Evolution of Medical Dosimetry: Training, Tools, and Technology

Evolution of Medical Dosimetry

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When I began my journey in radiation therapy more than 40 years ago, I never imagined how drastically the field of medical dosimetry would evolve. From learning on the job to seeing today’s AI-assisted planning, the transformation has been nothing short of remarkable. In this blog, I’d like to share how training, certification, and technology have changed not only the field—but the way I’ve grown within it.

From On-the-Job Training to Accredited Programs

After working as a radiation therapist for about a year and a half, I had the opportunity to transition into dosimetry through an on-the-job training position within my department. At the time, that was the most common way to enter the field—no certification required.

In 1988 the first Medical Dosimetry Certification Board (MDCB) certification exam was given, which was a first step toward setting a recognized minimum standard for dosimetrists. Although not a required certification, I gained my certification in 1990 and proudly maintain it to this day.

However, it became clear over time that on-the-job training varied widely in quality. Some dosimetrists are trained in well-rounded clinical environments, while others have limited experience in specific disease sites. That’s why I fully supported the MDCB’s 2017 decision to raise the bar by requiring a bachelor’s degree and graduation from a JRCERT-accredited training program. It was a necessary step to ensure all dosimetrists met consistent and rigorous standards.

For those exploring modern educational options, including remote and hybrid learning, check out our guide on Online Medical Dosimetry Programs.

The Early Tools of the Trade

Looking back, it’s almost hard to believe the tools we used at the start of my career. The first patient I saw planned was done by wrapping solder wire around the patient to trace a contour, then transferring that shape to graph paper for digitization. That one slice was all we had to work with—no tissue density corrections, no 3D calculations. Just a basic plan that still took over an hour to compute.
That was our reality. And yet, it laid the foundation for where we are today.

Watching Imaging & Planning Evolve

One of the most pivotal moments in my career was the introduction of CT simulation around 1994. Before that, CT scans were printed on film, placed on projectors, and traced by hand. Once CT simulators entered the picture, we could import hundreds of slices directly into planning systems. It revolutionized how we viewed patient anatomy and calculated dose.
I also witnessed the rise of image fusion. With the advent of rigid and deformable registration, we could finally incorporate MRI and PET scans into our planning workflow—something that drastically improved accuracy in defining target volumes.

From Cerrobend Blocks to Dynamic Modulation

In the early years, we shaped beams with Cerrobend blocks—heavy, manually placed, and stored per patient. Then came asymmetric collimation, dynamic wedges, and eventually multi-leaf collimators (MLCs). These were game-changers.
Suddenly, we had the ability to dynamically shape with millimeter-level precision. I remember the first time I saw intensity-modulated radiation therapy (IMRT) in action—it was like stepping into the future.

The Modern Dosimetrist’s Toolbox

Just yesterday, I planned a treatment using a dataset of over 200 CT slices. The system handled advanced corrections, precisely adjusted the MLCs into 2.5 x 2.5 mm beamlets, and calculated the dose in just a few minutes, a drastic improvement from the hour it used to take for a single-slice plan when I first started. The technological progress is truly remarkable.
Record and verify systems have also come a long way. What used to be manually entered—beam settings, couch positions, compensators—is now automated with built-in safety checks. It’s dramatically improved both efficiency and patient safety.

Looking Back, Looking Ahead

This journey—from solder wire and graph paper to AI-assisted dose planning—has been one of the most rewarding parts of my life. The field of dosimetry has grown, and I’ve grown along with it.
What started as a leap of faith into on-the-job training has become a career built on certification, continuing education, and cutting-edge tools. I truly believe today’s dosimetrists are more qualified and better equipped than ever before—and the technology we have now is just the beginning.

If you’re curious about where I believe the field is headed next, I’ve shared my full vision in a separate blog: The Future of Medical Dosimetry.