الملخص
Objective:To calibrate the absorbed doses of the configured ray water with different gears of energies in accelerator based on<The use of plane-parallel ionization chambers in high-energy electron and photon beams>of International Atomic Energy Agency(IAEA)277 and 381 reports,so as to ensure the accuracy of the output dose of the linear accelerator during clinical radiotherapy.Methods:Elekta Infinity linear accelerator was used in this study,and the photon beam energies were respectively 6MV flattening filter(FF)mode and 6MV flattening filter free(FFF)mode.The electron beam energies were respectively 4,6,8,10,12 and 15MeV.According to the IAEA TRS277 and TRS381 reports,the calibrations of output doses in photon and electron beam waters were performed respectively by using the PTW dosimeter,PTW30013 finger type of ionization chamber and PTW34001 parallel plate ionization chamber.The error of each step was analyzed,and the accuracies of the calibrations of using different standards for the output waters of linear accelerator were compared.Results:The output amounts of photon beams of FF mode and FFF mode of 6MV at the maximum dose point in water were respectively 1.003 and 1.008cGy/MU.The output amounts of the energy of each gear of electron beams of 4,6,8,10,12 and 15MeV at the maximum dose point in water were respectively 1.003,1.002,0.998,0.999,1.000 and 1.003 cGy/MU.The calibration of the output of each gear of energy rays at the maximum dose point in water was 1cCy corresponded to 1MU,which error was less than 1%.Conclusion:The calibration for the output dose amount of accelerator in water on the basis of IAEA TRS277 and trs381 can ensure the accuracy of the output dose of the accelerator.
الملخص
Objective:To preliminarily observe the feasibility of different immobilization techniques for total skin irradiation (TSI) using helical tomotherapy.Methods:Three eczema scrophuloderma patients treated with TSI in Sun Yat-sen University Cancer Center were immobilized with low-temperature thermoplastic in a prone position, diving suit combined with negative pressure vacuum bag in a supine position, low-temperature thermoplastic combined with vacuum bag in a supine position, respectively. Different immobilization effects were observed. The conformity index (CI) of the target area, heterogeneity index (HI) of the target area, and the mean dose (D mean) of the target area were calculated. Results:Three immobilization methods could achieve satisfactory immobilization effects, and all the dosimetric parameters of radiation treatment plans met the clinical requirements. The average set-up errors in the left and right, head and foot, and abdomen and back directions of three patients were (0.26±3.40) mm, (-2.63±4.63) mm and (6.13±4.86) mm, respectively. The CI, HI andD mean were0.56±0.09, 1.186±0.059 and (2586.56±63.28) cGy. Conclusions:Low-temperature thermoplastic or diving suits can be combined with vacuum bags for immobilization in TSI. The epidermal dose can be increased with bolus through the dose-building effect, which can provide a safe and reliable method for TSI in helical tomotherapy.
الملخص
[Objective]To compare and contrast the dosimetry between Tomo planning and BrainLab planning for lung metasta-ses in stereotactic body radiation therapy(SBRT).[Methods]Four Patients with one,two,three and four metastases were selected. The PTV is 2.89 ± 1.15 cm3. Two plannings with total dose of 50 Gy to cover 95% of PTV ,5 Gy/Fraction and 10 fractions were designed using Tomo planning system and BrainLab planning system respectively. The DVH curves of spinal cord ,both lungs and normal tissue were compared. The conformity index andhomogeneityindex were analyzed as well.[Results]The homogeneity index (HI)and conformity index(CI)of the targets in Tomo planning system were 1.0314 ± 0.0700 and 0.687 ± 0.075,respectively. In BrainLab planning system the HI and CI of the targets were 1.0764 ± 0.1241 and 0.571 ± 0.042,respectively. To HI the P value in T test was less than 0.01 and the HI was better in Tomo than BrainLab and so was CI. The dose to spinal cord was higher in BrainLab planning system than that in Tomo. The dose to nomal tissue and both lungs were not different in the two planning systems and V20 of lung is as small as 10%.[Conclusions]For small volume lung metastases which longest diameter were less than 4 cm,the tomotherapy should be better choice.
الملخص
Objective To investigate the maximum-tolerated dose (MTD) of cisplatin in docetaxel,cisplatin,and fluorouracil (TPF) induction chemotherapy followed by intensity-modulated radiotherapy (IMRT) and concomitant chemotherapy as well as the safety and short-term efficacy of TPF induction chemotherapy in the treatment of locally advanced nasopharyngeal carcinoma (NPC).Methods Thirtythree patients with locally advanced NPC were enrolled in this trial.The MTD of cisplatin was determined by dose escalation study,and the short-term efficacy and toxicities were evaluated.Results When the doses of docetaxel and fluorouracil were 60 mg/m2 d1 and 550 mg/m2 d1-5,respectively,the MTD of cisplatin was 65 mg/m2 d1.In this regimen (repeated every 3 weeks),grade 3-4 toxicities included neutropenia (67％),febrile neutropenia (9％),diarrhea (21％),and oral mucositis (6％).Except those who experienced dose-limited toxicity,other patients completed the whole treatment schedule.After TPF induction chemotherapy,the overall response rate was 97％,and the complete response rate was 21％.Conclusions In the endemic areas of NPC,induction chemotherapy with docetaxel (60 mg/m2 d1),cisplatin (65 mg/m2 d1),and fluorouracil (550 mg/m2 d1-5),which is repeated every 3 weeks,is proved safe and effective for Asian patients with locally advanced NPC.