Stanford University

Radiation Safety for Clinical Use

As radioisotopes and X-ray devices are increasingly used in diagnostic and therapeutic procedures, the need for adequate radiation safety becomes ever greater. It is our priority to protect our patients and their families, workers, and the general public.

Health Physics provides radiation safety oversight and guidance to all groups who use radioactive material or radiation-producing devices in clinical or research applications, including radiology, interventional radiology, nuclear medicine, and radiation oncology.

Computed Tomography (CT)
  1. Computed tomography (CT) is one of the most commonly used diagnostic imaging techniques. Its use is regulated by the California Department of Public Health (CDPH), the Joint Commission (TJC), and the American College of Radiology (ACR). Because it is used frequently and involves exposing patients to relatively higher levels of radiation, a strong quality assurance program is critical. The medical physicists in the Health Physics group are involved in all aspects of the CT practice at Stanford hospitals and clinics, including:

    • CT scanner quality control testing to ensure adequate image quality and dose performance
    • ACR accreditation and compliance of CA State Law, CDPH regulation and TJC requirements
    • CT dose monitoring: help Radiology department establish a CT dose monitoring system to record, review and analyze dose data of all CT scans at Stanford hospital and clinics.
    • CT protocol optimization for specific clinical tasks by utilizing our state-of-the-art CT equipment and novel iterative reconstruction techniques
    • Develop and provide lectures to hospital faculty, staff, and trainees on topics including CT technology, CT dose optimization, Fluoroscopy dose optimization, and radiation risk from ionizing imaging exams
    • Advise hospital faculty and staff on the strategy of reducing medical ionizing exposures and provide risk communication information for patients who underwent ionizing radiation exams

Human Research
  1. If you are a protocol director or a research coordinator for human research studies, you must use the eProtocol system to enter the details of the study.

    If your human research involves radiation (e.g. CT scans, PET/CT scans, nuclear medicine scans, or DEXA scans), you will be required to complete Section 4: ʺRadioisotopes or Radiation Machinesʺ and Section 9: ʺRisksʺ for all procedures that involve radiation. In parallel to the Institutional Review Board (IRB), we will review your protocol and provide a radiation dose estimate, as well as risk language for the informed consent process.

    The ultimate goal of eProtocol (and our review) is to ensure that each subject is properly informed of the risks he or she may be exposed to while participating in the study. After the eProtocol radiation exposure edits are complete, your human research protocol will be reviewed by the Clinical Radiation Safety Committee (CRSCO). CRSCO approval is then communicated directly to the IRB.

    To view the guidance document for preparing research proposals involving diagnostic use of ionizing radiation in human use research, please click here.

Interventional Radiology
  1. Interventional Radiology utilizes fluoroscopy as an imaging tool during semi-invasive surgical procedures. During fluoroscopy, the fluoroscope shoots x-rays directed at the patient, but also causes a lot of radiation scatter to the surrounding surgical room. In addition, another source of radiation exposure in interventional radiology comes from the numerous radioembolization procedures completed every week. There are two types of radioembolization procedures, Theraspheres and Sirspheres, which use Yttrium-90 (Y-90) microspheres that both emit a high energy beta utilized in the treatment of liver cancer.

    Without the services provided by Health Physics, these vital procedures could not be handled safely as well as in compliance with State and Federal regulations. Health Physics is the liaison between the Interventional Radiology and Nuclear Medicine departments, where working between these two groups ensures accurate radiation doses, safe delivery to the patient, and radiation safety for all involved.

Nuclear Medicine
  1. Nuclear Medicine is a medical specialty involving the application of radioactive substances in the diagnosis and treatment of disease. What distinguishes nuclear medicine from other imaging modalities is in its ability to not only image the anatomy but also its function utilizing Single Photon Emission Computed Tomgography (SPECT) and Positron Emission Tomography (PET) modalities. As imaging technology has evolved, hybrid imaging has become the standard by combining the nuclear medicine modalilties mentioned with computed tomography (CT). These advances in medical technology carry many benefits in the diagnosis for patients but also introduces potential hazards from using radioisotopes and X-ray devices. To ensure radiation safety, the Health Physicist is involved in all aspects of the utilization of radiation at all Stanford Hospital and Clinics.

Radiation Oncology
  1. Radiation Oncology offers radiation therapy using high-dose rate (HDR) brachytherapy and linear accelerators for the treatment of cancers. High-dose rate brachytherapy is a treatment in which a protected radioactive material source, usually Ir-192, is placed directly within or near the tumor site for a short period of time. Linear accelerators such as Cyberknife or TrueBeam are high energy x-ray sources that use highly precise beams to treat various cancers.

    Due to potentially unwanted high exposure rates from radiation therapy, Health Physics collaborates with Radiation Oncology to ensure that doses to staff and patients are minimized.   Health Physics also provides shielding evaluations during the design phase of these types of facilities and registers and drafts reports for compliance with the State of California.

  1. X-rays are used in both research and clinical settings at Stanford. Health Physics provides the University and Hospital with the services necessary to comply with all X-ray regulatory requirements, and may be consulted with any radiation safety issues or questions.

    X-rays are commonly used in diagnostic imaging practice, including radiography, fluoroscopy, computed tomography, mammography, etc. Our group at Health Physics provide service and support to Stanford hospital and clinics in managing all ionizing imaging equipment:

    • Machine registration with the State of CA
    • X-ray machine quality control testing
    • Facility room shielding review

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