Send imagedata with prompt in nodejs API

I have been trying to make a call to worker-ai model : @cf/unum/uform-gen2-qwen-500m

But I get null as a response. Can you suggest how to send imagedata, and prompt together as json ?

Here is the code I have been to make it work. Please suggest any changes. It I just send imageData as value of body it works, but throws error, when send as a json.

    fs.readFile(imagePath, (err, imageData) => {
        if (err) {
          console.error('Error reading image:', err);
          return;
        }

        var headers = {
            'Authorization': 'Bearer ' + process.env['CLOUDFLARE_API_TOKEN'],
            'Content-Type': 'application/json'
        };
        
       
        
        var options = {
            url: 'https://api.cloudflare.com/client/v4/accounts/' + process.env['CLOUDFLARE_ACCOUNT_ID'] + '/ai/run/@cf/unum/uform-gen2-qwen-500m',
            method: 'POST',
            headers: headers,
            body: {
                image: imageData,
                'prompt': "what is this image about ?",
              }
        };
        
        function callback(error, response, body) {
            console.log(error);
            if (!error && response.statusCode == 200) {
                console.log(body);
            }
        }
        
        request(options, callback);
      });