How to Become a Medical Dosimetrist

Lead dosimetrist Kenn Florell looks over a cancer patient's image scan to help plan a radiation treatment at Cape Fear Valley Cancer Center August 4, 2010 in Fayetteville, North Carolina.
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When a cancer patient requires treatment with radiation, a radiation oncologist will prescribe the course of therapy. But a healthcare professional known as a medical dosimetrist will actually calculate the precise dose of radiation to make sure the tumor gets a large enough dose to destroy the tumor while sparing the normal tissues. Dosimetrists also determine the frequency and duration of treatment.

Job Responsibilities and Required Skills

Dosimetrists typically work in a hospital or cancer center as part of a medical team that includes radiation oncologists, radiation therapists, oncology nurses, and medical physicists.

Radiation therapy usually requires daily doses over the course of several weeks, depending on the type and location of the cancer. The total dose is usually divided into smaller doses called fractions. Most patients get radiation treatments daily, five days a week for five to eight weeks. Weekend rest breaks allow time for normal cells to recover. The total dose of radiation and the number of treatments is based on:

  • The size and location of the cancer
  • The type of cancer
  • The reason for the treatment
  • The patient's general health
  • Any other treatments the patient is receiving

The most common type of radiation is external beam radiation. A machine called a linear accelerator (or "linac") is used to aim high-energy rays (or beams) from outside the body into the tumor. There are many other techniques and types of equipment that may be used, depending on the individual patient's needs. Stereotactic radiosurgery, for example, is a special type of radiation treatment that gives a large dose of radiation to a small tumor area, usually in one session. It’s used for brain tumors and other tumors inside the head. In some cases, a head frame or shell may be used to help keep the patient’s head still. Once the exact location of the tumor is known from brain scans, radiation is sent to the area from many different angles.

Another type of radiation is brachytherapy. With this procedure, radioactive material is placed inside the body near the site of the tumor, in the form of small pellets; this is often used for prostate cancer and some breast cancers.

Many of these treatment plans and techniques are very complex, so a dosimetrist must be well-versed in all the available technologies.

Requirements to Become a Medical Dosimetrist

Dosimetrists must be critical thinkers and be able to analyze data and implement a course of therapy based on images and measurements. Strong math skills are required, as these professionals verify the accuracy of calculations in determining the precise dosage of radiation after pinpointing the location of the tumor.

Additionally, dosimetrists must have strong technical skills, as they are often responsible for ensuring the calibrations and functionality of medical equipment used in radiation therapy. Technology is constantly changing in radiation oncology, requiring a dosimetrist to keep up with evolving treatment methods.

Often it's registered radiation therapists that will pursue further education to become a medical dosimetrist. However, some candidates simply have a bachelor's degree with physical science pre-requisites. (Physics topics relevant to dosimetry touch on fundamental particles, strong and weak nuclear forces, electromagnetism, and radioactive decay. In a biology program, you study the structure, behavior, life cycle, and evolution of living organisms.)

The next step is to apply to a Medical Dosimetry JRCERT accredited program, which will last at least 12 months. Classroom-based courses address medical imaging, cross-sectional anatomy, radiation physics, cancer biology, and radiation oncology. You will also need to participate in supervised clinical practicums to help you get hands-on experience working with patients and planning radiation treatments.

Upon completion of this year-long program, you can apply to take the certification exam from the Medical Dosimetrist Certification Board (MDCB) and earn a CMD (Certified Medical Dosimetrist) designation. Previously, there was a path to certification based on clinical experience, but as of 2017 only graduates from the 12-month accredited programs who hold a bachelor's degree can take the certification exam. The CMD certification exam consists of 155 multiple-choice questions in nine subject areas, including treatment planning, dose calculation. and radiation physics.

Job Prospects

Specific figures for medical dosimetrists aren't available, but the U.S. Bureau of Labor Statistics has projected a 14 percent increase in job opportunities for radiation therapists from 2014-2024; this growth is thought to be due to the expanding population of elderly patients and improvements to the safety of radiation therapies. Hospitals and physicians' offices are your best bets for employment, although there may also be opportunities with long-term care facilities and outpatient care centers. 

In December 2018, Salary.com reported that the average salary for a radiation dosimetrist in the United States was $115,209, but the range typically falls between $105,238 and $125,277. Salary ranges can vary widely depending on your education, certifications, additional skills, and the number of years spent in the profession.

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