Example:
Calculating Irradiation Time If Dose is NOT listed on Dose Chart
Suppose you wish to give a specimen a dose of 34 Gy on Level 3. Looking at the Dose Chart,
the dose rate at Level 3 is 1.8 Gy/minute. Dividing dose by the dose rate
(34 ÷ 1.8) gives a total irradiation time of 18.89 minutes.
Doses are for machine setting: 160 KV, 25mA
RAD+(blac
k boran
carbonite
box)
ANIMAL
CAGE
LEVEL 1
LEVEL 2
LEVEL 3
LEVEL 4
LEVEL 5
cGy/Rad
dose
Gray(Gy)
dose
Dose Rate:
112 rads
Or
1.1Gy/min
Dose Rate:
114 rads
Or
1.4Gy/min
Dose Rate:
101 rads
Or
1.0Gy/min
Dose Rate:
132 rads
Or
1.3Gy/min
Dose Rate:
180 rads
Or
1.8 Gy/min
Dose Rate:
256 rads
Or
2.6 Gy/min
Dose Rate:
410 rads
Or
4.1 Gy/min
100
1
54S
55S
1M 00S
46S
34S
22S
15S
250
2.5
2M 14S
2M 11S
2M 28S
1M 53S
1M 23S
59S
33S
500
5
4M 28S
4M 23S
4M 57S
3M 47S
2M 47S
1M 57S
1M 13S
1,000
10
8M 56S
8M 47S
9M 54S
7M 35S
5M 33S
3M 55S
2M 27S
1,500
15
13M 25S
13M 09S
14M 51S
11M 22S
8M 19S
5M 51S
3M 39S
2,000
20
17M 51S
17M 33S
19M48S
15M 9S
11M 06S
7M 49S
4M 53S
2,500
25
22M 19S
21M 56S
24M 45S
18M 57S
13M 53S
9M 46S
6M 06S
3,000
30
26M 48S
26M 19S
29M 42S
22M 43S
16M 40S
11M 43S
7M 19S
3,500
35
31M 15S
30M 42S
34M 39S
26M 32S
19M 27S
13M 41S
8M 33S
4,000
40
35M 42S
35M 06S
39M 36S
30M 18S
22M 14S
15M 38S
9M 45S
6,000
60
53M 35S
52M 32S
59M 24S
45M 27S
33M 19S
23M 27S
14M 37S
10,000
100
see Deb
see Deb
see Deb
see Deb
55M 34S
39M 04S
24M 24S
12,500
125
see Deb
see Deb
see Deb
see Deb
1H 09M 27S 48M 51S
30M 29S
17,500
175
see Deb
see Deb
see Deb
see Deb
see Deb 1H 08M 22S 42M 41S
20,000
200
see Deb
see Deb
see Deb
see Deb
see Deb
see Deb
48M 47S
1cGy=1 Rad
1Gy=100cGy (100 Rads)
10Gy=1000cGy (1000 Rads)=1 kiloRad
100Gy=10000cGy
Note that some of the times have a notation to “See Deb” that is because if the
machine is continuously ran for more than an hour it will over heat and shut down.
To prevent the machine from overheating we run our sample for 59minutes, let the
machine turn off the X-ray but keep the fans going for 15 minutes, this allows the
200 gallons of internal water to cool down to maintain a lower core temp for the X-
ray tube. Once the cool down is done, simply enter your remaining time and
continue your run.
In most cases, the Dose Chart will provide the irradiation time needed. However,
if a dose is not provided you can use the dose rate to calculate the irradiation
time, as shown in the example below: