Allied Health Profession


Medical Dosimetrist

I have been asked many times since choosing my career to explain, "What is a dosimetrist? Or what do we do?" 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 Profession
After the physician has consulted with the patient on their plan of treatment, the Radiation Oncologist will write a prescription dose to a defined tumor volume. The dosimetrist will then design a treatment plan by means of computer and/or manual computation that will deliver that prescribed radiation dose and field placement technique. When designing that plan also taken into consideration is the dose-limiting structures. These structures could include the eye when treating the brain, the heart when treating the lung or the spinal cord when it is included in the area of treatment.

The dosimetrist has to perform this delicate balance between delivering the prescription the physician has written, and making sure the patient will not loose important healthy organ function. In many places the dosimetrist has the ability to execute planning for intracavitary and interstitial brachytherapy procedures as well as radiation teletheraphy.

Following the planning process, the patient will have a simulation for tumor localization to insure reproducibility of treatment set up and plan delivery. It may be necessary in simulation to produce moulds, casts, and other immobilization devices for accurate treatment delivery. A dosimetrist may supervise, perform, or assist in this process.

The dosimetrist will then work with the therapist staff in the implementation of the patient treatment plans including: the correct use of immobilization devices, compensators, wedges, field arrangement, and other treatment variables.

Another area we make a contribution in is giving 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. The dosimetrist carries out calculations for the accurate delivery of the Radiation Oncologist's prescribed dose, documents pertinent information in the patient record, and will verify the mathematical accuracy of all calculations using a system established by the Medical Physicist. We will perform, or assist in the application of specific methods of dosimetry including ion chamber, TLD, or film measurement as directed by the Medical Physicist.

Often we take on the role of educator in facilities that have residents, therapy students or dosimetry students.

With computer technology moving into the medical field we are in the forefront of many new processes. We plan with 3D computers that enable us to give higher doses of radiation to a tumor while lowering the doses to the sensitive structures around it. Our treatment plans use CT scans in combination with MRI or PET scans. 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 help to produce cancer survivors on a daily basis.

The Skills
Possesses an understanding of the technical aspects of radiation oncology and medical physics to derive computerized treatment plans, and communicate these aspects to the Radiation Oncologist for plan approval, and to the Radiation Therapist for plan implementation.

Able to perform routine duties independent of supervision, but consults with the Radiation Oncologist and Medical Physicist as required.

Operates and performs quality assurance, under the direction of the Medical Physicist, on the treatment planning computer.

Will have a working knowledge of radiation safety and current rules and regulations of the Nuclear Regulatory Commission.

Able to interpret and execute treatment plans as defined in relevant treatment protocols.

Must possess mathematical skills including algebra, trigonometry, and introductory calculus and be able to visualize objects in three-dimensional concepts to facilitate the treatment planning process.

Experienced and comfortable with computer processes and functions.

In a medical setting at ease with having close patient contact.

Three Avenues for Entry
The person is a graduate of a formally organized hospital or college affiliated medical dosimetry program with clinical and classroom curriculum, and other training and/or experience as a medical dosimetrist so that the total duration of study, training and experience is at least 18 months, OR

The person possesses a Bachelor of Arts or Bachelor of Sciences degree with a major in the physical or biological sciences, or is a registered radiation therapy technologist. Together with either of these credentials, the applicant also demonstrates completion of two or more years on-the-job training and work experience in medical dosimetry under the supervision of a Certified Medical Dosimetrist or Medical Physicist, OR

The person possesses an Associate of Science, a Bachelor of Arts or a Bachelor of Science degree in a field other than those of the physical or biological sciences. Together with this degree, the applicant also demonstrates completion of on-the-job training in medical dosimetry under the supervision of a Certified Medical Dosimetrist or Medical Physicist and has a subsequent period of supervised work experience in medical dosimetry of a minimum of four years.

Career Outlook
The future job market for Medical Dosimetry is strong. The many advances in treatment planning increases the demand for qualified dosimetrists. Wages are comparable with other health professions. Given the diversity and ever changing technology of the job, lifelong career satisfaction is achievable.

For more information regarding educational programs and the medical dosimetry profession.

Last updated: August 2002