Category: Diagnostic Physics

01 Jun 2022
diagnostic imaging procedure

Diagnostic Medical Physics in Medicine: Why It’s Important

Many are unfamiliar with the important role that diagnostic medical physics plays in medicine, particularly in the diagnosis and treatment of diseases like cancer.

At Versant Physics, we provide a wide range of diagnostic medical physics services that help healthcare facilities safely and effectively execute procedures for the health and well-being of their patients. Our goal is to help facilities ensure their patients are protected from excessive levels of radiation and that diagnostic equipment is working appropriately, all while maintaining compliance with state and federal regulations.

In this blog post, we’ll break down what diagnostic imaging is, how and why physics principles are applied to diagnostic medicine, and the various roles of a diagnostic medical physicist to help clarify the importance of this profession.

What is Diagnostic Imaging?

Diagnostic Imaging is a range of techniques and equipment used to look inside the body. The purpose of this is to help physicians identify injuries and illnesses, and to help make an accurate diagnosis and treatment plan. This can include a variety of procedures, from simple X-rays for broken bones to more complex procedures involving the brain, heart, or lungs.

Diagnostic imaging procedures are usually painless and noninvasive. However, depending on the test being performed, some patients may be exposed to small amounts of radiation.

diagnostic medical physics

CT scans are a common example of a diagnostic imaging test that emits radiation. In a CT scan, the patient is exposed to a series of X-rays from a variety of angles which are then processed via a computer. The computer creates cross-sectional images of the inside of the body. CT scans are higher-quality images than a normal X-ray and allow physicians to view both hard and soft tissues in the body. They can check for stroke, internal bleeding, chest abnormalities, enlarged lymph nodes, abdominal or pelvic pain, tumors, and more. It is also used to monitor existing diseases such as heart disease and cancer. 

Other common diagnostic imaging procedures include mammography, which helps detect and diagnose breast cancer, fluoroscopy, magnetic resonance imaging (MRI), and ultrasounds.  

Diagnostic Physics and Medicine

Medical physics as a field is divided into five categories, including:

  • nuclear medicine
  • therapeutic medical physics,
  • medical health physics,
  • magnetic resonance imaging physics, and
  • diagnostic imaging.

Diagnostic medical physicists are responsible for ensuring the safe and effective application of radiation used in medical treatments. Specifically, radiology procedures. They work as a member of a patient’s care team, which typically includes physicians, dosimetrists, and radiologic technologists among others.

Equipment Evaluation and Compliance

One of the main roles of a diagnostic medical physicist is to ensure the safe operation of radiation-producing machines and diagnostic radiation detectors. This can include developing imaging equipment specifications, measuring the radiation produced by a piece of equipment prior to clinical use, and proving that the equipment is compliant with regulatory and accreditation requirements.

This also includes assessing all the software, algorithms, data, and computer systems associated with the radiation-producing equipment for accuracy and performance.

Acceptance Testing

Any unit that is used in a diagnostic setting must be periodically reviewed to ensure not only that the image quality is maintained, but that the unit is operating in compliance with the manufacturer’s specifications.

Most states require that a newly installed piece of diagnostic imaging equipment, whether it is brand new or used, be tested by a qualified medical physicist prior to first clinical use. This extremely thorough survey confirms that the unit was installed and set up correctly and ensures that it meets vendor and industry performance standards. It is also an opportunity to identify any potential issues with the unit before it is used on patients.

mammography unit

Typical units that require acceptance testing include fluoroscopic x-rays, radiographic x-rays, PET and PET/CT units, mammography equipment, C-arms, CTs, SPECT cameras, and PACS workstations.

Commissioning

The commissioning process for diagnostic radiation therapy machines such as Linear Accelerators involves testing the unit’s functionality and verifying that dose calculation algorithms work appropriately to produce measured dose calculations.  

Radiation-producing equipment like a LINAC is highly technical and specific. There are many requirements and protocols that detail how this unit should work, from how much energy it produces to the shape and direction of the beam. Diagnostic medical physicists are trained to measure, assess, and implement the optimal baseline values for a unit during the commissioning process.

Patient safety is the end goal of all diagnostic physics commissioning work.

Shielding

Another important aspect of diagnostic physics includes the planning and placement of shielding in areas that use radiation. In the United States, 35+ states require specific shielding designs in any room that houses radiation-producing equipment.

A diagnostic medical physicist can evaluate any shielding that is installed to determine if it will adequately protect workers, patients, and the public from the radiation outside of the scope of a specific treatment. This includes planning for material thickness as well as appropriate placement.

Versant Physics physicists are experienced with a range of equipment shielding requirements, including dental units, Cone-beam CTs, mobile c-arms, high-energy LINACS, Proton Therapy units, and Cyclotrons.

Our team is also experienced with different types of shielding materials, including non-lead materials, which are guaranteed to meet regulatory guidelines and ALARA principles.

Patient Dose & Treatment

Part of a diagnostic physicist’s job is also to ensure the safety of medical imaging modalities being applied in the treatment of individual patients.

They are responsible for determining the exact radiation dose a patient will receive in accordance with the radiation oncologist’s prescription before the patient begins treatment. Creating this therapy plan can take a few hours or multiple days, depending on the complexity of the illness. They also ensure radiation protection guidelines are in place, develop QA tools that ensure optimal image quality, and make sure that all operators are trained in the use of the best imaging techniques.

A diagnostic medical physicist may also monitor the dose of the patient throughout the course of their treatment.

Patients rarely interact directly with the medical physicist on their care team; however, they are a vital part of a safe and effective treatment process.

Versant Physics Diagnostic Support

Our board-certified physicists are able to handle diagnostic physics support for a variety of facilities, including hospitals, clinics, dental offices, and university health systems. With decades of experience, top-of-the-line equipment, and a passion for patient safety, our team is the best choice to assist with your diagnostic medical physics needs.

Contact us for a quote or to learn more about our medical physics support services.

28 Apr 2022
Radiation Protection Survey of Package with Pancake Probe

A Beginner’s Guide to Radiation Protection Surveys

The purpose of a radiation protection survey is to identify higher-than-normal doses of radiation in medical environments, labs, and anywhere radiation-emitting machines or radioactive materials (RAM) are used. They are required by state and federal regulations to be performed regularly to ensure the safety of technicians, technologists, nurses, doctors, researchers, and patients.

In this brief guide we’ll talk about what a radiation protection survey is, why it is important, and the type of equipment required to perform a radiation protection survey.

What is a radiation protection survey?

Radiation protection surveys are a way to directly measure radiation levels and identify potential leakage through breaks or voids in shielding.

Surveys are performed on:

  • Diagnostic fluoroscopic and radiographic equipment
  • Non-medical industrial equipment such as those found in veterinary offices
  • CT and CBCT machines
  • Particle accelerators
  • Irradiators
  • Bone mineral densitometers
  • Cabinet x-ray machines
  • Areas that use sealed sources of RAM
  • Packages containing RAM

The Different Types of Radiation Surveys

Not all radiation surveys are created equal. Let’s talk about some of the different surveys you may encounter a need for in your radiation safety program.

Radiation Emitting Device Survey

X-ray machines and other radiation-emitting devices require regular surveys to be performed to confirm that the machine is operating as expected. Radiation producing machines are surveyed for:

  • Timer accuracy
  • Radiation output
  • Focal spot size
  • kVp and mA
  • Beam limitation accuracy
  • Filtration
  • Skin entrance exposure / rate of exposure
  • Scatter radiation measurements
  • Photo-timer operation
  • Proper signage, labels, and postings

If high or unexpected dose rates are measured during a survey, the machine should be turned off and undergo appropriate maintenance.

Area Survey

Area surveys are required anywhere a radiation device is in use and the potential for receiving a higher-than-normal radiation dose is present. These surveys are typically measured in milliRoentgen per hour (mR/hr). The Roentgen is a measure of the amount of ionization in the air from the radiation.

Anytime you have an area survey performed, you are required to keep the official records of the survey results for 3 years.

Contamination Wipe Test

A contamination wipe test, also known as an indirect or swipe survey, is used to identify radioactive material contamination on surfaces, equipment, and clothing such as those found in a lab. This type of survey can identify non-fixed radiation left behind from radioactive solids, liquids, or gasses.

Lab tech performing a wipe test

Wipe tests are recommended to be performed frequently, especially if you are a HAZMAT employee that receives or ships RAM packages. A wipe test involves wiping at least 300cm2 of the package’s surfaces using an absorbent material. Afterward, the activity on the swipe is measured assuming a removal efficiency of 0.1 unless the actual efficiency is known.

Users in lab settings typically survey their work areas after an experiment or when a minor spill is suspected.

Radioactive Sealed Source

A radioactive sealed source is a source of special form RAM that has been contained or encapsulated to prevent contamination. These sources can only be opened by destruction. Semi-annual surveys of these sources are required to check for leakage.

Bioassay Survey

Internal exposure monitoring, or a bioassay survey, is performed on individuals that use unsealed radioactive materials. The survey estimates the internal organ dose to determine if any RAM has entered the body. It can also help determine if RAM is present in the air.

Bioassay surveys are performed by analyzing blood, tissue, or urine samples or by carefully monitoring the presence and/or quality of isotopes present in the organ of concern.

How often do I need to have a survey performed?

The frequency of a radiation protection survey depends on several factors, most of which depend on different state and federal regulations.

  • When a new or used x-ray equipment is installed
  • When existing x-ray equipment has been moved
  • If shielding has been modified
  • After the equipment has undergone significant repairs
  • If a potential problem is indicated

Who performs these surveys?

In general, surveys on radiation-producing equipment are conducted by health physicists and medical physicists.

Is special equipment required for a survey?

Special equipment is required to detect ionizing radiation. Most equipment is hand-held measurement instruments called survey meters. This equipment is required to be calibrated annually to maintain accuracy and to ensure that reliable measurements are recorded.

Survey meters consist of:

  • A probe which produces electrical signals when it is exposed to radiation
  • A control panel readout with an electronic meter that gauges the amount of radiation exposure
  • A speaker which provides an audible indication of the radiation exposure

There are several different kinds of survey meters physicists use to perform radiation surveys.

Geiger-Mueller Pancake Probe

One of the more commonly used survey meters is the Geiger-Mueller Pancake Detector. Although there is no “universal” radiation detector, the G-M Pancake Probe comes pretty close. This is because the probe can detect alpha, beta, and gamma radiation, although they are generally used for detecting Beta Emitters. These probes come in a variety of models and configurations.

Surveying open package with pancake probe

The probe detects radiation by collecting counting gas within the tube. The counting gas is ionized when a photon or particle interacts with a released electron. When the voltage is high, radiation that interacts with the counting gas produces an electronic pulse that is measured with a separate counting instrument.

A pancake probe has a thin layer of mica on the active face of the detector, which allows most alpha and beta particles to interact with the counting gas inside the tube.

G-M Pancake Probes are frequently used to detect C-14, Ca-45, P-32, P-33, and S-35.

Scintillation Survey Meter

A scintillation survey meter is used to detect low-energy Gamma Emitters and x-rays. The scintillator, or sensor, is made of a transparent crystal or liquid which shines when it interacts with ionizing radiation. The scintillator is attached to a photosensor like a photomultiplier tube which detects the generated light.

This survey meter detects I-125 and Cr-51. They are an ideal equipment choice for surveying electron microscopes and x-ray diffractometers.

Diagnostic Physics Support and Radiation Surveys by Versant Physics

When it comes to hiring a consultant to perform radiation protection or QA surveys for your equipment, you want to make sure you’re working with the best. People who are experts in state and federal regulations regarding radiation machines and RAM, have access to top-of-the-line survey equipment and understand the importance of adhering to ALARA standards.

Versant Physics’ proactive and transparent diagnostic physics support process minimizes safety concerns and reduces the likelihood of compliance violations. We support our clients by sharing our knowledge of best practices in advanced technologies, and by utilizing a team-based approach we feel enables our clients to focus on maximizing the quality of patient care.

Contact our team for a free 30-minute consultation to learn more about our diagnostic physics and radiation survey expertise.


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Forum Article "Radiopharmaceutical Extravasation: Pragmatic Radiation Protection" published ahead of print

An article written by Versant team members Dr. Darrell R. Fisher, Ph.D. and Misty Liverett, M.S., CNMT was recently published ahead of print in Health Physics. The article provides an unbiased, scientific assessment of pragmatic and reasonable health physics actions that should be taken in response to inadvertent extravasation events. Click the link below to view the article.

Permits

THE PERMISSION SYSTEM FOR INVENTORY TRACKING, MACHINE MANAGEMENT & EQUIPMENT CATALOG MODULES

Permit Profile

Each permit has a dedicated profile of information that includes authorized personnel, radioactive material, machines, and devices. Permit conditions, completed audits, and forms are also found on this profile.

Authorized Condition Database

Create and view authorized conditions included on permits. Previously created authorized conditions are listed with their code, category, and description.

Permit Enforcement

Information specified on a permit not only serves as a record of that permit, but also controls what can be added to other modules. The location, owner and type of radioactive materials, machines, and equipment can be enforced by permits.

Permit Audits

Perform permit audits, mail the results to relevant personnel, and track responses to non-compliances.