Laboratory for Nuclear Calibrations Ghent

Our offer

We perform primary and secondary standard calibrations of ionisation chambers used in radiotherapy and radiology departments of Belgian hospitals. The laboratory uses Farmer type NE2571 ionisation chambers as secondary standards for calibrations in ⁶⁰Co beams.

We are performing routinely the following calibrations under ISO 17025 accreditation from BELAC:

• Secondary standard calibrations in terms of absorbed dose to water in ⁶⁰Co beam.
  The combined expanded uncertainty is 1.3 % for k = 2 (confidence level 95.4 %)

• Secondary standard calibrations in terms of air kerma in ⁶⁰Co beam.
  The combined expanded uncertainty is 1.1 % for k = 2 (confidence level 95.4 %)

Cylindrical ionisation chambers (e.g. Farmer type 0.6 cm³, semiflex 0.125 cm³ and Extradin A1SL type) and plane-parallel chambers (e.g. Roos, Advanced Markus and NACP-02 chambers) can be calibrated in terms of absorbed dose to water in ⁶⁰Co beam. If special chambers need to be calibrated we can investigate the possibility of doing it. The calibrations in terms of air kerma in ⁶⁰Co beam are more flexible regarding the size and shape of the chamber.

Quality assurance is one of our priorities. The ISO-17025 accreditation was granted by BELAC at the beginning of 2011.

The calibrations of the ionization chambers can be done with and without the electrometer of the user. Unfortunately we are not able to perform calibrations of electrometers in terms of electrical charge.

A cylindrical graphite cavity chamber is maintained as a primary standard for measurement of kerma in air in ⁶⁰Co beam. We are working on the re-evaluation of the correction factors for this primary standard. The combined expanded uncertainty of a calibration against the primary standard is about 1.0 % for k = 2 (confidence level 95.4 %)

Who we are

The laboratory is run as a collaboration between SCK•CEN and Ghent University with the support of FANC (Federal Agency for Nuclear Control). The Laboratory for Standard Dosimetry Ghent has a history of more than 20 years in standard calibrations.

The advantages of the present collaboration between the RDC expert group of SCK•CEN and Ghent University are the following:

• The existing infrastructure for therapy level nuclear calibrations is provided and maintained by Ghent University.
• The experience of the RDC expert group of SCK•CEN in performing nuclear calibrations
• The experience of the RDC expert group in implementing the quality assurance system ISO-17025.
• The increased number of personnel involved in these calibrations. Three scientists and two technicians will be part-time involved in the activity at LNK Ghent. This will increase the flexibility and the continuity of the activity.

Our equipment

Theratron 780 unit – the ⁶⁰Co source presently installed at LNK Ghent

• ⁶⁰Co source (The ratron780 unit)
  In 2008 we installed a new ⁶⁰Co source of the type Theratron780 unit . This unit has a movable arm in 360° but is presently locked in horizontal beam position. The absorbed dose rate to water (D_w) is about 10.0 mGy/s (reference date July 2009) at a source to chamber distance SCD = 100 cm and depth in water z_ref = 5 g/cm. This new source allows calibrations at dose rate comparable with the dose rates used in the hospitals.

• 3 secondary standard chambers for calibrations in terms of absorbed dose to water in ⁶⁰Co beams. These chambers are presently calibrated against the water calorimeter (primary standard for absorbed dose to water) of VSL (former NMi), Delft, The Netherlands. One of these chambers is calibrated also in terms of kerma in air with traceability to the primary standard of VSL.

• A graphite cavity chamber CC1 used as primary standard for air kerma.

Contacts

Laboratory for nuclear calibrations / Laboratory for standard dosimetry Ghent (LNK Ghent)
Radiation Protection Dosimetry and Calibration expert group (RDC)
SCK•CEN (Studiecentrum voor Kernenergie - Centre d'Etude de l'Energie Nucléaire)
GKD building
Boeretang 200
BE-2400 Mol

Contact persons:

Responsible LNK Gent & Mol: Mihailescu Cristian
Head of expert group RDC: Vanhavere Filip

How to reach the laboratory in Ghent

The calibrations are always performed at the laboratory in Ghent located at the Ghent University campus INW (“Instituut voor Nucleaire Wetenschappen”). The address is: Proeftuinstraat 86, 9000 Gent.

Once on campus, you have to go to the building of the Dienst Fysische Controle (one-floor building).

1. By car

The laboratory is located closely to the exit Nr. 9 (UZ Gent) of the E17. When coming from the E40, exit at the junction with the E17 in Gent and carry on the E17 in the direction of Antwerpen, Gent. The exit UZ Gent is 600 m further. At the exit turn to the left and then turn directly to the left into the first (relatively small) street. This is the Proeftuinstraat. Just follow this road (ignore one turn to the right) until you reach the entrance of the campus INW.

Be aware that some GPS's and online maps do not find this number. They will send you to number 84 which is actually on the other end of the street. It is much easier to use GPS coordinates:
Campus entrance: 51º01'23.26"N and 3º44'19.26"E
Dienst Fysische Controle building: 51º01'25.83"N and 3º44'30.29"E

2. By public transport

Take the train to Gent Sint-Pieters. In front of the station (on the left) it is possible to take a bus (Nr 65 or 67 in the direction of “Groothandelsmarkt”) every half hour (15 minutes past the hour or 16 minutes before the hour). Get off the bus (the ride takes approximately 15 minutes) at the first exit after crossing the bridge (at the Holiday Inn hotel). Then walk back towards the bridge and take the small street on the right (Proeftuinstraat) and follow this road (ignore one turn to the right) until you reach the entrance of the campus INW (“Instituut voor Nucleaire Wetenschappen”).