Radiochromic film

Radiochromic Film

Radiochromic film in hand

Radiochromic film is a type of film used in radiation dosimetry to measure and record the dose of ionizing radiation. It is particularly useful in medical applications, such as radiation therapy, where precise dose measurements are critical for effective treatment planning and delivery.

Properties

Radiochromic films are self-developing, meaning they do not require any chemical processing to visualize the dose distribution. The film changes color in response to radiation exposure, typically darkening in proportion to the absorbed dose. This color change is due to a polymerization reaction in the film's active layer, which is sensitive to ionizing radiation.

The films are composed of a thin layer of radiation-sensitive material coated onto a polyester base. The active layer contains a dye or a dye precursor that undergoes a chemical change when exposed to radiation, resulting in a visible color change. The degree of color change is proportional to the amount of radiation absorbed, allowing for quantitative analysis.

Applications

Radiochromic films are widely used in various fields, including:

• Radiation therapy: In radiation therapy, radiochromic films are used to verify the dose distribution delivered to patients. They are placed in a phantom or directly on the patient's skin to measure the dose received during treatment.

• Quality assurance: In medical physics, radiochromic films are used for quality assurance of radiation therapy equipment. They help ensure that the equipment is delivering the correct dose and that the dose distribution is accurate.

• Research: Radiochromic films are used in research settings to study the effects of radiation and to develop new radiation therapy techniques.

Advantages

Radiochromic films offer several advantages over other dosimetry methods:

• High spatial resolution: The films provide high-resolution dose measurements, which are essential for accurately mapping dose distributions.

• Ease of use: They do not require chemical processing, making them convenient and easy to use.

• Wide dose range: Radiochromic films can measure a wide range of doses, from very low to very high, making them versatile for different applications.

• Stability: Once developed, the films are stable and can be stored for long periods without significant fading, allowing for retrospective analysis.

Limitations

Despite their advantages, radiochromic films have some limitations:

• Energy dependence: The response of radiochromic films can vary with the energy of the radiation, which may require calibration for different energy levels.

• Temperature sensitivity: The films can be sensitive to temperature changes, which may affect the accuracy of dose measurements.

• Cost: Radiochromic films can be more expensive than other dosimetry methods, particularly for large-scale applications.

Related Pages

• Radiation dosimetry
• Radiation therapy
• Medical physics
• Ionizing radiation