| With the development of radiotherapy technology and the increasing requirements for clinical dose verification,two-dimensional dose verification based on a uniform phantom can only reflect a plane dose distribution,for the place where gamma is less than 1,the deviation of its specific location and actual dose cannot be determined,therefore,it has been unable to meet the requirements of clinical use.3Dmap is a high-resolution semiconductor detection matrix that can not only verify the two-dimensional dose of the plan,but also perform three-dimensional dose verification.3Dmap is a high-resolution semiconductor detection matrix that can not only verify the twodimensional dose of the plan,but also perform three-dimensional dose verification.At present,it is gradually in the process of commercialization,so there is not much research on the clinical application of this matrix.This subject will use the 3Dmap matrix to study its application in the verification of intensity-modulated therapeutic doses.The thesis mainly has the following contents: 1)Research the dosimetry characteristics of the matrix;2)Establish a two-dimensional dose verification model to verify the plan of 10 patients;3)Establish a three-dimensional dose verification model,Choose IMRT technology and VMAT technology for nasopharyngeal cancer and lung cancer patient plans of 20 cases each,and perform three-dimensional dose verification based on the patient’s CT image.The gamma pass rate and dose volume histograms of different evaluation methods are used to evaluate the dose verification results,and the action limit(AL)and tolerance limit(TL)of the target area and normal tissue based on the gamma pass rate are calculated.Results: 1)The matrix has good repeatability and dosimetric linearity,and the dose rate response change is also within 0.5%.2)Use the established two-dimensional dose to verify the measurement results of the model and compared it with Mapcheck.Whether it is the actual gantry angle irradiation or the irradiation when the gantry exceeds 0 degrees,there is little difference in the measurement results between the two,and there is no statistical difference in the difference.3)Based on the threedimensional dose verification of the patient’s CT image,under the standards of 3%/3mm,3%/2mm and 2%/2mm,compare the body dose,the average gamma pass rate of nasopharyngeal carcinoma TMRT plan and VMAT plan is(99.32±0.32)% 、(98.36±0.59)% 、(96.27±1.20)% and(99.15±0.37)%、(97.67±0.86)%、(94.66±1.73)%,respectively.The average gamma passing rates of lung cancer TMRT plan and VMAT plan were(99.17±0.74)%、(98.09±1.33)%、(95.83±2.22)% and(99.08±0.58)%、(97.82±1.39)%、(95.59±1.74)%,respectively.The pass rate of the target zone and some normal tissues is slightly lower.The deviation of the percentage dose of all target areas is mostly within 3%,but the deviation of Dmax of small organs such as optic nerve and optic chiasm is relatively large.The AL values of TMRT plan and VMAT plan for nasopharyngeal carcinoma were 94.37% and 96.13%;and the TL values were 92.55% and95.00%,respectively;The AL value of the body under the lung cancer TMRT technology and VMAT technology are 93.02% and 95.16%,and the TL value is 92.24% and 95.43%,respectively.both of which can meet the requirements of the report of TG218. |
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