PTW Calibration Lab

Radiological calibrations you can trust.


As an accredited dosimetry calibration laboratory and member of the IAEA/WHO SSDL Network, the PTW Calibration Lab helps you maintain the highest level of accuracy and reliability for your dosimetry equipment.

Take a tour through our lab, learn about our accreditations and services, get in touch with our experts.

Because accuracy always matters.

Your measurements are important. Measurement results provide the basis for you to make critical pass and fail decisions for precise patient treatments. To obtain valid measurement readings and thus ensure correct decisions, proper and regular instrument calibration is imperative.

Radiation instruments calibrated by accredited dosimetry laboratories like the PTW Calibration Lab give you the confidence that your measurement results not only remain accurate and consistently precise over time, but are also directly traceable to national (e.g., the PTB) and international primary standards.

Explore our lab

Our Lab in Figures

Did you know that we are one of the oldest and largest dosimetry
calibration laboratories worldwide?

The oldest private dosimetry calibration laboratory worldwide
Accredited to international laboratory standard EN ISO/IEC 17025 since 1979
Calibrations performed on average per year
Member of the IAEA/WHO SSDL Network since 2000
Gamma and X-ray calibration facilities in full operation on 500 m²
Different radiation detectors or instruments calibrated on average per year

Our Calibration Services

Regular calibrations are crucial to ensure long-term measurement accuracy. Choose the right calibration for your radiation measurement instruments.


Factory Calibration

Accredited Calibration


Legal Calibration

Three Questions. Three Answers.


Why is it so important to calibrate your measuring instruments? What makes a good calibration lab? How can I assess lab quality?

Read here what our managing partner Dr. Christian Pychlau thinks about small deviations and the quality of calibrations.

Interview with Dr. Christian Pychlau


Why is the calibration of dosimeters so important?

If radiation measuring equipment is not recalibrated regularly, the user runs the risk that it will not function as designed. Small but significant deviations within the measurements can thus remain undetected. The detectors and instruments are very stable and can generally be used for a long time, if handled professionally. We recommend recalibration for our own equipment once every two years. If a detector is defective to the extent that there are large deviations, this becomes immediately apparent to the user. However, small deviations of e.g. below five percent may go unnoticed in the daily hustle and bustle in the clinic. Regular calibrations allow errors to be discovered and corrected in time. Hence the call from us to all users: Take the calibrations seriously! If a detector behaves differently than it normally does, investigate it further in order to protect your patients.

Worst case scenario: What can happen if calibrations are not carried out regularly?

A detector can look intact from the outside but can still be defective. Detectors are generally very stable, but if an ionization chamber falls on the floor just once, or even if it is put down too hard on the table, it can be damaged. In the 1990s a colleague of mine visited a number of rural hospitals in Asia. In many cases there were no doctors or physicists present, and staff had very little knowledge about medical physics. Thus, the dosimetry and quality assurance measurements were carried out – if at all – at a low level. He witnessed many deficiencies – from non-functional X-ray tubes to defective beam-scanning mechanisms, all of which could have been detected by appropriate quality assurance measures and calibrated equipment.

How can users assess the quality of a calibration?

A pre-requisite is the successful accreditation of the calibration laboratory to the current standards and then consistently positive audit results. One indication of high quality are the high level of qualifications and many years of experience of the laboratory staff. The PTW Secondary Standard Calibration Laboratory has been around since the 1920s. Every year we carry out more than 12,000 calibrations on hundreds of different dosimeters and appliances, including those of other manufacturers. Comparison measurements with PTB or IAEA are always within the pro-Mille range, therefore well below the combined uncertainty. These facts demonstrate the high quality of our calibrations.

Read the full article in EFOMP’s EMP Summer News, page 70 – 71.


“One accurate measurement is worth
a thousand expert opinions.”


Grace M. Hopper, American mathematician and rear admiral in the U.S. Navy


Lab FAQs

Find a quick answer to frequently asked questions about our calibration lab
and the services we offer.

By choosing an accredited calibration laboratory, you can be sure that the calibration is performed according to international standards. This means that the laboratory and all of its procedures are controlled by an independent authority, e.g., DAkkS, and that the calibration of all measuring devices in the accredited measuring quantities is directly traceable to a primary standard laboratory, e.g., the PTB.

For specific measuring quantities we maintain traceability to NIST.

DAkkS calibrations are recognized worldwide under the international agreements of ILAC MRA and EA.

The distinctive feature of an accredited calibration is that all relevant procedures are verified by both of our main accreditation bodies - DEKRA and DakkS. The calibration certificate issued displays the logo of our official Certification Body DAkkS. For a factory calibration, DEKRA certification would be sufficient, but calibration facilities, equipment and procedures used are practically identical to those of an accredited calibration.

Whenever your relevant authorities or local laws require an accredited calibration, e.g., when your measuring instrument is used as a reference standard, a particularly high degree of safety or formal third-party recognition are needed.

Simply put: Measurement uncertainty is the doubt that exists about the result of a measurement.

You might think that well-made rulers, clocks and thermometers should be trustworthy and give the right answers. But for every measurement - even the most careful one - there is always a margin of uncertainty. In everyday speech, this might be expressed as ‘give or take’ (e.g., a stick might be two meters long ‘give or take a centimeter’).

The measurement uncertainties presented in our calibration certificates comprise the uncertainty of the measuring quantity (provided by the primary standard of the national standards laboratory) and the uncertainty of the transfer process (calibration procedure) with all its components. PTW determines calibration uncertainties according to the internationally agreed ISO GUM.

Yes, absolutely! The uncertainty is a quantitative indication of the quality of the result. It gives an answer to the question about how well the result represents the value of the quantity being measured.

The PTW calibration laboratory provides calibration services for various types of PTW measuring instruments used in dosimetry and related applications.

The calibration of instruments from other manufacturers has been well established over decades. Please refer to our Calibration Guide to find the calibration possibilities of instruments from other manufacturers.

If your instrument is not listed, please contact the PTW calibration lab directly to check availability. The calibration of instruments from other manufacturers generally requires a user manual which should be provided along with the instrument.

When recalibration intervals are shown, this is only as a recommendation. In fact, most international standards frown on recommending recalibration intervals. This might be because fixed recalibration intervals could conflict with other (national) regulations. Our recalibration recommendations are based on long-term experience with our instruments, instrument specifications and technical facts.

Register with our customer portal myPTW to set and monitor calibration intervals for your measuring instruments conveniently in one place.

In principle, it is possible to request specific calibration points. However, we recommend selecting calibration points or series according to the product-calibration-matrix in our Calibration Guide. If a specific calibration point is not to be found in this matrix, this could mean:

  • The calibration point is not available for the selected detector/instrument.
  • The calibration point is not available at all.

In the latter case, the specific calibration point might only available at a primary standard laboratory (e.g., the PTB), either directly or organized by PTW. As a secondary standard laboratory, PTW provides a wide range of radiological measuring quantities, which are based on international standards and well accepted in the field.

Requesting service is very easy. You do not need an order number prior to shipment. Just pack your instrument and send it to PTW. If you have any doubt about whether service and/or recalibration is available for your instrument, please either check with the PTW service department or with the calibration lab.

There might be some cases where a calibration is not possible for your instrument, e.g.:

  • No calibration is available for your instrument.
  • Your instrument is defective and cannot be repaired.
  • Your instrument doesn't meet its specifications and cannot be repaired.

If this is the case, we will give recommendations on how to get alternative service or a replacement.

Please contact the PTW service department for calibration certificate copies. Just send your request along with the price quote you received for your calibration order, and the copies will be shipped to you. If requested, we can send the documents in advance by email.

Calibration certificates and documents can also be easily accessed any time through our customer portal myPTW. Register now.  

Express service is available on request. Please contact the PTW service department for availability and scheduling.

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