Dosimetrist

A Medical Dosimetrist is a critical member of the Radiation Oncology Team. According to the AAMD (American Association of Medical Dosimetrists), 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.

Education
Medical Dosimetry programs are scattered across the U.S. accepting an average of 2-3 students per program. Admission to such a program is highly competitive and extensive knowledge and understanding in Medical Physics and mathematics is crucial to success in the field. The standard course of study is a bachelor's degree in the physical sciences and a year of clinical work.

The Profession
After the Radiation Oncologist has consulted with the patient on their plan of treatment, he/she will write a prescription of radiation dose to a defined tumor volume. The medical dosimetrist will then design a treatment plan by means of computer and/or manual computation to determine a treatment field technique that will deliver that prescribed radiation dose. When designing that plan, also taken into consideration are 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 medical dosimetrist maintains a delicate balance between delivering the prescription the physician has written while ensuring the patient will not lose important healthy organ function. In many institutions, the medical dosimetrist also has the ability to execute planning for intracavitary and interstitial brachytherapy procedures.

Following the planning process, the patient will have a simulation for tumor localization to ensure reproducibility of treatment set up and plan delivery. Here, it may be necessary to produce moulds, casts, and other immobilization devices for accurate treatment delivery. A medical dosimetrist may supervise, perform, or assist in this process. The medical dosimetrist will then work with the radiation therapists in the implementation of the patient treatment plans including: the correct application of immobilization devices, beam modification devices, approved field arrangements, and other treatment variables.

The advancements in computer technology places us at the forefront of many new processes. Using imaging modalities such as CT scans, alone or in combination with MRI or PET scans, we plan 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.

In summation, 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 including ion chamber, thermoluminescent dosimeters (TLD), or film measurement as directed by the Medical Physicist. Another area that we may contribute to 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. Also, we often take on the role of educator in facilities that have radiation oncology residents, radiation therapy students or medical dosimetry students.

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

We are able to perform routine duties independent of supervision, consulting with the Radiation Oncologist and Medical Physicist as required.

We operate and perform quality assurance, under the direction of the Medical Physicist, on the treatment planning system.

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

We are able to interpret and execute treatment plans as defined in relevant treatment protocols.

We 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.

We are experienced and comfortable with computer operations and functions.

Being in a medical setting, we are at ease with having close patient contact.