| OBJECTIVE: By applying linear accelerator Airborne kilovolt cone-beam CT(Kilo-voltage cone-beam computer tomography, KV-CBCT) and using independent-written deformable registration software of FBCT- CBCT "CBCT Pasting" to collect online anatomical images of target and surrounding tissues from patients who had received breast-conserving surgery and underwent IMRT subsequently, image from CBCT and the planning was integrated, mapping relationship between target and surrounding normal tissues was obtained, timely adjustment of treatment plan after registration deformation was achieved, making adaptive radiotherapy possiable. To produce a dose distribution and re- optimization ideals radiotherapy planning, three-dimensional image based on fast deformable registration technology online portal modified correction strategy and offline adaptive dosage compensation technology was adopted, leading to online and offline adaptive radiation field dose modification breast image-guided adaptive and dose- compensation radiotherapy, which took advantage of volume image information acquired in the treatment day. At the same time, a retrospective analysis was conducted of morphological and anatomical characteristics from 110 cases of CBCT correction adaptive radiotherapy after breast-conserving patients, to further explore its relationship with cardiorespiratory dose.METHODS: 1. In 32 cases of breast cancer postoperative tumor bed synchronization(simultaneous integrated boost intensity-modulated and radiation therapy, SIB-IMRT) or late course boost intensity-modulated radiation therapy for patients, patient positioning on 4DCT scan, assessment of respiratory motion to choose whether or not to use active breathing control(ABC) assisted localization and treatment. The patients before and after radiotherapy wereperformed every online CBCT scan in each direction CBCT registration between images and planning CT images(left and right, head and feet, and get the displacement of each patient before and after) real-time target area. 2. The first automatic rigid registration, then the fine manual registration after to the treatment planning system in TPS. FBCT-CBCT deformable registration registration techniques with independent research and development and integration. Using self prepared image stitching software "CBCT Pasting" seamless splicing of KV-CBCT image, expand to CBCT scan width, CBCT evaluation of tumor target and organs at risk the integrity, to provide conditions for the design and evaluation on CBCT images in radiotherapy planning. The image gradient mainly reflects the tumor and normal organs of the edge information, the registration of the gradient field, can largely reduce the density of CBCT and FBCT does not match the registration error caused by. The establishment of the online direct shoot rapid deformation image registration method of wild modified correction. Between the target and critical structure, adjusting the beam shape and radiotherapy according to the projection vector matrix, a fast online registration technology based on direct field modification. Independent research and development of 4DCT retrospective phase separation of software and the individual ITV draw 4DCT data acquisition software, and at the same time, through the analysis of the respiratory signal, discusses the off-line adaptive dosage compensation directly shoot wild modified residual after correction of online technology. After the improvement of basic technology of image guided radiotherapy combined with online and offline, for breast cancer patients to carry out combined with image guided adaptive technique in the offline, to verify the efficiency and benefit in the clinical application of this technique. 3. To investigate the impact of the breast size, shape, maximum heart depth(MDH), and chest wall hypotenuse(the distance connecting middle point of the sternum and the length of lung draw on the selected transverse CT slice) on the volumetric dose to heart with whole breast irradiation(WBI) of left-sided breast cancer patients. Materials and Methods: Fifty-three patients with left-sided breast cancer undergoing adjuvant intensity-modulated radiotherapy(IMRT) were enrolled in the study. The primary breast size and shape, MHD and DCWH(chest wall hypotenuse) were contoured on radiotherapy(RT) planning CT slices. The dose data of hearts were obtained from the dose-volume histograms(DVHs). Data were analyzed by oneway analysis of variance(ANOVA), Student’s t-test and linear regression analysis.RESULTS:In 32 cases of breast cancer patients received a total of 672 sets of CBCT images. After the improvement of basic technology of image guided radiotherapy combined with online and offline, this group of patients with breast cancer before radiotherapy combined with a 5 image guided adaptive technique in the offline, to verify the efficiency and benefits of the application of this technology in the body of tumor. The CBCT image and CT image registration, the adjustment of the initial radiotherapy beam shape, and then the implementation of radiotherapy; airborne CBCT image head foot direction span can contain the target area, can not be a complete reproduction of normal lung and heart of breast cancer, off line dosimetric evaluation carried out, therefore, the end of radiotherapy after repeated online portal modification process, and the mosaic of online collection of 2 sets of CBCT image using reconstruction algorithm development, after analyzing the field after the modification, the difference of target and organs at risk of exposure dose and exposure dose of the plan, and lays out the defect region dose, to provide online CBCT image anatomy as the foundation to optimize the radiotherapy plan, the new plan for Plan1, second for radiotherapy, second radiotherapy using Plan1 online CBCT image modified adjusted online collection field, off-line analysis also for second times after the end of radiotherapy, so move in circles. The results show that, for breast cancer patients, including 2 sets of CBCT image acquisition, image rigid registration, remote treatment bed correction of setup error, 3D image registration, the density correction of CBCT image generation, organ automatic mapping and portal online correction steps, can be completed in 5 minutes, can meet the clinical immediate the application requirements. While the offline dosage compensation strategies need to process, repeated online portal modified to complete the 2 sets of CBCT seamless splicing, to reproduce the image and draw the outline of the defect area, defect area compensation dose assessment dose size, especially reverse dose optimization process, the target area containing the defect area therefore, off-line dosage compensation process took a total of about 30 minutes. Breast size was independent of heart dose, whereas breast shape, MHD and DCWH were correlated with heart dose. The shapes of breasts were divided into four types, as the flap type, hemisphere type, cone type and pendulous type with heart mean dose being 491.8±234.6c Gy, 752.7±219.0c Gy, 620.2±275.7c Gy, and 666.1±238.0c Gy, respectively. The flap type of breasts shows a strong statistically reduction in heart dose, compared to others(p=0.008 for V30 of heart). DCWH and MHD were found to be the most important parameters correlating with heart dose in WBI. CONCLUSIONS:Individualized exercise effective control strategy made it possible to balance the reducation of the target volume and the improvement of the efficiency of treatment. Conbined the implementation of online and offline IGRT radiotherapy technology, can achieve the same effect of the optimal daily plan. More attention should be paid to the heart dose of non-flap type patients. The MHD was found to be the most important parameter to correlate with heart dose in tangential WBI, closely followed by the DCWH, which could help radiation oncologists and physicsts evaluate heart dose and design RT plan in advance. |
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