Brachial Plexus in H&N planning

[Ray D. Ayshun]

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Have had an ongoing discussion with the physicist i work with re the plexus in H&N planning and his wish that it be contoured. I wasn't trained to do this as we didn't put constraints on the plexus. I ask the plan hotspot be <75 Gy, which would in turn, be below the only paper I could find re brachial plexopathy in H&N cancers. That said, is anyone contouring/constraining the plexus? I'm happy to contour, but don't want to do something unless it impacts planning. I contour it for upper lobe tumors.

Edit: Have found a few more papers, and RTOG has protocol constraints, which are a little absurd. Someone must routinely contour the plexus in H&N. Wel, guess I don't care if you contour it, but do you constrain it?

 

[dieABRdie]

Have had an ongoing discussion with the physicist i work with re the plexus in H&N planning and his wish that it be contoured. I wasn't trained to do this as we didn't put constraints on the plexus. I ask the plan hotspot be <75 Gy, which would in turn, be below the only paper I could find re brachial plexopathy in H&N cancers. That said, is anyone contouring/constraining the plexus? I'm happy to contour, but don't want to do something unless it impacts planning. I contour it for upper lobe tumors.

I would tell him he is welcome to draw it.

 

[deleted1111261]

Have had an ongoing discussion with the physicist i work with re the plexus in H&N planning and his wish that it be contoured. I wasn't trained to do this as we didn't put constraints on the plexus. I ask the plan hotspot be <75 Gy, which would in turn, be below the only paper I could find re brachial plexopathy in H&N cancers. That said, is anyone contouring/constraining the plexus? I'm happy to contour, but don't want to do something unless it impacts planning. I contour it for upper lobe tumors.

Yeah. Occasionally if asked to.
Once you do it a few times with atlas, you’ll be able to do quickly and comfortable.
That Being said, if not constraining, why do it?

 

[Ray D. Ayshun]

Yeah. Occasionally if asked to.
Once you do it a few times with atlas, you’ll be able to do quickly and comfortable.
That Being said, if not constraining, why do it?

Right, that's my question. No issues with drawing it, but philosophically I don't see the point of drawing something that won't inform planning. May just be a physics vs physician thing.

 

[elementaryschooleconomics]

Right, that's my question. No issues with drawing it, but philosophically I don't see the point of drawing something that won't inform planning. May just be a physics vs physician thing.

I had this same philosophical issue with some faculty in my residency program, it essentially came down to a style preference. They felt that it was "best practice" or "per consensus atlas" or whatever that a certain set of OARs always be drawn when treating a certain disease site.

My two favorite examples:

1) Leptomeningeal carcinomatosis with it's standard poor prognosis, doing WBRT mostly so the family felt that everyone was doing everything that could be done. I quickly put together an appropriate plan, and angled the beams so they weren't passing through the lens, but didn't explicitly contour the lens. The attending chastised me for it and drew them in. When I asked why, I was told that it was "the right thing to do", or something to that effect. Patient was dead within 6 weeks...without cataracts, I guess.

2) Lung SBRT, and the Great Vessels. Even for very apical tumors, there was an attending that insisted on drawing the aorta down to at least the diaphragm (if not further). When I asked why, all I got "it's what I was trained to do".

That is to say - in my experience, either physics or physician, some people do things because they're Box Checkers™. Instead of asking themselves why should the brachial plexus be contoured if you're not going to constrain it, their brain stops at "I was trained that the brachial plexus should be contoured, always, for every case". Maybe the Box Checkers are right? I don't know.

As an aside, I do generally contour the plexus for H&N, but I like to see a DMax in the true structure of <7000 cGy, if possible. But yeah...if you're telling me your hard stop is a plan DMax of 7500 cGy (and I assume you want to see that in your target volumes)...I would be hard pressed to find anything wrong with not drawing the plexuses (plexi?).

Some folks wanna contour for style over substance, I guess.

 

[Ray D. Ayshun]

I had this same philosophical issue with some faculty in my residency program, it essentially came down to a style preference. They felt that it was "best practice" or "per consensus atlas" or whatever that a certain set of OARs always be drawn when treating a certain disease site.

My two favorite examples:

1) Leptomeningeal carcinomatosis with it's standard poor prognosis, doing WBRT mostly so the family felt that everyone was doing everything that could be done. I quickly put together an appropriate plan, and angled the beams so they weren't passing through the lens, but didn't explicitly contour the lens. The attending chastised me for it and drew them in. When I asked why, I was told that it was "the right thing to do", or something to that effect. Patient was dead within 6 weeks...without cataracts, I guess.

2) Lung SBRT, and the Great Vessels. Even for very apical tumors, there was an attending that insisted on drawing the aorta down to at least the diaphragm (if not further). When I asked why, all I got "it's what I was trained to do".

That is to say - in my experience, either physics or physician, some people do things because they're Box Checkers™. Instead of asking themselves why should the brachial plexus be contoured if you're not going to constrain it, their brain stops at "I was trained that the brachial plexus should be contoured, always, for every case". Maybe the Box Checkers are right? I don't know.

As an aside, I do generally contour the plexus for H&N, but I like to see a DMax in the true structure of <7000 cGy, if possible. But yeah...if you're telling me your hard stop is a plan DMax of 7500 cGy (and I assume you want to see that in your target volumes)...I would be hard pressed to find anything wrong with not drawing the plexuses (plexi?).

Some folks wanna contour for style over substance, I guess.

I do in PTv and outta PTv hotspot maxes. In training was simply a hotspot max of around 80 gy. If a patient had a brachial plexopathy at 5 yrs it was good news, as it meant they weren't dead...

 

[StIGMA]

Almost never draw it for H&N (exceptions could be significant disease burden in low neck or reirradiation). In cases of gross disease in low neck, priority is still to cover the gross disease.

 

[gmsquid]

Always draw for HN. Constrain per DEFINE_ME

 

[Ray D. Ayshun]

Always draw for HN. Constrain per DEFINE_ME

So, D70 <10% and D74 <4%. My typical plan hotspot is <74 Gy, and would be easy to just make that a new rule without compromising coverage. Re the 70 Gy constraint, would you prioritize that over PTV coverage? If it were D71, I'd find it interesting, but I struggle with a normal tissue constraint that matches the prescription dose, regardless of how I constrain my PTV, 95% covers 99%. Is the approach you cited common?

 

[gmsquid]

So, D70 <10% and D74 <4%. My typical plan hotspot is <74 Gy, and would be easy to just make that a new rule without compromising coverage. Re the 70 Gy constraint, would you prioritize that over PTV coverage? If it were D71, I'd find it interesting, but I struggle with a normal tissue constraint that matches the prescription dose, regardless of how I constrain my PTV, 95% covers 99%. Is the approach you cited common?

Usually able to make v70<10% without compromising coverage if you contour the plexus well. The ctv should exclude the anterior scalene (unless grossly involved) which is anterior to the plexus and the ptv expansion I use 3 mm usually doesn’t overlap with the plexus even with a gtv there.

not sure how common my approach Is but figured I would share. I’m able to meet without sacrificing coverage, and I treat hn for a living so lots of cases with it. And even if you accept 95% rx coverage you would be at 6650 which should work.

 

[Gfunk6]

Early in my career I was treating a p16+ definitive H&N with CRT. He had a large juicy lymph node right in the path of the brachial plexus. I made that region of treatment a bit cooler to avoid extremity paralysis and a few months later he recurred in that very lymph node. I was kicking myself over it for months.

There is hardly any scenario that is worth sparing the brachial plexus to deliver sub-therapeutic doses to the target. Also, the brachial plexus is unfortunately a surrogate structure that you draw on the basis of other structures. You can't clearly see it.

Ignorance is bliss?

 

[Radonky]

At our institution, we do not contour the plexus unless it was a retreatment, with the argument being we would never attempt to spare the plexus at the expense of coverage.

 

[gmsquid]

Early in my career I was treating a p16+ definitive H&N with CRT. He had a large juicy lymph node right in the path of the brachial plexus. I made that region of treatment a bit cooler to avoid extremity paralysis and a few months later he recurred in that very lymph node. I was kicking myself over it for months.

There is hardly any scenario that is worth sparing the brachial plexus to deliver sub-therapeutic doses to the target. Also, the brachial plexus is unfortunately a surrogate structure that you draw on the basis of other structures. You can't clearly see it.

Ignorance is bliss?

On a high quality ct or mr you can see it. Probably would’ve recurred in that node regardless if it was that big, nonetheless I understand the fear. I never spare to deliver subtherapeutic dose but you don’t need to do that.

 

[Ray D. Ayshun]

At our institution, we do not contour the plexus unless it was a retreatment, with the argument being we would never attempt to spare the plexus at the expense of coverage.

That's as I was trained. Otoh, there could be meaningful constraints as gmsquid posted. From this discussion I remain unconvinced that it's worth the time, but do think lowering my plan hotspot to 74 is reasonable.

 

[Lamount]

Early in my career I was treating a p16+ definitive H&N with CRT. He had a large juicy lymph node right in the path of the brachial plexus. I made that region of treatment a bit cooler to avoid extremity paralysis and a few months later he recurred in that very lymph node. I was kicking myself over it for months.

There is hardly any scenario that is worth sparing the brachial plexus to deliver sub-therapeutic doses to the target. Also, the brachial plexus is unfortunately a surrogate structure that you draw on the basis of other structures. You can't clearly see it.

Ignorance is bliss?

Maybe I am fooling myself, but I am convinced I can see it when I contour it for apical lung SBRT/hypoFx. If you look carefully, you can trace the nerve roots as they exit the canal. The T1 one can sometimes be tricky but it usually sneaks up to join the rest in front of the medial first rib.

 

[medgator]

Maybe I am fooling myself, but I am convinced I can see it when I contour it for apical lung SBRT/hypoFx. If you look carefully, you can trace the nerve roots as they exit the canal. The T1 one can sometimes be tricky but it usually sneaks up to join the rest in front of the medial first rib.

It is pretty easy to follow along the vessels once the roots come off the scalenes with a good contrast enhanced CT sim

 

[TheWallnerus]

I don't mind sharing this. It's a clinical review my hospital did on one of my cases in 2010. For edification of the young ones! My physicist also didn't like that I (occasionally) wouldn't contour things. In the below case, I used a multi-field non-coplanar arrangement. In every single beam's eye view, I fixed the field size by adjusting the necessary jaw to completely cover the humerus and set the optimization to use fixed field sizes. Even though this "cut through the PTV" in some BEVs, the inverse optimization algorithm "handled it" and the dose to the PTV was homogenous and the max dose to the humerus was less than 10 Gy (this could only be confirmed by looking at each individual CT humerus slice though; read below). I didn't contour the brachial plexus because it more or less suffused the PTV region... and that was a primary reason I backed off on the Rx dose.

This same principle ("you don't have to contour it because you know it's spared") could not apply to brachial plexus in H&N, but most times in most of my H&N cases it is plainly obvious just from 1) mind's eye anatomic knowledge, and 2) understanding spatial distribution of the PTVs, that the uncontoured brachial plexus is not at risk from high dose RT. Ditto for lenses in whole brain plans etc etc etc. The primary reason to contour is to define where we want doses to go or not; the DVH is a fringe benefit of the contouring process but not the primary reason we contour. I never contour brachial plexus in HNSCC and have never had a brachial plexopathy as far as I know.

REVIEWER'S SUMMARY

The patient was a 43-year-old man who presented with a recurrent mass involving his right axilla, upper arm and flank. By report, he had undergone previous resections of lipomas from this area in 2004, 2006 and 2007. A CT scan of the chest on February 2, 2010 revealed a 9.3cm x 8.9cm fatty mass in the right axilla, extending down the medial upper arm, with another component extending down the right lateral chest wall (reportedly roughly stable compared with a prior study on October 7, 2001). On May 3, 2010, the patient underwent a resection of a large T2aN0M0 liposarcoma involving the right axilla and flank at another facility. He was referred to the Practitioner for post-operative radiation treatment. The patient was seen in consultation by the Practitioner on May 26, 2010. The Practitioner states that “IMRT will be absolute [sic] necessary in this situation to spare the brachioplexus as maximally as possible versus 3D and lung as maximally as possible.”​

​

The Practitioner’s initial treatment plan and orders dated May 27, 2010 documents that the Practitioner planned to deliver 66Gy in 33 fractions (fx) using IMRT to spare lung and soft tissue. The physician intent form, last modified on June 9, 2010, documents that the patient received 5840cGy in four (4) 200cGy fractions and 28 180cGy fractions. The radiation treatment summary dated July 30, 2010 states that the patient received a total dose of 58.4Gy, with a dose of 50Gy in 25 fractions (200cGy/fx) delivered to a wide area, including the operative bed, scar, and margin, with the preoperative tumor volume/operative bed receiving an additional 8-9 Gy. The dose was limited due to the proximity of the brachial plexus and humeral head to the clinical target volume. The patient was seen in follow-up on September 3, 2010.​

​

The use of IMRT in this case was indicated given the initial extent to the patient’s disease and the post-operative surgical bed. Fusing the patient’s preoperative CT scan dated February 2, 2010 with the CT simulation was appropriate to accurately demarcate the planning treatment volume (PTV). The Practitioner’s goal to limit radiation dose to the lung, humerus, and brachial plexus was also appropriate given the location of the treatment area. The radiation dose actually delivered was slightly less than recommended, reportedly due to the need to limit radiation dose to normal tissues.​

​

The cumulative dose volume histogram displays the radiation doses received by the clinical target volume (CTV), PTV, and right lung. During the Consultant’s review of the treatment plan on the Eclipse treatment planning system, it was noted that the right humerus was not separately contoured as an important organ (all bones including the humerus, scapula, ribs, and clavicle were outlined as one organ). Therefore, the radiation dose delivered to the humerus was not calculated or displayed on the dose volume histogram, and the humerus was not designated as a separate organ to limit radiation dose on the treatment plan. The failure to designate the humerus and humeral head as a separate organ may have resulted in an inferior treatment plan being chosen. The brachial plexus was also not separately contoured, but this would not be considered a deviation from the standard of care because of the potential difficulty in precisely localizing the brachial plexus. The Consultant also had potential concerns regarding the anterior-posterior and superior-inferior extent of the treatment volume, but a definitive opinion regarding the extent of the radiation fields would require a review of the pre-operative diagnostic films. ​

​

Overall, given the patient’s presenting extent of disease, the treatment delivered was reasonable and within the standard of care. However, the documentation of the plan, in particular the failure to calculate and limit the dose to the humerus, was suboptimal.​

​

We got a chance to talk about the case. There was a transcript. Here's a portion of that:

REVIEWER: You said in your treatment summary that you limited dose to the humeral head and the brachial plexus. Do you remember that from your treatment summary?​

ME: Yes.​

REVIEWER: Well, you didn’t contour the humeral head or the brachial plexus in the planning system. Do you usually contour things in the planning system that you try to limit doses to?​

ME: Well you can certainly identify them on the scan, right?​

REVIEWER: Yep.​

ME: So then you can identify your isodoses in the plan. And then if you find that your isodoses are acceptable in those regions, then you have limited doses to those structures.​

REVIEWER: Right.​

ME: So the simple explanation on that would be… and you might think this is a dumb example… but let’s say I’m doing whole brain irradiation. And I say, “I limited dose to the foot.” I might not contour the foot, but I have limited dose to the foot by just having radiation beams go to the head.​

REVIEWER: But this isn’t that case. The brachial plexus and humeral head are very close by…​

ME: But did you see the fluence maps?​

REVIEWER: Yes.​

ME: So you saw that I had intentionally fixed the field sizes in the plan to block the humeral head?​

REVIEWER: Right.​

ME: OK. ​

REVIEWER: Well at least in our planning system you don’t start a priori…​

ME: But you certainly start a lot of things a priori… you choose beam angle, you choose beam energy…​

REVIEWER: Right.​

ME: … it wouldn’t have made a difference if I would have contoured these structures or not. ​

REVIEWER: Well you don’t know that. For example you might have contoured the structures and then told the computer to come up with a plan where it would have chosen different beam angles.​

ME: Well… the computer never chooses beam angles. You know that right?​

REVIEWER: Right.​

ME: But you just said the computer would choose different beam angles. ​

REVIEWER: But you might have drawn some in that were weighted, or were next to things… I mean this is a unique case and very challenging.​

ME: Right, very challenging. But I just want to get your sense of planning, because you do realize that when you are planning an IMRT case that you choose the beam angles, right, and not the computer?​

REVIEWER: Yes. … ​

ME: Did you try a different plan?​

REVIEWER: No, because I think it’s a quite challenging plan.​

ME: Well did you think it was a good plan?​

REVIEWER: I thought… it was a quite good plan…​

 

[Ray D. Ayshun]

I don't mind sharing this. It's a clinical review my hospital did on one of my cases in 2010. For edification of the young ones! My physicist also didn't like that I (occasionally) wouldn't contour things. In the below case, I used a multi-field non-coplanar arrangement. In every single beam's eye view, I fixed the field size by adjusting the necessary jaw to completely cover the humerus and set the optimization to use fixed field sizes. Even though this "cut through the PTV" in some BEVs, the inverse optimization algorithm "handled it" and the dose to the PTV was homogenous and the max dose to the humerus was less than 10 Gy (this could only be confirmed by looking at each individual CT humerus slice though; read below). I didn't contour the brachial plexus because it more or less suffused the PTV region... and that was a primary reason I backed off on the Rx dose.

This same principle ("you don't have to contour it because you know it's spared") could not apply to brachial plexus in H&N, but most times in most of my H&N cases it is plainly obvious just from 1) mind's eye anatomic knowledge, and 2) understanding spatial distribution of the PTVs, that the uncontoured brachial plexus is not at risk from high dose RT. Ditto for lenses in whole brain plans etc etc etc. The primary reason to contour is to define where we want doses to go or not; the DVH is a fringe benefit of the contouring process but not the primary reason we contour. I never contour brachial plexus in HNSCC and have never had a brachial plexopathy as far as I know.

REVIEWER'S SUMMARY

The patient was a 43-year-old man who presented with a recurrent mass involving his right axilla, upper arm and flank. By report, he had undergone previous resections of lipomas from this area in 2004, 2006 and 2007. A CT scan of the chest on February 2, 2010 revealed a 9.3cm x 8.9cm fatty mass in the right axilla, extending down the medial upper arm, with another component extending down the right lateral chest wall (reportedly roughly stable compared with a prior study on October 7, 2001). On May 3, 2010, the patient underwent a resection of a large T2aN0M0 liposarcoma involving the right axilla and flank at another facility. He was referred to the Practitioner for post-operative radiation treatment. The patient was seen in consultation by the Practitioner on May 26, 2010. The Practitioner states that “IMRT will be absolute [sic] necessary in this situation to spare the brachioplexus as maximally as possible versus 3D and lung as maximally as possible.”​

​

The Practitioner’s initial treatment plan and orders dated May 27, 2010 documents that the Practitioner planned to deliver 66Gy in 33 fractions (fx) using IMRT to spare lung and soft tissue. The physician intent form, last modified on June 9, 2010, documents that the patient received 5840cGy in four (4) 200cGy fractions and 28 180cGy fractions. The radiation treatment summary dated July 30, 2010 states that the patient received a total dose of 58.4Gy, with a dose of 50Gy in 25 fractions (200cGy/fx) delivered to a wide area, including the operative bed, scar, and margin, with the preoperative tumor volume/operative bed receiving an additional 8-9 Gy. The dose was limited due to the proximity of the brachial plexus and humeral head to the clinical target volume. The patient was seen in follow-up on September 3, 2010.​

​

The use of IMRT in this case was indicated given the initial extent to the patient’s disease and the post-operative surgical bed. Fusing the patient’s preoperative CT scan dated February 2, 2010 with the CT simulation was appropriate to accurately demarcate the planning treatment volume (PTV). The Practitioner’s goal to limit radiation dose to the lung, humerus, and brachial plexus was also appropriate given the location of the treatment area. The radiation dose actually delivered was slightly less than recommended, reportedly due to the need to limit radiation dose to normal tissues.​

​

The cumulative dose volume histogram displays the radiation doses received by the clinical target volume (CTV), PTV, and right lung. During the Consultant’s review of the treatment plan on the Eclipse treatment planning system, it was noted that the right humerus was not separately contoured as an important organ (all bones including the humerus, scapula, ribs, and clavicle were outlined as one organ). Therefore, the radiation dose delivered to the humerus was not calculated or displayed on the dose volume histogram, and the humerus was not designated as a separate organ to limit radiation dose on the treatment plan. The failure to designate the humerus and humeral head as a separate organ may have resulted in an inferior treatment plan being chosen. The brachial plexus was also not separately contoured, but this would not be considered a deviation from the standard of care because of the potential difficulty in precisely localizing the brachial plexus. The Consultant also had potential concerns regarding the anterior-posterior and superior-inferior extent of the treatment volume, but a definitive opinion regarding the extent of the radiation fields would require a review of the pre-operative diagnostic films. ​

​

Overall, given the patient’s presenting extent of disease, the treatment delivered was reasonable and within the standard of care. However, the documentation of the plan, in particular the failure to calculate and limit the dose to the humerus, was suboptimal.​

​

We got a chance to talk about the case. There was a transcript. Here's a portion of that:

REVIEWER: You said in your treatment summary that you limited dose to the humeral head and the brachial plexus. Do you remember that from your treatment summary?​

ME: Yes.​

REVIEWER: Well, you didn’t contour the humeral head or the brachial plexus in the planning system. Do you usually contour things in the planning system that you try to limit doses to?​

ME: Well you can certainly identify them on the scan, right?​

REVIEWER: Yep.​

ME: So then you can identify your isodoses in the plan. And then if you find that your isodoses are acceptable in those regions, then you have limited doses to those structures.​

REVIEWER: Right.​

ME: So the simple explanation on that would be… and you might think this is a dumb example… but let’s say I’m doing whole brain irradiation. And I say, “I limited dose to the foot.” I might not contour the foot, but I have limited dose to the foot by just having radiation beams go to the head.​

REVIEWER: But this isn’t that case. The brachial plexus and humeral head are very close by…​

ME: But did you see the fluence maps?​

REVIEWER: Yes.​

ME: So you saw that I had intentionally fixed the field sizes in the plan to block the humeral head?​

REVIEWER: Right.​

ME: OK. ​

REVIEWER: Well at least in our planning system you don’t start a priori…​

ME: But you certainly start a lot of things a priori… you choose beam angle, you choose beam energy…​

REVIEWER: Right.​

ME: … it wouldn’t have made a difference if I would have contoured these structures or not. ​

REVIEWER: Well you don’t know that. For example you might have contoured the structures and then told the computer to come up with a plan where it would have chosen different beam angles.​

ME: Well… the computer never chooses beam angles. You know that right?​

REVIEWER: Right.​

ME: But you just said the computer would choose different beam angles. ​

REVIEWER: But you might have drawn some in that were weighted, or were next to things… I mean this is a unique case and very challenging.​

ME: Right, very challenging. But I just want to get your sense of planning, because you do realize that when you are planning an IMRT case that you choose the beam angles, right, and not the computer?​

REVIEWER: Yes. … ​

ME: Did you try a different plan?​

REVIEWER: No, because I think it’s a quite challenging plan.​

ME: Well did you think it was a good plan?​

REVIEWER: I thought… it was a quite good plan…​

This leaves me wanting more.

 

[deleted1111261]

This leaves me wanting more.

With bated breath

 

[gmsquid]

I don't mind sharing this. It's a clinical review my hospital did on one of my cases in 2010. For edification of the young ones! My physicist also didn't like that I (occasionally) wouldn't contour things. In the below case, I used a multi-field non-coplanar arrangement. In every single beam's eye view, I fixed the field size by adjusting the necessary jaw to completely cover the humerus and set the optimization to use fixed field sizes. Even though this "cut through the PTV" in some BEVs, the inverse optimization algorithm "handled it" and the dose to the PTV was homogenous and the max dose to the humerus was less than 10 Gy (this could only be confirmed by looking at each individual CT humerus slice though; read below). I didn't contour the brachial plexus because it more or less suffused the PTV region... and that was a primary reason I backed off on the Rx dose.

This same principle ("you don't have to contour it because you know it's spared") could not apply to brachial plexus in H&N, but most times in most of my H&N cases it is plainly obvious just from 1) mind's eye anatomic knowledge, and 2) understanding spatial distribution of the PTVs, that the uncontoured brachial plexus is not at risk from high dose RT. Ditto for lenses in whole brain plans etc etc etc. The primary reason to contour is to define where we want doses to go or not; the DVH is a fringe benefit of the contouring process but not the primary reason we contour. I never contour brachial plexus in HNSCC and have never had a brachial plexopathy as far as I know.

REVIEWER'S SUMMARY

The patient was a 43-year-old man who presented with a recurrent mass involving his right axilla, upper arm and flank. By report, he had undergone previous resections of lipomas from this area in 2004, 2006 and 2007. A CT scan of the chest on February 2, 2010 revealed a 9.3cm x 8.9cm fatty mass in the right axilla, extending down the medial upper arm, with another component extending down the right lateral chest wall (reportedly roughly stable compared with a prior study on October 7, 2001). On May 3, 2010, the patient underwent a resection of a large T2aN0M0 liposarcoma involving the right axilla and flank at another facility. He was referred to the Practitioner for post-operative radiation treatment. The patient was seen in consultation by the Practitioner on May 26, 2010. The Practitioner states that “IMRT will be absolute [sic] necessary in this situation to spare the brachioplexus as maximally as possible versus 3D and lung as maximally as possible.”​

​

The Practitioner’s initial treatment plan and orders dated May 27, 2010 documents that the Practitioner planned to deliver 66Gy in 33 fractions (fx) using IMRT to spare lung and soft tissue. The physician intent form, last modified on June 9, 2010, documents that the patient received 5840cGy in four (4) 200cGy fractions and 28 180cGy fractions. The radiation treatment summary dated July 30, 2010 states that the patient received a total dose of 58.4Gy, with a dose of 50Gy in 25 fractions (200cGy/fx) delivered to a wide area, including the operative bed, scar, and margin, with the preoperative tumor volume/operative bed receiving an additional 8-9 Gy. The dose was limited due to the proximity of the brachial plexus and humeral head to the clinical target volume. The patient was seen in follow-up on September 3, 2010.​

​

The use of IMRT in this case was indicated given the initial extent to the patient’s disease and the post-operative surgical bed. Fusing the patient’s preoperative CT scan dated February 2, 2010 with the CT simulation was appropriate to accurately demarcate the planning treatment volume (PTV). The Practitioner’s goal to limit radiation dose to the lung, humerus, and brachial plexus was also appropriate given the location of the treatment area. The radiation dose actually delivered was slightly less than recommended, reportedly due to the need to limit radiation dose to normal tissues.​

​

The cumulative dose volume histogram displays the radiation doses received by the clinical target volume (CTV), PTV, and right lung. During the Consultant’s review of the treatment plan on the Eclipse treatment planning system, it was noted that the right humerus was not separately contoured as an important organ (all bones including the humerus, scapula, ribs, and clavicle were outlined as one organ). Therefore, the radiation dose delivered to the humerus was not calculated or displayed on the dose volume histogram, and the humerus was not designated as a separate organ to limit radiation dose on the treatment plan. The failure to designate the humerus and humeral head as a separate organ may have resulted in an inferior treatment plan being chosen. The brachial plexus was also not separately contoured, but this would not be considered a deviation from the standard of care because of the potential difficulty in precisely localizing the brachial plexus. The Consultant also had potential concerns regarding the anterior-posterior and superior-inferior extent of the treatment volume, but a definitive opinion regarding the extent of the radiation fields would require a review of the pre-operative diagnostic films. ​

​

Overall, given the patient’s presenting extent of disease, the treatment delivered was reasonable and within the standard of care. However, the documentation of the plan, in particular the failure to calculate and limit the dose to the humerus, was suboptimal.​

​

We got a chance to talk about the case. There was a transcript. Here's a portion of that:

REVIEWER: You said in your treatment summary that you limited dose to the humeral head and the brachial plexus. Do you remember that from your treatment summary?​

ME: Yes.​

REVIEWER: Well, you didn’t contour the humeral head or the brachial plexus in the planning system. Do you usually contour things in the planning system that you try to limit doses to?​

ME: Well you can certainly identify them on the scan, right?​

REVIEWER: Yep.​

ME: So then you can identify your isodoses in the plan. And then if you find that your isodoses are acceptable in those regions, then you have limited doses to those structures.​

REVIEWER: Right.​

ME: So the simple explanation on that would be… and you might think this is a dumb example… but let’s say I’m doing whole brain irradiation. And I say, “I limited dose to the foot.” I might not contour the foot, but I have limited dose to the foot by just having radiation beams go to the head.​

REVIEWER: But this isn’t that case. The brachial plexus and humeral head are very close by…​

ME: But did you see the fluence maps?​

REVIEWER: Yes.​

ME: So you saw that I had intentionally fixed the field sizes in the plan to block the humeral head?​

REVIEWER: Right.​

ME: OK. ​

REVIEWER: Well at least in our planning system you don’t start a priori…​

ME: But you certainly start a lot of things a priori… you choose beam angle, you choose beam energy…​

REVIEWER: Right.​

ME: … it wouldn’t have made a difference if I would have contoured these structures or not. ​

REVIEWER: Well you don’t know that. For example you might have contoured the structures and then told the computer to come up with a plan where it would have chosen different beam angles.​

ME: Well… the computer never chooses beam angles. You know that right?​

REVIEWER: Right.​

ME: But you just said the computer would choose different beam angles. ​

REVIEWER: But you might have drawn some in that were weighted, or were next to things… I mean this is a unique case and very challenging.​

ME: Right, very challenging. But I just want to get your sense of planning, because you do realize that when you are planning an IMRT case that you choose the beam angles, right, and not the computer?​

REVIEWER: Yes. … ​

ME: Did you try a different plan?​

REVIEWER: No, because I think it’s a quite challenging plan.​

ME: Well did you think it was a good plan?​

REVIEWER: I thought… it was a quite good plan…​

As an aside, you may still be able to further constrain without limiting beam angles. A few months back I helped rework a vmat plan to reduce spinal cord dose. The planner had used a spinal cord avoidance which meant no primary beam exits or enters the cord so all dose to the cord was scatter. I did not and was able to better constrain the cord while meeting all other constraints. Sometimes having the flexibility of more beam angles may allow you to meet other constraints easier even if you have ab absolute constraint on something like the cord.

 

[kimplera]

care for one patient in 10 years of H&N with a significant brachial plexopathy - low neck node touching the plexus - hot spot was to my recollection <<3.5 Gy. i would have done the same thing. i still dont' routinely contour plexus but with low neck node i do watch the dose spill in that area and if concerning would contour to document what i thought was ok. For the vast majority of cases it doesn't matter because our dose in that region is on the order of 54-56 Gy in 30-35 fractions.

 

[CaesarRO]

... That is to say - in my experience, either physics or physician, some people do things because they're Box Checkers™. Instead of asking themselves why should the brachial plexus be contoured if you're not going to constrain it, their brain stops at "I was trained that the brachial plexus should be contoured, always, for every case". Maybe the Box Checkers are right? I don't know....

In defense of Box Checkers™, see Atul Gawande's Checklist Manifesto. While there are certainly cases where common sense can and should prevail, there is something to be said for being systematic in your approach. It can help you catch things you might otherwise miss if you are in a rush.

 

[metallica81788]

Tell that physicist if they're not busy enough to also contour hippocampi and temporal lobes on your incompletely resected GBMs

 

[communitydoc13]

I can't have any confidence in a volumetric constraint for a structure as difficult to contour and as small volumetrically as the BP. (Just see what your volume does when you expand laterally 1 cm). 74 Dmax good for me. Lung data from MDACC really drives home point that a progressive tumor in the region of the BP is the overwhelming cause of plexopathy. Visual confirmation of dose spill to where I think plexus is is good for me. I will occasionally contour BP as I see it to have dose drive dose gradient away from it but very rarely. I never under-dose a bulky low node.

 

[Ray D. Ayshun]

All joking aside, if you did let someone else draw a contour on your plan, even if you don't constrain it, wouldn't you spend time ensuring it's reasonably done? Sounds like another thing to deal with. Death by a thousand paper cuts.

 

[elementaryschooleconomics]

In defense of Box Checkers™, see Atul Gawande's Checklist Manifesto. While there are certainly cases where common sense can and should prevail, there is something to be said for being systematic in your approach. It can help you catch things you might otherwise miss if you are in a rush.

Ha, normally I'm the one talking about the virtues of the Checklist Manifesto!

So, similarly to @TheWallnerus's story above, in these examples, I considered both these items (making sure the lens wasn't in the beam, making sure the abdominal aorta was several centimeters away from any potential dose), and was happy with how things appeared without explicitly contouring structures.

But...I would say I agree about checklists about 95% of the time.

 

[medgator]

All joking aside, if you did let someone else draw a contour on your plan, even if you don't constrain it, wouldn't you spend time ensuring it's reasonably done? Sounds like another thing to deal with. Death by a thousand paper cuts.

I always check the normals on my plan when dosimetry does them. Not unusual for dosi to do them in a lot of places outside of things like optic structures, parotids etc

 

[TheWallnerus]

The planner had used a spinal cord avoidance which meant no primary beam exits or enters the cord so all dose to the cord was scatter.

A form of this... a complete "cord block" in the middle of an idealized circular "body" to create concave/convex dose distributions... were the first hypothesized forms of intensity modulation 🙂

 

[Gfunk6]

I think there is a bit of generation gap between older and younger Radiation Oncologists on this topic. In my training and practice, I've always held true to the tenet that, "if you care about dose to any OAR, contour it." This makes plan review much more rapid, quantitative and efficient for me. Going one step further, I contour all of the OARs that I care about as I don't have to review them again as I would for dosimetry. As treatment planning algorithms become more complex, I think OAR contouring will remain relevant. I do a lot of my XRT on a CyberKnife which has a "true" inverse planning algorithm. The TPS will put the dose anywhere if you don't specify with an OAR.

 

[Aphtalyfe]

Knowing what dose the brachial plexus gets also allows for a better discussion with the patient regarding (potential) toxicity.

 

[Ray D. Ayshun]

I think there is a bit of generation gap between older and younger Radiation Oncologists on this topic. In my training and practice, I've always held true to the tenet that, "if you care about dose to any OAR, contour it." This makes plan review much more rapid, quantitative and efficient for me. Going one step further, I contour all of the OARs that I care about as I don't have to review them again as I would for dosimetry. As treatment planning algorithms become more complex, I think OAR contouring will remain relevant. I do a lot of my XRT on a CyberKnife which has a "true" inverse planning algorithm. The TPS will put the dose anywhere if you don't specify with an OAR.

Now, I can't tell which side you support. I had you in the don't contour camp. Now, I'm thinking you do. I kinda want to do a poll.

 

[deleted1111261]

With auto contouring, point will be moo

 

[gmsquid]

With auto contouring, point will be moo

There’s a lot of poor autocontouring out there.

 

[RadOncDoc21]

With auto contouring, point will be moo

Like a cow moo?

 

[deleted1111261]

Like a cow moo?

Yah, like it won’t make sense to humans. Moo

 

[evilbooyaa]

So I contour brachial plexus if there is gross disease anywhere in proximity to it. If there is just 56 or 63Gy elective nodal volumes then I don't. I contour brachial plexus for apical lung tumors getting SBRT or definitive chemoRT.

I personally favor Brachial plexus getting point doses < 66Gy, although I will allow it up to 70Gy in 2Gy/fx if directly abutting. I have not run into an issue where a PTV70 volume is not getting 95/100 because of the brachial plexus contour. I have no reason to allow brachial plexus to get 74Gy point doses when my highest Rx dose goes to 70Gy in 2Gy dosing.

I see no reason to give brachial plexus a higher dose than your Rx dose in the era of IMRT and VMAT. If you have 70Gy going anywhere near the plexus, I would consider it potentially an issue viable for a lawsuit if you did not constraint and limit the brachial plexus to some number - I personally favor 66Gy point dose but would allow as high as Rx dose only. Maybe if Plexus was directly within my 70Gy PTV (which I have been fortunate enough to not have to deal with in recent memory) then I would feel differently.

 

[Ray D. Ayshun]

So I contour brachial plexus if there is gross disease anywhere in proximity to it. If there is just 56 or 63Gy elective nodal volumes then I don't. I contour brachial plexus for apical lung tumors getting SBRT or definitive chemoRT.

I personally favor Brachial plexus getting point doses < 66Gy, although I will allow it up to 70Gy in 2Gy/fx if directly abutting. I have not run into an issue where a PTV70 volume is not getting 95/100 because of the brachial plexus contour. I have no reason to allow brachial plexus to get 74Gy point doses when my highest Rx dose goes to 70Gy in 2Gy dosing.

I see no reason to give brachial plexus a higher dose than your Rx dose in the era of IMRT and VMAT. If you have 70Gy going anywhere near the plexus, I would consider it potentially an issue viable for a lawsuit if you did not constraint and limit the brachial plexus to some number - I personally favor 66Gy point dose but would allow as high as Rx dose only. Maybe if Plexus was directly within my 70Gy PTV (which I have been fortunate enough to not have to deal with in recent memory) then I would feel differently.

This seems like a bit of a stretch being as there's no great convincing data out there regarding how this should be constrained If your PTV70 got 66 Gy to meet constraints and the patient recurred there could you be sued? Where I trained we ignored it in H&N, which isn't to say I always will. In fact, placing a plan max constraint of 74 Gy seems to meet one of the recs cited in gmsquid's paper while not relying on the contouring of a structure that's just the space between two muscles and subject to relatively large positional differences on a daily basis.

 

[evilbooyaa]

This seems like a bit of a stretch being as there's no great convincing data out there regarding how this should be constrained If your PTV70 got 66 Gy to meet constraints and the patient recurred there could you be sued? Where I trained we ignored it in H&N, which isn't to say I always will. In fact, placing a plan max constraint of 74 Gy seems to meet one of the recs cited in gmsquid's paper while not relying on the contouring of a structure that's just the space between two muscles and subject to relatively large positional differences on a daily basis.

That paper @gmsquid references V70 < 10% as a predictor, but it's still 11% risk of incidence with V70 < 10% (vs 56% at V70 > 10%). To me that is still unacceptably high risk of brachial plexopathy, especially in a patient who doesn't need to be put at risk for it. What's the incidence with a lower constraint? I can say I've never seen somebody with a bad plexopathy (yes some shoulder weakness usually from neck dissection, but not pain in a plexial distribution or arm radiculopathy), but I know that's just because I haven't been seen follow-up patients long enough to see one.

As to your retort, I would not underdose GTV70 because of brachial plexus - I shoot for 95/100 coverage of the entire PTV70 volume and generally 100/100 of the entire GTV70 volume.

I like to stick with brachial plexus point dose < 66Gy, hard constraint of < 70Gy. Perhaps if there is a case where a node is literally abutting or invading into brachial plexus I'd allow higher, but ever case I've seen (which is probably like 10-20% of my total H&Ns) is there gross disease or ENE in a region near where the plexus is. I just do not routinely see a reason to allow brachial plexus to get above 70Gy.

To me, it's lazy planning. I draw my own brachial plexuses when it's closer to gross disease and I get it lower than 66 or 70Gy. To not do it when there is gross disease (or ENE) near by that may push you above that number and put your patient at a double digit risk of plexopathy? I can't get on board with that. Yes it's somewhat annoying to contour them but honestly takes less than a minute usually as the important area is where there is gross disease.

 

[seper]

Brachial plexopathy after H&N XRT is real… some hypervigilant, well-functioning patients are really fixated on it. I always contour and document.

 

[Ray D. Ayshun]

Brachial plexopathy after H&N XRT is real… some hypervigilant, well-functioning patients are really fixated on it. I always contour and document.

What I've really gathered is that plexus contouring is more of a medicolegal endeavor. Those relative volumetric constraints discussed earlier would really only ever be violated in an absurdly huge cancer or absurdly bad plan. Even drawing it according to atlas metrics, which could entail using a 3 mm brush means it may not be relatively close to where it was at sim on a daily basis. Patients are consented for plexopathy. I'm not trying to convince other people not to contour it as I want to do best by the patient (hence why I asked the question), but if it's not there to shape dose, then I don't see the point of it being there. And if people are constraining it, they're risking underdosing gross disease, or using constraints that are nearly impossible to violate.

 

[TheWallnerus]

but if it's not there to shape dose, then I don't see the point of it being there.

the key point

 

[RadOncMegatron]

I think there is a bit of generation gap between older and younger Radiation Oncologists on this topic. In my training and practice, I've always held true to the tenet that, "if you care about dose to any OAR, contour it." This makes plan review much more rapid, quantitative and efficient for me. Going one step further, I contour all of the OARs that I care about as I don't have to review them again as I would for dosimetry. As treatment planning algorithms become more complex, I think OAR contouring will remain relevant. I do a lot of my XRT on a CyberKnife which has a "true" inverse planning algorithm. The TPS will put the dose anywhere if you don't specify with an OAR.

I contour everything I am paranoid about. I almost always contour the ipsilateral brachial plexus, just out of and to make it a habit, though if it is only in a n elective volume, I don't think it is necessary. I am a strong believer in the Checklist Manifesto. Having a checklist has helped me out on more than one occasion.

 

[mavrik13]

Very interesting discussion. I don't see the point in contouring, and the attendings I worked with didn't contour a plexus either. I guess the medicolegal aspect is one part, but I think undertreated tumour is likely a greater risk for plexopathy than 70/35

 

[gmsquid]

What I've really gathered is that plexus contouring is more of a medicolegal endeavor. Those relative volumetric constraints discussed earlier would really only ever be violated in an absurdly huge cancer or absurdly bad plan. Even drawing it according to atlas metrics, which could entail using a 3 mm brush means it may not be relatively close to where it was at sim on a daily basis. Patients are consented for plexopathy. I'm not trying to convince other people not to contour it as I want to do best by the patient (hence why I asked the question), but if it's not there to shape dose, then I don't see the point of it being there. And if people are constraining it, they're risking underdosing gross disease, or using constraints that are nearly impossible to violate.

But if you don’t contour it and don’t know where it is, you can easily throw unnecessary hot spots in it, especially depending on the conformality of your plan.

 

[Ray D. Ayshun]

But if you don’t contour it and don’t know where it is, you can easily throw unnecessary hot spots in it, especially depending on the conformality of your plan.

Granted, but I might argue that a global plan hotspot of 74 Gy is less likely to lead to significant hotspot than 74 Gy to <4%. I also have concerns about relative volumetric constraints when the plexus is in general meant to look like this.

Given the extent to which the plexus goes into the vertebral canal and out into the supraclavicular area/axilla, the vast majority of the plexus should already be outside of the low dose PTV, even in the over-contoured above PTV, somewhat negating the relevance of a <10% and <4% constraint, though you may draw yours differently (this is just the pic I got from the paper). Lastly, I question how much confidence we can have in the day-to-day location of a volume that measures an average of 8.5 cc (range 1.2-17.7 cc) (ten fold difference in size!?!) and spans >10 cm. I'd be more worried that the 78 Gy hotspot just outside the plexus on sim is in the plexus on a daily basis.

 

[Neuronix]

Good discussion. I only draw it if it's going to change what I do. This is more relevant for me in re-irradiation or oligo met SBRT cases than primary H&N cancer.

If it's just to monitor dose I don't bother. With VMAT the plans are not very hot in general, so I'm not really worried about significant hotspot in the plexus.

 

[TheWallnerus]

Good discussion. I only draw it if it's going to change what I do.

A reiteration of the key point.

Right now I am planning a prostate. Met many people in life who insist on contouring the hips. When they do, don't see them using hips as a constraint though (although probably used to in old 5-field IMRT days). Why contour the hips? "You must." You be over there doing your thing, I'll be over here doing mine. We'll both be taking great care of patients.

 

[Krukenberg]

A reiteration of the key point.

Right now I am planning a prostate. Met many people in life who insist on contouring the hips. When they do, don't see them using hips as a constraint though (although probably used to in old 5-field IMRT days). Why contour the hips? "You must." You be over there doing your thing, I'll be over here doing mine. We'll both be taking great care of patients.

I contour them and constrain just to make sure the algorithm doesn’t dump a ton of MUs through the hips. Nothing else laterally to stop it from doing that.

 

[TheWallnerus]

I contour them and constrain just to make sure the algorithm doesn’t dump a ton of MUs through the hips. Nothing else laterally to stop it from doing that.

The algorithm literally never will (dump a ton of MUs in the hips) in a multi-arc VMAT.

 

[deleted1111261]

Agree, w/VMAT.. it’s like trying to eat low carb Indian - mostly a naan issue.