Radioactive Check Source, 90Sr, 20 MBq (541 µCi)

Radiation Therapy

Radioactive Check Source,

90 Sr, 20 MBq (541 µCi)

Model 30-658

Introduction

The Radioactive Check Source, Model 30-658, provides

• Radioactive check device for constancy

checks of flat plane-parallel type ion

chambers

the Medical Physicist with an easy way to check the

constancy of response of flat plane-parallel type

• Checks for proper functioning of the

complete dosimetry system

ionization chambers. The device contains 20 MBq of 90 Sr

in a fully shielded container, and is equivalent to

ISO Class C64444. Holders for reproducible chamber

• Holders available for Markus™, Advanced

Markus™, and Roos™ ion chambers

positioning during check measurements are available

for the Markus, Advanced Markus, and Roos ion

chambers.

Applications

Use of the Radioactive Check Source, Model 30-658, is recommended for high

precision dosimetry and is required by IEC 60731 - Dosimeters with ionization

chambers as used in radiotherapy, 1977. A check measurement performed

before each dose measurement will assure the ionization chamber is responding

Specifications

Radioactive content 20 MBq (541 µCi)

properly. Since the radioactive source is cylindrical, the entrance window of the flat

plane-parallel is placed near the source by means of the appropriate holding device.

Half-value time 28.7 years

Optional accessories

Check readings must be corrected for the 28.7 year half-life time of the 90 Sr source.

Holder for 0.055 cm 3 Markus (Model 30-329)

and 0.02 cm 3 Advanced Markus (Model 30-331)

Electron Ion Chambers Model 30-658-1000

However, under constant environmental conditions (temperature, pressure, air

humidity) the current produced in an ionization chamber is reproducible with an

uncertainty of ± 1%.

Holder for 0.35 cm 3 Roos (Model 30-332)

Electron Ion Chamber Model 30-658-2000

Holders to assure correct positioning and repositioning accuracy for the 0.055 cm 3

Available model(s)

Markus chamber (Model 30-329), 0.02 cm 3 Advanced Markus chamber (Model 30-331),

30-658 Radioactive Check Source,

⁹⁰Sr, 20 MBq (541 µCi).

A radioactive materials license is required

and 0.35 cm³ Roos chamber (Model 30-332) are available. If this device is used with

other types of chambers, proper positioning becomes the responsibility of the user.

When making check measurements with the Radioactive Check Source, Model 30-658,

care must be taken to obtain temperature equilibrium between the ionization

chamber, check device, and the surrounding environment. After use, the protective

cover should be replaced and secured. With the protective cover in place the dose rate

from the source is reduced to less than 1 µSv/h at 10 cm. Leaving an ionization

chamber in the check device when not in use is not recommended since this can

damage the ion chamber.

Note: A radioactive materials license for ⁹⁰Sr is required for purchase.