Dosimetry Archives

18 Dec 2023

Large size motorized 3D water phantom system for dose distribution measurement of radiation therapy beams in real daily routine practice used as a part of quality control of radiation therapy.

Cancer Treatment, Dosimetry, Nuclear Medicine, Radiation Therapy, Uncategorized Versant Physics 0 comment

What’s Inside Matters Most: Internal Dosimetry

Medical physics has been an integral part of medicine and healthcare over the greater part of the last century. Applying physics theory, concepts, and methods, scientists have created patient imaging, measurement, and treatment techniques that revolutionized the medical world. One product of medical physics has been the evolving specialty called radiopharmaceutical dosimetry, the calculation of absorbed dose and optimization of radiation dose delivery in cancer treatment. Today, we address internal dosimetry, the subset of medical physics that aims to optimize treatment and protect the patient from any undesirable side effects.

What is internal dosimetry?

Dosimetry is the measurement of radiation energy imparted to body organs and tissues. Radionuclides emit beneficial ionizing radiation that is useful for both diagnostic imaging of various diseases as well as for cancer treatment. Thus, medical internal dosimetry is the assessment of internal radiation dose from incorporated radionuclides associated with such life-saving radiopharmaceuticals.¹ Radiation dose is the amount of energy imparted by radiations emitted during disintegration of radioactive atoms that constitute part of the radiopharmaceutical chemistry. Dose to organs of the body is quantified per unit mass (or weight) irradiated tissue. Dosimetry provides the fundamental quantities needed for several important purposes, including record-keeping, radiation protection decision-making, risk assessment, and cancer-treatment planning.² The purpose and objective is to optimize medical benefit while minimizing potential radiation damage to body cells, tissues, and organs.

Dosimetry is a complex physical and biological science. Internal dosimetry provides critical information needed to better understand the biological mechanisms governing radionuclide uptake, translocation, and excretion from the body. The radiation dose imparted depends on the type, amount, and distribution of radionuclides, as well as specific nuclear properties, such as energy emitted.

Internal dosimetry differs from “external” dosimetry, which deals with the radiation dose from sources outside the body. Devices such as dosimeters measure external dosimetry directly, while internal dosimetry relies on indirect methods of radioactivity inside the patient using bioassay and imaging measurements.³ Bioassay is the measurement of the activity or concentration of radionuclides in biological samples. Samples can include urine specimens, feces, blood, or breath. Imaging techniques, such as whole-body counters or gamma cameras, can detect the radiation emitted by the radionuclides inside the body. This helps to provide information on their location and quantity.¹

When is internal dosimetry used in healthcare?

Internal dosimetry mainly benefits patients who receive radionuclide therapy, a treatment that involves administering radioactively labeled proteins, such as monoclonal antibodies, to target specific types of cancer.³ It also helps to evaluate and account for unique patient variations in biodistribution—the way that different subjects respond to treatment. Internal dose assessments analyze radionuclide behavior in both normal (healthy) organs, as well as tumors. For example, imaging measurements provide physicists with important information to determine tumor uptake, retention, and clearance. In doing so, administered activity can be tailored according to patient health status, age, size, sex, and basal metabolic rates.

How does internal dosimetry produce useful data?

The main challenge of internal dosimetry is to track and follow the uptake, redistribution, metabolism, and clearance of the administered radiopharmaceutical inside the body over extended time periods after administration.⁴ Tracking sometimes involves mathematical modeling to describe the absorption, distribution, metabolization, and excretion of radionuclides by the body. Biokinetic models may be developed from the study of population groups, knowledge of radionuclide behavior in different organs, and the unique chemistry of each radiopharmaceutical. Biokinetic models incorporate mathematical compartments representing a particular organ or a tissue, and descriptions of the transfer rates that reflect the movement of radionuclides from one body compartment to another.¹

Summary

Internal dosimetry is an important tool for radiation protection, especially in the fields of nuclear medicine, occupational health, and environmental monitoring. Dosimetry helps to customize or personalize nuclear medicine in cancer patients. In a broader sense, internal dosimetry is also applied to occupational and environmental health to prevent or reduce the exposure to radionuclides, by providing information on the sources, pathways, and levels of intake, and by suggesting appropriate measures, such as respiratory protection, contamination control, or dose limits. Internal dosimetry can also help to verify the adequacy of workplace controls, to demonstrate regulatory compliance, and to provide medical and legal evidence in case of accidental or intentional exposure.

Special software tools have been developed for the clinical nuclear medicine setting to facilitate medical imaging and calculate internal doses.

QDOSE^®Multi-purpose Voxel Dosimetry (Personalized Dosimetry in Molecular Radiotherapy) is a complete, one-stop solution software for all internal dosimetry needs with multiple parallel workflows. With USFDA 510(k) clearance granted in August 2023, QDOSE^®has proven its quality and compliance. To learn more, visit our QDOSE^®webpage or schedule a meeting with our team.

Sources

Sudprasert W, Belyakov OV, Tashiro S. Biological and internal dosimetry for radiation medicine: current status and future perspectives. J Radiat Res. 2022;63(2):247-254. doi:10.1093/jrr/rrab119
Bartlett R, Bolch W, Brill AB, et al. MIRD Primer 2022: A Complete Guide to Radiopharmaceutical Dosimetry. Society of Nuclear Medicine & Molecular Imaging; 2022.
Chapter 7 External and Internal Dosimetry. Accessed November 15, 2023. https://www.nrc.gov/docs/ML1121/ML11210B523.pdf
What is Internal Dosimetry – Definition. Radiation Dosimetry. Published December 14, 2019. Accessed November 16, 2023. https://www.radiation-dosimetry.org/what-is-internal-dosimetry-definition/

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24 Aug 2022

Dosimetry, Instadose+, Personnel Dosimetry, Radiation Safety, Radiation Safety Officer Versant Physics 0 comment

The 3 Best Personnel Dosimeters: Which Should You Choose?

Continual advances in medicine and medical technology have introduced a greater risk of exposure to ionizing radiation for occupational workers. This has increased the need for effective radiation monitoring services which are a key component of a compliant, well-run radiation safety program.

The problem for most new radiation safety officers is the sheer number of dosimeter types to choose from. How do you know which is the best personnel dosimeter for your radiation safety program? When should you consider phasing out your program’s existing dosimeters for something new?

To help you make your decision, we’ve put together this expert guide on the 3 best personnel dosimeters, their applications, and general specifications.

Instadose+ Wireless Dosimeter

The Instadose+ dosimeter badge is one of the best ways to effectively track cumulative dose for high-risk employees.

These revolutionary electronic dosimeters utilize Bluetooth technology, Direct Ion Storage (DIS), and SmartMonitoring to wirelessly and remotely transmit on-demand dose data. Mobile devices, such as a smartphone or tablets, as well as PCs or hotspot stations, are used to transmit and record the readings to the wearer’s private account.

The Instadose+ is the best personnel dosimeter for occupational workers like:

Healthcare workers
Nuclear medicine professionals
Chiropractors
Veterinarians
Power plant employees
Military personnel
Flight attendants
Lab assistants

Instadose+ badges have a useful dose range of 1 mrem – 500 rem (0.01 mSv – 5 Sv) and a minimum reportable dose of 3 mrem (0.03 mSv).

Energy response:

Photon 5 keV – 6 keV

Instadose+ badges are ideal for occupational workers who want access to their own data at the drop of a hat. The digital read-outs are recorded on a regular basis in accordance with the needs of the radiation safety program. This means no off-site processing.

TLD/OSL Dosimeters

The Genesis Ultra TLD-BP is a lightweight, eco-friendly, thermoluminescent dosimeter. It consists of two parts: a sealed blister pack, which protects the TLD’s internal components, and a separate holder with a clip for attaching to the collar or waist. The TLD also comes with a unique serial number that makes reassigning and tracking an individual’s occupational dose easier.

This personal dosimeter is useful for occupational workers with potential exposure to gamma, beta, neutron, or X-ray radiation. It can be used in a wide range of applications, including:

Nuclear medicine facilities
Medical imaging centers
Diagnostic research facilities
Hospitals
Universities
Nuclear power plants
Industrial facilities

The Genesis Ultra TLD-BP has a minimum reportable dose of 1 mrem (0.01 mSv) and a useful dose range of 1 mrem – 1000 rad (0.01 mSv – 10 Gy).

Energy response:

Photon 5 keV – 6MeV
Beta 0.251 MeV – 5 MeV
Neutron (TLD): Thermal – 6 MeV

Unlike with the Instadose+ dosimeter, TLDs require off-site processing to obtain the dose information. This process requires an in-house staff person to collect the dosimeters from wearers, send them out for processing, and re-assign new badges on a regular basis.

Ring Dosimeters

Mirion’s durable extremity dosimeters, commonly referred to as ring dosimeters, are the best personnel dosimeter choice for individuals who perform interventional radiographic procedures or who regularly handle radioisotopes.

There are several different options to choose from, including:

These are ideal for measuring low or high energy beta, gamma, or X-ray radiation to the hands and fingers. These dosimeters pair well with the Instadose+, which measures radiation exposure to the whole body, particularly in research and surgical environments.

Depending on the ring badge, the wear period can last from one week up to six months. They also are comfortable to wear under surgical gloves.

So, Which Is the Right Dosimeter for Your Radiation Safety Program?

When choosing a dosimeter for your radiation safety program, we recommend considering the following:

Functionality and scope of use. How will it be worn and by whom?
The information you need the dosimeter to record. Do you need to track full body dose, or the dose received to the extremities, like the hands and fingers?
Quality. A higher quality better made dosimeter might cost more up front, but it will withstand continual use and record accurate radiation dose.
Processing Requirements. Do you have the administrative support to collect badges from employees, send them out for processing, and redistribute new badges on a regular basis? If not, you may require a digital dosimeter like the Instadose+ that does not require processing.

If you’re still unsure, you can reach out to our physicists for a personal consultation about the best personnel dosimeter for your program.

Personnel Dosimetry Management with Versant Physics

Here at Versant Physics, we are passionate about radiation safety, adhering to ALARA principles, and helping radiation workers feel confident their dose measurements are accurate.

Our team of experienced physicists and technical support specialists will work with you one-on-one to ensure every aspect of your badge program runs smoothly and efficiently.

With Versant managing your badge program, you can expect:

Unparalleled customer service and technical support. We take care of everything from the initialization of badges for new wearers to badge troubleshooting.

Quality badge administration. Our team manages high-dose reports, adding and removing wearers from the program, and communicates consistently with your RSO.
Effective compliance administration. Our effective badge management processes are proven to improve compliance, from read day reminders to comprehensive monthly reports.

Schedule a consultation with our dosimetry program management specialists to get started!

07 Feb 2022

Dosimetry, Instadose+, Personnel Dosimetry, Radiation Safety, Regulatory Versant Physics 0 comment

How to Increase Dosimetry Compliance Rates with Versant Physics Proven Management Process

One of the many responsibilities of a Radiation Safety Officer is to manage their facility’s personnel dosimetry program and monitor the exposures of the radiation workers employed there. This may seem like a simple task; however, it can be a challenge to get workers to wear and exchange/read their dosimeters in accordance with state and federal regulations. This leads many RSOs to wonder if it is possible to improve dosimetry compliance rates, particularly in large programs that have hundreds of occupationally exposed individuals to monitor.

With the right dosimeter and the right management process, improving dosimetry compliance rates is very possible, regardless of the size of your dosimetry program.

Below we explain the common problems associated with traditional methods of personnel dosimetry program management, as well as offer a solution for improving your dosimetry compliance rates without increasing costs or workload for your staff.

The Problem with Traditional Methods of Dosimetry Management

Dosimetry is one of the key elements of a radiation safety program, but it can also be one of the biggest headaches for Radiation Safety Officers and Environmental, Health, and Safety managers. There are several problems with traditional methods of dosimetry management that managers often encounter, including:

A time-consuming badge collection and redistribution process
High costs of running a badge monitoring program
Time between when an exposure or anomaly is received and when an individual is made aware of the exposure
Keeping track of historical dose reads and measurements
Efficient communication with wearers regarding read reminders, exceeding dose limits, and more

These problems can make an RSO feel as though they’re herding cats at worst and like they’re constantly one step behind at best. Juggling these many tasks within just one aspect of a radiation safety program, along with a variety of other responsibilities, it’s not hard to see why dosimetry compliance rates can be rather low.

Versant Physics Personnel Dosimetry Management

Versant Physics manages personnel dosimetry programs a bit differently. In addition to using top-of-the-line electronic dosimeters that utilize the latest monitoring technology, our team of badge specialists and physicists combines customer service, technical support, and quality administration tactics to manage everything your program needs to run successfully. From ordering new badges to ensuring wearers read their badges promptly, our team’s management process is proven and effective.

Versant Physics also utilizes their proprietary radiation safety software Odyssey to manage the personnel dosimetry programs of their clients.

Odyssey is a cloud-based software that features an entire module devoted to personnel dosimetry management. The module includes useful tools like a query builder for compiling data records and a Form Generator for easy management of Form-5s. The module also features a series of customizable widgets that allow users to visualize pre-set metrics in their program, including a User Watch List for wearers likely to exceed internal or annual dose limits, Read Activity, and Badges Communicated.

Instadose+ by Mirion Technologies

Personnel dosimetry programs managed by Versant Physics also utilize the Instadose+ dosimeter. These small, lightweight badges combine Bluetooth technology, Direct Ion Storage (DIS), and SmartMonitoring to wirelessly and remotely transmit radiation dose data. Mobile devices, such as a smartphone or tablet, as well as PCs or hotspot stations, assist with this process.

Each dosimeter has a built-in memory chip with a unique serial code that is assigned to the specific wearer. The badges are assigned long-term, meaning they do not need to be sent in for processing at the end of a monitoring period. Instead, wearers are responsible for reading their badges per the monitoring period set up by their radiation safety program.

Reading the badge is easy and takes less than a minute to complete from start to finish. Wearers typically read their badge by opening the Instadose+ app on their mobile device and holding down the button on the back of the dosimeter for 5 seconds, or until the light on the top of the badge turns green. Readings are then stored within their secure account.

The Instadose+ allows for unlimited, on-demand dose reads, so wearers can complete this process as often as they desire. Not only is this useful from a dose history standpoint, but it also gives wearers the power to view their current and historical dose reads from their online account anytime they want. If they have a question or a concern, the answers are already at their fingertips.

Overall, the Instadose+ simplifies dose reads and makes them more accessible to the individual worker and radiation safety officer. This allows for improved dosimetry compliance across the board.

Its user-friendly read process, historical dose transparency, and accurate, reliable readings are some of the reasons why it is a key player in Versant Physics’ badge management process.

Badge Administration

Our experienced technical support specialists are equipped to handle the entire badge management process. This includes ordering badges from the manufacturer to removing wearers from the program. They also handle:

Remote and/or in-person badge training
Initialization of badges
Vendor credentialing and attestation
On-site event support

Compliance Administration

Versant Physics assigns a physicist to each client to help drive program compliance. The physicist works with the program RSO to develop an effective plan for making sure wearers read their badges. In the event there is no program RSO, Versant Physics’ physicists can serve as in-house RSOs as well.

Together with the badge team, they are also responsible for:

Regular communication with wearers (weekly, monthly, or quarterly)
Read-day reminders
Non-communicated follow-up reminders
Comprehensive monthly compliance reports
Dose monitoring
High dose alerts
Dose discussions with RSOs/workers

Consistent communication with wearers is a necessary part of improving overall dosimetry compliance rates. Depending on the monitoring period set by the program RSO, Versant Physics sends out scheduled read-day reminder emails. They also send follow-up emails to those that have not read their badge.

Furthermore, RSOs and program leadership are always kept in the loop as to where their program currently stands. This is done through the use of a comprehensive monthly report.

Versant Physics monthly report displays badges that have not submitted a reading during the monitoring period. It also lists duplicate badges, lost and defective badges, as well as any new badges that were assigned in that month. The report provides status updates on mid-month follow-up with wearers, an active wearer list organized by location, and high dose reports as well.

This report paints a clear picture of program compliance month over month and helps pinpoint areas of concern. It also addresses program elements that could be improved upon in the following months.

Customer Service and Technical Support

When issues arise or wearers experience problems with their badges, Versant Physics’ team of technical support specialists are trained and ready to handle them promptly. They will help with:

Badge troubleshooting
Issuing replacement badges
Phone and email support

Additionally, wearers have access to the Versant Physics support desk, where they can submit questions or concerns with their badges 24/7. All requests submitted by wearers and program personnel receive a response within 24-hours.

A Note on Radiation Dose Limits

Versant Physics clients can set their own dose limits for their employees (within the regulatory limits) depending on what works best for their program.

For example, some clients prefer to set specific limits for single doses. Others have more lenient thresholds that are measured quarterly. Whatever your program’s monitoring preferences are, Versant Physics is prepared to help you implement and manage them.

The Takeaway

Versant Physics badge specialists, physicists, and technical support teams provide efficient badge management catered to the needs of your program. With the help of the Instadose+ dosimeter, Odyssey radiation safety software, and years of experience managing dosimetry programs of all sizes, we can work with you to help improve dosimetry compliance rates in your program.

Contact our team to learn more about our badge management process and pricing.

27 Oct 2021

Small cute dog examined at the veterinary doctor, close-up

Dosimetry, Nuclear Medicine, Radiation Safety, Veterinary Care Dr. Darrell R. Fisher 0 comment

Radiation Dosimetry for Animal Subjects

This brief article describes ways in which Versant Medical Physics and Radiation Safety supports veterinarians and laboratory scientists who work with animal patients and laboratory research animals. Dosimetry is the science of measuring radiation and determining the amount of radiation energy that is imparted to living tissues. Radiation dosimetry is helpful in many medical science applications, such as correlating dose with biological effect, diagnosing disease, and planning radiation therapy for cancer treatment.

Nuclear medicine is a fundamental medical specialty in radiology. In nuclear medicine, radiologists administer radioactive drug products to patients to diagnose and treat many different health conditions.

In the healthcare setting, radiation dosimetry helps doctors to better understand the complex relationships between the amount (activity) of a radiopharmaceutical administered and the drug product’s biodistribution and metabolism in the body–such as its localization, retention, and clearance patterns.

The biological behavior of the pharmaceutical inside the patient can be imaged using modern radiation-detection systems in two or three dimensions. The localized uptake of a radiopharmaceutical can indicate the function of organs, such as the heart, brain, liver, and kidneys (among others), and is particularly helpful in diagnosing cancer.

Radiation dosimetry provides the fundamental quantities used for radiation protection, risk assessment, and treatment planning.

Animal subjects and humans are similar biologically in many ways. Therefore, different animal species may also be diagnosed and treated using the same or similar radiopharmaceuticals given to humans. And laboratory animals help researchers develop and test new drug products to ensure their safety and efficacy. Internal radiation dosimetry for animals has therefore become an important subspecialty of nuclear medicine physics.

Fundamental principles

Basic physics methods for internal radiation dosimetry are similar for animal and human models. Differences include the size and geometry of source-target organ pairs. Source organs are the internal organs for which images have been acquired or for which measurements have been made to determine the specific uptake, retention, and clearance patterns for the radioisotope.

Target organs are the organs and tissues for which radiation doses are calculated. Recognizing the important size and metabolic rate differences among species, care must be taken by the nuclear medicine physicist to use correct calculation methods and the most relevant animal model.

Common animal species

In veterinary medicine, pet owners take their animals to clinics for evaluation and treatment of cancer, hyperthyroidism, and organ function. The most common species include dogs, cats, and horses. In laboratory research, scientists use normal and immunodeficient mice, rats, rabbits, and sometimes dogs, monkeys, and miniature pigs.

Most biomedical research involves mice because they are less expensive, more easily housed and fed, and more efficiently bred for certain desirable genetic or mutational characteristics. Experiments with mice can also be accomplished in shorter time periods and with greater numbers for statistical purposes than other animal species.

Optimizing radiation dose for diagnostics or cancer treatment

Radiation dosimetry guides the veterinarian when choosing the right amount of radiopharmaceutical for a specific purpose. Every radionuclide in the chart has unique energy emission characteristics, half-life, and chemistry for applications as drug products. Some radionuclides are good for imaging in the clinic, whereas others are more appropriate for therapeutics. For each type, dosimetry is important to determine the characteristics that provide either the most useful images or the most effective treatment.

In both diagnostic imaging and cancer treatment, which are subspecialties of nuclear medicine physics, a balance must be achieved between administering too much or too little. Too little diagnostic drug renders poor images, too much radionuclide results in poorer quality images, making medical interpretation all the more difficult. In cancer therapy, too little radionuclide may result in an ineffective therapy, whereas too much radionuclide may result in undesirable normal tissue toxicity.

Excessive radionuclide handling in the pharmacy or clinic may also present an unnecessary radiation hazard to staff—or to pet owners, post-treatment. Radiation dose assessment helps veterinarians and research teams investigate the safest and most effective use of radiopharmaceuticals for the diagnosis and treatment of many disorders in animal subjects.

Dosimetry methods and models

For more than 50 years, specific methods and models for internal organ and tumor dose assessment have been developed by the special committee on Medical Internal Radiation Dose (MIRD) of the Society of Nuclear Medicine and Medical Imaging as a technical resource for both physicians and physicists. The virtue of the MIRD approach is that it systematically reduces complex dosimetric analyses to methods that are relatively simple to use, including software tools for experimental and clinical use.

Radiopharmaceutical dosimetry accounts for both physical and biological factors. Methods for internal radiation dosimetry tackle the challenge of assessing dose for many different radionuclides—each with its unique radiological characteristics and chemical properties as labeled compounds—in the highly diverse biological environment represented by the living body, internal organs, tissues, fluid compartments, and microscopic cells. Methods developed for human internal dosimetry are readily adaptable to animal subjects–taking into account the differences in size, geometry, and metabolic rates.

Why Versant Physics provides medical internal radiation dosimetry for animal subjects

Dogs, cats, and horses can be diagnosed and treated with radiopharmaceuticals for cancer and some non-malignant growths or overactive thyroid glands. Pet owners have often developed close family-like relationships with their pets, and veterinary care can be essential for preserving the animal’s health and well-being.

The development and testing of new radiopharmaceuticals usually begin with laboratory studies in mice. When promising results are achieved in mice, the investigators may advance to dog studies or even early clinical trials in humans, if approved by the Food and Drug Administration (FDA).

The FDA expects reliable and trustworthy radiation dosimetry for safety and efficacy evaluations. These assessments may rely on careful extrapolation of dosimetry results in animals to humans before drug trials can be approved for human patients.

Learn more about Dr. Darrell Fisher and his work in nuclear medicine physics here. Contact Versant Physics for your clinical dosimetry and personnel dosimetry needs.

Category: Dosimetry