Radiochromic film

Radiochromic film in hand

Radiochromic film is a type of dosimeter used primarily in the measurement and mapping of radiation doses. This technology is crucial in various fields, including radiation therapy, radiobiology, and industrial radiography, due to its high spatial resolution and ability to record a cumulative dose over time without the need for external power or readout equipment.

Overview

Radiochromic film contains a radiation-sensitive material that changes color when exposed to radiation. The degree of color change is proportional to the amount of radiation absorbed, making it possible to determine the dose based on the film's optical density. The films are typically made of a thin layer of active material coated onto a transparent substrate. The active layer consists of a polymer matrix embedded with radiation-sensitive dye molecules. When exposed to radiation, the dye molecules undergo a chemical change that results in a visible color change.

Applications

Radiation Therapy

In radiation therapy, radiochromic film is used for dose verification and quality assurance. It helps ensure that the radiation dose delivered to the patient matches the planned dose, minimizing the risk of under or overdosing. The film's high spatial resolution allows for detailed mapping of the dose distribution, which is essential for the accurate treatment of tumors while sparing surrounding healthy tissue.

Radiobiology

In radiobiology, researchers use radiochromic film to study the effects of radiation on biological systems. The film can measure dose distributions in irradiated samples, providing valuable data on how different types of radiation affect cells and tissues.

Industrial Radiography

Industrial radiography utilizes radiochromic film for non-destructive testing and inspection. The film can detect flaws in materials and components by highlighting areas of different radiation absorption, which may indicate cracks, voids, or other defects.

Advantages

Radiochromic film offers several advantages over other dosimetry methods:

• **High Spatial Resolution**: The film can resolve fine details in the dose distribution, making it suitable for complex dose measurements.
• **Energy Independence**: The response of the film is relatively independent of the energy of the radiation, making it versatile for use with different radiation types.
• **Self-Developing**: Unlike photographic film, radiochromic film does not require chemical processing to develop the image, reducing handling and processing time.

Limitations

Despite its advantages, radiochromic film has some limitations:

• **Cost**: The film can be more expensive than other dosimetry methods, limiting its use in some applications.
• **Sensitivity**: Some types of radiochromic film may have lower sensitivity compared to other dosimeters, requiring higher doses to achieve measurable color changes.
• **Calibration**: The film must be properly calibrated for accurate dose measurement, which can be time-consuming and requires access to calibration facilities.

Conclusion

Radiochromic film is a valuable tool in the measurement and analysis of radiation doses across various applications. Its high spatial resolution and ease of use make it an essential component of modern radiation dosimetry. Despite its limitations, ongoing research and development continue to improve the performance and accessibility of radiochromic film for both clinical and research purposes.