J.

Brandon West

Radiation Protection in Medical Applications: Dosimetry in

Introduction:

In modern medicine, one of the most innovative approaches to treating

serious diseases, especially cancer, involves radiopharmaceuticals. These

special and unique drugs deliver targeted doses of radiation to affected

areas in the body that can then offer a glimpse into otherwise hidden

processes through radiographic imaging. With any use of radiation in

treatment, there is an underlying challenge. That challenge is how to deliver

enough radiation to treat the disease effectively without exposing patients

and healthcare workers to excessive and harmful levels of radiation.

Radiation safety is a concern for patients, physicians, and staff in many

departments. This is where dosimetry used to monitor radiation levels

becomes essential. By monitoring and controlling radiation doses, via

dosimetry, we can make radiopharmaceutical therapies both effective and

safe for patients and healthcare staff alike.

Dosimetry in Radiopharmaceutical Therapy:

Radiopharmaceutical therapy is well established for the treatment of

certain diseases, but monitoring the dose to patients and healthcare workers

is vital. Dosimetry, simply put, is the science of measuring radiation

exposure and dosage, and it is a key aspect of using radiopharmaceuticals

safely. Imagine radiation treatment as a precision tool: without dosimetry, we

wouldn’t know how much of it is reaching the intended area or if it’s

spreading elsewhere. Dosimetry ensures we’re delivering the right amount of

radiation to kill or shrink tumors while keeping exposure as low as possible

for the surrounding healthy tissues.

The aim of dosimetry is to estimate the radiation that an induvial

receives, but that is not easy. Every patient is different, and factors like body

weight, organ size, and how each patient metabolizes the

radiopharmaceutical effects how much radiation they receive (JNM, 2022).

Dosimetry methods, such as Single Photon Emission Computed Tomography

(SPECT) and Positron Emission Tomography (PET), offer a way to visualize

and calculate the radiation dose. However, these methods come with their

own challenges. One is ensuring that the radiation dose is high enough to

treat the cancer effectively while being controlled enough to avoid side

effects. Because these measurements are critical, there’s often a constant

push in the field to improve the precision of dosimetry calculations,

especially with the development of newer, more powerful

radiopharmaceuticals.

Radiation Protection in Therapy:

Radiation protection is the other slice of this medical treatment pie. To

keep both patients and healthcare workers safe, radiation protection

measures rely on the concept of ALARA, or “As Low As Reasonably

Achievable.” This principle requires healthcare workers to limit exposure

time, increase their distance from radiation sources, and use shielding

wherever possible. Physical forms of radiation protection include PPE and

Shields to aid in mitigating does to unintended targets. For patients,

dosimetry ensures that the dose is specific to the treatment while avoiding

unnecessary exposure while accounting for their specific anatomical

characteristics. Proper storage and testing of equipment is also done to

ensure the desired performance

Radiation protection efforts consider not only the type and amount of

radiation, but also other factors like frequency of exposure and proximity to

others. The three basic principles of radiation protection are justification,

optimization and dose limitation (NCBI, 2023) . Patients undergoing

radiopharmaceutical treatments might be advised to limit close contact with

others for a certain period afterward, reducing the chances of inadvertent

radiation exposure to family and friends. As experience and understanding,

from the medical field and other radiation sources as well, evolves so do the

principles of radiation protection for staff and patients. Radiation protection

is the balancing act that delivers enough radiation to treat while protecting

everyone involved is at the heart of responsible radiopharmaceutical therapy.

Case Study: Iodine-131 in Thyroid Cancer

One of the clearest examples of radiopharmaceutical therapy in action

is the use of Iodine-131 to treat thyroid cancer. Called Radioactive Iodine

Therapy, or RAI, this treatment uses radioactive iodine to target thyroid cells

specifically, given that iodine is naturally absorbed by thyroid tissue. In

dosimetry terms, this is ideal since the radiation dose is delivered directly to

the cancerous thyroid cells with limited effect on the rest of the body. It can

cause short-term and long-term adverse effects, including hypothyroidism,

radiation induced thyroiditis, secondary malignancy and reproductive harm

(NCBI, 2024).

Iodine-131 treatment shows the benefits of precise dose monitoring

and radiation protection. By calculating the right dose, clinicians can

maximize the treatment’s effectiveness while minimizing side effects.

Handling and administering Iodine-131 requires rigorous safety protocols.

Since the drug is radioactive, healthcare workers follow strict guidelines to

protect themselves and others while handling the isotope with specialized

equipment to ensure proper disposal of any waste. These measures extend

to patients as well who might need to avoid close contact with others for a

few days post-treatment. RAI is an essential tool in regulating differentiated

thyroid cancers

Conclusion:
J. Brandon West

In summary, dosimetry is not just a technical detail; it’s a foundational

part of radiation protection in radiopharmaceutical therapy, making sure that

treatments like those with Iodine-131 work as intended while safeguarding

everyone involved. Radiation protection strategies, bolstered by dosimetry,

are what enable us to effectively use powerful treatments against diseases

like cancer without undue risk. Continued research in this field isn’t just

beneficial; it’s essential. New imaging hardware, such as solid-state

detectors, full-ring detector geometries, and whole-body PET scanners, is

rapidly advancing, providing new opportunities for standardization of

methods across medical care centers. As we develop more advanced

treatments, the science of dosimetry and radiation protection will continue to

be our best ally in ensuring that these therapies remain both effective and

safe.
J. Brandon West

Sources:

JNM: Dosimetry in Radiopharmaceuticals

https://jnm.snmjournals.org/content/63/10/1467

NCBI: Radiation Safety Protection

https://www.ncbi.nlm.nih.gov/books/NBK557499/

NCBI: Nuclear Medicine Safety

https://www.ncbi.nlm.nih.gov/books/NBK603730/

NCBI: Radioactive Iodine for Thyroid Malignancies

https://www.ncbi.nlm.nih.gov/books/NBK580567/#:~:text=I
%2D131%3A%20This%20is%20a,safety%20materials%3A%20RAI%20is
%20hazardous.