
INTRODUCTION
Personnel dosimeter refers to monitoring of individuals who are exposed to radiation during the course of the work.
To avoid the excessive exposure, appropriate and efficient radiation monitoring device is needed.
Radiation exposure must be monitored for both personal safety and regulatory purpose,
Many instruments are used for individual monitoring.
The instruments used for recording the dose equivalents received by individuals working with radiation are referred to as personal dosimeters (or individual dosimeters).
AIM OF PERSONNEL MONITORING
Monitor and control the individual dose.
Maintain lifetime cumulative dose record.
Assurances that dose is within permissible limit.
It is useful for detecting changes in radiation levels in the workplace and to provide information in case of accidental exposure.
In India, country wide monitoring service is offered by BhaBha Atomic research centre (BARC) Mumbai.
IDEAL MONITORING DEVICE
Instantaneous response
Accurately measure the dose equivalent from all forms of ionizing radiation with energy from KeV- MeV
Small, lightweight, rugged, inexpensive, easy to use.
Unaffected by environmental condition (heat, humidity, pressure)
There are different types of personnel monitoring devices ex- film badge, TLD, OSLD, pocket dosimeter.
What is film badge dosimeter?
A film badge dosimeter or film badge is a personal monitoring cumulative radiation dose due to ionizing radiation.
film badges are the cheapest and most common monitoring device.
It is used to measure the individual dose from x-rays, beta particle, gamma radiation, thermal neutrons on the basis of different filters (windows).
It was developed by Ernest O Wollan whilst working on the Manhattan project during 1942.
CONSTRUCTION
Film badge is made up of
1.Photographic film
2.Filters
3.Badge holder
PHOTOGRAPHIC FILM
Photographic film is a sheet of transparent plastic film base coated on one/both side with a gelatin emulsion containing small light sensitive silver halide crystals.
Film size is 4*3 cm wrapped inside by a light tight polythene or paper cover
There are two film in the badge one is slow and another is fast
Supply of film is for a period of one calendar month(4 weeks)
FILM HOLDER WINDOWS

FILM HOLDER HAS SIX WINDOWS
1.Open window
2.Plastic
3.Cadmium
4.Thin copper
5.Thick copper
6.Lead
FIRST WINDOW
- Without any filter
- It detects alpha particles
- Due to minimum penetration power of
- alpha particles no metallic filter is used
SECOND WINDOW
- Filter is made of plastic
- Light white colour
- It detects (beta)particles
- Thickness of filter :1mm
FOURTH WINDOW
- Filter is made of thin copper
- Green in colour
- It detects low energy x-rays
- Thickness of filter :0.15mm
FIFTH WINDOW
- Filter is made of thick copper
- Pink in colour
- It detects high energy x-rays
- Thickness of filter :1mm
SIXTH WINDOW
- Filter is made of lead
- Black in colour
- It detects gamma rays
- Thickness of filter :1mm
All the filters are 1mm thick, except thin copper which is 0.15mm thick
Film is sealed with a plastic cover which contain the name, ID no or duration.
The filters allow the radiation to penetrate and thus permit the energy to be stored and estimated.
The BARC processed the film, and measure the optical densities by densitometer’


Film badge consist of stainless steel holder, photographic film and all six filter fixed in particular window
WORKING
When radiation exposes the film after passing through the filters it cause formation of latent image on the film.
Latent image has regions of different density under the different filters due to their different penetration power
After each months (4 weeks) it is returned to the agency where the film is processed and the optical density under different filters is measured by a densitometer.
Dose under each filter is evaluated using the standard calibration curve
After processing the film badge monthly dose report is sent to the institution This report contains current month’s report and up to date cumulative dose of the current year.
Dose is reported in mSv.
TYPES OF HOLDER
The type of holder are
1.Chest holder
2.Wrist holder
3.Head holder
Minimum dose that can be detected by film badge is 0.2 mSv
Range of film badge is 10 KeV to 2MeV
This badge should be kept in cool, dry and control area
The badge is typically worn on the outside of clothing, around the chest or torso to represent dose to the “whole body”.
Additional dosimeters can be worn to assess dose to extremities or in radiation fields that vary considerably depending on orientation of the body to the source.
ADVANTAGES
It gives permanent record.
Wide exposure range
Independent of dose rate
Type of radiation and energy can be evaluated
Least expensive device
Small, light weight ,easy to handle
DISADVANTAGE
High sensitivity to light, pressure and chemicals
Fades at high temperature and humidity
Limited shelf life (one month)
Only records exposure where it’s worn.
DO’S AND DON’T IN FILM BADGE
DO;
Wear your dosimeter correctly
Check your exposure dose
Report any unusual radiation incident to your RSO
DON’T
Don’t share your film badge with anyone.
Don’t open the film badge till the end of service period.
Don’t leave the badge in radiation area, or in chemical hazardous place .