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Questions regarding fractionated treatment for hearing retention
dlight
Posted: Wednesday, February 10, 2016 9:24 AM
Joined: 2/10/2016
Posts: 4


Recently diagnosed with a left side AN, 5x3x4 mm, very near the cochlea (~1mm), and I have severe hearing loss at higher frequencies but very serviceable hearing. I have all but eliminated surgery as an option. One doctor has recommended fractionated radiation treatment (3 dose) as a means to help preserve hearing. I have several questions regarding this that came to me after my appointment: 1) What is the mechanism that provides the advantage; is it simply the lower doses spread over more time? 2) The doctor mentioned that U of Pitt MC, long synonymous with GK, is using more fractionated treatment, presumably CK, to increase odds of hearing retention. Has this been published anywhere? 3) The center I was talking to uses TrueBeam with Novalis Brainlab. I gather the base technology is similar to or same as CK, but what are the differences? 4) He mentioned the use of IMRT. Is that an option with all types of radiosurgery (CK and GK), limited to the linear accelerator types, or specific to Novalis? I tried researching these questions but came up empty (or just became confused). Thank you in advance for any advice and answers you can provide - Terry
Diagnosed 1/14/16 AN/VS left side 5x3x4 mm 1 mm from cochlea Severe hearing loss at higher frequencies, but still functional
radsrus
Posted: Wednesday, February 10, 2016 12:46 PM
Joined: 10/10/2008
Posts: 4435


1. I t is not really clear that multiple fractions do more to preserve hearing. BNI compared thier Gamma Knife patients (1 fraction) to their CK treated patients (3 fractions) with better hearing preservation in the CK group, but others have gotten similar hearing preservation with single fraction treatment. If there is an advantage, it is because of less dose per day. 2. I don't know what UPMC is doing right now. They have historically treated AN with Gamma Knife. 3. TrueBeam technology is very different. FOr some thing it may not really matter, but for an AN that small you are almost certainly better off with either Gamma Knife or CyberKNife. 4. IMRT is standard fractionation radiation usually, and has lower control rate. It is a way of trying unsuccessfully to achieve the dose distributions of CK and GK. You should seek a CK or GK site

Clinton A. Medbery, III, M.D. Southwest Radiation Oncology buddy@swrads.org
dlight
Posted: Wednesday, February 10, 2016 1:05 PM
Joined: 2/10/2016
Posts: 4


Thank you, Dr Medbery for the quick reply. Regarding number 3; I would be better off with GK or CK because of improved accuracy? - Terry

Diagnosed 1/14/16 AN/VS left side 5x3x4 mm 1 mm from cochlea Severe hearing loss at higher frequencies, but still functional
radsrus
Posted: Wednesday, February 10, 2016 1:44 PM
Joined: 10/10/2008
Posts: 4435


There is no significant difference in accuracy.

Clinton A. Medbery, III, M.D. Southwest Radiation Oncology buddy@swrads.org
dlight
Posted: Wednesday, February 10, 2016 3:04 PM
Joined: 2/10/2016
Posts: 4


Thanks again for the reply. Above you said, "... for an AN that small you are almost certainly better off with either Gamma Knife or CyberKNife." Why is that? Is there something inherently wrong with TrueBeam that makes it undesirable for a small AN? - Terry

Diagnosed 1/14/16 AN/VS left side 5x3x4 mm 1 mm from cochlea Severe hearing loss at higher frequencies, but still functional
radsrus
Posted: Wednesday, February 10, 2016 3:25 PM
Joined: 10/10/2008
Posts: 4435


The answer is a little complex, but the short version is that with very small tumors the advantages of CK and GK become much more important. They are more "accurate" (there is more to it than mere mechanical accuracy).

Clinton A. Medbery, III, M.D. Southwest Radiation Oncology buddy@swrads.org
dlight
Posted: Monday, February 15, 2016 6:43 AM
Joined: 2/10/2016
Posts: 4


Thank you Dr. Medbery. Are the doctors on this forum compensated in any way by Accuray/CyberKnife? I was not able to find a statement one way or the other on the site.

Diagnosed 1/14/16 AN/VS left side 5x3x4 mm 1 mm from cochlea Severe hearing loss at higher frequencies, but still functional
radsrus
Posted: Monday, February 15, 2016 6:49 AM
Joined: 10/10/2008
Posts: 4435


Doctors on this forum have never been compensated

Clinton A. Medbery, III, M.D. Southwest Radiation Oncology buddy@swrads.org
 

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