How send QR code image create with chart.googleapis from Google Apps Script Telegram bot?

I want send the QR code image to Telegram bot programmed by Google Apps Script .

I send images with SendPhoto function

function sendPhoto(id,foto,caption)
{
var url = telegramUrl + "/sendPhoto?chat_id=" + id + "&photo=" + foto+"&caption=" + caption ;

  var response = UrlFetchApp.fetch(url);
  Logger.log(response.getContentText());
}

And create the wr code image at :

var qr = "https://chart.googleapis.com/chart?chs=250x250&cht=qr&chl=Test&choe=UTF-8"; 
sendPhoto(id,qr,"Test... ");

It nom send the QR image , i don't know why.

Anyone can help me ?