Nausea and rep rate

[MedPhysGuy]

My supervising doctors here are both 25-year veteran radiation oncologists, one trained at University of Iowa and the other at Cincinnati. Both claim that during training, they heard the following to be anecdotal truth, but I have yet to find another radonc who has ever heard of this, or anything in print to back this up. PLEASE ask around and if you find corroboration let me know!

Supposedly, if you are treating fields which include some or all of the stomach, using a rep rate of 200 MU/min or slower will prevent radiation induced nausea.

It makes no sense to me that delivering 200 cGy in 60 seconds versus 30 seconds makes any difference whatsoever. Thanks for the help!

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[Gfunk6]

I admit that I have heard the same anecdote and I also abide by it. Whenever I am treating the stomach (adenocarcinoma, MALT) or large portions of para-aortics (testicular seminoma) I try to reduce the MU rate to < 200 per min. With modern day approaches, include IMRT, however this is not always feasible.

To clarify, this is supposed to mitigate nausea rather than completely prevent it.

 

[Phantom1]

My supervising doctors here are both 25-year veteran radiation oncologists, one trained at University of Iowa and the other at Cincinnati. Both claim that during training, they heard the following to be anecdotal truth, but I have yet to find another radonc who has ever heard of this, or anything in print to back this up. PLEASE ask around and if you find corroboration let me know!

Supposedly, if you are treating fields which include some or all of the stomach, using a rep rate of 200 MU/min or slower will prevent radiation induced nausea.

It makes no sense to me that delivering 200 cGy in 60 seconds versus 30 seconds makes any difference whatsoever. Thanks for the help!

There is a lot of published literature demonstrating differential effects of radiation dose RATE on cells in vitro (here is an example article..PMID 15333004). So it actually makes a lot of sense that different dose rates could make differences in patients... Radiation therapy is more complex than you might think!

 

[mpdoc2]

My supervising doctors here are both 25-year veteran radiation oncologists, one trained at University of Iowa and the other at Cincinnati. Both claim that during training, they heard the following to be anecdotal truth, but I have yet to find another radonc who has ever heard of this, or anything in print to back this up. PLEASE ask around and if you find corroboration let me know!

Supposedly, if you are treating fields which include some or all of the stomach, using a rep rate of 200 MU/min or slower will prevent radiation induced nausea.

It makes no sense to me that delivering 200 cGy in 60 seconds versus 30 seconds makes any difference whatsoever. Thanks for the help!

Agreed, also coming to this forum and Questioning your supervising docs then giving fairly specific information on who they are is poor form. This is a small field.

 

[seper]

a bit of healthy doubt never hurts anybody )

 

[MedPhysGuy]

Agreed, also coming to this forum and Questioning your supervising docs then giving fairly specific information on who they are is poor form. This is a small field.

I doubt my information clues anybody into specifics, even if you were curious and investigated, but the point was that they were trained in reputable places. Meanwhile, I trained at Mayo Clinic and never heard this information and never saw any patients treated in this manner. Sat through every medical physics, every radiation therapist, every dosimetrist, and every radiation oncology conference and lecture for almost 7 years, from before IMRT was around to after IGRT was standard. I just thought I had heard it all, but this was new to me (or predated me, as the case might be).

 

[Palex80]

Well there is sone data put there claiming that decreased dose rate may reduce the chance of pneumonitis and renal damage in total body irradiation, so who knows?