Few questions on treatment indices

[mainsail]

Hi everyone,

The medical student here (again) - I have found some information on treatment indices but I'm still a bit confused.

Q1: When the term "isodose" is used, it refers the radiation dosage and not the isodose volume correct? The latter would be PIV, right?

Q2: When the term TV is used, does it stand for Target Volume, Treatment Volume, or Tumor Volume? I suppose target and tumor volume must be the same??

My project is on radiosurgery and as after reading through literature and online search results, my understanding of treatment indices is as follows:

1) Conformity Index (PITV) - the ratio of prescription isodose volume to target/tumor volume. [Q3: Why would this index not take into account position? Hypothetically if the PIV and target volume were exactly identical, this index would be a 1 even if the PI had only a 10% overlap with the tumor)

2) Homogeneity Index - ratio of Dmax/PI

3) Coverage index - ratio of isodose (of line surrounding target) to prescription isodose

Thank you so much for your help in advance

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[mainsail]

Thanks anyway everyone - a very kind resident sat me down and explained everything

Hi everyone,

The medical student here (again) - I have found some information on treatment indices but I'm still a bit confused.

Q1: When the term "isodose" is used, it refers the radiation dosage and not the isodose volume correct? The latter would be PIV, right?

Q2: When the term TV is used, does it stand for Target Volume, Treatment Volume, or Tumor Volume? I suppose target and tumor volume must be the same??

My project is on radiosurgery and as after reading through literature and online search results, my understanding of treatment indices is as follows:

1) Conformity Index (PITV) - the ratio of prescription isodose volume to target/tumor volume. [Q3: Why would this index not take into account position? Hypothetically if the PIV and target volume were exactly identical, this index would be a 1 even if the PI had only a 10% overlap with the tumor)

2) Homogeneity Index - ratio of Dmax/PI

3) Coverage index - ratio of isodose (of line surrounding target) to prescription isodose

Thank you so much for your help in advance