A dosimetrist is a key member of a radiation oncology team who specializes in the physics behind radiation therapy treatment. Dosimetrists are the experts who design radiation therapy treatment plans for cancer patients. The AAMD (American Association of Medical Dosimetrists) defines the Medical Dosimetrist as 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.

[edit] Education

Dosimetry is a relatively new field. Most former education was done through on job training for Physicists and Radiation Therapists. In some countries, Dosimetry positions are filled by Clinical Physicists(ie. Chinese dosimetrists require a minimum of a Bachelor's in physics or equivalent), in some, Dosimetry positions can be filled by graduates from both Physics and Radiation Therapy (ie. USA), while in others Dosimetrists must also be registered Radiation Therapists which requires a minimum of Bachelor's in Radiation Therapy(ie. Canada and Australia).

Only a handful of Medical Dosimetry programs are scattered across the U.S. accepting an average of 2-3 students per program. Admission to such a program is extremely competitive and extensive knowledge and understanding in Medical Physics and mathematics is crucial to success in the field. The current standard route to become a dosimetrist is to undergo a certification, a Bachelor's, or a Master's degree program for Medical Dosimetry. However, there are alternate routes to a career in Medical Dosimetry. The traditional route requires a certification in radiation therapy (A.R.R.T), and 2 years of clinical training in dosimetry, prior to eligibility for the MDCB Board Exam. Other routes involve obtaining a minimum of Bachelor's degree in Physics (or oher related science fields such as biophysics, mathematics), followed by 2 years of clinical internship in dosimetry prior to becoming eligible for the CMD examination. [1]) Medical Dosimetry Certification is optional and is not a requirement by any State. This voluntary exam certification has a very low pass rate (~35%) because it is considered an advanced skills exam and not an entry level exam, as are the Radiologic Technology and Radiation Therapy certification exams. While board certification is not a must to obtain a position within the field, certification is preferred by most employers. Implementation of the CARE bill will determine its future requirement.

[edit] 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 (healthy tissue).

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. He/she 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. In many institutions, the medical dosimetrist also has the ability to execute planning for intracavitary and interstitial brachytherapy procedures, the application of specific methods of radiation measurement including ion chamber, thermoluminescent dosimeters (TLD), or film measurement.

Prior to the planning process, the patient will have a simulation for tumor localization to ensure reproducibility of treatment set up. 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.

Advancements in computer technology place dosimetrists at the forefront of many new processes. Using imaging modalities such as CT scans, alone or in combination with MRI or PET scans, 3-D computerised treatment-planning that allows the delivery of higher doses of radiation to a tumor while lowering the doses to the sensitive structures around it has been the state of the art for more than ten years now. Most recent advancements allow for the modulation of the intensity of individual beams of radiation to more greatly conform the radiation doses to the tumor and away from critical structures. Not only does this require that dosimetrists constantly stay abreast of the latest treatment planning methods/software/procedures, but also that they have extensive knowledge of anatomy, specifically CT, MRI and PET scan visualization of cross-sectional anatomy. This is necessary because every structure that dose is prescribed to or limited from must be contoured (drawn by the dosimetrist) on the treatment planning CT scan, with the exception of the tumor volume, which the physician must delineate. Continuing education is very important and is required to maintain a dosimetry certification. In some environments the medical dosimetrist plays a part in cutting edge clinical research for the development and implementation of new techniques in cancer treatment. Medical dosimetrists may also be active in teaching and research roles in an academic setting.

[edit] Salary

In 2008, according to the American Association of Medical Dosimetrists, the median annual salary of Certified Medical Dosimetrists with 0-4 years of experience was $87,500, with the typical salary range being $80,000-$95,000. The survey also demonstrates that salaries can vary greatly by geographical region, with the median salaries by division ranging from $89,000 in the North Central states to $109,600 in the Pacific states.*(AAMD 2006 Survey)[2].

The mean annual wage of American Medical Dosimetrists is around $100,000. New graduates are expected to make from $80,000 and the income for senior and chief dosimetrists ranges from $100,000-$130,000. .