Prior to performing a radiation survey using the survey meter, the RHSO must first ensure that the instrument is functioning properly. The RHSO must perform an operational check using the check source (Strontium-90) that is affixed to the side of the instrument. The location of the check source is marked with "Caution - Radioactive Material" (CRAM) tape and an "X" to indicate where to position the probe when performing the operational check.
Also, affixed to the instrument is a sticker that states the range limit for the probe. The operational reading must fall within the range for the instrument to be considered functional. If any reading is not within +20% of the reference check source reading, the instrument should be operationally checked and recalibrated if necessary. Prior to using the survey instrument, the RHSO are required to perform the following steps:
• Check the batteries by turning the selector switch to "battery check". If the voltage is below the battery test line, REPLACE the batteries.EMERGENCY PROCEDURES
• Position the window of the probe over the "X" marked location on the CRAM tape.
• Compare the reading on the instrument face with the range limit stated on the sticker.
• If the reading falls outside the range, make sure the probe is flush against the instrument and it is set on the appropriate range.
• If the reading still falls outside the range, DO NOT USE THE INSTRUMENT. Contact the Office of Radiation Safety.
In Case of Theft or Loss of Radioactive Material Procedure Before Reporting to PNRI
- Determine the description of the radioactive material involved including kind, quantity, chemical, and physical form.
- Determine the description of the circumstance under which the loss or theft occurred.
- Determine the estimated radiation exposures to individuals, circumstances under which the exposures occurred, and the extent of possible hazards.
- Identify the statement of disposition or probable disposition of the radioactive material involved.
a. Verify regularly that the check source is present at its place of use or ofRADIOACTIVE MATERIAL STORAGE PROCEDURE
b. Ensure that the check source is subjected to adequate measures to
prevent unauthorized access to or loss, theft, fire, and unlawful use of
c. Return or transfer the disused radioactive material to the supplier as
soon as possible.
d. Ascertain before transferring the disused source that the recipient holds
an appropriate authorization.
The radioactive check source is stored and shielded to maintain radiation exposure to the personnel As Low As Reasonably Achievable (ALARA). The storage area is clearly marked with appropriate warning signs and the radioactive material must be secured from unauthorized access or removal. Radioactive material will be returned to the storage location immediately after use. Sufficient shielding to reduce radiation levels to 2 mrem/hr (0.02 mSv) at 30 cm from the storage area. The storage area is secured against unauthorized access and removal of radioactive material.
The unused and depleted radioactive check source will be sent back to the manufacturer. Receipt and certificate are available for inspection.
LEAK TEST PROGRAM
The source that is shipped by the manufacturer has been leak-tested. It’s leak test certificate which comes together with the check source will indicate leak results. The strontium-90 check source will be used until the useful life has been used. In this regard, the PNRI will perform all required leak test.
CALIBRATION PROGRAM OF SURVEY METER
• The survey instruments should be calibrated annually, before first use, and following repair. Any SSDL unit (PNRI-DOST or BHDT-DOH) can perform the calibration.
• If there is a check source, the constancy of the survey meter should be checked at regular intervals.
• Records of calibration should be retained for at least two years.
• Batteries should be checked on a daily basis. Spare batteries should always be available.
• The survey instrument should be stored in the control room all the time for easy in case of emergency.
PERSONNEL MONITORING PROGRAM
Personnel monitoring device such as film badge must be provided to all radiation users.
A personnel monitoring device is also called a personal radiation monitor. The monitor must be worn by the same person for the duration of the monitoring period, hence the word “personal.”
All doctors, medical physicist, radiologic technologists, nurses, and aides assigned to Linear Accelerator and Brachytherapy must wear the film badge or pen dosimeter. Film badges and pen dosimeters must be worn while at wok inside the center. THIS SHALL FORM PART OF THE UNIFORM OF AN EMPLOYEE.
he following are the 6 DON’T’S in wearing film badge:
• Leaving the film badge on the lab-coal and washing the lab-coat. This renders the reading invalid..Film badge must be worn on the left side of the chest of the uniform of laboratory gown.
• Leaving the badge on the lead apron and hanging the apron on the rack in the room. This exposes the badge to radiation in the room while radiographic films are taken.
• Leaving the film badge in an area exposed to cosmic radiation and heat from the sun.
• Not always wearing the badge.
• Wearing the badge when the radiation worker him/herself is the patient.
• Bringing home the badge.
For those wearing a lead gown, the badge should be worn UNDER the apron. This will approximate the radiation dose received by most of the internal organs. Film inside the badge is very sensitive to temperature and humidity while pen dosimeter is sensitive to mechanical vibration. These monitoring devices should be cared for and used properly. A rack must be set up for proper monitoring and safekeeping of badges. The monitor must be placed at the rack at the end of the shift for safekeeping.