Hi,
Usually the B constant is given at 25 degrees C but you should check it if you can find it to make sure.
The formula given by Eric looks like the formula i've used in the past and it works pretty well. You might also want to note that when measuring the voltage it causes in a voltage divider made with upper resistor R fixed and lower resistor the thermistor (or vice versa) the highest dv/dT occurs when R=RT, which for your thermistor would be 18k at 60 degrees C. It also produces a rather convenient voltage point being half the supply voltage at 60 deg C.