medical physics

How to Become a Medical Physicist in 3653 Easy Steps

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For many physics students, Medical Physics is that branch of the discipline that seems to hover in the no-man’s land between academia and “industry.”  It’s not as glamorous or fundamental as some of the other branches that may have originally drawn students into physics in the first place.  It didn’t get a chapter in Hawking’s “A Brief History of Time” or and episode of Sagan’s “Cosmos” or Tyson’s recent reboot.  But it comes with a lot of pragmatic appeal – particularly when one begins to think about translating an education in physics into a career.  The median salary for a Medical Physicist in the US is in the ballpark of $190,000 USD for PhDs with board certification.  And the work will genuinely make a difference in people’s lives.

It’s a decent gig if you can get it.

Here, I hope to offer some insight based on my own experience to students or recent graduates curious about Medical Physics careers.

What the Heck is Medical Physics?

In its broadest scope, Medical Physics is the branch of physics that applies to solving problems in medicine – problems regarding how various forms of electromagnetic and particulate radiation interact with the human body, development of imaging devices, optimization theory, modeling biological responses to treatment or disease kinetics, etc. are all examples.  In that sense, there is actually a lot of research in physics and in engineering, mathematics, chemistry and biology that could qualify as “Medical Physics.”

I’ll largely be focusing on clinical Medical Physics though.  By that I mean the practice of physics in the professional provision of clinical services.

Radiation Oncology Physicists

Roughly 80% of Medical Physicists work in the field of radiation oncology – the application of radiation for the treatment of cancer (and a few other types of diseases).  This work has many dimensions, which is why sometimes it can be difficult to get a straight answer on what a Medical Physicist does.  It’s important to underscore that although patients may not frequently see a Medical Physicist as often as they would a physician or a nurse, nearly all the work a Medical Physicist does has a direct impact on patient care.  Broadly speaking, the work of a clinical radiation oncology physicist involves:

  • establishing, supervising and executing a quality assurance program for the devices used to deliver radiation and their supporting systems (linear accelerators, brachytherapy afterloaders, image guidance systems, proton or heavy ion accelerators, CT simulators, MRI simulators, etc.)
  • commissioning of new radiation treatment devices, facilities and their supporting systems as they are introduced into clinics
  • administration of the computer networks and software used to run the radiation delivery machines and generate treatment plans
  • responsibility for the integrity of radiation therapy treatment plans (which can take the form of plan checking, consulting on difficult, abnormal or new modality plans, and in some cases planning treatments)
  • developing and updating procedures for radiation therapy treatment, and providing technical guidance for administrative decisions
  • investigating clinical problems (everything from calculating the dosimetric consequences of a treatment error to computer network slowness to chasing down the source of an asymmetry in a treatment beam)
  • leading clinical investigations or projects (examples include measuring how accurate your treatment planning system is at calculating dose in the presence of prosthetic hips, or investigating the clinical consequences of delivering radiation at a faster dose rate)

Diagnostic Imaging, MRI, and Nuclear Medicine

The other roughly 20% of Clinical Medical Physicists work in diagnostic imaging, MRI (MRI is its own specialty), and nuclear medicine.  I won’t go into as much detail with respect to these sub-specialties, but conceptually much of the work is similar and again, has a direct impact on patient care.  These sub-disciplines involve commissioning new imaging devices, establishing and maintaining quality assurance testing, network administration, clinical problem solving, consulting, administration and clinical research.  In the imaging specialties the focus of the commissioning and quality assurance work is to provide the optimum image quality for the best possible diagnoses, while balancing that with the safe delivery of radiation and minimizing unnecessary exposure.

Radiation Safety

Medical Physicists (from all disciplines) often also function as radiation safety officers (RSOs) – dealing with the occupational issues involved with the safe delivery of radiation.  This can involve personal dose monitoring, supervising a radiation safety program, teaching, and dealing with all of the licensing (applications, record-keeping, inspections, follow-up actions) involved with operating devices the deliver ionizing radiation.  I should note however that RSOs are not always Medical Physicists.  There is an entire sub-field called Health Physics that deals specifically with radiation safety.  Because of the cross-over between the fields, it’s not uncommon to see Medical Physicists in these roles.

Academics (Teaching and Research)

In addition to clinical duties, many Medical Physicists also have academic appointments at universities and therefore are involved in both teaching and research.  I don’t have exact breakdowns, but academic appointments appear to be more common in Canada than in the USA.  In the USA, there are more small and independent facilities.  Roughly one fifth of American Medical Physicists are solo practitioners and in such circumstances, academic responsibilities are unlikely.  In Canada, cancer centers are all publicly funded and tend to be larger facilities associated with universities, and as such have a mandate to conduct research.  According to a recent COMP survey, roughly a quarter of Canadian Medical Physicists’ time is, when averaged out, spent on teaching and research combined (the standard deviation is quite wide in my experience).

Teaching duties can involve instructing medical physics graduate students, medical physics residents, undergraduate physics students, radiation oncology residents, radiation therapy students, medical students, and many others.  These can be through formal university courses, laboratories, or semi-formal teaching situations such as in-services.

Medical Physics research is difficult to summarize because there are a very large number of problems in medicine that draw on physics to solve.  If you want to get a real idea of what current research involves I would recommend reading the following journals:

There are a lot of other very good journals in the field, and if you’re serious about exploring research in Medical Physics, I suggest starting with one of these and following your nose.  If you are an undergraduate student, your library should have a subscription to these journals.  If not, many of them provide open access to the more popular articles – editor’s choices, or award winners.  Another very good resource that I use to help keep on top of research in the community is Medical Physics Web. This site provides layperson-friendly summaries of recent publications in the fields along with author interviews that can help one learn about the field, which can be especially helpful as you learn a lot of the technical jargon.


The Long Road – Becoming a Medical Physicist

I’ll start at the end point, with the term Qualified Medical Physicist.  What that usually refers to is a clinical Medical Physicist who has obtained a recognized certification of clinical competence.  That certification has more-or-less become the gateway into the profession.  This certification is given by a number of internationally recognized bodies.  In North America these bodies are:

Technically speaking there are only a handful of states that legally restrict the practice of medical physics to state-licensed Medical Physicists.  In most other places in North America, to work as a Medical Physicist, board certification is not technically mandated.  But don’t let that allow you to brush off its importance.  Any person considering a career in Medical Physics should really treat board certification as a mandatory career step because:

(a) in any job competition those with certification are chosen over those without it,
(b) general trends in all healthcare fields are moving towards increased regulation, and
(c) preparing for certification actually does make you more competent in the clinic.

In order to get to board certification, the post-secondary education and training route typically looks something like this:

  1. Undergraduate Degree in Physics (or a closely related field)
    Your undergraduate degree should provide you with a solid foundation in physics.  Medical Physics is very much an applied physics field, and in many ways a lot closer to engineering than some other branches of physics.  Closely-related fields include engineering physics, nuclear engineering, physical chemistry, biomedical engineering and some (but not all) undergraduate programs that focus specifically on medical or health physics.  Competitive GPAs for entry into most graduate programs are in the ballpark of 3.5 on the 4.0 scale.
  2. Graduate Degree in Medical Physics
    Graduate programs in Medical Physics combine (in different ways) roughly one year of didactic courses that you need to cover to be competent in the field, and a research project, and differing degrees of hands-on experience.  At minimum you require a master’s degree for certification, however due to the competition for residencies a PhD is often the status quo.  It’s not uncommon for students to get the MSc first, attempt to get a residency and return for the PhD if unsuccessful.  Just as in other branches of physics, the PhD has a much larger research project that is expected to be novel. Program accreditation is critical.  CAMPEP, the Commission on Accreditation of Medical Physics Education Programs, is a commission set up to ensure consistent quality of education in Medical Physics graduate programs and residencies, and they maintain a list of accredited graduate programs.  By 2016, the CCPM will require that applicants for membership have completed either an accredited graduate program or an accredited residency.  In order to write part 1 of the ABR Medical Physics exam, candidates will need to be enrolled in or have graduated from an accredited medical physics program.
  3. Medical Physics Residency
    A residency is a 2-3 year position where the resident moves through various clinical rosters (in radiation oncology these would include: machine QA, commissioning, treatment planning, CT simulation, brachytherapy, special techniques, etc.) while working under the supervision of a Qualified Medical Physicist.  It is also common for residents to be expected to make substantial contributions to clinical or research projects (which is why the PhD is often preferred for these positions).  Again the CCPM will require either the graduate program or the residency to be accredited.  In order to write part 2 of the ABR medical physics exam, you need to have completed an accredited residency.
    I also have to mention the odds of getting a residency.  For the past few years, CAMPEP statistics suggest that about 280 students are graduating from accredited graduate programs.  At last count there were roughly 120 residency positions.  This is a major issue in the system right now.  There are lots of things you can do to help make sure you get a residency.  And the AAPM is working to address the issue on multiple fronts.  I suspect that in five years it will be much less of an issue, but the numbers are what they are for the time being.
  4. Other Options – DMP Programs
    Another option for students coming out of undergrad are the Doctor of Medical Physics (DMP) programs, which roughly combine an MSc with a residency over four years.  These are fully accredited programs and offer the guarantee of a residency.  My understanding, however, is that the student pays for the residency component, where I personally feel that residents need to be reimbursed for the valuable work they do for a Medical Physics Department.
    Side note: I believe there is currently only one of these programs that is accredited.
  5. Other Options – Physics PhDs from Other Fields
    There are also options available for those who have PhDs in other branches of physics who are interested in a professional career in Medical Physics without completing a second PhD.  The first, is obviously to do an accredited two-year MSc.  In my experience a person with a PhD in a different field and and MSc in Medical Physics is seen as equivalent to a candidate with a PhD in Medical Physics in terms of competing for jobs (all other factors being equal).Another option is a post-PhD certificate program (see accredited graduate programs, or University of Calgary ROP), which can be completed in under a year.  These essentially allow the PhD to complete the didactic coursework in Medical Physics and are treated as equivalent to having completed a graduate degree in medical physics.

For details about how the training process works in other parts of the world, I would recommend:

So there you have it – the good, bad, and ugly about a career in Medical Physics.



26 replies
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  1. D
    Desafino says:

    Maybe this is a dumb question, but what kind of long-term radiation exposure risks are there for medical physicists?  Is the cancer rate amongst radiation oncologists higher than the general population?

  2. G
    Gruxg says:

    400 patients/year with 2 linear accelerators, wow, what a luxury! Is it more or less the normal ratio in north america?In my country the typical ratio is about 400 patients/year per linac. In my hospital even more: we have 2 linacs and we treat about 900-1000 patients/year (the health system is very different with its advantages and its drawbacks) Besides, the profesion of "dosimetrist" is not well stablished here (they are therapists trained for this task) and about 50% of the treatment planning is done by the medical physicists.

  3. G
    Gruxg says:

    ————Oops!  I don't know what happened, I wanted to reply to Choppy but my response is not displayed as I expected, it seems as if write a Choppy's paragrah and the isn't any break between his words an mine. Sorry!

  4. A
    Alexmer says:

    Thank you for the great article. I've noticed that medical physics PhD and masters programs don't involve any of the advanced physics courses that a normal physics PhD/masters student would take. Do you feel like it is difficult to keep up with current research in physics without that education?

  5. C
    Choppy says:

    [QUOTE=”Greg Bernhardt, post: 5106566, member: 1″]Would love to hear about you day to day work too.[/QUOTE]

    My personal day-to-day work can vary considerably. I work in a smaller clinic that has two linear accelerators and treats about 400 patients per year.

    Examples of some recent clinical projects:
    [*]Recommissioning both on-board imaging systems (these are used for taking CT images or orthogonal images of patients immediately prior to treatment). This work involves making a large set of measurements to ensure that the electronics are working properly, that the system has the proper resolution, contrast, image scaling, physical alignment, etc, that the dose per image is what we think it is, that we’ve properly characterized the Houndsfield units, etc., and that all legal obligations are met.
    [*]We just finished annual calibrations. This involves scanning to ensure that the beam profiles are consistent with the planning system and then using a calibrated ion chamber to verify and tweak the outputs of the linear accelerators. We need to be very accurate precise about the amount of radiation (dose) we put into people.
    [*]Commissioning of a new dose calculation algorithm for our treatment planning system. For years we’ve been using a superposition-convolution system, but this new system solves the Boltzmann equation numerically on a grid. Bringing this into the clinic meant verifying its operation under a set of known conditions, and then investigating situations of particular interest – how well does it calculate does far outside of the primary field, or how does it perform for small fields, for example. We also have draft guidelines for when and how to use it, what options are appropriate, and develop an experience base for inconsistencies with past clinical experience.
    [*]Commissioning a new film dosimetry system. Radiochromic film is used for making planar measurements of dose. I had to write software to translate scan images of the film into dose maps.
    [*]Establishing a procedure for planning around prosthetic implants. CT data sets have a maximum pixel value, and so having a photon beam go through high density objects (metals) can introduce a lot of uncertainty in a plan. Attenuation may be incorrect, but by how much? Is backscatter modelled correctly? We turn to good ol’ Monte Carlo calculations for a benchmark.
    [*]Measuring the radiographic properties of the “couch” (table top support that patients lie on while being irradiated) to update the model of it in our treatment planning system.

    Regular “day-to-day” activities:
    [*]Checking treatment plans. This can involve everything from a set of basic safety checks to assessments of patient-specific measurements of the fields that we intend to deliver to a patient to make sure the intensity modulation is delivered correctly.
    [*]Responding to problems with the linear accelerators or CT simulator. This can involve everything from assessing/clearing an interlock that’s caused by either a serious electronics failure that could harm a patient or a simple “glitch,” to figuring out why the network has suddenly slowed down and files are taking too long to transfer.
    [*]Planning consults. Sometimes the treatment planners will run into an abnormal case and they need another opinion on something. How much radiation is a patient with a pacemaker like to receive and what’s the risk of malfunction for a given course of therapy?
    [*]Quality assurance measurements. We’re fortunate to have a physics assistant to help out with the regular monthly measurements, but the Medical Physicist is responsible for the oversight of the program. That means we’re continually updating devices and procedures, and making decisions about how to respond to measurements that fall outside of tolerance. Can you continue treating for the day if your linac output is off by 2%?
    [*]Meetings. Medical Physicists tend to get asked to a lot of meetings because we speak different languages. Sometimes I feel like a translator between the radiation oncologists and therapists, the electronics technicians, IT, managers, dosimetrists, nurses, etc. which is a necessary role because working as a team we need to make decisions that can affect patient care. Sometimes it’s lifeguard duty where 90% of the meeting is not relevant, but 10% is life-or-death critical.
    My day also has some academic dimensions to it. I teach a graduate course in the fall, I supervise two graduate students, and I have my own research projects.

    I’m sure I’m forgetting something. Maybe [USER=298988]@gleem[/USER] or some of the other Medical Physicists on the forums could chime in about their experiences in the field.

  6. E
    EricVT says:

    In addition to providing treatment planning consults medical physicists can also perform quite a bit of treatment planning directly.

    At my facility the medical physics group performs all of the stereotactic radiosurgery planning (where a large amount of highly focused radiation is delivered in one treatment) and brachytherapy planning (where radioactive materials are positioned inside of or directly adjacent to the tumor itself). We are also directly involved in the administration of these and other special treatments by being present and available to see that they are given safely and correctly. Often this can even involve spending time in operating rooms assisting the physicians with the technical aspects of their radiotherapy procedures.

    It is also relatively likely that at some point in your career you will be designated as the radiation safety officer (RSO) for your facility, which requires familiarity with state and federal regulations related to radioactive materials and radiation-producing equipment. You will be responsible for the education and monitoring of all staff involved in radiation procedures (radiation oncology, nuclear medicine, radiology, etc.) and will interface with government agencies to ensure compliance with their rules. Should you be working somewhere that decides to replace or add radiation equipment you may also be tasked with the design and evaluation of shielded rooms that protect staff and the general public from medical radiation.

    You may also have responsibilities where other physicists and dosimetrists report directly to you as a manager and you are responsible for managing certain supplies and budgets and employee hours. You could still have clinical physics responsibilities but also have supervision responsibilities for other employees.

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