CAJ | 학술논문

目的测试移动式术中放疗Mobetron加速器,分析它的电子束剂量学特点.方法测量移动式术中放疗Mobetron加速器电子束的剂量学特点,并与西门子常规加速器电子束进行比较.Mobetron加速器配置有4、6、9、12 MeV电子束.测量项目包括垂直于水模体表面的中心轴百分深度剂量和平行于水模体表面的射野离轴比、输出因子、限光简外漏射剂量、铅挡块对电子束的衰减、输出量校准.使用的测量仪器包括三维水箱、静电计、0.6 cm3Farmer电离室、平行板电离室和固体水.测量时将不同端面和直径限光筒依次与加速器机头连接,并使端面与模体表面相切.结果除12 MeV外其他能量的表面剂量均低于90%,相同能量下术中加速器表面剂量明显高于常规加速器剂量.对10 cm直径、0°倾斜角的限光筒四档能量的最大剂量深度依次为0.7、1.3、2.0、2.2 cm,治疗深度依次为1.0、1.8、2.7、3.6 cm;对0°限光筒治疗时只需选直径比瘤床大1cm的筒即可.由于斜端面的限光筒照射野平坦度和对称性明显变差,限光筒尺寸的选择要依据等剂量分布图.四档能量的限光筒外1 cm处漏射线分别为1.2%、5.1%、10.0%、9.1%,全挡时铅挡厚度分别为1.5、3.0、4.5、6.0 mm.结论通过测试了解了Mobetron加速器性能特点并获得了临床应用和日常质量保证所需数据.
목적 측시이동식술중방료Mobetron가속기,분석타적전자속제량학특점.방법 측량이동식술중방료Mobetron가속기전자속적제량학특점,병여서문자상규가속기전자속진행비교.Mobetron가속기배치유4、6、9、12 MeV전자속.측량항목포괄수직우수모체표면적중심축백분심도제량화평행우수모체표면적사야리축비、수출인자、한광간외루사제량、연당괴대전자속적쇠감、수출량교준.사용적측량의기포괄삼유수상、정전계、0.6 cm3Farmer전리실、평행판전리실화고체수.측량시장불동단면화직경한광통의차여가속기궤두련접,병사단면여모체표면상절.결과 제12 MeV외기타능량적표면제량균저우90%,상동능량하술중가속기표면제량명현고우상규가속기제량.대10 cm직경、0°경사각적한광통사당능량적최대제량심도의차위0.7、1.3、2.0、2.2 cm,치료심도의차위1.0、1.8、2.7、3.6 cm;대0°한광통치료시지수선직경비류상대1cm적통즉가.유우사단면적한광통조사야평탄도화대칭성명현변차,한광통척촌적선택요의거등제량분포도.사당능량적한광통외1 cm처루사선분별위1.2%、5.1%、10.0%、9.1%,전당시연당후도분별위1.5、3.0、4.5、6.0 mm.결론 통과측시료해료Mobetron가속기성능특점병획득료림상응용화일상질량보증소수수거.
Objective To commission a Mobetron intra-operative mobile accelerator and analyze the characteristics of its electron beams. Methods The dosimetrie characteristics of the electron beams genera-ted by Mobetron accelerator were measured and compared with those generated by conventional accelerator (Primus, Siemens). M oberton accelerator can generate electron beams of nominal energies of 4,6,9 and 12 MeV. The measurement items were as followings : percentage depth dose perpendicular to water phantom sur-face and beam profiles parallel to water phantom surface, output factors, applicator leakage, electron beam at-tenuation made by lead blocks,and machine output calibration. The measurement devices included a three-dimensional ( 3 D) water scanning phantom, an electrometer, a 0.6 cm3 Farmer ionization chamber, a parallel-plate ionization chamber and solid water slabs. During measurement, all applicators of different tilt angles and diameters were attached to the machine head,and their ends were adjusted to be tangent to the phantom surface. Results Except for the 12 MeV,skin dose for all energies was no more than 90%. The skin dose was higher for Mobetron accelerator electron beams than for regular electron beams. The Dmax depth in water for a 10 cm flat applicator were 0.7,1.3,2.0 and 2.2 cm for the 4 energies,respectively. The depths of 90% dose were 1.0,1.8,2.7 and 3.6 cm, respectively. The selected flat applicator was just 1 cm larger than the tumor bed. But for the beveled applicators,the field flatness and symmetry became worse,and con-sequently,the applicator size had to be selected based on the isodose distribution. The leakage dose at 1 cm outside the applicator was 1.2% ,5.1%, 10.0% and 9.1%, respectively. The lead thickness for full block was 1.5,3.0,4.5 and 6.0 mm,respectively. Conclusions Through the commissioning of Mobetron accel-erator, the machine characteristics are understood, and the data for clinical implementation and routine quality assurance are acquired.