Description

There are three basic types of personal monitors: film badges, TLD & pocket ionization chambers.
Radiation is not detectable by ordinary means; that is, we cannot see, hear or feel it. The detection of radiation requires instruments specifically designed to detect ionizing radiation. This is done indirectly by measuring the effect radiation has on a medium such as air (ionization) or film (density). 
Occupational dose limits are set by law to protect people who work with ionizing radiation and the limits are 50 rem/year to the occupational staff. The best way to determine how much exposure a person receives over a long time period is through the use of personal dosimetry devices.

TLD systems were introduced in SMC on 30/10/1997. Before that, film badges were sent to UK for processing & reading and results were received within 2 months.

Procedure

TLD use lithium fluoride (LiF), which stores radiant energy that is released when heated. This energy is emitted as light, which is measured by a device that then records the exposure based on light emitted. TLDs can be worn for up three months, can be reused & are more sensitive than film badges (to about 5 mrem or 0.05 mSv).
Following irradiation, the TLD phosphor is placed on a special dish, or planchet, for analysis in an instrument called a TLD analyzer. The temperature of the planchet can be carefully controlled. The TLD is reusable. When irradiated, the energy absorbed by the TLD remains stored until released as visible light by heat during analysis. This heating restores the crystal to its original condition and makes it ready for another radiation exposure.
TLD is used for both patient and personnel radiation monitoring (PRM), TLD badge should be worn at the level of the waist or at the collar/neck region. Radiographers rarely wear ring badges; most often, they are worn by nuclear medicine technologists because of their exposure from handling radioisotopes.

Location

There is 1 room located in the Radiology Department - SMC Old Building - Ground Floor (adjacent to the Chief Radiologic Technologist office).

Tel. No.:  17285541 / 17284017 / 17284023 

Ext. No. : 4023

Fax No.:  17285540

Equipment

Ministry of Health has one personal TLD system - modle 4500, manufactured by Harwsh.

Available Staff

Jagadeesh Babu & Nada Ali: Nuclear Medicine Physicist

Technologist: Mahdi Al Kalaiti
Radiographers: Amira Hassan & S.Majeed Al.Alawi
Radiation Protection Consultant: Jaffer Matter

Timing

Usually, TLD badge readings are taken in the beginning of each month. There is a special schedule for each department in MOH and BDF hospital to read the TLD badges.

The schedule for personal monitoring TLD badge readings is as follows:

1. SMC Radiology : 1st to 3rd working day (each month).
2. Health centers & Dental Staff : 3rd to 8th working day (each month).
3. Oncology & Bio-Medical Eng.: 5th working day (each month).
4. CHS students: 6TH working day (each month).
5. Operation theater, ward 411 & endoscopy unit: 7th working day (each month).
6. BDF Hospital & Sh. Issa Military Airport: 8th working day (each month).