CSN Login
Members Online: 11

CyberKnife Basic questions

hopeful and opt...
Posts: 1317
Joined: Apr 2009

Dual Post ... CyberKnife.com and CSN.cancer.org

My friend has just been diagnosed with intermediate low level PCa 3+4=7, 0.2 involvement, one of twelve cores positive,(confirmed by an expert second opinion), had a rising PSA, high PCA3, MRI with Tesla 3.0 shows various suspicious lesions, one at 2.0 CM. No extracapsular extension. MRI indicates a 104 enlarged prostate size while the biopsy comes out at 75. He has some trouble with urnination. Right now he is taking flowmax. He had a quad bypass surgery in the nineties, he has some heart irregularity. He will be 71 in October.

He is exploring surgery, cyberknife, and other radiation such as tomo therapy. Some radiation treatments such as bracky are not acceptable because of his large prostate size.

(As a man who is currently being treated with "Active Surveillance with Delayed Treatment" I am also very interested in reading of any inputs...........THANK YOU VERY MUCH)

Some questions now aboutCyberKnife Radiosurgery for Prostate Cancer:

What are the advantages and disadvantages of CyberKnife over Novalis, if any?

What are advantage and disadvantages of Novalis over CyberKnife, if any?

Bsically will Novalis do the same job as Cyberknife in delivering the the radiation.

What is an IRIS Variable Collimator? How is this used, what are the benefits?

What is a LINAC?

Please talk about a fused MRI in planning planning a CT scan., as opposed to a CT Scan only used at Stanford?

What generation CyberKnife and Novalis machines are most up to date? Are the above mentioned equipment automated in these late model machines.

How does his current urinary problems need to be treated if he selects CyberKnife.

Is a single modality of treatment appropriate, or would some kind of homone treatment appropriate.

What is the ideal total dose of Gy that needs to be delivered in 5 fractions, every other day.( I hope that I am using the right terminology). What are the effects on erectile function preservation rate(what are the rates?) Grade 3+ Late Urinary Toxicity; and Late Bowel Toxicity, and PSA Freedom from Relapse?

What margin is recommended for him, would close, I think 1mm be appropriate or is a wider one a better choice?

Not being a health care professional or very knowledgeable about cyberknife radiation delivery, I tried to think of everything important, however is there anything that you can think of that will be important for us to know?

Thank you very much.

Swingshiftworker
Posts: 634
Joined: Mar 2010

These questions are WAY too technical for me to answer. Delayed responding for that reason but thought I should chime in to at least let you know that you're not being ignored. Perhaps Kongo can offer some answers.

All I can say is that my treatment involved 9.5 gy per treatment - 4 x's for a total of 29 gy total. No ED or incontinence. I had both an MRI and CT scan done after marker placement and before treatment. Using both aides in the accuracy of treatment planning. I believe the program is designed to use the max margins available, which can be in the sub-mm range.

I am now (21 months following treatment) experiencing some minor urinary irritation (burning sensation) and some renewed frequency/urgency issues that I had before treatment. The RO says this is due to a PSA bounce (my response - what bounce? since my PSA has been in the 1.55-1.81 range for the past 6 months.) Was told to try ibuprofen to alleviate the burning sensation and, if necessarry, to go on FlowMax or similar drugs to deal w/the urgency/frequency issue. Am only taking ibuprofen for now.

Good luck finding the answers you're seeking.

hopeful and opt...
Posts: 1317
Joined: Apr 2009

I'vde gotten some very excellent answers from some men at the cyberknife site...right now I am digesting thier comments. I have not yet responded to them

One thing that one of them mentioned is:

Dr. Katz uses 35Gy(7Gy in 5 fractions) and gets great results with mimimum toxity.

Dr. Fuller uses 37 Gy=925 in 4 fractions

Dr. King uses 40 Gy in 5 fractions

Most ck docs give 36.25 Gy= 7.25 Gy times 5 fractions

............................

I'm thinking that you probably had 38 Gy = 4 times 9.5 which falls in that range.

Renewed irritation and urinary issues....from the way I read this, it does not appear to be a clinical severe toxity, but to you it's still a big deal.......does the doc indicate how long this will last?......good luck with this

Kongo's picture
Kongo
Posts: 1167
Joined: Mar 2010

Ira,

Here is a link to a technical paper from October 2010 that provides a detailed description of the equipment used in the Accuray CyberKnife system.

http://www.tcrt.org/The-CyberKnife-Robotic-Radiosurgery-System-in-2010-433-452-p17809.html

I had 36.25 Gy in five fractions of 7.25 Gy each with a day in between each treatment.

During my research I consulted both with Novalis and CK. While I didn't research the technical details to the level you are asking questions about at the time, I looked at the machine and talked at length with the radiologist and was impressed with her range of knowledge and overall professionalism.

At the time i was making a choice Novalis was very new to the market of treating prostate cancer. I qualified for a clinical trial but they had only signed up three other guys for it. While I am also in a trial with the CK system, there were about 400 signed up and it was a refinement of earlier work King had done at Stanford.

In the end I chose CK but from everything I have read since then I believe the Novalis system is probably as effective although I haven't seen any papers, even early study results, that support that. There are probably some technical arguments to be made about the ability of the CK robotic arm to deliver better coverage than the Novalis system (which looks and acts pretty much like an IMRT machine...you lay in a tube and the beam rotates about you) but I would leave that to a radiologist to discuss. I do recall that the Novalis radiologist I met with told me that the machine was originally designed for IMRT but advancements had allowed it to be used to deliver SBRT as well. I am seeing my radiologist tomorrow and will ask the question.

Best.

K

Swingshiftworker
Posts: 634
Joined: Mar 2010

You're right, Hopeful. Should have said 38 Gy total. I obviously didn't multiply 9.5 x 4 correctly!!!

RO didn't say how long to expect the current problems would last but shouldn't be "too long" (3-6 months) or I'll ask for a further examination.

Kongo's picture
Kongo
Posts: 1167
Joined: Mar 2010

Ira,

I spoke to my radiologist about the Novalis equipment today. He indicated that the Novalis equipment required a higher margin than CK and was not as accurate in beam placement overall. He felt that made a difference but we agreed that there wasn't any evidence to suggest that Novalis was less effective than CK at this point. In fact, there's little evidence at all about the Novalis track record with PCa but they've only been doing it a few years. He did indicate that the Novalis machine was originally developed for IMRT types of applications and had been adapted through software adjustments to compensate for prostate movement by using the gold fiducials similar to what CK uses to track the prostate in real time.

I don't know how much of this is "Ford" vs. "Chevy" type talk. When I mentioned Dr. King and the Novalis machine he did tell met that UCLA does not have a CK machine and wasn't going to spend the $10M or so to acquire and install one when he came down from Stanford since they had already invested in the Novalis equipment.

Hope this helps.

K

Subscribe with RSS
About Cancer Society

The content on this site is for informational purposes only. It is not a substitute for professional medical advice. Do not use this information to diagnose or treat a health problem or disease without consulting with a qualified healthcare provider. Please consult your healthcare provider with any questions or concerns you may have regarding your condition. Use of this online service is subject to the disclaimer and the terms and conditions.

Copyright 2000-2014 © Cancer Survivors Network