Personal Dosimetry. Radiation Protection Section Department of Medical Physics Colchester Hospital University NHS Foundation Trust

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1 Personal Dosimetry Radiation Protection Section Department of Medical Physics Colchester Hospital University NHS Foundation Trust

2 Why do we monitor members of staff? The staff dosimetry service of the Radiation Protection Section issues personal dosimeters to members of staff who enter Controlled Areas to satisfy Reg.18 (3) of the Ionising Radiation Regulations 1999: An employer who has designated an area as a controlled area shall not permit a person to enter or remain in such area in accordance with the written arrangements under paragraph (2)(c), unless he can demonstrate, by personal dose monitoring or other suitable measurements, that the doses are restricted in accordance with that sub-paragraph

3 Why do we monitor members of staff? Information about the personal monitoring can be found: In the Local Rules In the Trust s Radiation Safety Policy (Policy No.165)

4 Types of dosimeter: Whole Body and Collar Dosimeters A TLD dosimeter consists of a plastic holder inside which is a sealed, silver, plastic envelope. This envelope contains a metal plate into which are fitted 4 Lithium Fluoride (LiF) detector plates These plates are sensitive to ionising radiation and it is these plates that enable evaluation of the amount and, to certain extent, the type of radiation to which the dosimeter has been exposed The holder has a bulge and one hole on one side. This side must always be facing outwards towards the radiation source (label facing away from the body)

5 Whole Body Dosimeter A Whole Body Dosimeter Department (e.g. MPD Medical Physics Department) Issue date Wearer name The collar badge is identical but red so it can be distinguished

6 Types of dosimeter: Whole Body and Collar Dosimeters The Whole Body (WB) dosimeter is black in colour and should be covered by any protective clothing you may have to wear (e.g. lead apron) The WB dosimeter should be worn at the waist level Most members of staff working with ionising radiation receive a WB dosimeter Collar dosimeters (CL) are very similar to the WB ones but they are red so that they can be distinguished A CL dosimeter should be worn on your collar or sleeve nearest to the source of radiation and outside any protective clothing CL dosimeters are usually issued to staff working with fluoroscopy

7 Types of dosimeter: Whole Body and Collar Dosimeters Correct position of a WB dosimeter at the waist level. The label is facing the source of radiation Correct position of a WB dosimeter on the front of the trunk. The label is facing the source of radiation and the dosimeter is not likely to turn around Wrong position of a WB dosimeter. It is not advised to hang dosimeters from name badge holders as often these turn around and the side of the dosimeter with the label is facing the body and could give a false reading

8 Types of dosimeter: Whole Body and Collar Dosimeters Wrong position of a WB dosimeter. It must be worn at the waist level and be covered by any protective equipment (i.e. inside the lead apron) Correct position of a CL dosimeter at the collar level. The label is facing the source of radiation Correct position of a CL dosimeter at the collar level and outside of any protective equipment

9 Types of dosimeter: Whole Body and Collar Dosimeters DO Please return your dosimeter to the nominated person for your area as soon as possible. This is to ensure a quick and accurate reading and to avoid late return costs If you are not on duty on the day your dosimeter is due to be changed, you must leave it with a responsible person so that it is changed on the due date If your dosimeter is damaged, washed, lost or inadvertently irradiated inform your RPS or Radiation Protection immediately. A replacement will be supplied DON T Do not write anything on the dosimeters or attach anything to them Do not attempt to open the dosimeters Do not expose to sources of heat and to the sunlight Do not wash the dosimeter Do not swap dosimeters with your colleagues

10 Types of dosimeter: Whole Body and Collar Dosimeters We are charged 14 for every WB and CL dosimeter not returned within 120 days WB and CL dosimeters are changed on the 1 st January, 1 st April, 1 st July and 1 st October Replacement dosimeters are sent out before these dates to the nominated individual for your area or in some cases individually

11 Types of dosimeter: Rings and Wrist Bands Some members of staff receive a ring or wrist band which contains a LiF chip. These are usually staff working in Nuclear Medicine, Radiopharmacy or some cardiologists and interventional radiologists It is essential that they are worn on the same finger/wrist and in the same position each time

12 Types of dosimeter: Rings and Wrist Bands Ensure that the chip is exposed to the maximum amount of radiation, e.g. for cardiologists and interventional radiologists the chip (label) should be facing the outside of the hand/wrist; for handling radionuclides, the chip (label) should be facing the inside Rings come in different sizes, you can select the size you want. They show ULE or URE (upper left extremity or upper right extremity) to indicate the wear location Wrist bands are marked with Rt or Lt to indicate wear location Rings and wrist bands are issued on the 1 st of each month We are charged with 5 for each non-returned ring/wrist band

13 Types of dosimeter: Rings and Wrist Bands Correct way of wearing a ring in Nuclear Medicine and Radiopharmacy: the label is facing the syringe (inside of hand) Correct way of wearing a ring in Cardiology: the ring is facing outside of the hand

14 Storage of all types of dosimeter As well as being sensitive to radiation, LiF is also sensitive to heat!! When the TLD dosimeter is not being worn, please ensure that it is stored away from radiation, sources of heat and direct sunlight. Also it must not be washed

15 If you require an X-ray If you require an X-ray to be taken of yourself YOU MUST NOT wear your dosimeter when the X-ray is taken Give your dosimeter to the person physically controlling the exposure, asking them to place it outside the radiation area

16 Report to your RPS You must report to your RPS at once if you believe that your dosimeter has been accidentally exposed to radiation, whether you were wearing it or not Your RPS will return it to Radiation Protection, who will arrange to have it assessed as soon as possible You will be issued with another dosimeter

17 Reports and investigations Results with the staff doses are sent to the RPS or nominated individual for your area If an Investigation Level is exceeded (see Local Rules for current levels) the RPS will be asked to investigate

18 Dose limits Typical staff doses Radiation dose limits for staff working with radiation and for the members of the public Employees (>18 years) Public and <16 years Effective Dose (msv) 20 1 Equivalent Dose to the Lens of the Eye (msv) Equivalent Dose to Extremities (msv) Typical doses for members of staff within CHUFT Department Typical Annual Whole Body Effective Dose (msv) Typical Annual Collar Badge Dose (msv) Typical Annual Extremity Dose (msv) Cardiology 0 < 4 < 10 Endoscopy 0 < 2 N/A Radiotherapy 0 N/A N/A Nuclear Medicine < 3 N/A < 10 Radiopharmacy < 1 N/A < 30 Vascular Surgery < 1 < 2 < 10 Radiology < 1 < 8 < 20

19 Data Protection Act The Medical Physics Department (where Radiation Protection Section belongs) is registered under the Data Protection Act Details of employees and their radiation exposure are held by the MPD computer You are entitled to examine your computer record provided that notice is given

20 Enforcement The Trust can be prosecuted if staff do not use properly their dosimeters or if they do not return them on time In 2009 the HSE prosecuted the Royal Free Hampstead NHS Trust at the City of London Magistrates Court for late returns and not wearing dosimeters correctly The Trust pleaded guilty to offences under Reg 8(1) and Reg 20(1) of the IRR99 and were fined 4k. Costs of 9k were awarded to the HSE

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