Really stupid question...

[samtheman]

Hello,

I am doing research and I have a dumb question. On the dose vs volume histogram, what is the meaning of V10, V70 etc...When a paper says the V30>30cm^3 or V82>7cm^3, what does that mean? Any help is appreciated. Thanks!

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[Gfunk6]

V stands for volume, V30 means some (specified) percentage of an organ got 30 Gy or more. If there is a number afterwards like V20 < 10 cc then it means that less than 10 cc's of the organ received 20 Gy or more.

Also, since you may not know . . .

Gy = Gray = absorbed dose = the unit which Radiation Oncologists use to prescribe radiation = 1 Joule/kilogram of mass

 

[chickflick]

V stands for volume, V30 means some (specified) percentage of an organ got 30 Gy or less. If there is a number afterwards like V20 < 10 cc then it means that less than 10 cc's of the organ received 20 Gy or less.

Also, since you may not know . . .

Gy = Gray = absorbed dose = the unit which Radiation Oncologists use to prescribe radiation = 1 Joule/kilogram of mass

Is there a resource for this stuff? Thanks btw...

 

[Gfunk6]

I guess a "really stupid question" deserves a "really stupid answer"

It was politely pointed out that I mis-typed the definion of V20 which should be the volume getting 20 Gy or more so I've modified my initial reply accordingly.

 

[kepler2]

It's worth mentioning that the V(x) designation does not always strictly refer to dose (as in x = 20 = 20 Gy), but occasionally the 'x' will refer to a % of the prescription dose. In prostate brachytherapy, for example, V100 is used and defined within literature reports as the % volume of the prostate getting 100% or more of the prescribed dose. V90 is the % volume of prostate getting at least 90% of the prescribed dose, etc...

That said, V20 particularly in the context of discussion about lung cancer irradiation has a well-accepted meaning, and typically people won't say "V20Gy," they will abbreviate to "V20" and the meaning is known.