Semiflex™ Ionization Chamber, 0.3 cm³, Waterproof

Radiation Therapy

Semiflex ™ Ionization Chamber,

0.3 cm 3 , Waterproof

Model 30-316

• Suitable for use in water phantoms

or solid state phantoms

• Measuring volume is fully vented

via the connector

• Fully guarded up to measuring

volume

• Touchable parts free of high voltage

• Extension cables up to 100 meters

in length are available

• Type tested by

PTB Braunschweig

23.21

85.1

The 0.3 cm 3 ionization chamber (Model 30-316) is designed for measurements in the

useful beam of high energy photon and electron fields. The chamber is waterproof and

is used mainly for relative measurements in a water phantom or in an air scanner. The

measuring volume is open to the surrounding air via the 4.3 ft (1.3 m) cable and BNC

Triax connector. This chamber has a short rigid stem for easy mounting, includes a

PMMA buildup cap, and is type tested by PTB Braunschweig.

Specifications

Volume 0.3 cm 3

Response 1 • 10 -8 C/Gy

Leakage ± 4 10 -15 A

Polarizing voltage Maximum 500 V

Cable length 4.3 ft (1.3 m)

Cable leakage 10 -12 C/(Gy cm)

Wall material PMMA (C 5 H 8 O 2 )

Wall density 1.19 gm/cm 3 (PMMA)

Wall thickness 0.7 mm PMMA

Area density 83.3 mg/cm 2

Electrode Aluminum, graphite coated, 1.0 mm Ø, 14.25 mm long

Nominal useful range 30 keV to 50 MeV

Range of temperature 10º to 40ºC

Range of relative humidity 20% to 75%

Ion collection time

300 V: 0.10 ms

400 V: 0.08 ms

500 V: 0.06 ms

Saturation behavior

Saturation

behavior

Polarizing

voltage

99.0%

saturation

99.5%

saturation

Maximum dose rate at

continuous irradiation

300 V

17.0 Gy/s

8.5 Gy/s

400 V

30.0 Gy/s

15.0 Gy/s

500 V

45.0 Gy/s

23.0 Gy/s

300 V

1.0 mGy

0.4 mGy

Maximum dose rate

per irradiation pulse

400 V

1.3 mGy

0.5 mGy

500 V

1.7 mGy

0.7 mGy

See next page for more specifications.

Specifications (continued)

Diagram

Energy dependence

1.10

Absorbed dose to water

Ai r k e r m a

1.05

1.00

0.98

0.99

1.00

0.95

0.97

1.00

0.96

0.95

0.90

145

Co-60

Photon Energy, kV

Directional dependence

90º

0º

180º

Reading / Dose, %

in Air

in PMMA

6º

12º 18º

24º 30º

60º

90º

120º

150º 162º 174º 180º

6º

12º

18º

24º

30º

60º

90º

120º

150º

162º

174º

180º

70 kV 44.1 65.6 80.2 87.5 92.5 99.7 100.0 99.6

96.1 93.0 88.7 85.4

70 kV

97.2 104.3 106.4 105.9 105.4 103.0 100.0 97.8

98.1

98.8

99.4

97.1

140 kV 68.7 82.9 92.2 95.0 97.4 99.7 100.0 99.4

97.7 96.5 94.5 91.0

140 kV

109.0 108.0 106.9 106.1 105.3 101.8 100.0 98.8

98.9

99.6 100.3 99.8

280 kV 79.9 87.1 93.1 95.5 97.5 99.5 100.0 99.7

98.5 97.4 96.1 94.9

280 kV

111.3 107.1 105.0 104.2 103.3 101.2 100.0 99.4 100.0 100.6 101.2 100.6

Co-60 83.2 91.1 94.6 96.0 97.1 99.4 100.0 99.4

97.5 96.8 96.0 94.6

Co-60

104.0 106.4 104.6 104.0 103.5 101.1 100.0 99.9 100.8 101.3 101.8 101.0

Optional accessories

Check Source, 90 Sr, 33 MBq (892 µCi) (Model 30-657)

Available model(s)

30-316 Semiflex Ionization Chamber, 0.3 cm 3 , Waterproof, includes

BNC Triax connector, PMMA buildup cap, and rigid stem for mounting

Other types of triaxial cable connectors available