ABSTRACT
Objective@#To quantitatively evaluate dose accuracy of radiotherapy for cervical cancer.@*Methods@#A CT image correction algorithm based on image transformation was proposed. Referring to CBCT images, CT images of radiotherapy plan for cervical cancer were corrected to obtain the corrected images which could reflect the actual body position of treatment. The clinical plan was transplanted to the corrected images for dose recalculation as a test plan, and the dosimetry parameters were statistically compared to evaluate the dose accuracy.@*Results@#Both of the target coverage of contrast plans could meet the clinical requirements (>98%), and there was no significant difference in the homogeneity index (P=0.150). The conformability of the test plan was significantly worse than that of the clinical plan (P<0.05). The maximum dose of each organ at risk in the test plan was approximately 30 cGy higher than that of the clinical plan (P<0.05), V50 was slightly higher than that of the clinical plan, whereas the average dose (Dmean) did not significantly differ.@*Conclusion@#The CT image correction algorithm based on image transformation can quantitatively evaluate the dose accuracy of radiotherapy for cervical cancer, which provides reference for resolving similar problems in clinical practice.
ABSTRACT
SUMMARY: Palatal rugae is an irregular soft tissue, which is located in the front third of the hard palate, and is asymmetrically distributed from the middle suture to the sides. The difference, stability and extensive characteristics of palatal rugae morphology have gradually make it a characteristic indicator of forensic identification. However, a mature digital palatal rugae identification system has not yet been established at present. Feature extraction is the premise of palatal rugae image recognition. In order to obtain palatal rugae feature information in all directions and improve the reliability of forensic identification, it is necessary to collect palatal rugae images from a plurality of different angles. When the collected images are sent to the recognition system, the diversity of angles will often cause problems such as error recognition. If the tilted images are not rotated properly, it will make the forensic identification face many difficulties. To solve the problem of image skew caused by the diversity of acquisition angle, an algorithm based on orientation vector to correct the tilted palatal rugae images was proposed in this paper. Firstly, the criteria for standard palatal rugae image and the selection rules for feature points were set; Secondly, characterizing feature points according to the rules, and fitting two lines and find their direction vector; Finally, to obtain the corrected images, the tilted images were rotated by the angle determined by the two direction vectors. Simulation results show that the proposed algorithm can correct the tilted palatal rugae images collected from different angles and has strong robustness.
RESUMEN: Las rugas palatinas son tejidos blandos irregulares, que se ubican en el tercio frontal del paladar duro y se distribuyen asimétricamente desde la sutura mediana hacia los lados. La diferencia, la estabilidad y las características extensivas de la morfología de las rugas palatinas la han convertido gradualmente en un indicador característico de la identificación forense. Sin embargo, un sistema de identificación de rugas palatinas digitales maduras todavía no se ha establecido en la actualidad. La extracción de características es la premisa del reconocimiento de imágenes de las rugas palatinas. Para obtener información sobre las características de las rugas palatinas en todas las direcciones, y mejorar la confiabilidad de la identificación forense, es necesario recopilar imágenes de las rugas palatinas desde una pluralidad de ángulos diferentes. Cuando las imágenes recogidas se envían al sistema de reconocimiento, la diversidad de ángulos a menudo causará problemas como el reconocimiento de errores. Si las imágenes inclinadas no se giran correctamente, la identificación forense se enfrentará a muchas dificultades. Para resolver el problema del sesgo de la imagen causado por la diversidad del ángulo de adquisición, en este documento se propuso un algoritmo basado en el vector de orientación para corregir las imágenes de las arrugas palatinas inclinadas. En primer lugar, se establecieron los criterios para la imagen de las rugas palatinas estándar, y las reglas de selección para los puntos de características. En segundo lugar, se determinaron puntos de características según las reglas, y se ajustaron dos líneas y encontrar la dirección del vector. Finalmente, para obtener las imágenes corregidas, las imágenes inclinadas se giraron según el ángulo determinado por la dirección de dos vectores. Los resultados de la simulación muestran que el algoritmo propuesto puede corregir las imágenes de rugas palatinas inclinadas recopiladas desde diferentes ángulos y tiene una gran robustez.
Subject(s)
Humans , Image Processing, Computer-Assisted/methods , Palate, Hard/anatomy & histology , Forensic Dentistry/methods , Algorithms , Calibration , Simulation ExerciseABSTRACT
In this report, we want to propose new one-dimensional parameters for eye-image correction through manipulations of lid elevation. The eye ball exposure area could be divided to three subdivisional areas: iris, medial sclera and lateral sclera. Ratios among these subdivisional square measures of eye ball exposure are the most important and effective factors to present for the eye-image. But, for the surgeons, it is not easy to measure this areas. So we came to propose paramedian widths, mid-scleral widths. We suggest several compositions of one-dimensional measures which would represent for eye-image like the ratios of square measures of subdivisional areas. However, there would be no exact rule in this ratios because there have been no exact rule also in the beautiful face, they would be useful rules for eye-image. It is entirely up to every surgeon to decide the rules of these parameters.
Subject(s)
Iris , ScleraABSTRACT
Objective To study elimination of the Micro CT projective image noise and improve the quality of the recon-structed image for the Micro CT system.Methods The forming factors of the Micro CT projective image noise were analyzed,and proposed the Micro CT projective image correction method to correct the random noise,dark field,light field,response nonuniformity and defect picture element and eliminate the random noise and the ring artifact respectively.Results Through the comparative study,it proposes a simple and practical correction method for the actual response nonuniformity which combines the corrections of light field,dark current and gain inconsistency and settles the three corrections with one circu-lation.The method can enhance the algorithm efficiency greatly and the validity of the correction protocol can be proved through experiments.Conclusion The Micro CT projective image noise is eliminated effectively and the good basis for the following work are established such as three-dimensional reconstruction.