The March Continues for Prostate Hypofractionation

[Radiated_GuineaPig]

So just to be controversial, with a good spaceOAR placement do we even need the fanciness that is SBRT. The whole idea of the image guidance and the physician being present is to keep away from the rectum. Do we even need inverse planning? Could we get to a point where we do 40/5 with 3D conformal when we can get 2-3cm rectal separation by optimizing spaceOAR placement.

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[xrthopeful]

yes.
yes.
no.

 

[scarbrtj]

Sorry to hijack this thread somewhat, but does anyone here regularly use one of the moderately hypofx prostate regimens (e.g. 70Gy/20fx)? If so, what dosing do you use for the pelvis or SV. For example, we often take the pelvis to 45Gy or SV to 50.4Gy before boosting the prostate?

Also, what dose constraints do you use for moderate hypofx? RTOG 0415? I know Kaiser will use 10% lower than RTOG 0415 constraints.

Any thoughts?

I guess you mean 70/28. And I guess you mean not boosting the prostate and instead SIB-type? Like 50.4/28 to the nodes/SVs and 2.5 a day to prostate? That would make good sense. If you only wanted 45 Gy to nodes and SVs, I would just do two plans. One SIB at 25 fractions and a final non-SIB "boost" as you say to the prostate of 3 fractions. AKA a sequential plan

 

[scarbrtj]

So just to be controversial, with a good spaceOAR placement do we even need the fanciness that is SBRT. The whole idea of the image guidance and the physician being present is to keep away from the rectum. Do we even need inverse planning? Could we get to a point where we do 40/5 with 3D conformal when we can get 2-3cm rectal separation by optimizing spaceOAR placement.

SBRT is simply high fraction size per day. Medicare defines it as more than 5 Gy a day for two one to five fractions. If you do six fractions of 5 Gy, it is not SBRT per Medicare; doesn't matter what the "science" or literature or definition of words means. You can do SBRT with 3D or IMRT; can do it with or without inverse planning. So you can easily do 40/5 to prostate with SpaceOAR using what we call a non-inverse planned approach, aka 3D. It is simply more time-consuming to plan and will after A LOT of work give you a plan about 90-99% as good as an inverse planned one.

edit: If what you do matches this, you can call it SBRT. (The physician being present or not really has no impact on ability to "keep away" from the rectum in SBRT any more than it does in non-SBRT prostate txs.) Note, no guidance on where physician must be during procedure, no "fanciness" really. No guidance on inverse planning, IMRT or not. The image guidance can be anything; it is not separately billed for. Could be SGRT. Even MV port films. What I'm giving you here is one viewpoint. This viewpoint could be expanded to include other requirements and that wouldn't be wrong; anything that would have less requirements than this probably would be wrong though.

SBRT is a treatment that couples a high degree of anatomic targeting accuracy and reproducibility with very high doses of extremely precise, externally generated, ionizing radiation, thereby maximizing the cell-killing effect on the target(s) while minimizing radiation-related injury in adjacent normal tissues. SBRT is used to treat extra-cranial sites as opposed to stereotactic radiosurgery (SRS) which is used to treat intra-cranial and spinal targets.

The adjective “stereotactic” describes a procedure during which a target lesion is localized relative to a known three dimensional reference system that allows for a high degree of anatomic accuracy and precision. Examples of devices used in SBRT for stereotactic guidance may include a body frame with external reference markers in which a patient is positioned securely, a system of implanted fiducial markers that can be visualized with low-energy (kV) x-rays, and CT-imaging-based systems used to confirmed the location of a tumor immediately prior to treatment.

Treatment of extra-cranial sites requires accounting for internal organ motion as well as for patient motion. Thus, reliable immobilization or repositioning systems must often be combined with devices capable of decreasing organ motion or accounting for organ motion e.g. respiratory gating. Additionally, all SBRT is performed with at least one form of image guidance to confirm proper patient positioning and tumor localization prior to delivery of each fraction. The ASTRO/ACR Practice Guidelines for SBRT outline the responsibilities and training requirements for personnel involved in the administration of SBRT.

SBRT may be delivered in one to five sessions (fractions). Each fraction requires an identical degree of precision, localization and image guidance. Since the goal of SBRT is to maximize the potency of the radiotherapy by completing an entire course of treatment within an extremely accelerated time frame, any course of radiation treatment extending beyond five fractions is not considered SBRT and is not to be billed using these codes.

 

[seper]

I don't think CMS defines SBRT dose per fraction, theoretically you can bill 4.5 Gy X 5 as SBRT

 

[medgator]

I don't think CMS defines SBRT dose per fraction, theoretically you can bill 4.5 Gy X 5 as SBRT

I think some of the payor guidelines mention it, maybe ASTRO does as well. I'm sure there is an LCD document about it from CMS somewhere

 

[scarbrtj]

I don't think CMS defines SBRT dose per fraction, theoretically you can bill 4.5 Gy X 5 as SBRT

I hear you & agree with you, but:

To qualify for SBRT, a high dose should be delivered in a single fraction or in 2-5 fractions. 500 cGy (5 Gray) is considered the minimum dose as a ‘high dose’ for SBRT.

 

[radiaterMike]

Since this was already hijacked once ... how you define SBRT is dependent on what country you live in. In Europe and Canada 6-8 fraction regimens (with all of the SBRT tech) is considered SBRT.