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RADIATION PROTECTION IN
DIAGNOSTIC radiology
NURAIN BORHANPEGAWAI SAINS
(FIZIK)17 OCTOBER 2013
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CONTENT
Protection to The PublicSource of Radiation Dose to PersonnelDose Reduction Methods and TechniquesProtection in Mobile X-ray RadiographyPersonnel Protective EquipmentsPersonnel Dose MonitoringDose Limits
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PROTECTION TO THE PUBLIC
Concern on the x-ray room design that includes:
1. X-ray room wall and shielding2. Lead lined door3. Interlock system4. Warning sign
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X-RAY ROOMS
X-Ray Room WallLead (Pb) is widely used for shielding because of its high atomic number (Z=82)
Lead is costly. Materials with lead equivalent property are introduced to substitute lead at lower cost.
The common lead equivalent materials used for shielding in diagnostic radiology are barium gypsum and concrete.
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Lead Lined Door• The doors of x-ray rooms should
be lead lined with no radiation leakage around the edges.
• lead-lined rebates or lead baffles where appropriate, depending on whether the door design is hinged or sliding.
X-RAY ROOMS
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X-RAY ROOMS
1. Prevent exposure unit from before the door is closed.
2. Turn off the x-ray beam immediately when the entrance door is open.
Room Interlock System
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X-RAY ROOMS
Warning Sign Displayed on each door to
discourage the entry of non-authorized persons.
Written in national language and can be understand by the personnel and member of the public.
The doors should always be closed during exposure.
Red light to signify when the x-rays are on.
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SOURCE OF RADIATION DOSE TO PERSONNEL
3 categories of radiation sources that contribute dose to the personnel:
i. Primary radiation sourceii. Scattered radiation sourceiii. Leakage radiation source
The scattered and leakage radiation sources are collectively known as
secondary radiation source.
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Leakage Radiation Source
SOURCE OF RADIATION DOSE TO PERSONNEL
x-ray that does not exit from the collimator opening but penetrates through protective tube housing.
Always present whenever x-ray is produced.
Contributing dose to personnel and background radiation within the x-ray room.
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DOSE REDUCTION METHODS & TECHNIQUES
The patient become the source for scattered radiation.
Scatter however also obeys the ± the Inverse Square Law, so distance from the patient improves safetyI1/I2 = D2
2/D12
Protective lead aprons and shielded barriers protect personnel from secondary radiation.
In case of fluoroscopy, the time of exposure should be kept as low as possible.
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Proper beam collimation will reduce off-axis Precisely only at the region of diagnostically interested.
A high-speed image receptor systems such as film-cassette combination and intensifying screen.
Repeat radiograph should be avoided or minimized through effective communication and correct radiographic techniques.
DOSE REDUCTION METHODS & TECHNIQUES
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EXAMPLES OF REJECT FILMS
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PROTECTION IN MOBILE X-RAY RADIOGRAPHY
Mobile radiography is conducted usually in ward with no specific protection to the surrounding.
Lead apron, gloves and thyroid shields should be worn whenever the mobile protective barrier is unavailable.
Remote control exposure device. The cord should permit the radiographer to stand at least 2m from the patient. .
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PERSONNEL PROTECTIVE EQUIPMENTS
Personnel Protective Equipments (PPE) should be worn by personnel whenever he/she cannot remain behind the protective barrier during exposure.
Lead apronThyroid shieldLead eyeglassLead gloves
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PERSONNEL PROTECTIVE EQUIPMENTS
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PERSONNEL DOSE MONITORINGFilm Badges
•Advantages
Permanent exposure recordGood accuracy at higher exposures
•Limitations
Exposure not read immediatelySensitivity to heatLess accuracy at lower exposures
The minimum recording level adopted for the film badge dosemeter is 0.10 mSv and all doses less than 0.10 mSv are reported as being below the recording level.
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Do not forget to change your film badge every month before 5th
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Whole Body Exposure Dose
Limit (mSv/year)
Public 1
Radiation Workers 20*
Fetus 1
Apprentices andstudents
6
* The maximum effective dose on the worker averaged over a period of 5 consecutive years shall not exceed 20mSv
DOSE LIMITS
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Dose limits do not apply to medical exposures and
natural background radiation
But, that does not mean that radiation dose to
patient should be ignored!
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OptimizationTrade-offs between
radiation dose and
image quality
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The ultimate goal of radiation protection is optimising radiation
exposures to levels consistent with the needs and
benefits of humanity and compatible with the other hazards
to which man is exposed
CONCLUSION
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