BRACHY THERAPY APPARATUS, NAMELY, A MINIATURE ELECTRONIC X-RAY TUBE, A BALLOON APPLICATOR AND CATHETER FOR RECEIVING THE MINIATURE X-RAY TUBE TO ADMINISTER RADIATION TO A PATIENT, AN ELECTRONIC CONTROLLER FOR THE X-RAY TUBE AND FOR THE BALLOON APPLICATOR, AND A FLEXIBLE X-RAY SHIELD FOR USE ON A PATIENT TO CONTAIN RADIATION