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1、1Linear Accelerator Acceptance Testing (加速器验收测试) and Routine QA (常规QA)Timothy C. Zhu Department of Radiation Oncology University of Pennsylvania Philadelphia, PA 19104 tzhumail.med.upenn.edu2009放疗设备质量保证培训班2Objectives ?Accelerator Installation (加速器安装)?Acceptance testing (加速器验收测试)?Photon beam (光子光束)?E
2、lectron beam (电子束)?Acceptance report (验收报告)?Routine Quality Assurance program (日常质 量保证计划)?Comprehensive QA program (全面质量保证计划)?Typical QA schemes (daily, monthly, annual) （每 日，每月，每年）2009放疗设备质量保证培训班3Accelerator Installation (加速器装置加速器装置)Accelerator Installation (加速器装置加速器装置)2009放疗设备质量保证培训班4Preliminary t
3、ests?Linac radiation leakage testing（漏射线测 试）?Door interlocks testing（门连锁测试）?Proper operation of the emergency switches（紧急开关测试）?Machine output calibration（输出剂量校准）?Radiation survey (辐射)2009放疗设备质量保证培训班5Acceptance testing (验收测试验收测试)Acceptance testing (验收测试验收测试)2009放疗设备质量保证培训班6Equipment for acceptance te
4、sting?3D water phantom scanner with computer interface (水假体扫描器)?Detectors (ionization chamber（电离室）, detector array（阵列探测器）, diodes (二极 管)?X-ray films, laser film scanner (X光片，激光 扫描仪)?Precision level (精密水平仪)2009放疗设备质量保证培训班7Dose monitoring system（剂量监测 系统）?Reproducibility（重复性）0.5%?Dependence on gantry a
5、ngle (龙门角)3%?Dependence on rotation (旋转) of the gantry2%?Proportionality (比例度) (1Gy, 30 MeV4%IEC Report 9772009放疗设备质量保证培训班24Definition of inplane (radial) and crossplane (transverse) directions2009放疗设备质量保证培训班25Uniformity of radiation fields (photons) 射野一致性?Symmetry（对称性） (ratio of symmetrical points)
6、103%?Maximum ratio of absorbed dose (at dmax) 5x5 to 30x30 cm2107% maximum square109%?Wedge filtered X-ray fields wedge factor（楔形因子）2% wedge angle（楔形角）2IEC Report 9772009放疗设备质量保证培训班26Beam flatness and symmetry definition?Flatness (F)?AAPM TG45 and IEC 1987?Symmetry (S)?AAPM TG45 and IEC 1987%100 min
7、maxminmax+=DDDDF%100+= rightleftrightleft DDDDS2009放疗设备质量保证培训班27Recommendation of flatness and symmetry for routine QATech. and Health Care 11 (2003) 283-2882009放疗设备质量保证培训班28Examples of profiles due to incorrect scanner setup (实例简介由于不正确安装扫描仪)2009放疗设备质量保证培训班29Axial profiles at different depths for 4x
8、4 cm2field with 1o arm tilt (臂倾斜臂倾斜) (Das and Watt, AAPM TG106)2009放疗设备质量保证培训班30Axial profiles for 30x30 cm field with and without gantry tilt for 6 MV photons (Watt, Das, AAPM TG106)2009放疗设备质量保证培训班31Effect of chamber orientation on Penumbra （半影）(Das)Various thimble chambers with different radius 4
9、6 mm and lengths 6 12 mm (Das)2009放疗设备质量保证培训班32Penumbra(半影) measurement?P20-80 or P10-90 penumbra width(半影宽度半影宽度) (Med Phys 11, 491, 1984) can be corrected using a standard slope of 0.5 cm/cm inside diameter, regardless of the chamber type and radiation quality.?Metcafe et al (Med Phys 20, 1439,1993
10、 ) conclude that the diode (2.5 mm dia.) and TLD (1x1x6 mm) is very close to a point detector.2009放疗设备质量保证培训班33Uniformity of radiation fields (electrons)?Flatness (shape of isodose contours) 80% contour (周线) to geometric edge (at base depth)15mm 90% contour to geometric edge&corner (at std. measurem
11、ent depth) 10mm&20 mm?Symmetry (ratio of symmetrical points) 105%IEC Report 9772009放疗设备质量保证培训班34IEC Report 9772009放疗设备质量保证培训班35Electron profiles with and without gantry tilt (龙门倾斜龙门倾斜) and with level scanning arm (Watt, Das, AAPM TG106)2009放疗设备质量保证培训班36Electron point data: cone factors (锥因子)?Cone ou
12、tput factor (输出因子) is ratio of dose at dmax(dref) for given cone to reference cone?Need to measure for simple MU calculations?Can be measured in water tank, or solid water?Solid water at least 30x30 cm2for 25x25 cm2cone?Different machines may have different cone output factors?Verify output factors
13、to confirm if they can be used for different machine2009放疗设备质量保证培训班37Indication of radiation fields (photons)?Light field（灯光野） indication, edges (% of field size) at normal TX distance, 5x5 to 20x20 cm2 2mm, 1% at 1.5x normal TX distance, 5x5 to 20x20 cm2 2mm, 2%IEC Report 9772009放疗设备质量保证培训班38Indica
14、tion of radiation fields (electrons)?Light field(灯光野) indication, edges 2mmIEC Report 9772009放疗设备质量保证培训班39Indication of radiation beam axis (束轴)?Entry, X radiation (NTD + 25 cm)2mm?Entry, e radiation (NTD + 25 cm)2mm?Exit, X radiation (NTD- to + 50 cm) 3mmNTD =标称治疗距离IEC Report 9772009放疗设备质量保证培训班40Is
15、ocenter (等中心)?Displacement of X ray beam axis:2mm?Displacement of indication of iso.:2mm?Indication of distance along radiation beam axis from isocenter: 3mmIEC Report 9772009放疗设备质量保证培训班41Zero position (零位置) of rotational scales (旋转表)?Gantry, beam limiting device, table, table top:0.5?Congruence (余)
16、 of opposed radiation fields at isocenter (等中心): 1mmIEC Report 9772009放疗设备质量保证培训班42Movements of the patient table (病人台 子)?Horizontal displacement (水平位移) for 20 cm vertical change: 2mm?Displacement of rotation axis from isocenter: 2mm?Angle between table and table top rotation axis (旋转轴):0.5IEC Report 9772009放疗设备质量保证培训班43Linac with special modes?TBI (全身照射): maximum MU and dose rate?TSI (全肤照射): maximum MU, dose rate and field size interlocks?Elec
