Ionizing radiation standards

Important: Please note that some of our services and prices have changed.

Facilities

NRC is equipped with X-ray generators, two 60Co therapy units, radioactive sources, three β - ray sources, an Elekta Precise clinical linear accelerator, and a 35 MeV electron linear accelerator.

The X-ray generators provide stable beams of X-rays at constant potentials from 10 kV to 300 kV. Exposure rates from 100 pA/kg to 60 µA/kg (about 1 mR/h to 15 R/min) can be selected, covering both protection and therapeutic levels. 60Co beams are standardized in terms of exposure, air-kerma and absorbed dose. 60Co exposure rates between 40  nA/kg and 300 µA/kg (100 mR/min to 80 R/min) are available.

The electron linear accelerator is a 35 MeV high-current short-pulse machine. The accelerator can be run up to 5  MeV unloaded and can sustain an average current of 60 µA at 35 MeV.

A low energy "pretzel" magnet placed between sections makes available the full electron current at energies between 5 MeV and 12 MeV. At the end of the accelerator, a conventional 2-magnet steering system provides electron beams with well-known energies. A variety of targets, beam flatteners, collimator systems, scattering foil systems, beam current monitors and beam steering systems allow a wide variety of clinical accelerator beams to be simulated. The accelerator can also be run with currents averaging less than a single electron per pulse. In addition to the provision of electron and photon beams for dosimetry, the electron linear accelerator is available to outside users.

The Elekta Precise Linac is a standard clinical radiotherapy machine with photon beams of 6, 10 and 25 MV, and 5 electron beams with energies between 4 and 22 MeV. The linac delivers clinical dose rates of about 5 Gy/minute.

Uncertainties

The uncertainties quoted in the descriptions below are standard uncertainties — that is, they are at the one-standard-deviation level. They were obtained by assuming a normal distribution.

Fees for service

If you wish to order a calibration service, please request a quote from the following technical contacts:

Contacts

60Co, 137Cs, MV Photon, Medium/Low Energy X-ray, Brachytherapy Calibration Services

Brad Downton
Telephone: 613-993-2715 ext. 245
Email: Brad.Downton@nrc-cnrc.gc.ca

Beta Calibration Services

Dr. Patrick Saull
Telephone: 613-993-2715 ext. 240
Email: Patrick.Saull@nrc-cnrc.gc.ca

Neutron Calibration Services

Dr. John Paul Archambault
Telephone: 613-993-2715 ext. 252
Email: JohnPaul.Archambault@nrc-cnrc.gc.ca

Radionuclide Calibration Services

Dr. Raphael Galea
Telephone: 613-993-2715 ext. 229
Email: Raphael.Galea@nrc-cnrc.gc.ca

Note that the calibration costs quoted DO NOT include shipping, insurance or the cost of a customs broker. The client must arrange and pay for these services separately.

Facilities

Calibration number Description Fee
A33-08-00-00 Custom ionizing radiation standards measurements or services Fee on request
A33-08-00-01 Handling fee. A charge is levied for any instrument or radioactive source that is found to be unsuitable for calibration. The fee covers inspection and return, and is based on the work done prior to the discovery of the fault. $250

Determination of source strengths

Calibration number Description Fee
A33-08-01-01 60Co therapy source. The exposure or air-kerma rate from a 60Co therapy source at the client's location is measured using an NRC calibrated cavity ion chamber. Fee on request
A33-08-01-02 Additional 60Co therapy source. Measurements of the exposure or air-kerma rate from additional sources will be made at a reduced rate per source when scheduled for testing at the same time and place as A33-08-01-01. Fee on request
A33-08-01-03 Low-activity 60Co source. The exposure or air-kerma rate from low-activity 60Co sources is measured at NRC. This service is available by special arrangement only. Fee on request
A33-08-01-04 Radioactive neutron source. This service measures the neutron flux from a radioactive neutron source. NRC no longer maintains a primary standard for neutron source strength. However, we do have several Am-Be neutron sources whose outputs and half-lives have been established. Using these sources and well characterized neutron long counters, the output from a client's neutron source can be established with a standard uncertainty of about 2 percent for sources with a spectrum similar to that of the Am-Be sources. $2,260

Instrument calibration

Calibration number Description Fee
A33-08-02-01 X-rays - exposure and air-kerma calibration for one X-ray quality. This service provides exposure and air-kerma calibration for one quality of radiation for one instrument and its probe, using one instrument range.
The primary exposure and air-kerma standards at X-ray energies are two free-air chambers. The smaller of these covers X-rays produced by accelerating potentials up to 80 kV and the larger one covers X-rays up to 300 kV. This range of X-ray energies is produced by several special generators in which both the potential across the X-ray tube and the anode current are highly stabilized and accurately monitored. By varying the anode current and distance from the source, calibrations of instruments can be provided at exposure rates varying by six orders of magnitude, from therapy exposure rates (60µA/kg (15R/min)) to radiation protection rates (100 pA/kg (1 mRh)). A variety of beam filtrations is available and, after discussion with the client, NRC will match the client's end-use beam quality as accurately as possible during the calibrations.
The value of the exposure, or related air-kerma, typically has a standard uncertainty of 0.5 percent at the higher exposure rates, although the overall accuracy of the instrument's calibration factor also depends on the precision of the instrument being calibrated.
NRC exposure standards have been used in various international comparisons with other national standards laboratories. Agreement with the standards of NIST (National Institute of Standards and Technology) in the U.S. and the Bureau International des Poids et Mesures in France is within ±0.3 percent.
$1,375
A33-08-02-02 Additional X-rays - additional X-ray beam qualities and/or instrument ranges. Calibrations in additional beam qualities and/or instrument ranges will be performed at a reduced cost when scheduled at the same time as A33-08-02-01 and for the same instrument. $290
A33-08-03-01 60Co - Exposure and air-kerma calibrations, or absorbed dose to water calibrations. Exposure and air-kerma calibrations, or absorbed dose to water calibrations, are carried out for one instrument and its probe using one instrument range. The primary exposure standard for gamma-radiation from 60Co is a carbon-walled cavity ion chamber. Extensive work has been done concerning the correction factors required for cavity chamber exposure standards, in particular the point of measurement correction factor and the wall attenuation and scatter correction factor.
The laboratory has two 60Co teletherapy heads with calibrated outputs. The older unit produces exposure rates at 1 m of about 20 µA/kg (5 R/min). In conjunction with a precision irradiation timer designed and built at NRC, this unit can deliver accurately-known exposures down to less than 25 µC/kg (100 mR). This unit is used primarily for the calibration of radiation protection instruments. The newer unit produces an exposure rate at 1 m of about 300 µA/kg (80 R/min), which is more typical of clinical units and is used primarily for the calibration of radiation therapy instruments.
For both units, the exposure rates are known with a standard uncertainty of 0.5 percent (one standard deviation), although the overall accuracy of a calibration factor also depends on the precision of the instrument.
The 60Co units at NRC are former therapy units and thus the spectrum from these units is similar to that used in therapy situations. Measurements and Monte Carlo simulations done at the Council indicate that over 25 percent of the photon fluence in the beams of these machines consists of scattered photons and these contribute about 15 percent of the exposure in the beam.
The 60Co air kerma standard at NRC has been compared to the standards in several other national standards laboratories, such as PTB (Physikalisch Technische Bundesanstalt) in Germany and the Bureau International des Poids et Mesures in France, and found to agree within 0.2 percent, although air kerma rates measured using NRC calibrations are 0.6 percent larger than those based on calibrations from NIST.
The standard for absorbed dose to water in a 60Co beam is a sealed water calorimeter. The instrument measures the radiation-induced temperature rise at a point in a water phantom. The absorbed dose to water rate is known at 5 cm depth in a water phantom irradiated by a 10 x 10 cm2 beam, with the surface of the phantom at 1 m from the source. Based on this knowledge, waterproof ion chambers can be calibrated directly in terms of absorbed dose to water by being placed in the water phantom.
The dose rates at the point of calibration are about 8 cGy/min and 60 cGy/min on the two 60Co units discussed above. The standard uncertainty in the absorbed dose rate is 0.6 percent.
$1,375
A33-08-03-02 Additional 60Co - additional instrument ranges. Calibrations on additional instrument ranges will be performed at a reduced cost when done at the same time as A33-08-03-01. $255
A33-08-04-01 Neutron meter calibration. A neutron survey meter is calibrated using an Am-Be source of known output. Using this source, and a knowledge of its spectrum (average energy 4.4 MeV), NRC can provide calibrations of neutron remmeters in a field of roughly 20 µSv /h (2 mrem h-1). $1,710
A33-08-05-01 ßeta meter calibration. Absorbed dose to tissue calibration of a direct reading ß dosimeter is performed in fields from 204Tl, 90Sr+90Y and 147Pm ß sources at a variety of specified distances.
The primary standard for ß-ray absorbed dose is an extrapolation ion chamber built at NRC following a design developed by PTB in Germany. With this chamber, the absorbed dose to tissue at a variety of depths in a tissue equivalent phantom has been determined at a variety of distances from 204Tl, 90Sr+90Y and 147Pm ß sources. At the calibration positions, the mean energies of these ß sources have been determined to be 300 keV, 670 keV and 70 keV respectively. The dose rates span more than three orders of magnitude and have been determined with a standard uncertainty of 2 percent. The measurements agree well with independent calibrations carried out on the same set of sources by PTB.
These sources can be used to calibrate radiation protection instrumentation, although great care must be taken in interpreting the results since calibration factors are very geometry dependent; that is, the calibration factor usually changes as a function of distance from the ß source because the ß spectrum changes due to slowing and scattering in the air.
This calibration service is available by special arrangement only. Only the 90Sr+90Y calibrations are routinely calibrated.
$1,815
A33-08-05-02 Additional ß-rays. Additional distance calibrations for the ß dosimeter used in A33-08-05-01 can be performed at the same time at a reduced rate per distance calibrated. This service is available by special arrangement only. Fee on request

LINAC services

Calibration number Description Fee
A33-08-06-03 MV X-ray calibration w/60Co1305/ per instrument (MV part only). Absorbed dose to water calibrations are carried out for one ion chamber/electrometer system (one instrument range) at the three x-ray energies produced by the linear accelerator maintained at the laboratory — 6, 10 and 25 MV nominal energies. The standard for absorbed dose to water is a sealed water calorimeter, which measures the radiation-induced temperature rise at a depth of 10 cm in a water phantom (10 x 10 cm2 beam, with the surface of the phantom at 1 m from the source). The standard dose rate at the point of measurement is 300 cGy/min. For reference-class 0.6 cc cylindrical ionization chambers the standard uncertainty in the absorbed dose calibration coefficient is typically 0.5 percent. The calibration process includes polarity and recombination measurements, as required for dosimetry protocols such as AAPM TG-51. Note: Because there is a time-saving factor in performing the two services during the same set-up, we are offering a reduced rate of $2,750 total for the 6, 10 and 25 MV calibrations plus 60Co, if all done together  at the same time on the same instrument. $1,375

Irradiations in known fields

Calibration number Description Fee
A33-08-07-02 Irradiation of material in 60Co, beta, and X-ray fields. Material is irradiated to a known dose or exposure in 60Co and X-ray fields. NRC's X-ray generators, 60Co teletherapy units and sources used in the various standards are available for irradiation purposes. NRC also has a variety of other sources with varying strengths, for example, a 60Co Gamma-cell with a dose rate of 8 Gy/minute and a variety of calibrated weak 60Co and radium sources for calibrating radiation protection instrumentation. This service is available by special arrangement only. Fee on request

Use of NRC irradiation facilities

Calibration number Description Fee
A33-08-08-01 35 MeV linear accelerator. NRC has a 35 MeV linear accelerator, which provides electron beams with energies between 5 MeV and 35 MeV with average beam currents up to 60 µA. This can be used to produce either electron or photon beams in a wide variety of configurations. The linear accelerator beam is available on an hourly basis. A minimum of four hours must be reserved. $505 (/hr)
A33-08-09-04 Electrometer calibration. Charge calibrations for therapy electrometers are carried out using NRC-traceable capacitors and voltage sources.  The expanded uncertainty on the electrometer calibration is 0.1 percent, using a coverage factor of k=2 and providing a confidence level of 95 percent. $310
A33-08-10-01 Use of 60Co or X-Ray facilities. The 60Co and X-ray unit facilities at NRC are available on an hourly basis. A minimum of four hours must be reserved. $175

Independent testing: quality assurance (QA)

60Co dosimetry

Facilities are available at NRC for quality assurance testing of personal dosimetry systems, most of which use TLDs. The service provided by NRC involves irradiating a batch of up to 150 TLDs free in air in a 60Co beam to a known exposure or air-kerma of between 30 µC/kg (1 mGy to air) and 30 mC/kg (1 Gy to air). The irradiated dosimeters are returned to the client dosimetry services which process them and report their results for the exposure or air-kerma to NRC. NRC compares the dosimetry service values to the known NRC values and reports the results simultaneously to the Canadian Nuclear Safety Commission and to the dosimetry services.

Calibration number Description Fee
A33-08-11-01 60Co TLD independent testing for QA. This service covers the first use of the 60Co facilities in a single calendar year. Facilities are available at NRC for quality assurance testing of personal dosimetry systems, most of which use TLDs. The service provided by NRC involves irradiating a batch of up to 150 TLDs free in air in a 60Co beam to a known exposure or air-kerma of between 30 µC/kg (1 mGy to air) and 30 mC/kg (1 Gy to air). The irradiated dosimeters are returned to the client dosimetry services, which process them and report their results for the exposure or air-kerma to NRC. NRC compares the dosimetry service values to the known NRC values, and reports the results simultaneously to the Canadian Nuclear Safety Commission and to the dosimetry services. $9,390
A33-08-11-02 60Co TLD independent testing for QA - subsequent use. Each subsequent use of the 60Co facilities in the same calendar year is charged at a reduced rate per usage. $515
A33-08-11-05 60Co TLD independent testing for QA, extra badges (over 150) $5
A33-08-11-07 60Co TLD independent testing for QA - electronic personal dosimeters (EPDs). $2,210

X-ray dosimetry

Facilities are available for X-ray dosimetry similar to the 60Co dosimetry services (A33-08-11-01 and A33-08-11-02) described above. The radiation procedure is consistent with the requirements outlined in Appendix H of the Independent Test Specifications for Dosimetry Services: X-radiation, in the Regulatory Standards S-106(e), Technical and Quality Assurance Standards for Dosimetry Services, published on March 20, 1998, by the Atomic Energy Control Board (now the Canadian Nuclear Safety Commission). The procedure is tailored to meet the client's requirements and the fees are set accordingly. NRC values and the client's measured values for exposure (air kerma) are sent to the Provincial Radiation Dosimetry Review Committee.

Calibration number Description Fee
A33-08-11-03 X-ray TLD independent testing for QA. This service covers the first use of the X-ray facilities in a single calendar year. Facilities are available for X-ray dosimetry similar to the 60Co dosimetry services (A33-08-11-01 and A33-08-11-02) described above. The radiation procedure is consistent with the requirements outlined in Appendix H of the Independent Test Specifications for Dosimetry Services: X-radiation, in the Regulatory Standards S-106(e), Technical and Quality Assurance Standards for Dosimetry Services, published on March 20, 1998, by the Atomic Energy Control Board (now the Canadian Nuclear Safety Commission). The procedure is tailored to meet the client's requirements and the fees are set accordingly. NRC values and the client's measured values for exposure (air kerma) are sent to the Provincial Radiation Dosimetry Review Committee. $9,390

Neutron dosimetry

Facilities are available at NRC for quality assurance testing of personal dosimetry systems, most of which use TLDs. The service provided by NRC involves irradiating two batches of five dosimeters on an ISO slab phantom in an AmBe neutron field to different but known values of Hp(10) due to neutrons of between 1 mSv and 10 mSv. The irradiated dosimeters are returned to the client dosimetry service, which processes them and reports the results for the dose to NRC. We compare the dosimetry service values to NRC's values, and report the results simultaneously to the Canadian Nuclear Safety Commission and to the dosimetry service.

Calibration number Description Fee
A33-08-13-01 Independent testing for neutron dosimetry. Facilities are available at NRC for quality assurance testing of personal dosimetry systems, most of which use TLDs. The service provided by NRC involves irradiating two batches of five dosimeters on an ISO slab phantom in an AmBe neutron field to different but known values of Hp(10) due to neutrons of between 1 mSv and 10 mSv. The irradiated dosimeters are returned to the client dosimetry service, which processes them and reports the results for the dose to NRC. We compare the dosimetry service values to NRC's values and report the results simultaneously to the Canadian Nuclear Safety Commission and to the dosimetry service. $3,215

Extremity (beta) dosimetry

Facilities are available at NRC for quality assurance testing of personal dosimetry systems, most of which use TLDs. The service provided by NRC involves irradiating five batches of five dosimeters on a finger or slab phantom in a Sr-90/Y-90 beta field to different but known values of absorbed dose to tissue of between 10 mGy and 90 mGy at a depth of 7 mg/cm2. The irradiated dosimeters are returned to the client dosimetry service, which processes them and reports the results in absorbed dose units to NRC. We compare the dosimetry service values toNRC's value and report the results simultaneously to the Canadian Nuclear Safety Commission and to the dosimetry service.

Independent testing for extremity (beta) dosimetry

Calibration number Description Fee
A33-08-14-01 Independent testing for extremity (beta) dosimetry. Facilities are available at NRC for quality assurance testing of personal dosimetry systems, most of which use TLDs. The service provided by NRC involves irradiating five batches of five dosimeters on a finger or slab phantom in a Sr-90/Y-90 beta field to different but known values of absorbed dose to tissue of between 10 mGy and 90 mGy at a depth of 7 mg/cm2. The irradiated dosimeters are returned to the client dosimetry service, which processes them and reports the results in absorbed dose units to NRC. We compare the dosimetry service values to NRC's values, and report the results simultaneously to the Canadian Nuclear Safety Commission and to the dosimetry service. $1,800

Contact

Brad Downton
Telephone: 613-993-2715 ext. 245
Email: Brad.Downton@nrc-cnrc.gc.ca