There are three basic types of personal monitors: film badges, TLD & pocket
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.
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
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.
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
Ministry of Health has one personal TLD system - modle 4500, manufactured by Harwsh.
Jagadeesh Babu & Nada Ali: Nuclear Medicine Physicist
Technologist: Mahdi Al Kalaiti
Radiographers: Amira Hassan & S.Majeed Al.Alawi
Radiation Protection Consultant: Jaffer Matter
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:
- SMC Radiology : 1st to 3rd working day (each month).
- Health centers & Dental Staff : 3rd to 8th working day (each month).
- Oncology & Bio-Medical Eng.: 5th working day (each month).
- CHS students: 6TH working day (each month).
- Operation theater, ward 411 & endoscopy unit: 7th working day (each month).
- BDF Hospital & Sh. Issa Military Airport: 8th working day (each month).