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CTA Dosimeter Product Image and box

FTR-125 Dosimeter

An accurate and precise film dosimeter for radiation processing, materials testing and related research and development

FTR-125 Dosimeter

CTA Dosimeter Product Image and box

Cellulose Triacetate (CTA) Dosimeter

for Dosimetry in Electron Beam, Gamma-ray and Ion Beam Irradiations.

CTA dosimeter is an accurate and precise film dosimeter of which the optical density increases by radiation exposure. It is most suitable for radiation processing, materials testings and related various research and development.


  • Linear dose response
  • Simple measurement procedure
  • High spatial resolution
  • Applicable to ion beam dosimetry


Accurate and precise dosimetry is essential to quality control in industrial radiation processing and R&D using radiation from large radionuclide and machine sources. CTA dosimeter, FTR-125, has been developed for routine dosimetry in these fields. The optical density of the dosimeter film increases linearly with absorbed dose for electron beams, gamma-rays, and ion beams. Since the dosimeter is in the shape of a thin long tape, it allows to accurately and conveniently measure dose distributions on the surface of irradiated samples and depth-dose distributions in the samples with high spatial resolution.

Method of Measurement

Absorbed dose is evaluated from the measured value of the increment of the optical density at the wavelength of 280nm induced by radiation. The optical density can be measured with ordinary U-V spectrophotometers. A reliable and convenient dose reader exclusively for CTA dosimeter is also commercially available from Nissin High Voltage Co., Ltd.

Dose Responses

Chart in the downloadable PDF on Overview page shows dose response curves for different particle beams of 2MeV electrons, 15MeV protons, and 30MeV helium ions. CTA dosimeter has linear response for all the particles, while the radiation sensitivity is relatively small in high LET region. The influences of temperature and relative humidity during irradiation on the sensitivity are negligible at high dose rates which are typical for electron irradiation.


Film thickness

125μm (~15mg/cm2)


width : 8mm, length : 100m/reel


cellulose triacetate, triphenyl phosphate

Analyzing Wavelength


Usable dose range

5kGy - 300kGy