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Technology applied: Radiation Regulations and Assessment Points for CT Scans


Technology applied: Radiation Regulations and Assessment Points for CT(Computed Tomography) Scans

CT, Industrial computed tomography, computed tomography, 工業用CT, 電腦斷層, X光機, 工业用CT, 电脑断层, X光机, 産業用CT, コンピュータ断層撮影, X-ray machine,

In the previous section, we introduced the practical operation of CT (Computed Tomography) scans. If you have already viewed it, you should now have a deeper understanding of CT scans. If you haven’t seen it yet, you can check it out from the link below.

From now on, we will introduce the radiation regulations regarding CT (Computed Tomography) and discuss the points to consider when introducing this equipment.

Radiation-Related Laws

After discovering the ability to observe the human body and substances by transmitting radiation, humanity actively applied this technology to various fields. However, as the application expanded, the realization of potential risks to human health emerged. Despite these risks, the technology still holds unknown and infinite applications. Therefore, countries worldwide, along with international organizations, have collaborated to establish laws and regulations regarding radiation, aiming to provide ongoing benefits to human society. While the specifics of radiation-related laws vary by country and region, they generally fall into categories of “Regulations on the Impact on the Human Body” and “Regulations on Equipment“.

(Note: The information provided below is a general overview, and actual laws and regulations may vary by country or region. For specific information on radiation-related laws in Taiwan, please consult the Atomic Energy Council of Taiwan, the Taiwan Radiation Protection Association, or authorized local organizations for radiation protection training.)

  • Units of Radiation

    In the realm of radiation measurement, commonly known units are the “Becquerel (Bq)” and the “Sievert (Sv)“. The former is primarily used to measure the amount of radiation emitted from radioactive substances (*), while the latter is a unit indicating the impact of radiation exposure on the human body.
    (* Examples of radioactive substances include elements like Radium (Ra), Uranium (92), or materials, soil, and food that become radioactive through absorption of neutrons or nuclear reactions involving high-energy radiation.)

  • Regulations on the Impact on the Human Body

    Excessive exposure to radiation can result in irreversible and permanent damage to cells or organs in the human body. Therefore, various national governments and international organizations (such as the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and the International Atomic Energy Agency (IAEA)) have established regulations and guidelines for devices and materials capable of generating radiation. The aim is to implement measures to ensure that operators of radiation equipment and the general public can use such technologies in a rational and safe environment.

    • International Regulations on Radiation
      The International Commission on Radiological Protection (ICRP), reorganized from the International X-ray and Radium Protection Committee in 1950, has been advising countries worldwide on the fundamental framework and protection standards for radiation. Particularly, recommendations made by the ICRP in 1977, 1990, and 2007 have had a profound impact on radiation protection laws and related regulations globally.
      For example, the ICRP’s 2007 recommendations specify that the effective dose for radiation workers is 100 mSv over a five-year period, with an annual limit of 50 mSv. The effective dose for the general public is set at 1 mSv per year.

      [Unit Conversion for Sievert (Sv)]
      1 Sv (Sievert) = 1,000 mSv (Millisievert)
      1 mSv (Millisievert) = 1,000 μSv (Microsievert)
      1 μSv (Microsievert) = 1,000 nSv (Nanosievert)

      If you want to learn more about international efforts on radiation, you can check the following links:

    • Regulations on Radiation in the Domestic Setting
      In Taiwan, the government refers to international standards, as mentioned earlier, and has established regulations on radiation. For instance, under the Radiation Protection Act, occupational exposure for radiation workers is regulated, stating that the effective dose for a period of five years should not exceed 100 mSv, and the annual effective dose should not exceed 50 mSv (Article 7). Additionally, the annual exposure limit for the general public is set at 1 mSv, aligning with the recommendations proposed by the ICRP in 2007.

      If you wish to learn more about regulations related to radiation, you can check the following links:

    • Reference Information
      In daily living environments, people are exposed to radiation to varying degrees. Radiation, in fact, comes from various sources such as cosmic rays, minerals, and food. For more details, please refer to the illustration below.

      一般游離輻射, 一般游离辐射, General Ionizing Radiation, 一般的な放射線,
      醫療游離輻射, 医疗游离辐射, Medical Ionizing Radiation, 医療用放射線,

      If you have any need for radiation-related education and training in the Taiwan region, please contact the Taiwan Nuclear Safety Commission , the Radiation Protection Association R.O.C., or radiation protection training institutions and organizations accredited by local authorities.

  • Regulations on Equipment

    In the domestic (Taiwan) legal framework, any room containing radioactive substances or equipment capable of generating radiation must adhere to radiation-related regulations. Typically, based on the intensity of releasable ionizing radiation, these are classified into four types: “High-Intensity Radiation Facility“, “Permit Type“, “Registered Type” and “Exemption Control“.

    • High-Intensity Radiation Facility
      It typically refers to facilities that can generate high-intensity radiation or use substances with high-intensity radioactivity.

      • Facilities using radiation-generating devices with an acceleration voltage of 30 MV (Megavolts) or higher.
      • Facilities using radiation-generating devices with particle beam energy of 30 MeV (Megaelectronvolts) or higher.
      • Facilities using sealed radioactive substances with an activity of 1,000 TBq (Terabecquerels) or higher.
    • Permit Type
      Facilities using non-exempt radiation sources that do not meet the requirements for registration and reporting, or those capable of directly irradiating the human body with ionizing radiation for non-medical purposes. Application for usage/possession permits must be made to the competent authority.
    • Registered Type
      • “Radioactive Substances”
        • Sealed radioactive substances specified in Attachment Sheet 1 of the Control Act, categories 4 and 5.
        • Radioactive substances that are part of devices or products, with emitted radiation being 1,000 times below the exempt dose, a dose rate below 5 μSv per hour at 5 cm from the surface under normal conditions of use.
        • Other radioactive substances not mentioned above, with emitted radiation 100 times below the exempt dose or as specified by the government or local authorities.
      • “Radiation-Generating Devices”
        • Devices with a voltage (kVp) of 150 kV (Kilovolts) or less or particle beam energy of 150 kV (Kiloelectronvolts) or less.
        • X-ray machines for box or baggage inspection, ion implantation machines, electron beam welding machines, or static eliminators with a dose rate below 5 μSv per hour at 5 cm from the surface under normal conditions of use.
        • Other devices specified by the government or local authorities.
    • Exemption Control
      Radiation sources where there is no safety concern regarding the generated radiation are exempt from regulation under the Radiation Protection Act. However, they must meet the following conditions.

      • “Radioactive Substances”
        • Emitted radiation does not exceed the exempt dose (different substances have different criteria).
        • Tritium (T or 3H) content in military targeting devices, grips, and aiming posts does not exceed 4 x 10^11 Bq.
        • Radioactive substances used in products like watches, smoke detectors, microwave receiver protective cases, navigational compasses, emergency indicator lights, compasses, and light bulbs meet the “Radiation Dose Standards for Goods.”
      • “Radiation-Generating Devices”
        Dose rate below 1 μSv per hour at 10 cm from the surface under normal conditions of use.

        • Voltage (kVp) of radiation-generating devices is 30 kVp or less.
        • Electron microscopes, cathode ray tubes, and devices specified by the government or local authorities.
    • Reference Information
  • Qualifications Required for Operators

    In accordance with relevant laws in Taiwan, individuals operating radiation-generating devices need to undergo training from government-approved training institutions or organizations and obtain specific qualifications based on the type of radiation source used.

    • High-Intensity Radiation Facility Category
      Operators should possess one of the following licenses or qualifications and, after completing training in equipment operation and practical operation, obtain a radiation equipment operator qualification.

      • Radiation Safety Certificate
      • Radiation Protection Personnel Approval Certificate
      • License for Radiology, Nuclear Medicine Specialist
      • Radiological Technologist License
    • Permit Category
      Operators should meet one of the qualifications listed below, pass the designated examination, and possess a Radiation Safety Certificate.

      • Complete a 36-hour operator training program from a government-approved training institution or organization.
      • Obtain at least 4 units in courses related to radiation protection.
    • Registration Category
      Operators need to meet one of the following qualifications.

      • Complete an 18-hour operator training program from a government-approved training institution or organization and obtain a certificate of completion.
      • Obtain at least 2 units in courses related to radiation protection (refer to the attachment sheet for the management of radiation protection operators for details).
      • Possess a Radiation Safety Certificate, Radiation Protection Personnel Approval Certificate, or a license for radiation equipment operation.
      • Hold a license for Radiology, Nuclear Medicine Specialist.
      • Hold a Radiological Technologist License.
    • Exemption Category
      Operators are not required to hold any of the mentioned licenses.
    • Reference Information

Things to consider before purchasing and operating equipment.

So far, we have provided a broad overview of the regulations related to radiation in Taiwan. However, many individuals may be wondering whether the installation of equipment, such as a CT (Computed Tomography) scanner, is beneficial and how it should be operated after implementation. For those facing such concerns, we would like to introduce key points to consider before purchasing and operating the equipment.

  • Clearly Define the Purpose of Equipment Operation

    Before considering a purchase, it is essential to clearly define the purpose and circumstances under which the equipment will be operated. Common use cases for operating a CT scanner include.

    • Inability to observe the internal structure of an object through visual inspection.
    • Incapability of conducting destructive testing on the object.
    • Verification of the internal condition and dimensions of assembled objects.
    • Identification of internal defects in the observed object.
    • Reverse engineering of the observed object.
      …And more

  • Verification of Object Dimensions

    Equipment for CT (Computed Tomography) scans can vary in terms of the range of objects they can capture, depending on the manufacturer. Therefore, it is advisable to confirm the dimensions of the objects to be scanned in advance and consult with the manufacturer or distributor.

    • Large CT Equipment
      Utilized for capturing large objects, often the size of office desks or even larger components. Due to the higher dose of radiation generated, these machines require a spatial environment equivalent to that of large machinery or production facilities. Installation is not possible without radiation protection measures (shielding). The strength of radiation categorizes them as “High-Intensity Radiation Facilities“.
    • Medium CT Equipment
      Designed for capturing medium-sized components, approximately the size of desktop computers. While the radiation generated is less than that of large equipment, it is stronger than that of small equipment. They require spatial environments suitable for medium-sized to small machinery or production facilities, and installation is contingent on radiation protection measures (shielding). The strength of radiation varies depending on the application but generally falls under the categories of “High-Intensity Radiation Facilities” or “Permitted Facilities.
    • Small CT Equipment
      Primarily used for capturing small objects, roughly the size of a 500ml bottle or smaller components. The radiation generated is lower, allowing for installation in spatial environments similar to an office desk (basic small equipment usually already incorporates radiation protection measures). The strength of radiation varies depending on the application, with many falling into the categories of “Permitted Facilities” or “Registered Facilities“.

  • Verification of Material Composition

    Computed Tomography (CT) scans fundamentally utilize X-rays to penetrate the object being scanned. The nature of the material’s composition can impact the transparency and image reconstruction. Generally, an approximate assessment can be made based on the atomic number in the periodic table. Materials with a higher atomic number make transparency more challenging, necessitating the use of more powerful radiation. However, the actual X-ray transmission rate and reconstruction accuracy can vary depending on the technology employed by different manufacturers.

  • Radiation Protection Measures

    reality, the radiation protection measures for Computed Tomography (CT) scanning equipment vary based on the dose of radiation it can generate. Here, we present the fundamental concepts of radiation protection. If you seek advice on radiation protection measures in the Taiwan region, please contact the Atomic Energy Council of Taiwan, the Taiwan Radiation Protection Association, or authorized local organizations for radiation protection training.

    • Facility Radiation Protection Measures
      Common radiation protection measures involve surrounding radiation-generating equipment with shielding materials such as lead (Pb, 82) plates or concrete to block or reduce radiation exposure.
      Radiation is categorized into “Particle radiation” and “Electromagnetic radiation,” with the former including Alpha particles, Beta particles, Neutron radiation, and the latter including Gamma rays and X-rays. Specific measures can be taken based on the nature of each type of radiation, as illustrated below.
      For example, Alpha particles can be blocked by a single sheet of paper, while Beta particles require thin metal sheets like aluminum or plastic. However, Gamma rays and X-rays, being more penetrating than Alpha and Beta particles, necessitate thick plates of iron (Fe, 26) or lead (Pb, 82) for effective blocking or reduction.

    • Human Body Radiation Protection Measures
      To prevent harm from radiation to the human body and ensure continuous benefits to society, the International Commission on Radiological Protection (ICRP) recommends adhering to three principles: “Justification“, “Optimization” and the “Application of Dose Limits“.
      Justification: The use of radiation-related technologies is only permitted when the benefits outweigh the risks.
      Optimization: If the benefits of an action involving radiation exceed the risks, the exposure should be reduced as much as reasonably achievable. This principle is also known as the ALARA principle (As Low As Reasonably Achievable).
      Application of Dose Limits: Dose limits are established for all exposure to radiation from any radiation source, whether it be operators of radiation facilities or the general public, to ensure they are not exceeded.
      Radiation protection measures for the human body can be categorized into “Prevention of External Exposure” and “Prevention of Internal Exposure“.

      • Prevention of External Exposure
        To prevent or reduce exposure from external sources, measures based on the principles of “Distance“, “Shielding” and “Time” can be taken.Distance: Increasing the distance from the radiation source reduces the exposure dose. The farther away, the lower the radiation dose.
        Shielding: Placing a heavy object between the radiation source and a person (shielding) reduces the exposure dose. The thicker the shielding material, the lower the radiation dose.
        Time: Reducing the duration of contact with the radiation source decreases the exposure dose. The shorter the contact time, the lower the radiation dose.

        *引用自US EPA(United States Environmental Protection Agency)-保護自己不受輻射傷害 [Protect Yourself from Radiation]
      • Prevention of Internal Exposure
        To prevent or reduce exposure from the inhalation or ingestion of radioactive substances, measures based on the principles of “Interception“, “Metabolism” and “Decontamination” can be taken.Interception: Preventing or reducing the inhalation or ingestion of radioactive substances by minimizing time spent in contaminated areas and avoiding contaminated food and drink.
        Metabolism: Enhancing the body’s metabolic function to eliminate ingested radioactive substances by increasing fluid intake and engaging in activities that improve metabolism.
        Decontamination: Removing residual radioactive substances from items like bags, clothing, and shoes to reduce the risk of inhalation or ingestion after leaving a contaminated area.
    • Reference Information


With the explanations provided above, I believe you may have gained a deeper understanding of the regulations related to radiation and the points to consider when introducing facilities. The discussion on CT (Computerized Tomography) scanning comes to a conclusion here. In the future, if there is an opportunity, we plan to introduce other applications and considerations related to CT scanning.

Until then, let’s meet again.

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