Medical Dosimetrist

The Medical Dosimetrist is a member of the radiation oncology team who has knowledge of the overall characteristics and clinical relevance of radiation oncology treatment machines and equipment, is cognizant of procedures commonly used in brachytherapy and has the education and expertise necessary to generate radiation dose distributions and dose calculations in collaboration with the medical physicist and radiation oncologist.

The medical dosimetrist designs a treatment plan by means of computer and/or manual computation to determine a treatment field technique that will deliver the prescribed radiation dose while taking into consideration the dose-limiting structures. The medical dosimetrist maintains a delicate balance between delivering the prescription that the physician has written while ensuring the patient will not lose important healthy organ function.

Using imaging modalities such as CT scans, alone or in combination with MRI or PET scans, planning is completed with 3-D computers that enable us to give higher doses of radiation to a tumor while lowering the doses to the sensitive structures around it. In some environments we play a part in cutting edge clinical research for the development and implementation of new techniques in cancer treatment. It is an exciting and amazing profession to work in. We are members of a team that contributes toward cancer survivorship on a daily basis.

The medical dosimetrist performs calculations for the accurate delivery of the Radiation Oncologist's prescribed dose, documents pertinent information in the patient record, and verifies the mathematical accuracy of all calculations using a system established by the Medical Physicist. We perform, or assist in, the application of specific methods of radiation measurement as directed by the Medical Physicist. We may provide technical and physics support to the Medical Physicist; this support could be in radiation protection, qualitative machine calibrations, and quality assurance of the radiation oncology equipment. Also, we often take on the role of educator in facilities that have radiation oncology residents, radiation therapy students or medical dosimetry students.


The skills needed to become a medical dosimetrist include, but are not limited to:

  • An understanding of the technical aspects of radiation oncology and medical physics to meticulously derive computerized treatment plans, and then communicate these aspects to the radiation oncologist for approval and then to the radiation therapists for plan implementation
  • Good oral and written communication skills
  • Working knowledge of radiation safety and regulations
  • Interpret and execute treatment plans as defined in relevant treatment protocols
  • Good math and anatomy skills, while able to visualize the three-dimensional concepts needed for the planning process
  • Experienced and confident with computer operations and functions
  • Excellent analytical skills and an ability to critically evaluate data


How Do I Become a Medical Dosimetrist?

There are two options for becoming a medical dosimetrist: 1) a formal educational program; or 2) completion of on-the-job training as a medical dosimetrist. Formal educational programs are listed on the Joint Review Committee on Education in Radiologic Technology (JRCERT) website at On-the-job training is a position offered within a radiation oncology department therefore requiring supervision by a certified medical physicist or certified medical dosimetrist. To acquire on-the-job training, one is usually a Radiation Therapist first. This requires attending a formal radiation therapy educational program. These programs may also be found on the JRCERT website.

To enroll in a formal educational program:

  • Most programs require the applicant to be a registered radiation therapist or an individual with a baccalaureate degree with physical science pre-requisites.
  • Courses such as biology, physics, calculus - trigonometry, chemistry, anatomy & physiology, computer science, medical terminology and general health care are examples of typical pre-requisites.
  • The applicant will be required to interview with an admissions committee and is selected on a competitive basis
  • Most programs require that a previous observation be completed in medical dosimetry to ensure the applicant knows what the profession is and if they truly want to do this.

The Medical Dosimetrist Certification Board (MDCB) sets the standards on eligibility for the certification board exam. The eligibility requirements are listed on their website at

Certified Medical Dosimetrists must renew their credentials annually, including maintaining the appropriate number of continuing education credits each cycle. The MDCB is the credentialing organization responsible for the certification process.

To learn more, please visit the American Association of Medical Dosimetrists website at

Last updated: August 2008