Author Topic: definitions of some radiation terms?  (Read 1703 times)

gratus

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definitions of some radiation terms?
« on: April 26, 2006, 09:48:29 am »
Hi! Thank you for this board!

In preparing for an appointment with a GK doctor, I am hoping to learn the definitions of the following terms: isocenter; conformality; dose homogeneity.

Thanks!
Joanne

ppearl214

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Re: definitions of some radiation terms?
« Reply #1 on: April 26, 2006, 05:08:47 pm »
Hi Joanne and welcome.

Ok, I did a Google search for you:

Isocenter:
Great link/glossary of terms:  http://www.e-radiography.net/radtech/d/dose_definitions.htm

Conformality:
Conformality: A term used to describe a desired quality in thin film technology -- the ability of a deposition process to deposit films in equal thickness without gaps over all parts of a complex topology, including high-aspect ratio features.   

Homogeneity:
Great link/glossary as well:  http://www.emrf.org/Education%20and%20Training/Glossary%20Page%20H.html

Hope this helps! Good luck with your appt! Please keep us updated as to how it goes!

Phyllis
"Gentlemen, I wash my hands of this weirdness", Capt Jack Sparrow - Davy Jones Locker, "Pirates of the Carribbean - At World's End"

gratus

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Re: definitions of some radiation terms?
« Reply #2 on: April 27, 2006, 02:47:53 pm »
Thank you, Phyliis, for this information and these links!

Encouraged, I wandered around a little in google, adding “stereotactic radiosurgery� to the request, and found from Johns Hopkins’ website:

"Tumor Shape?The shape of the brain tumor (regular vs. irregular) can affect the "homogeneity" of the dose in the brain tumor. The dose to the tumor should be as uniform as possible with very low dose to the surrounding normal brain.

Targeting?The radiosurgeon selects the position within the brain tumor that will be the center of the arc of rotation of the linear accelerator. This is the "isocenter." For each isocenter, the diameter of the beam that best conforms to the brain tumor can be selected. Metal tubes called "collimators" of different diameters shape the beam. The collimators can be combined to yield very precise coverage of the brain tumor. The dose plan is developed on the computer, checked by the physicist, and tested on the accelerator using a phantom to confirm the correct position of the dose and size of the dose."

And, from some paper:
"The (Gamma Knife radiosurgery treatment) plan aims to deliver a high dose of radiation to the intracranial target volume with minimum damage to the surrounding normal tissue. The treatment goals can vary from one neurosurgeon to the next, so a planning tool must be able to accommodate several different requirements.  Among these requirements, the following are typical, although the level of treatment and importance of each may vary.

A ``homogeneity'' requirement: the complete target must be covered by a dose that has intensity at least 50% of the maximum delivered dosage.  This is necessary for tumor kill.

A ``conformity'' requirement: minimize the non-target volume that is covered by a shot or the series of delivered shots.   This helps
normal cell recovery.

Various ``avoidance'' requirements: limit the amount of dose that is delivered to certain sensitive structures close to the target.  It is
imperative not to damage certain other parts of the brain.

There are standard rules established by various professional and advisory groups that specify acceptable homogeneity and conformity
requirements."



Thank you again for your help and good wishes! Your story has been very inspirational.

Joanne



Battyp

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Re: definitions of some radiation terms?
« Reply #3 on: April 27, 2006, 03:26:22 pm »
Joanne good post..interesting!  Wasn't an option for me but still ike to know what it's all about.