How has the X-ray bill been interpreted in the context of medical malpractice cases?

People v. Grazer (1956) 138 Cal.App.2d 274, 291 P.2d 957, 958, held this provision to be applicable to the following facts: '[t]hat during the tax period ² Grazer was engaged in the business of taking X-ray pictures of persons referred to him by physicians and surgeons; that he employed a qualified radiologist to read the X-ray pictures and to report his findings to the referring physician; that the pictures were at all times the property of Grazer and were always kept in his possession except during any period that a picture ordered by a physician was taken out of Grazer's laboratory for the purpose of examination by the physician who had ordered it; that the pictures were always returned to Grazer when the physician had completed his use thereof in connection with past treatment; that Grazer kept the pictures on file in his laboratory at all other times; that Grazer took no pictures except on request of a licensed physician, surgeon, dentist or osteopath and never delivered a picture directly to a patient for his use; * * * that the fee charged him was principally for services performed in picture taking and developing, and in the payment of the fees of the radiologist to report his findings to the referring physician or surgeon; that the cost of the materials and supplies used in taking the pictures was only a small part of the total charge made by Grazer for picture taking, producing, developing and for the radiologist's report thereon; that Grazer never read or reported on any X-ray picture taken by him; * * *.'