iOS上的ITK库-加载DICOM

Question

I have built the ITK library for the ipad - and it works. Then I tried to make an ITK example - something like that:

// Load DICOM files
typedef itk::ImageSeriesReader< InputImageType > ReaderType;
ReaderType::Pointer reader = ReaderType::New();
typedef itk::GDCMImageIO ImageIOType;
typedef itk::GDCMSeriesFileNames NamesGeneratorType;
ImageIOType::Pointer gdcmIO = ImageIOType::New();
NamesGeneratorType::Pointer namesGenerator = NamesGeneratorType::New();
namesGenerator->SetInputDirectory( "C:/test" );

But I tried a lot of possibilites to load a DICOM stack in a directory on the documents folder of the ipad instead of the c:/test path. But that didn't work.

So my idea is to load a DICOM like that over the internet:

NSData *dicomImage = [NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://www.someurl.ch/dicom/blabla.dcm"]];   

And now I think about trying to get out the dicom data (patient name etc) and separate it from the image data. Then I think it must be possible to have at the end an UIImage to display on the IPAD.

I searched for an example for that, but sadly...i didnt found something good. If anybody has got an idea how to load a dcm on the ipad through ITK or an idea how to get the image data out of the NSData object?

Answer 1

ITK actually uses GDCM to read DICOM files, so it's probably easier to use GDCM directly. http://sourceforge.net/apps/mediawiki/gdcm/index.php

As for loading DICOM files on the iPad (or any mobile device), I would be careful when doing so. Some DICOM files are very large (on the order of GBs), and that would probably just crash your application. Of course, you'd probably have a difficult time loading files that large onto the iPad anyway :)

---

The pixel data is not necessarily RGB data as you would expect to find in a JPEG. Check the photometric interpretation. If it's RGB, then you're good to go (after decoding & decompression). If it's monochrome, you may need to convert to RGB values (see How to translate DICOM image width and level to JPEG brightness and contrast? ) before passing the data to UIImage.

Answer 2

You may want to investigate DCMTK. On an iphone you will likely need the network protocol capabilities that are in DCMTK.

Answer 3

Since my last post, I have now a little solution for my problem.

namesGenerator->SetInputDirectory( documentFolderPath );
typedef std::vector<std::string> FileNamesContainer; 
FileNamesContainer fileNames = nameGenerator->GetInputFileNames();
reader->SetFileNames( fileNames );
reader->Update();
ImageType *  imageTest = reader->GetOutput(); // get 3d volume
PixelType * pixelData = imageTest->GetBufferPointer(); // get bufferpointer

With that, I can load DICOM stacks and get out the whole dicom header information :) Now my problem is about getting the image pixel data into an UIImage. I can load single pixelvalues with this code:(just for a test, getPixel is a slow method)

ImageType::IndexType pixelIndex;
pixelIndex[0] = 100; 
pixelIndex[1] = 100; 
pixelIndex[2] = 0;

ImageType::PixelType pixelValue = imageTest->GetPixel( pixelIndex );

But my problem is, that I dont understand how I can handle the data of *pixeldata (the bufferpointer) to create a UIImage. Sadly I didnt found some example in the ITK documentation :(

Answer 4

//assume that the image width is 880 and the image height is 635
int imageWidth = 880;
int imageHeight = 635;
NSString *dicomPath = [[[[NSBundle mainBundle] resourcePath] stringByAppendingString:@"/"] stringByAppendingString:@"your dicom file name"];
const char *c_dicomPath = [dicomPath UTF8String];

typedef unsigned char InputPixelType; 
const unsigned int InputDimension = 3;
typedef itk::Image< InputPixelType, InputDimension > InputImageType;

typedef itk::ImageFileReader< InputImageType > ReaderType;
ReaderType::Pointer reader = ReaderType::New();
reader->SetFileName(c_dicomPath);

typedef itk::GDCMImageIO ImageIOType; 
ImageIOType::Pointer gdcmImageIO = ImageIOType::New(); 
reader->SetImageIO(gdcmImageIO);

InputPixelType *imageBuf = (InputPixelType*)malloc(sizeof(InputPixelType)*imageHeight*imageWidth*3);
reader->Update();

//get dicom image
memset(imageBuf, 0, sizeof(InputPixelType)*imageHeight*imageWidth*3);

gdcmImageIO->Read(imageBuf);
CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
CGDataProviderRef provider = CGDataProviderCreateWithData(nil, imageBuf, imageWidth*imageHeight*3*sizeof(InputPixelType), nil);  

CGImageRef imageRef = CGImageCreate(imageWidth,//width
                                    imageHeight,//height 
                                    8,//size_t bitsPerComponent, 
                                    24,//size_t bitsPerPixel,
                                    imageWidth*sizeof(InputPixelType)*3,//size_t bytesPerRow, 
                                    colorspace,//CGColorSpaceRef space,
                                    kCGBitmapByteOrderDefault,//CGBitmapInfo bitmapInfo,
                                    provider,//CGDataProviderRef provider,
                                    nil,//const CGFloat *decode,
                                    NO,//bool shouldInterpolate, 
                                    kCGRenderingIntentDefault//CGColorRenderingIntent intent
                                    );
//here is the dicom image decode from dicom file
UIImage *dicomImage = [[UIImage alloc] initWithCGImage:imageRef scale:1.0 orientation:UIImageOrientationUp];