prostate ptv

[Reaganite]

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For those of you doing daily cbcts, what ptv margins are you using for definitive prostate cases? Do you use same margins post prostatectomy?

Also, when doing whole pelvis imrt, what are you guys aligning to (bony anat vs prostate) and what are your corresponding ptv margins for prostate/sv vs nodes?

 

[BraggPeak]

7 mm all around, except 5 mm posteriorily for the prostate

bony anatomy for whole pelvic cbct

 

[Gfunk6]

We have the exact same PTV expansions in my clinic. We also align to bone for WPRT.

 

[medgator]

I add a mm everywhere to the above (8 mm everywhere except 6 mm posteriorly) using implanted fiducials with daily kV imaging.

For whole pelvis IMRT, I do 1 cm except 0.8 post and align to the bony anatomy during that initial phase with daily kV imaging.

 

[Reaganite]

Do you guys still use 7/5 mm on the prostate when treating WP and aligning to bony anatomy or do you use slightly bigger margins since you aren't directly aligning to the prostate?

 

[BraggPeak]

7mm all around, including posteriorly for WP

 

[medgator]

Do you guys still use 7/5 mm on the prostate when treating WP and aligning to bony anatomy or do you use slightly bigger margins since you aren't directly aligning to the prostate?

I use bigger margins. The plan sum doesn't look appreciably worse, since the margins go tighter after 45 Gy

 

[deleted4401]

7/5mm on prostate, 7mm on pelvic LN, matching to prostate on conebeam CT daily. My feeling is the target is the prostate, I don't even really believe in treating the nodes, so they should be thankful they get any at all. Same margins on post-prostatectomy, though I'm not sure where it comes from (maybe a protocol).

Dose post prostatectomy? Swog and eortc were 60 Gy to isocenter. I'm going 66.6 to PTV, which is a little higher than 70 Gy to isocenter. I don't know why. That's how my attendings did it. Anyone going higher or lower? Some data saying 70.2 for salvage, seems excessive to me, seeing that 3 more fractions would knock gross tumor out.

 

[ShirleyT]

i use a mm smaller than everyone on here and use 6mm everywhere except 4mm posterior. i usually do daily kv and line up with implanted fiducials and all of the patients get a rectal ballon which i believe may decrease prostate motion. i usually only do daily CBCT if they have unusual anatomy and i am concerned about bowel or sigmoid falling into high dose isodose lines. or i will do daily CBCT if they are on significant blood thinners and can't get fiducials. For postop cases i use 7mm everywhere except 5 mm posterior since i don't have fiducials for these cases. i almost never treat the nodes but if i did i would keep the same margins.

seems like there is a wide variation in postop salvage doses. I use 70 Gy in 35 fx since that is what we did where I trained (and 66 Gy in 33 if true adjuvant with neg PSA), but as far as i know there is not a lot of solid data for the optimal dose. One of the more recent RTOG post op trials looking at hormones versus no hormones i believe allowed a range from 64.8 (I think)-70.2.

 

[Gfunk6]

Dose post prostatectomy? Swog and eortc were 60 Gy to isocenter. I'm going 66.6 to PTV, .

I go to 68.4 Gy. Mainly because I like to one up SimulD whenever possible . . .🙂

 

[BraggPeak]

I go to 68.4 Gy. Mainly because I like to one up SimulD whenever possible . . .🙂

I do 68.4 as well. I know some people are using higher; didn't Christopher King publish a retrospective series showing benefit to dose-escalation in the post-prostatectomy setting?

Anyone doing HypoFx for post-prostatectomy?

 

[Reaganite]

Speaking of dose in the salvage setting, what are you guys doing for a gross recurrence of disease s/p prostatectomy? Let me preface this by saying that I had always been taught to treat the prostatic fossa to a dose in the 66-70 Gy range, and to follow this with a boost to gross disease (MRI-defined, if possible). Recently, though, I heard an Astro lecturer say that he would never take an anasthasmosis above 70 Gy, and that if a patient had a gross recurrence of disease, he would offer 70 Gy + short course ADT. Thoughts?

 

[Palex80]

We have an open post-prostatectomy-trial randomizing to 64 Gy or 70 Gy.
When patients are not in the trial, we generally give 66 Gy.

 

[CAbroiler]

I treat to 6840 (all doses are to PTV) in the post prostatectomy setting for either adjuvant or salvage, in residency we treated slightly lower to 6480.

Margins are similar to many here of 7/5mm and 7 on pelvic nodes, daily kV with fiducials for intact and daily CBCT for postop setting w/o fiducials. In residency, we used Calypso in both intact and postop with same margins.

 

[deleted4401]

For gross recurrence, using SimulD SIB, 1.8/2.0 to 66.6/74.
It's gross disease. Go heavy or go home.
S

 

[TarHeelRadOnc]

For intact prostate, I use implanted fiducials with daily center-of-mass kv-kv image guidance. Uniform PTV margins of 5mm in that setting. Several studies show that you can use margins of less than that (as low as 2-3mm with kv-kv marker match), but I have yet to be that bold in community practice. Almost never do whole pelvic RT (except for T4 or node positive), so virtually all image guidance in my practice is to fiducials.

For post-prostectomy, have been using RTOG 0534 doses of 64.8-70.2Gy. Most get 68.4 or 70.2Gy. Same dose for adjuvant and salvage. Agree with SimulD, for gross residual/recurrence on MRI, would push the dose to 72-74Gy to GTV. In this setting, use margins of 8mm and 6mm posteriorly with IG to bony anatomy.

For both intact prostate and post-prostatectomy, we obtain MRI in treatment position for target delineation.