In recent years,there has been a considerable research effort concerning the application of magnetic resonance imaging (MRI) for the external radiotherapy.This paper reviewed the progress of MRI in radiotherapy for cancer,such as magnetic resonance simulator,target volumes,dose calculation and efficacy evaluation.Furthermore,the potential applications of 4D-MRI and MRI guided radiotherapy are summarized.

Medical translation is not onlya kind of transmission of medical information but also mutual communication in culture. It is absolutely necessary to train medical students for the translation skills of medical English. This paper has exemplified training on how to deal with medical terms,phrases,texts as well as culture when translating,which is of some importance for the education of medical students.

In real life,vague expression is ubiquitous in any nation and any language.Medical English,as a branch of English for Science and Technology ( EST ),is typical in accuracy of word use.However,like other kind of language,it adopts vague expression,too.Vague expression plays an important role in medical practice.In communication of medical practitioners and patients,appropriate vague expression will improve language expression and communication efficiency.In medical English,the vague words that express approximate,presuming,or uncertain meaning are usually used to replace the exact meaning words.The correspondent translation methods such as literal translation,meaning translation,specialization etc can be used according to the different context.

Objective To investigate the features of 2-D air vented ionization chamber array MatriXX system to use the QA procedures of radiotherapy. Methods Some important QA procedure of clinical radiotherapy practice were investigated by using a MatriXX system and a phantom made in house, mainly including the calibration of MatriXX, the off-axis rate (OAR) of virtual wedge fields, the connection between two half-fields or two asymmetry-fields, the skillful adjustment of the clinac flat filter, the 2-D dose distribution verification of radiotherapy planning, the influence of scatter screen to a large area electron beam field, the effect and best thickness and shielding position of block for a large area electron beam fields with scatter screen. Results The OAR of any virtual wedge field can be measured by a MatriXX system in a single irradiation. The conjunction accuracy of two half-fields or two asymmetry-fields may be less than 1 ram. The difference between the calculated and measured dose of any point or any isodose or any OAR of a field can be determined by using a MatriXX system. After the adjustment of the elinae flat filter with the help of MatriXX system, the flatness and symmetry of the field are 1. 85 % and 0.98 %, respectively. The dose characteristic of a large area electron beam field may be distinctively influenced by a scatter screen, and under this condition, the block faraway from the shielded target can hardly protect the organ at risk, and directe block which is put on or near the organ at risk is perfect. Conclusion Compared with conventional ionization chamber (Farmer type) or film dose measuring, the MatriXX combined with the OmniPre I'mRT software is much more convenient and effective in QA practice of clinical radiotherapy, and it's a perfect tool for the QA procedure of radiation therapy.

Objective To explore the shielding effects of 1-4 layers of lead aprons (LPs) and body shielding devices (BSDs) against stray radiation (SR) outside the electron beam field of 6-15 MeV.Methods JR-115B LiF TLDs were used to measure the stray radiation doses (SRDs) to the patient undergoing treatment,before and after being shielding,for different distances,different energies,different applicators,variable layers of LPs,and different thickness of body shielding devices (BSDs),respectively,along long calculating and comparing the shielding ratios of LPs and BSDs against SR.Results When the applicator (10 cm × 10 cm) is unchanged,the shielding ratio increased with the increased distance from measuring point (r =0.717,P ＜ 0.05) and decreased with the increased electron energy (r =-0.678,P ＜ 0.05);when the energy was constant,there was no correlation between the shielding ratio and the size of applicator (P ＞ 0.05);For lower energy electron beam of 6 and 9 MeV,the shielding ratio for 1 mm Pb-BSD was slightly higher than that for 2 layers of LA (t =2.519,2 662,P ＜ 0.05),ranging from 81.5％ to 95.3％ and 55.4％ to 84.6％,respectively.For 12 and 15 MeV higher energy electron beam,the shielding ratio for 2 mm Pb-BSD was slightly higher than that for 4 layers of LA (t=3.768,7.934,P＜0.05),ranging from 64.6％ to 93.4％ and 51.1％ to 92.4％,respectively.Conclusions LAs or BSDs are availavle for effectively reducing the doses from stray radiation,and may help reduce the secondary risks from stray radiation.BSDs have more obvious advantages than LPs with regard to shielding effect.