F-18 (Fluorine-18) Radiation Safety Data

Source: Ionactive Radiation Protection Resource

F-18 (Fluorine-18)

Half life: 1.83 hours (110 minutes)

Specific activity: 3.52×1018 Bq/g

Decay product: O-18 (non radioactive)

Significant emissions (keV) [F-18 (Fluorine-18)]

In the data below, % refers to the probability of emission of a particular type of radiation at a specified energy

Gamma / x-ray: 511 keV (194%) [i.e. due to two 511 keV photons being released per annihilation event]

Beta (Emax): 634 keV (97 %)

Electrons: 1 keV (3 %) - negligible radiation safety impact

Alpha particles: n/a

External exposure (in air) [F-18 (Fluorine-18)]

The values below are specified as mSv/h for either 1 MBq of activity or an area source of 1 MBq/m2 depending on the geometry. Unless specified below, any bremsstrahlung dose rate is not specified. (HP 0.07) represents a skin dose rate and (HP 10) represents an 'at depth' tissue dose rate (> 10mm).

Point source (at 30cm)

Point source : 0.120 mSv/h (beta)

Point source : 0.00181 mSv/h (gamma "photon") - use this for radiation protection purposes

Infinite place source (at 10 cm)

Beta (HP 0.07) : 0.096 mSv/h

Photon (HP 0.07) : 0.0068 mSv/h

Photons (HP 10) : 0.0064 mSv/h

External exposure (arising from personal contamination) [F-18 (Fluorine-18)]

The values below are either for uniform contamination on the skin (for 1 kBq/cm2) or as a single droplet (1 kBq) and are specified in mSv/h. It is assumed that no PPE is being worn which would attenuate the radiation.

Uniform deposit on the skin: 1.95 mSv/h

0.05ml droplet on the skin: 0.79 mSv/h

[Note: For F-18 special care is required to avoid direct contamination of the body. Consider a 1MBq droplet on the skin. Using the data given that will yield a dose rate of 0.79 Sv/h or 13.2 mSv/min. Consider a 1 GBq droplet on the skin. That will yield 790 Sv/h or 13.2 Sv/min to the skin. These are significant and could produce deterministic effects, and would certainly lead to dose limits being exceeded in a matter of seconds].

Shielding (external radiation) [F-18 (Fluorine-18)]

In the data below beta shielding is specified as mm of material to provide 100% absorption of the beta particle (or electron). Gamma (and x-ray) shielding is specified in terms of mm of material relating to 1 TVT or 1 HVT. The TVT is the thickness of material (in mm) which will reduce the radiation intensity (dose rate) down to 1/10 of the pre-shielded dose rate. The HVT is the thickness of material (in mm) which will reduce the radiation intensity down to 1/2 of the pre-shielded dose rate

Beta radiation (for 100% absorption)

Glass: 0.9mm

Plastic: 1.8mm

Typical PPE (glove): will provide minimal attention to beta (-) radiation. Note that for F-18 extremity dose is dominated by the annihilation 511 keV photons.

Gamma / x-ray radiation (TVT and HVT)

Lead: 6mm (HVT) and 17mm (TVT)

Steel: 26mm (HVT) and 64mm (TVT)

Internal exposure [F-18 (Fluorine-18)]

The data featured below is derived for employees who work with ionising radiation (and are therefore subject to dose limits specified by the Ionising Radiations Regulations 2017 in the UK, and similar regulation around the world). Whilst not directly applicable to public exposure (e.g. exposure resulting from environmental releases - either planned or accidental), the data will provide a good indication of likely exposures and is therefore adequate for general research, illustration and asking 'what if?' type questions. If you need professional advice, please consider consulting a Radiation Protection Adviser (RPA).

Internal radiation exposure generally means the intake of a radioactive substances by inhalation, ingestion or through cuts (or absorption) in the skin. For this resource assume cuts / absorption are similar to the ingestion values.

This data provides the dose delivered (committed effective dose equivalent) for an intake of [F-18 (Fluorine-18)] by inhalation or ingestion to yield 1mSv effective dose. The dose value provided assumes that all the dose is delivered in the first year of intake, in reality this will vary greatly with radioisotope due to a combination of physical half-life, biological half-life and the biochemical behaviour of the particular radioactive substances in the body.

Target organ: Lungs

Inhalation dose (1 mSv): 11 MBq

Ingestion dose (1 mSv): 20.5 MBq

Workplace Monitoring and Dosimetry [F-18 (Fluorine-18)]

General comment

Workplace monitoring means using techniques to detect ionising radiation sources in the working environment (e.g. on benchtops, floors, walls, drains and similar). The monitoring can be direct (e.g. using a radiation detector to gain real time measurements of dose rate and / or activity) or indirect (where a smear / wipe of an area is made and this is then offered up to a radiation monitoring probe or placed in scintillation fluid for liquid scintillation counting).

Dosimetry is used to measure personal exposure from a source of ionising radiation. Passive dosimetry (e.g. film badge, thermoluminescent dosimeter - TLD etc) is worn on the body (e.g. trunk / extremities / near eyes) and measures total integrated dose over time. Active dosimetry (e.g. electronic personal dosimeter - EPD, personal electronic dosimeter - PED etc) is worn on the trunk of the body and provides real time accumulated dose (and sometimes dose rate) - audible dose and dose rate alarms may also be available. Biological monitoring [bioassay] (e.g. urine sampling, faecal sampling etc) takes biological samples from the body where they are analysed in a sensitive detector to determine activity of radionuclides in the body (usually due to the intake of radioactive material by inhalation, ingestion or through absorption / cuts in the skin).

Workplace monitoring [F-18 (Fluorine-18)]
  • Proportional counter (e.g. Berthold LB 124 B Xenon detector) - about 17% efficiency (for contamination monitoring)
  • Ion chamber (e.g fluke 471 ion chamber) - useful for dose rate monitoring
Dosimetry [F-18 (Fluorine-18)]
  • Passive dosimetry - TLD / film for whole body dose monitoring (essential)
  • Passive dosimetry - TLD extremity (finger) dosimeter for measuring potential exposures to the hand
  • Active dosimetry - use of real time (EPD / PED etc) essential for real time dose control (also relevant for use in a cyclotron vault - see below)

Occurrences and uses [F-18 (Fluorine-18)]

  • Not found in nature (artificially produced)
  • F-18 is created in a cyclotron (particle accelerator)
  • PET (positron emission tomography) - a medical diagnostic procedure. After production in the cyclotron, F-18 is attached to glucose forming Fludeoxyglucose (FDG). FDG is administered to a patient usually by injection. The patient is then placed in a dose uptake room for up to an hour in order for the body to take up the FDG (particularly tumors / cancers which have a high glucose metabolism). The patient then undergoes a PET scan - this uses a detector geometry that takes advantage of the fact that F-18 is a positron emitter, so with every decay of F-18 there are two annihilation 511 keV photons created moving away at 180 degrees to each other. A coincidence counting system is used to plot the location of the two annihilation photons which provides information regarding the location and nature of the clinical area under investigation. Often the PET scan is combined with a CT (x-ray ) scan.

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