| OBJECTIVE:Image guided radiotherapy adopts the method of using the moving treatment bed to check the position error aimed at the changes of position and shape through accessing to online images of patients(the image we have gotten before the implementation of every radiotherapy). The limitation of this method lies in unable to check the relative position and deformation of tumor and its surrounding vital organs, which can lead to wrong radiophoto or the normal tissue being taken photos. Software image guiding radiotherapy workstation is being researched independently and possesses the function of online optimization, the CT(Cone-Beam CT, CBCT) which is integrated cone in the medical linear accelerator of the beam on online acquisition chest upper esophageal carcinoma IMRT(intensity modulated radiotherapy, IMRT) anatomical image esophageal lesions and the surrounding normal tissues and organs, we can get displacement tumor and surrounding critical organs and deformation information through image registration online image and plan CT. And according to these information, on the foundation of the original radiotherapy planning, we can optimize IMRT plans on line quickly to make newly produced radiotherapy plan meet the displacement and deformation(accuracy of IMRT plans dose generated online calculation of the need to go through the type test experimental verification), By comparing radiotherapy planning clinical conditions before and after modification of acceptable situation to assess clinical efficacy and safety evaluation of image guided radiotherapy workstation software application in the chest of upper esophageal carcinoma. This research is the clinical active try of new technology and new methods in online adaptive radiotherapy application.METHODS:1.The experiment simulates the changing of location and shape of tumor or dangerous organs while accepting localization and treatment. Through the image guided radiotherapy workstation software to modify IMRT plans online. At last, in reference to the AAPM119 reporting requirements, to compare the measuring data of online generated new IMRT plans in solid water calculation data to verify the accuracy of IMRT plans dose calculation.2.5 cases of breast carcinoma of upper esophagus intensity-modulated radiotherapy(IMRT) patients are in consideration to ensure the target head foot direction is not more than 15 cm, and to verify and calibrate weekly for CBCT position. Each CBCT image after scanning with image guided radiotherapy, workstation software online image fusion and online target delineation and evaluation of original radiotherapy radio-therapy plan. If the original data is ideal, you do not need to modify the radiotherapy plan, otherwise the online modification of radiotherapy planning. Analyzing and researching through online planning system after optimization plan for the target and normal tissue(spinal cord and lung) dose effect.RESULTS:1. Per-field measurements,used gamma criteria of 3%/3 mm.We had our film dosimetry normalized to a point or to an area that corresponds to ion chamber measurement. The confidence limit here is expressed as the reduction from 100%. The overall results are 97.69 ± 2.66, leading to a confidence limit of 7.5 or 92.5%. Ion chamber results,for the high dose low gradient regions in the target, the average difference between the measured and planned doses, expressed as a ratio to the prescribed dose and averaged over all tests, was 0.012 ± 0.019, corresponding to a confidence limit(mean + 1.96<x) of 0.049. For the low dose avoidance structures, the average difference between the measured and planned doses, expressed as a ratio to the prescription dose and averaged over all tests, was 0.0093 ± 0.01, corresponding to a confidence limit of 0.029. Composite film measurements, combining all the film planes gives an average of 95.4±3.1. Using the same approach to establishing a confidence limit but recognizing that it is the reduction from 100% of points passing that is important leads to a somewhat different formulation:(100-mean) + 1.96<x is the percentage less than 100 that constitutes the limit. This gives a value of 10.7, or 89.3%. 93% of the film results reported gamma pass rates of 89% or higher..2. 5 cases of chest upper esophageal patients have received a total of 30 sets of CBCT images, 30 sets of m CBCT images. PTV CT plans to target area and the actual plan conformal difference degree CI and dose uniformity of HI had statistical significance, visible, target area generated online modification plan conformal uniformity of HI degree CI and dose were higher than the plan of CT, relative to the CT the plan, with the maximum dose of spinal cord practical plan, double mean lung dose D-mean reduced significantly, the differences were statistically significant; in addition, double lung V20 accumulation in the actual plan is obviously reduced, the above differences were statistically significant.CONCLUSIONS:Workstation software of image guided radiotherapy consists of dose calculation, image registration, planned modify and planned evaluation. Based on the methods of deformable registration algorithm of gradient information, GPU accelerated computation and localized direct machine parameter optimization, this work station has basically realized the online therapy plans for rapid optimization of function. At the same time, through strict test verification, accuracy of IMRT dose calculation of online radiotherapy planning system has reached the required standard AAPM119 report. Clinical study on chest and upper esophageal carcinoma IMRT boot workstation software application in radiation image, and comparing online program and original plan DVH map, after radiotherapy planning online optimization has significantly improved tumor target dose, while reducing the dose lung, spinal cord of normal tissue. Workstation software of image guided radiotherapy can settle deformation and relative position changes of tumor and surrounding critical organs problems without patients leaving the treatment bed on one hand; On the other hand, by improving the accuracy of the dose of radiation therapy, can be adjusted according to the changes of radiotherapy dose anatomical images in the treatment process, re optimization of radiotherapy planning in the premise, to maximize the protection of normal tissue, as much as possible to kill tumor cells, so as to improve the survival rates of the patients. |
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