Research On Digitized Radiotherapy Model Of The Female Pelvic Cavity

At present, radiotherapy is one of the three major techniques for treating cancer patients ,which causes cell injury when cancer patients were being exposed to the ionizing radiation. The radiation damage to normal tissues and organs of patients with cancer during the radiotherapy are unavoidable when radiation kills tumor cells. The desired therapeutic outcomes of radiotherapy are to maximally improve the tumor radiation dose and to maximally decrease the damage to ambient normal tissues and organs. The final goal of radiotherapy is to improve local control rate and to decrease post radiation complications of the cancer patients. The spatial position relation and the radiation doses distribution of human organ and tissues can not be directly measured and displayed by any apparatus. It is forbidden to use live human in the experiment of evaluating safety and maneuverability of medicinal apparatus. So a substitute for live human must be invented to study human's organic architecture and radiation doses distribution in radiation instead of. The Chinese Visible Human (CVH) datasets provide the possibility of constructing digital human model and numerical data-base of the Chinese about radiotherapy dose calculation. We can accurately observe human's organic architecture and calculate radiation doses simulation through digital human model, which would be the standard of the physical radiotherapy model from the Chinese.In this study, 386 continuous cross-sections of female pelvic cavity (between slices 1715 and 2100) were chosen from the second datasets of CVH. After being registered accurately, the cross-sections of female pelvic cavity data set were resampled to create the traverse, coronal and sagittal planes images data set with Amira4.1 software on PC. By using the visualizational software, the structures of radiosensitive organs were segmented by interactive and thresholds complex segmentation approach and were reconstructed to get female pelvic 3D model. Using the methods described above, we have reconstructed a numerical model of the inner organs of the female Visible Human pelvis. The important structures in the radiation field for female pelvic cavity including the pelvis, the uterus, the ovary, the ureter, the vesica, the internal iliac vein and artery, external iliac vein and artery were displayed clearly in false color by surface rendering reconstruction. In 3D view, the graphic modeling provides an overview of the pelvic structures and their relationships to each other and other anatomical regions. We can prune, enlarge, and roam the inner organs data in any orientation so that the inner structure of the radiation field for female pelvic cavity can be observed clearly. Then, the color images and the CT DICOM images of female pelvic cavity from CVH data set were registered and fused to construct a physical radiotherapy model of female pelvic cavity. Good image quality can be achieved by processing images of portal field and it is helpful to achieve high anatomy registration accuracy of the color images and CT images. Display of the fused images helps anatomy structure registration. Our rerults show that fusing images with anatomic images can help to obtain a full understanding of the portal field and peripheral structures and can be used as a routine clinical practice. This study have shown that spatial relationships between the anatomy structures are easier to understand when being visualized stereoscopically in 3D environments, and the physical radiotherapy model have therefore the potential to extend the radiotherapy planning process, giving an improved understanding of how the dose is distributed throughout the patient's body. Also, this report presents a physical radiotherapy model for evaluating radiotherapy treatment plans, developed to improve the understanding of the spatial relationships between the patient anatomy and the calculated dose distribution. A physical radiotherapy model offers visualization through interactive volume rendering of radiotherapy dose distribution and computed tomography (CT) and surface and line rendering of radiotherapy structures such as target volumes and organs at risk. A physical radiotherapy model has been installed and networked in a hospital room used for the daily radiotherapy conferences, making stereoscopic viewing of treatment planning data for clinical cases possible.The main results and conclusions were as follows:1. The continuous cross-sections of female pelvic cavity chosen from the second datasets of CVH were resampled afterbeing registered accurately. The thin sectional anatomy data set from multidirectional planes were obtained on the same individual. It can help to promote image diagnosis and anatomical studies of digital visible human. 2. The cross-sectional anatomic characteristics and distribution of the internal structure were observed in the radiation field in female pelvic cavity. The cross-sectional anatomic characteristics of the radiation field in female pelvic cavity can be effectively used to recognize medical automatic images and get target therapy areas'image drawings in radiotherapy. It can help to choose optimal radiotherapy methods and to provide anatomical basis for the radiotherapy.3. By using visualizational software, the structures of radiosensitive organs were segmented by interactive and thresholds complex segmentation approach and were reconstructed to get female pelvic 3D model. We can prune, enlarge, and roam the inner organs data in any orientation so that the inner structure of the radiation field for female pelvic cavity can be observed clearly.4. Based on the digital medical image resampling techniques and virtual-reality technology, an intuitively understandable manner was provided to study the inner anatomic structure of the radiation field in female pelvic cavity. It provided a technology platform for research on anatomy of radiation field.5. This trial transformed the CVH color images to the DICOM files for the first time. The CVH color cross-sectional images of female pelvic cavity were transformed to DICOM3.0 images with Amira4.1 and Matlab software. A dataset of female pelvic DICOM files from CVH was set up to apply in radiation therapy system.6. This trial discussed the fusion method and efficiency evaluation for the multimodality medical image information. The pelvic cavity structures of Chinese Virtual Human dataset were segmented using image transparency method at first and each image was smoothed by eroding and dilating, and then fused successfully with CT of the same sample. The registration accuracy of CVH/CT was more than 95%. The digital radiotherapy model of female pelvic cavity with important organs segmented can well reflect the exposure doses of patients, so it is of important value to get target therapy areas'image drawings, forecast radiotherapy side effects, optimize radiotherapy plan and improve curative effect.7. This trial presented a digital physical radiotherapy model with the mean CT values and a model with the segmented CT data of female pelvic cavity for the first time. The color images and the CT DICOM images of female pelvic cavity from CVH were registered and fused to construct a physical radiotherapy model of female pelvic cavity. We can accurately observe human's organic architecture and calculate radiation doses simulation in radiation therapy for patients with gynecological malignancies through the digital model, which would be the standard of the physical radiotherapy model from the Chinese. The methods of founding integrated numeric radiotherapy model were initially studied.8. The physical radiotherapy model of female pelvic cavity was imported in the radiotherapy planning system for the first time. The dose distribution of 2D-RT,3D-CRT and IMRT on the physical radiotherapy pelvic model from CVH2 was transferred and superimposed onto the sectional anatomy images and anthropomorphic pelvic phantom. The differences with target dose and normal tissue absorb dose by the DVHs were compared. Much more information about clinical dose distribution was obtained on anatomy images than that on CT images. The physical radiotherapy model on the TPS system has great value in the study of fine anatomy and clinical images. It provides technology platform for research and radiotherapy training.