写一段代码 要求能用PyQt结合VTK读取指定的.dcm文件，将其转换成.nii.gz文件并做三维可视化

以下是一个示例代码，可以使用PyQt和VTK读取指定的.dcm文件，将其转换为.nii.gz文件，并进行三维可视化：

import vtk
import numpy as np
import SimpleITK as sitk
from PyQt5.QtWidgets import QApplication, QMainWindow, QFileDialog, QWidget, QVBoxLayout
from vtk.qt.QVTKRenderWindowInteractor import QVTKRenderWindowInteractor

class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("DICOM to NIFTI Converter and Viewer")
        self.setGeometry(100, 100, 800, 600)
        self.central_widget = QWidget(self)
        self.setCentralWidget(self.central_widget)
        self.vtk_widget = QVTKRenderWindowInteractor(self.central_widget)
        self.layout = QVBoxLayout(self.central_widget)
        self.layout.addWidget(self.vtk_widget)
        self.reader = vtk.vtkDICOMImageReader()
        self.renderer = vtk.vtkRenderer()
        self.vtk_widget.GetRenderWindow().AddRenderer(self.renderer)
        self.renWin = self.vtk_widget.GetRenderWindow()
        self.interactor = self.renWin.GetInteractor()
        self.interactor.SetInteractorStyle(vtk.vtkInteractorStyleTrackballCamera())
        self.interactor.SetRenderWindow(self.renWin)
        self.file_dialog = QFileDialog(self.central_widget)
        self.file_dialog.setNameFilter("DICOM files (*.dcm)")
        self.file_dialog.fileSelected.connect(self.load_dicom)
        self.menu_bar = self.menuBar()
        self.file_menu = self.menu_bar.addMenu("File")
        self.open_file_action = self.file_menu.addAction("Open DICOM file")
        self.open_file_action.triggered.connect(self.file_dialog.exec_)
        self.convert_to_nifti_action = self.file_menu.addAction("Convert to NIFTI")
        self.convert_to_nifti_action.triggered.connect(self.convert_to_nifti)
    
    def load_dicom(self, filename):
        self.reader.SetDirectoryName(filename)
        self.reader.Update()
        image_data = self.reader.GetOutput()
        extent = image_data.GetExtent()
        mapper = vtk.vtkFixedPointVolumeRayCastMapper()
        mapper.SetInputData(image_data)
        volume = vtk.vtkVolume()
        volume.SetMapper(mapper)
        self.renderer.AddVolume(volume)
        self.renderer.ResetCamera()
        self.renWin.Render()
    
    def convert_to_nifti(self):
        filename, _ = self.file_dialog.getSaveFileName(self.central_widget, "Save NIFTI file", "", "NIFTI files (*.nii.gz)")
        if filename:
            image_data = self.reader.GetOutput()
            array = vtk.util.numpy_support.vtk_to_numpy(image_data.GetPointData().GetScalars())
            array = np.reshape(array, image_data.GetDimensions(), order='F')
            sitk_image = sitk.GetImageFromArray(array)
            sitk_image.SetSpacing(image_data.GetSpacing())
            sitk_image.SetOrigin(image_data.GetOrigin())
            sitk_image.SetDirection(image_data.GetDirection())
            sitk.WriteImage(sitk_image, filename)
            print("Converted to NIFTI:", filename)

if __name__ == "__main__":
    app = QApplication([])
    window = MainWindow()
    window.show()
    app.exec_()

运行此代码后，将打开一个具有菜单栏的窗口。单击“文件”菜单中的“打开DICOM文件”选项，选择要加载的.dcm文件。加载DICOM文件后，将在窗口中显示三维可视化。单击“文件”菜单中的“转换为NIFTI”选项，选择要将DICOM文件转换为的.nii.gz文件的路径。转换完成后，将在控制台中显示“已转换为NIFTI：”和文件路径。