summarize the outcome of nasopharyngeal carcinoma ( NPC) treated by helical tomotherapy in the Chinese PLA general hospital. Methods Between September 2007 and August 2010, 121 newly diagnosed NPC patients were treated by radiotherapy with Tomotherapy system, with ( n =90) or without ( n = 31) concurrent chemotherapy or molecular target therapy. The prescription dose was 70 - 74 Gy/33f to primary tumor and positive lymph node planning target volume,60. 0 - 62. 7 Gy/33f to high risk planning target volume, and 52 -56 Gy/33f to low risk planning target volume. Acute side-effects were evaluated with RTOG/EORTC criteria. Results The remission rate of primary lesion and positive lymph nodes was 95. 0％ and 99. 0％ , respectively. The follow-up rate was 100％ . The number of patients with 1 ,2 and 3 years followed-up were 99 , 49 , and 7. The 1-, 2-and 3-year local relapse-free survival rates were 97. 30％ , 97. 3％ and 97. 3％ , respectively. The 1-,2-and 3-year nodal relapse-free survival rates were 100％ , 100％ and lOO％, respectively. The 1-, 2-and 3-year distant metastasis-free survival rates were 98. 4％ , 96. 3％ and 96. 3％ , respectively. The 1-, 2-and 3-year overall survival rates were 96. 5％ ,92. 6％ and 86. 8％ , respectively. Acute toxicities of skin, oral mucosa and xerostomia with grade 0,1,2 and 3 were 5. 0％ , 74. 4％ , 15. 7％ and 4. 9％ ; 0. 8％ , 37. 2％ , 57. 9％ and 4. 1％ ; 3. 3％ , 53. 7％ ,43. 0％ and 0％ , respectively. Xerostomia restored with time, no grade 2 or more xerostomia was observed 1 year after radiation therapy. Concurrent chemotherapy significantly increased incidence of mucositis,esophagitis and tracheitis. Conclusion Helical tomotherapy is efficient, secure and effective modality for the treatment of nasopharyngeal carcinoma.