Hospitals which produce photographs of the human anatomy by the X-ray or roentgen process on the request of licensed physicians for use by them in the diagnosis or treatment of a patient’s illness or condition shall retain such photographs or films as part of their regularly maintained records for a period of 5 years provided that retention of said photographs or film may be by microfilm or other recognized means of minification that does not adversely affect their use for diagnostic purposes. However, if the hospital has been notified in writing by an attorney at law before the expiration of the 5 year period that there is a litigation pending in court involving a particular X-ray or roentgen photograph in their records as possible evidence, and that the subject person of such photograph is his client, or is the person who has instituted such litigation against his client, then the hospital shall keep such photograph or film or minified copy thereof in its regular records until notified in writing by the plaintiff‘s attorney with the approval thereon of the defendant‘s attorney of record that the case in court involving such photograph has been concluded, or for a period of 12 years from the date that the X-ray photograph film was produced, whichever occurs first in time.