What is a Dosimeter in Radiology?

Dosimeters are a type of device used to monitor ionizing radiation. They are commonly used for a variety of purposes, such as personal and patient dosimetry, environmental monitoring, spectroscopy, radiopharmaceuticals, and equipment verification. A dosimeter is a device that measures the amount of external ionizing radiation absorbed. It is used by the person being monitored when used as a personal dosimeter and serves as a record of the radiation dose received.

Modern electronic personal dosimeters can provide a continuous reading of the cumulative dose and the current dose rate, and can alert the user with an audible alarm when a specified dose rate or cumulative dose is exceeded. Other dosimeters, such as thermoluminescent or film types, require post-use processing to reveal the cumulative dose received, and cannot give a current dose indication while in use. Dosimetry devices are used to measure a person's exposure to radiation, also known as an external dose. Regulatory dose limits are in place for both the general public and occupational workers.

Federal guidance for emergency workers is included in state and local radiological emergency plans. The results of prior personal monitoring can be used as an indication, noting that the external radiation dose to the fetus is unlikely to exceed 25% of the personal dosimeter measurement (ICRP, 2000). The personal ionizing radiation dosimeter is of fundamental importance in the disciplines of radiation dosimetry and radiation health physics and is primarily used to estimate the radiation dose deposited on a person wearing the device. The vitamin D dosimeter indicates the photoisomerization of provitamin D3 to previtamin D3, which is the initial step in cutaneous vitamin D3 synthesis. Dosimeter badges control radiation doses using a small piece of X-ray film or, much more often, thermoluminescent dosimeter (TLD) chips. It is not really a direct dosimeter because there is no way of knowing the calibration constant in units of ferric ion molecules produced per unit of absorbed dose. MOSFET gate oxide, which is conventionally silicon dioxide, is an active sensor material in MOSFET dosimeters.

Diodes are increasingly being used to complement cameras, especially for dosimetry measurements in small fields. The most commonly used reference dosimeters include the Fricke, ceric—waxy, dichromate, ethanol—monochlorobenzene (ECB) and alanine dosimeters. Ideally, dosimetry measures the radiation dose; however, the instrument measures all the radiation to which you are exposed. This is necessary in order to be able to properly estimate the reflected pressure and, therefore, the true pressure felt by the surface underlying the assembled dosimeter. Routine (or work) dosimeters are used in radiation facilities for dose mapping and for monitoring processes under quality control. Such devices are known as legal dosimeters if they have been approved for use in personnel dose recording for regulatory purposes.

Inside the dosimeter, which is a plastic box with different filters as in film dosimeters, there is a detector slide.