Mass. Gen. Laws ch. 112 § 9B
Temporary registration as a qualified physician may be granted (1) to a visiting physician holding a license to practice in another state or territory or in the District of Columbia or in another country and having a temporary faculty appointment certified by the dean of a medical school in the commonwealth for purposes of medical education in an accredited hospital associated with the medical school, such registration to terminate automatically upon termination of the faculty appointment and, in any event, at the end of three years; (2) to a physician holding a license to practice in another state or territory or in the District of Columbia to permit him to act as a substitute physician for a registered physician in the commonwealth, to be granted only upon written request of said registered physician and to be limited to three months or less; (3) to a physician eligible for examination or registration in the commonwealth who is a diplomate of a specialty board approved by the American Medical Association or the American Osteopathic Association to permit him to act as a substitute physician for a registered physician in the commonwealth to be granted only upon written request of said registered physician, to be limited to the specialty in which the applicant is certified and to be limited to three months or less; (4) to a physician holding a license to practice in another state or territory or in the District of Columbia or in another country and enrolled in a course of continuing medical education, such registration to terminate automatically upon termination of the course and, in any event, at the end of three months. The fee for such temporary registration shall be determined annually by the commissioner of administration under the provision of section three B of chapter seven.
Mass. Gen. Laws ch. 112, § 9B