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мАс

English translation: milliamper-seconds (mAs)

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GLOSSARY ENTRY (DERIVED FROM QUESTION BELOW)
Russian term or phrase:мАс
English translation:milliamper-seconds (mAs)
Entered by: Vidmantas Stilius
Options:
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- Include in personal glossary

15:10 Jun 28, 2001
Russian to English translations [PRO]
Medical
Russian term or phrase: мАс
Экспозиция при съемке на ортопантомографическом аппарате - 100 мАс. (Рентгенография)
Alexander Alexandrov
Russian Federation
Local time: 04:15
milliamper-seconds (mAs)
Explanation:
The following question was submitted on January 11, 2001, and was answered by an expert in the appropriate field:

Q: I am doing a high school project and can't find the difference between mas radiation levels and krad levels. I had some seeds x rayed and was told that the exposure level was in mas. Can you explain?
A: The term krad is short for kilorad or thousands of rad. This is a unit of absorbed dose, which in turn is the amount of energy absorbed per unit mass by the irradiated object (in this case, your sample of seeds).


1 rad = 0.01 joules/kilogram; 1 krad = 10 J/kg.

The term mas (more commonly written as mAs) stands for milliampere-seconds. It is the product of the current through the x-ray tube (mA) and the time the tube was energized (s). For a given x-ray machine, operated at a given kilovoltage potential, the radiation output rate is proportional to the current (mA) and the total radiation output for an exposure episode is proportional to the mAs.

The absorbed dose (krad) to the sample (seeds) is the important factor for your experiment. The mAs is how the machine operator describes the particular exposure. How do we reconcile the two?

First of all, if all other factors are held constant (particularly machine kilovoltage, distance from the x-ray tube focal spot to the irradiated sample, and the size and shape of the sample), then the absorbed dose (krad) for each of the various irradiated samples is proportional to the mAs delivered. For example, if the mAs was doubled from sample 1 to sample 2, the absorbed dose to sample 2 was twice that to sample 1; if the mAs was increased by 4 times, the absorbed dose increased by four times, etc. This tells you the relative dose delivered to your various samples but doesn't tell you the actual quantitative values.

The relationship between the mAs delivered by the machine and the absorbed dose (krad) received by the sample depends upon a number of factors which you did not specify with your question. Some of the more important factors are:
The potential (kilovoltage or kVp) at which the machine was operated—radiation output increases strongly with potential.

"Filtration" in the beam.

Distance from the focal point of the x-ray tube to the irradiated sample. The radiation intensity varies approximately inversely with the square of the distance. For example, if the dose rate was specified for a 1-meter distance, the dose rate would be 1/4 as great if the sample were irradiated at a 2-meter distance and would be four times as high if the sample were placed at a 0.5-meter distance.

Other factors such as the type of power supplied to the machine (single phase or 3-phase), materials of the x-ray tube target, etc., also affect the radiation output for a given mAs.
The best way to assign an absorbed dose value to your irradiated seeds is to measure the absorbed dose per mAs using a suitable radiation instrument.

Alternatively, if the x-ray machine has been calibrated recently by a radiation physicist, the calibration report should indicate radiation output per mAs. Note that it is important that the measurement be for the same kilovoltage (possibly expressed as kVp) as used for the seed irradiation. If the distances were different between the calibration and your seed irradiation, you can correct using the inverse square law mentioned above.


Selected response from:

Vidmantas Stilius
Local time: 03:15
Grading comment
Thank you very much!
4 KudoZ points were awarded for this answer

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Summary of answers provided
na +2milliamper-seconds (mAs)
Vidmantas Stilius


  

Answers


26 mins peer agreement (net): +2
milliamper-seconds (mAs)


Explanation:
The following question was submitted on January 11, 2001, and was answered by an expert in the appropriate field:

Q: I am doing a high school project and can't find the difference between mas radiation levels and krad levels. I had some seeds x rayed and was told that the exposure level was in mas. Can you explain?
A: The term krad is short for kilorad or thousands of rad. This is a unit of absorbed dose, which in turn is the amount of energy absorbed per unit mass by the irradiated object (in this case, your sample of seeds).


1 rad = 0.01 joules/kilogram; 1 krad = 10 J/kg.

The term mas (more commonly written as mAs) stands for milliampere-seconds. It is the product of the current through the x-ray tube (mA) and the time the tube was energized (s). For a given x-ray machine, operated at a given kilovoltage potential, the radiation output rate is proportional to the current (mA) and the total radiation output for an exposure episode is proportional to the mAs.

The absorbed dose (krad) to the sample (seeds) is the important factor for your experiment. The mAs is how the machine operator describes the particular exposure. How do we reconcile the two?

First of all, if all other factors are held constant (particularly machine kilovoltage, distance from the x-ray tube focal spot to the irradiated sample, and the size and shape of the sample), then the absorbed dose (krad) for each of the various irradiated samples is proportional to the mAs delivered. For example, if the mAs was doubled from sample 1 to sample 2, the absorbed dose to sample 2 was twice that to sample 1; if the mAs was increased by 4 times, the absorbed dose increased by four times, etc. This tells you the relative dose delivered to your various samples but doesn't tell you the actual quantitative values.

The relationship between the mAs delivered by the machine and the absorbed dose (krad) received by the sample depends upon a number of factors which you did not specify with your question. Some of the more important factors are:
The potential (kilovoltage or kVp) at which the machine was operated—radiation output increases strongly with potential.

"Filtration" in the beam.

Distance from the focal point of the x-ray tube to the irradiated sample. The radiation intensity varies approximately inversely with the square of the distance. For example, if the dose rate was specified for a 1-meter distance, the dose rate would be 1/4 as great if the sample were irradiated at a 2-meter distance and would be four times as high if the sample were placed at a 0.5-meter distance.

Other factors such as the type of power supplied to the machine (single phase or 3-phase), materials of the x-ray tube target, etc., also affect the radiation output for a given mAs.
The best way to assign an absorbed dose value to your irradiated seeds is to measure the absorbed dose per mAs using a suitable radiation instrument.

Alternatively, if the x-ray machine has been calibrated recently by a radiation physicist, the calibration report should indicate radiation output per mAs. Note that it is important that the measurement be for the same kilovoltage (possibly expressed as kVp) as used for the seed irradiation. If the distances were different between the calibration and your seed irradiation, you can correct using the inverse square law mentioned above.





    www.hps.org/publicinformation/ate/q610.html - 12k
Vidmantas Stilius
Local time: 03:15
Native speaker of: Native in LithuanianLithuanian
PRO pts in pair: 118
Grading comment
Thank you very much!

Peer comments on this answer (and responses from the answerer)
agree  DrSantos
8 hrs

agree  Andrei Vrabtchev
8 hrs
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