Physics How to Become a Medical Physicist in 3653 Easy Steps - Comments

[Choppy]

Choppy submitted a new PF Insights post

How to Become a Medical Physicist in 3653 Easy Steps

Continue reading the Original PF Insights Post.

 

[Greg Bernhardt]

Fantastic resource @Choppy!

 

[Greg Bernhardt]

Anyone here considering going into Medical Physics?

 

[Greg Bernhardt]

Would love to hear about you day to day work too.

 

[Choppy]

Would love to hear about you day to day work too.

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 modeled 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 @gleem or some of the other Medical Physicists on the forums could chime in about their experiences in the field.

 

[EricVT]

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.

 

[Desafino]

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?

 

[Godric]

This was a good read, thank you Choppy! I am just in the planning stages for grad school applications and medical physics is where I would like to go. Some questions:

Are the accredited Canadian programs mostly equal? Or are there some that are above the rest?

What are the hours like? Do they compare well to the salary?

 

[Choppy]

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?

That's actually a very good question. The short answer is that the most risky thing I do every day, by far, is drive to and from work. (Even more so as I am a fair weather bicycle commuter.)

The longer answer is that medical physicists work with ionizing radiation and therefore receive some occupational exposure beyond what they would receive in daily life. The work is monitored and must adhere to federal (and provincial) regulations. Facilities and procedures are designed so as t1o keep doses "as low as reasonably achievable, social and economic factors considered" (ALARA).

Because of this occupational exposure we are classified as Nuclear Energy Workers (I'm speaking specific to Canada here. The terminology and specific details may be somewhat different in the US or elsewhere, but the general concepts are fairly universal), and as NEWs we can legally receive a higher effective dose than anyone else. In Canada the limit is 50 mSv for anyone year period and 100 mSv over any five year period, whereas anyone else (except pregnant NEWs) is limited to 1 mSv for a year. For reference, mean exposure from background radiation is about 2-3 mSv per year, a dental x-ray ~ 0.01 mSv, and a CT scan ~ 10 mSv.

See table 1 in this link for a comparison of different measured exposures between professions. Medical physicists and other NEWs will often carry around personal dosimeters (little carbon-doped aluminum oxide crystals - optically stimulated luminescence dosimeters) that are read out on a quarterly basis, to track their occupational exposure. So we have a good idea of how much radiation people in these professions get statistically. According to that data, medical physicists receive on average about 0.04 mSv per year. To put that in context, aircrew receive on average about 0.26 mSv per year. Other professions that work with radiation receive significantly more dose. Nuclear medicine technicians for example have a higher exposure (~1.6 mSv) because they regularly handle radioactive tracers. Medical physicists, are, for the most part, well away from the radiation sources they use.

According to the International Commission on Radiation Protection, the risk of cancer incidence due to occupational radiation exposure works out to about 4%/Sv. At 0.04 mSv/year you have to assume that this rate extends linearly towards the low doses area, which is a big assumption (see the linear no threshold hypothesis). But even then, the risk of developing cancer is very small.

At one point I did a calculation using my own personal data and the probability of dying in a fatal car crash (not just getting in a crash, but dying) on my way to work was about two orders of magnitude higher than developing cancer through occupational radiation exposure. And cancer can sometimes be cured.

 

[Choppy]

Are the accredited Canadian programs mostly equal? Or are there some that are above the rest?

There are advantages and disadvantages to each. CAMPEP accreditation is the big key. Beyond that you need to find something that fits your needs. Point to keep in mind (copied from my own personal blog):

• Access to modern equipment and facilities.
  Is the program affiliated with a hospital? What imaging and treatment modalities are available there? Has anything new been installed recently? Does the program have access to a PET or PET/CT machine for example? An MRI machine? Does the facility perform any form of stereotactic radiotherapy?
• Hands-on experience with that equipment.
  Most students won't get to use hospital equipment freely, but are you going to get through the program without ever having touched a linac?
• An empahsis on the physics of medical physics compared to rote regurgitation of the didactic material.
  Technology in medical physics changes quickly. The physics doesn't change that much. (Flags to look for might include lower admission standards compared to other programs [don't require a physics degree], students who tell you the course work is easy compared to undergrad, minimal research done by faculty, etc.
• Opportunities to do QA work.
  This will (i) give practical, relevant experience, (ii) give insight into the work involved with being a clinical Medical Physicist, and (iii) help to pay some of the bills.
• Research interests of the faculty.
  Even if you are more oriented towards clinical work than research, you'll be doing some kind of project for your graduate work and as a clinician, you'll be bringing new technology into the clinic on a regular basis and constantly challenged by problems for which there is no readily available answer. Look at the current projects being done in the department. Look at how much funding the faculty has and for which projects. How closely does what's being done align with your own interests?
• Another dimension of research that can be easily overlooked is commercialization opportunities.
  Over the years there have been lots of start-up companies that have come out of medical physics research. Not everyone is interested in such things, but if I was a student today I would certainly factor this in.
• Faculty dedicated teaching time.
  When you talk to current students in the program, do they have regular meeting times with their supervisors? Are they happy with the quality of the lectures? Or are the faculty impossible to pin down due to clinical commitments?
• Where do the graduates end up?
  Most accredited medical physics programs now publish such information online. Are the graduates getting residencies? Are they going places you could see yourself going?
• Cost and financial support.
  Not all programs cost the same. Not all guarantee financial support or opportunities for QA work or TA/RA positions. Also factor in cost of living.
• Quality of extra-curricular life.
  It's important to weigh in all the other stuff too (available activities, sport, groups, city life, commute times, weather, will your partner be happy there, etc.) You don't want to be miserable in your down time.

What are the hours like? Do they compare well to the salary?

Long. May long weekend... I was in the clinic. Friday, I left just after 6:00 and our clinical day ended at 4:30.
Medical physics is not a profession to dive into if you like having a lot of free time, in my experience.

 

[Godric]

Thanks for your answers Choppy. Medical Physics continues to sound very interesting and very rewarding to me, but also very intimidating for a variety of reasons.

Like any professional program it is a little terrifying not knowing if it is really right for you before applying. Of course hopefully I would figure out if it was right before I go through a Masters and a PHD. I know I would prefer professional work to academia, but there are other options out there too that I should probably consider, yet I keep finding myself coming back to Medical Physics. I suppose I have some time to figure this out, as long as I get applications submitted by December.

Another question, what would you say would be the general time split between different activities when doing clinical work? Like for example is the majority of your work QA?

 

[Choppy]

Another question, what would you say would be the general time split between different activities when doing clinical work? Like for example is the majority of your work QA?

Very generally I'd say my time breaks down as:
10% Teaching
20% Research (including professional development)
10% Administration (meetings, paperwork, radiation safety, dissemination of information, planning activities, etc.)
60% Clinical (broken down further as follows)
10% treatment planning related activities (checking plans, investigating planning-related problems)
25% clinical projects (commissioning new equipment/software, writing procedures, following up on outstanding problems, etc.)
05% responding to urgent problems (assessing and clearing machine interlocks, assessing or fixing a down machine, etc.)
10% computing and medical devices network administration (including software upgrades, chasing connectivity problems, account admin, device admin, and treatment planning system administration)
10% quality assurance work (maybe 5% making actual measurements, and the other 5% analyzing, assessing, archiving, etc.)

Note that the staffing model where I work includes a physics assistant, who will do a lot of the QA measurements. In the US it's a lot more common not to have a physics assistant and in the research and teaching dimensions often aren't there. I might argue that even purely clinical physicists will have to give the occasional in service presentations, and they will still need time for professional development though. So whereas I can devote about 30% of my time to such activities, those in purely clinical roles will only have a little bit of time here and there for it. And sometimes professional development has to be done off-the clock. (For what it's worth a good chunk of my research is done after clinical hours.)

It's also important to remember that this is an average over a year. It's not uncommon to spend the entire day responding to an urgent problem or trying to figure out some dimension of a clinical project.

 

[gleem]

In the US in a community hospital or free standing clinic teaching is limited to in-service talks which depending on the program may includes nurses, technologists, physicians, maintenance/housekeeping/ security personnel. Research might be a clinical paper on some physics aspect of treatments or collaboration with a physicist(s) at another institution. And as Choppy indicated this will mostly be done outside clinical hours. Networking is important to develop helpful relationships for professional development (you need to periodically talk to other physicists to keep you sharp). Depending on the program your in department time can be up to 60+ hours per week averaging maybe 45- 50 hours/week. This assumes dosimetry support but you will probably do some dosimetry because of spiking treatment load or because you feel you should do some of the more complex plans. You must learn to manage your time effectively and maintain a doable schedule.

One final point, communication and cooperation is very important and will help make your job more enjoyable. You will depend on the technologist to do their job well including keeping you informed of equipment or treatment issues. So you must establish a rapport. You don't want to be overbearing. People skills are very important. All this applies to all members of the department.

 

[Cumberland]

Thanks for the post.

I've noticed that many medical physics graduate programs do not require a BS in physics, but require at least a physics minor alongside a closely related major such as engineering. Are there certain undergraduate physics courses that an engineering student may not have in their curriculum that would be beneficial in a medical physics program?

Did you take any life science courses in undergraduate study, and do you recommend it for students interested in medical physics? Some programs require such courses, but others do not. For example, the University of Kentucky requires a year of anatomy and physiology.

 

[Godric]

Thanks again Choppy, I like the sound of how varied the work can be. That's definitely encouraging.

If I told you the schools I was interested in applying to is it possible you would know more specifics about them?

 

[gleem]

Are there certain undergraduate physics courses that an engineering student may not have in their curriculum that would be beneficial in a medical physics program?

Nothing that is critical however engineering knowledge can be useful especially in electronics. Also courses in general biomedical engineering could be beneficial. I sat on electrical safety committees most of my career and had frequent interactions with the Clinical/Biomedical Engineering departments. And as Choppy pointed out you may have network administrator duties in the department so some knowledge of networks is advantageous.

Did you take any life science courses in undergraduate study,

As an undergraduate I had idea of medical physics. I took a fellowship in MP after my doctorate. Most of my knowledge of A&P was self taught. I would recommend taking it. Doc's may assume you are familiar with terminology and procedures. General medical science knowledge is good for job enrichment. You will feel more at home. We teach radiation therapy technologists Physics not because they "need" but to give then a rational background to understand their work and the tools they use so why not learn as much medical science as the technologists.

 

[Choppy]

I've noticed that many medical physics graduate programs do not require a BS in physics, but require at least a physics minor alongside a closely related major such as engineering. Are there certain undergraduate physics courses that an engineering student may not have in their curriculum that would be beneficial in a medical physics program?

A lot can depend on the specifics of the engineering program. There are some courses in a standard undergraduate physics program that are perhaps not all that directly relevant to clinical medical physics, and a lot of courses within some engineering streams that would be highly relevant. A signal or image processing course would be very relevant to a career in medical physics for example and those are usually offered through engineering departments.

Entrance requirements are department-specific. For me, it's a flag if a department is lax on its physics requirements - a flag, not a "no go" mind you. A lot of clinical medical physics is very basic stuff. If a student doesn't have an introductory general relativity course, it probably won't make much of a difference in a typical medical physics career. But courses like a senior lab, or a computational physics course can make a huge difference. I've heard that there are some programs that will admit life science undergrads, but I don't know the details there. You'll struggle with basic imaging theory if you've never seen a Fourier transform.

Did you take any life science courses in undergraduate study, and do you recommend it for students interested in medical physics? Some programs require such courses, but others do not. For example, the University of Kentucky requires a year of anatomy and physiology.

I took first year biology and a physiology course for engineers and physical science students. You tend to "pick up" the biology that you need, but if you don't have a solid grounding in it (at the first year level - an understanding of DNA, respiration, mitosis, cell cycle, etc.) you'll have a lot of catching up to do.

The problem is always that there are more courses that are likely to help you than there is time to take. I would recommend a first year biology course if you can fit it in though.

 

[Cumberland]

Thanks for the replies.

I'm an NE major. The department at my school has a two semester medical physics sequence that I'm hoping to take as technical electives if I'm able. They're 500 level courses. I assume it's a broad overview of the field.

Is chemistry at all relevant to medical physicists? I'm only a few hours from a chemistry minor. I've already finished organic chemistry, and I'm considering following up with biochemistry or biophysical chemistry to complete my minor; however, if biologic chemistry is not relevant to medical physics, I may take an inorganic chemistry sequence to level my understanding.

Nine hours of the physics minor requirements at my school are 300 level and above courses of my choosing. Any recommendations? I was considering a year of quantum mechanics and something else, but I'm undecided.

 

[gleem]

Is chemistry at all relevant to medical physicists?

In my experience no. But my experience is clinical MP not research. If you where to be able to do radiobiology research it might be useful but I'm not positive. As a physicist you should have some QM, although you will not use it.

 

[Choppy]

If I told you the schools I was interested in applying to is it possible you would know more specifics about them?

Possibly, but I'm a lot more familiar with the Canadian programs than the American ones, and I'd rather not spout opinions on whether one program is better than another. In most cases there are advantages and disadvantages.

Is chemistry at all relevant to medical physicists? I'm only a few hours from a chemistry minor. I've already finished organic chemistry, and I'm considering following up with biochemistry or biophysical chemistry to complete my minor; however, if biologic chemistry is not relevant to medical physics, I may take an inorganic chemistry sequence to level my understanding.

Nine hours of the physics minor requirements at my school are 300 level and above courses of my choosing. Any recommendations? I was considering a year of quantum mechanics and something else, but I'm undecided.

Basic chemistry - the kind of stuff that you would cover in a first year class - is definitely helpful. (And for what it's worth I would be surprised if a program would grant a physics degree, or in your case a nuclear engineering degree, without it). Advanced biochemistry is not all that relevant on the level of clinical medical physics, but as Gleem said it can be important depending on the research interests you have. I also agree with Gleem about QM.

I know it would be nice to have a definitive answer - take these courses any you'll be set for a career in medical physics. But really, once you have a core course load that qualifies you to get into the graduate programs you want, you're generally best to follow your own interests.

 

[gravenewworld]

Here's a job posting I came across for those that want to do Med Physics:

https://hrnt.jhu.edu/jhujobs/job_view.cfm?view_req_id=66945&view=sch

Nice salary to boot.

 

[Gruxg]

Would love to hear about you day to day work too.

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 modeled 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 @gleem or some of the other Medical Physicists on the forums could chime in about their experiences in the field.

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.

 

[Gruxg]

------------
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!

 

[Choppy]

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.

No, I think we're the exception. About 300 - 400 patients per year per linac is more the norm and sometimes this is even exceeded. I should probably say that our centre is fairly new and only running at about 60% of our capacity. That's expected to change in the coming years though.

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.

Thanks for adding your experience. Do you have any academic responsibilities as well?

 

[Gruxg]

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.

No, I think we're the exception. About 300 - 400 patients per year per linac is more the norm and sometimes this is even exceeded. I should probably say that our centre is fairly new and only running at about 60% of our capacity. That's expected to change in the coming years though.

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.

Thanks for adding your experience. Do you have any academic responsibilities as well?

-----
I don'tt have academic responsabilities for the moment, but some of my mates do have.

 

[Alexmer]

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?

 

[Choppy]

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?

Good question.

First, a lot can depend on the specifics of the program that you go through. My personal experience tended to be a lot closer to the "normal" physics route. In addition to the didactic medical physics courses, for the PhD I was also expected to complete the same core courses as the other physics graduate students.

One of the issues with the medical physics curricula though, is that there is so much material to cover, most programs have moved away from the model I experienced and are trending towards more of a professional school model. It's definitely possible to get into a program where you might be frustrated or disappointed with the level of actual physics that's covered, where they throw a lot of "superficial" stuff at you without really digging into it's detailed derivation (I'm looking at you Klien-Nishina cross section).

So yes, I would say that it certainly can be difficult to keep up with current research in other branches of physics. But as a medical physicist, your primary goal (as far as keeping up with things goes) is to be able to keep up with research in your own field, and if you come through a good program, that shouldn't be too difficult. On top of that, you also have to keep up with a lot of medical research. You need to know what technologies or treatment methods your team will be pushing you to implement, and why they want it (and whether it's a good idea in the first place). Research in other fields comes after that. And there really is a lot of time left over for that, unfortunately.

And just like any PhD, a lot can also depend on the specific project that you take on for your graduate work (and later on the projects you take on as a resident, post-doc, or medical physicist). Sometimes in order to make progress in your own field you have to get intimately involved with another.

The take-home message is to really look into the programs that you apply to and make sure they're a good fit for where you see yourself going.