# Radiation Oncology/Head & Neck/Anatomy

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Head & Neck Anatomy

## Examination of the larynx

* MD Anderson; 2008 PMID 18199857 -- "Videos in clinical medicine. Examination of the larynx and pharynx." (Holsinger FC, N Engl J Med. 2008 Jan 17;358(3):e2.)
** Interactive Tutorial

## Lymph Node Surgical Anatomy

* American Head & Neck Society Consensus
** 2008 PMID 18490577 -- "Consensus statement on the classification and terminology of neck dissection." (Robbins KT, Arch Otolaryngol Head Neck Surg. 2008 May;134(5):536-8.)
*** Update of guidelines. New recommendations for boundaries between levels I and II, between levels III/IV and VI, terminology of superior mediastinal nodes, method of submitting surgical specimens
** 2002 Full Text PMID 12117328 -- "Neck dissection classification update: revisions proposed by the American Head and Neck Society and the American Academy of Otolaryngology-Head and Neck Surgery." (Robbins KT, Arch Otolaryngol Head Neck Surg. 2002 Jul;128(7):751-8.)
*** Update of guidelines. New recommendations for sublevels IA vs IB, IIA vs IIB, and VA vs VB, radiographic correlation of nodal levels
** 1991PMID 2036180 — "Standardizing neck dissection terminology. Official report of the Academy's Committee for Head and Neck Surgery and Oncology." (Robbins KT, Arch Otolaryngol Head Neck Surg. 1991 Jun;117(6):601-5.)
*** Original terminology standardization
* Subclavian triangle (Ho's triangle): the smaller division of the posterior triangle bounded, above, by the inferior belly of the omohyoideus; below, by the clavicle; base formed by the posterior border of the sternocleidomastoideus. Enlarged nodes in this triangle irrespective of size are categorized at N3 in the TNM classification for nasopharyngeal carcinoma.

## Primary targets

* Review: (2002), PMID 12118389 — "Intensity-modulated radiation therapy for head and neck cancer: emphasis on the selection and delineation of the targets." Eisbruch A et al. Semin Radiat Oncol. 2002 Jul;12(3):238-49.
** Guidelines for delineation of targets, treatment of neck regions

## Lymph node target volumes

* CT-based LN levels
* Bern University
** 2010 PMID 20231070 -- "Incidence of Small Lymph Node Metastases With Evidence of Extracapsular Extension: Clinical Implications in Patients With Head and Neck Squamous Cell Carcinoma." (Ghadjar P, Int J Radiat Oncol Biol Phys. 2010 Mar 16. [Epub ahead of print])
*** Retrospective. 74 patients with at least one ECE, analyzed for LN diameter and extent of ECE. Median F/U 2.1 years
*** Outcome: ECE+ LN <10 mm in 60% (median diameter 7 mm). ECE+ LN <7mm in 41%. On MVA, presence of ECE+ LN <7mm significant predictor for decreased regional control (HR 2.7, SS), DMFS (HR 2.6, SS), and OS (HR 2.5, SS)
*** Conclusion: Small LN mets with ECE significant prognostic factor
** 2010 PMID 19647955 -- "Quantitative analysis of extracapsular extension of metastatic lymph nodes and its significance in radiotherapy planning in head and neck squamous cell carcinoma." (Ghadjar P, Int J Radiat Oncol Biol Phys. 2010 Mar 15;76(4):1127-32. Epub 2009 Aug 3.)
*** Retrospective. 98 patients with LN+ and ECE+
*** Outcome: ECE+ in LNs <10mm 48%, and LNs <5mm 29%. ECE+ extent <=5 mm outside LN in 97% and <=3mm in 91%. Extent of ECE correlated with large LN size
*** Conclusion: Use of 10 mm CTV margin around gross LN volume appropriate
* Som (1999) - PMID 10208676 — "An imaging-based classification for the cervical nodes designed as an adjunct to recent clinically based nodal classifications." Som PM et al. Arch Otolaryngol Head Neck Surg. 1999 Apr;125(4):388-96.
* Original Rotterdam, Nowak (1999) - anatomy based
** PMID 10477003 — "A three-dimensional CT-based target definition for elective irradiation of the neck." Nowak PJ et al. Int J Radiat Oncol Biol Phys. 1999 Aug 1;45(1):33-9.
* Revised Rotterdam, Wijers (1999) - uses easy to depict anatomic landmarks
** PMID 10577684 — "A simplified CT-based definition of the lymph node levels in the node negative neck." Wijers OB et al. Radiother Oncol. 1999 Jul;52(1):35-42.
* Brussels (2000)
** PMID 10927132 — "Selection and delineation of lymph node target volumes in head and neck conformal radiotherapy. Proposal for standardizing terminology and procedure based on the surgical experience." Gregoire V et al. Radiother Oncol. 2000 Aug;56(2):135-50.
* Consensus (2003) - PMID 14644481 — "CT-based delineation of lymph node levels and related CTVs in the node-negative neck: DAHANCA, EORTC, GORTEC, NCIC, RTOG consensus guidelines." Radiother Oncol. 2003 Dec;69(3):227-36.
* Rotterdam and Brussels consensus (2004) - makes adjustments to the Rotterdamn & Brussels guidelines
** PMID 14697428 — "Rotterdam and Brussels CT-based neck nodal delineation compared with the surgical levels as defined by the American Academy of Otolaryngology-Head and Neck Surgery." Levendag P et al. Int J Radiat Oncol Biol Phys. 2004 Jan 1;58(1):113-23.
* UCSF
** 2004 PMID 15275713 — "A population-based atlas and clinical target volume for the head-and-neck lymph nodes." Poon I et al. Int J Radiat Oncol Biol Phys. 2004 Aug 1;59(5):1301-11.
*** MRI-based contouring of lymph nodes. Used to create an atlas.
** 2003 PMID 12909215 -- "Intensity-modulated radiation therapy for head-and-neck cancer: the UCSF experience focusing on target volume delineation." (Lee N, Int J Radiat Oncol Biol Phys. 2003 Sep 1;57(1):49-60.)
*** Technique and outcomes
* PMID 15936547 -- Intraoperative validation of CT-based lymph nodal levels, sublevels IIa and IIb: Is it of clinical relevance in selective radiation therapy? (Levendag P, Int J Radiat Oncol Biol Phys. 2005)
** Conclusion: "The cranial border of the neck, i.e., the cranial border of level IIa/IIb, corresponds to the caudal edge of the lateral process of C-I. Except for the posterior border between level IIa and level IIb, a perfect match was observed between the other surgical-clip-identified levels II-V boundaries (surgical-anatomy) and the CT-based delineation contours. It is argued that (1) because of the parotid gland overlapping part of level II, and (2) the frequent infestation of occult metastatic cells in the lymph channels around the IJV, the division of level II into radiologic sublevels IIa and IIb may not be relevant. Sparing of, for example, the ipsilateral parotid gland in selective RT can even be a treacherous undertaking with respect to regional tumor control. In contrast, the surgeon's reasoning for preserving the surgical sublevel IIb is that the morbidity associated with dissection of the supraspinal accessory nerve compartment of level II is reduced, whereas there is evidence from the surgical literature that no extra risk for regional tumor control is observed. Therefore, in selective neck dissections, the division into surgical sublevels IIa/IIb makes sense."
* Germany (2011) PMID 21854585 -- "Guidelines for delineation of lymphatic clinical target volumes for high conformal radiotherapy: head and neck region." (Vorwerk H, Radiat Oncol. 2011 Aug 19;6:97)
* Dr. Kenneth Hu - Contouring (date ? 2010, possibly) -- "Intensity Modulated Radiation Therapy for Head and Neck Cancer—Contouring Session"
** link
** Sample contours (like RTOG atlas) but with brachial plexus and a few other structures included
* Node-positive and post-operative (2006)
** PMID 16616387 — "Proposal for the delineation of the nodal CTV in the node-positive and the post-operative neck." Gregoire V et al. Radiother Oncol. 2006 Apr;79(1):15-20
* RTOG Website
** PDF: CT-based delineation of lymph nodes in the N0 neck
** Table of anatomic boundaries for lymph node levels
* Clinical pearls
** Level II - if low risk of involvement, but need elective coverage, consider superior border where internal jugular artery crosses the posterior belly of digastric muscle

### Specific sites

* Retropharyngeal LNs
** 2006 PMID 16751061 -- "Retropharyngeal nodes in squamous cell carcinoma of oropharynx: Incidence, localization, and implications for target volume." (Bussels B, Int J Radiat Oncol Biol Phys. 2006 Jul 1;65(3):733-8.)
* Parotid
** COSTAR trial - Target Volume Definition Guidelines
* Nasopharynx
** Dr. Nancy Lee (2010) (Powerpoint slides) link -- "Target delineation for head & neck cancer: Nasopharyngeal and Oropharyngeal ca"
* Oropharynx
** Dr. Nancy Lee (2010) (Powerpoint slides) link -- "Target delineation for head & neck cancer: Nasopharyngeal and Oropharyngeal ca"

## Clinical Evidence for Contouring
### General H&N

* Washington University, 2002 (1997-2000)
** 126 pts (52 definitive, 74 post-op).
** PMID 12128118 — "Determination and delineation of nodal target volumes for head-and-neck cancer based on patterns of failure in patients receiving definitive and postoperative IMRT." Chao KS et al. Int J Radiat Oncol Biol Phys. 2002 Aug 1;53(5):1174-84.
*** Results: Median f/u 26 mos. Failure in 6 of 52 (12%) pts receiving definitive RT, 7 of 74 (9%) post-op RT.

### Skull base

* U.Michigan, 2004 (1994-2002) - PMID 15093896 — "Recurrences near base of skull after IMRT for head-and-neck cancer: implications for target delineation in high neck and for parotid gland sparing." Eisbruch A et al. Int J Radiat Oncol Biol Phys. 2004 May 1;59(1):28-42.
** 133 pts. Parotid-sparing RT, primary RT in 60, post-op RT in 73. 115 N+. All pts received bilateral neck RT. For the contralateral neck, the upper boundary of the neck CTV was intended to cover the subdigastric (jugulodigastric) LN; was defined at the CT slice where the posterior belly of the digastric muscle crossed the jugular vein (approx 1-1.5 cm above SD LN) -- this excludes the top of level II, specifically excluding most of IIB. In the ipsilateral neck, the CTV was delineated to the skull base. RP nodes (medial) contoured to the top of C1. Treatment was given using 3D-CRT or IMRT, using parotid-sparing techniques.
** Analyzed location of tumor recurrence as infield, marginal, or outside. Median f/u 32 mo. 21 pts (16%) had LRR. Most likely recurrence was level II bilaterally (all were in-field). No recurrences were in contralateral neck above the subdigastric nodes. 3 recurrences in RP nodes above C1.
** Conclusions: contralateral, node-negative neck volume should extend superiorly to the subdigastric node. When RP nodes are at risk, they should be covered bilaterally to the skull base.

### Parotid Sparing

* Also please see parotid toxicity and NTCP section
* Memorial Sloan Kettering; 2008 PMID 18037580 -- "Recurrence in region of spared parotid gland after definitive intensity-modulated radiotherapy for head and neck cancer." (Cannon DM, Int J Radiat Oncol Biol Phys. 2008 Mar 1;70(3):660-5. Epub 2007 Nov 26.)
** Case report. 3 patients with HNC, definitive IMRT, early treatment failure in/near spared parotid gland
** Editorial (PMID 18262084): Need to be cautious about geographic miss; ipsilateral parotid should probably not be spared if Level II LN+
* Washington University; 2003 (1997-2000) - PMID 12527043 — "Patterns of failure in patients receiving definitive and postoperative IMRT for head-and-neck cancer." Chao KS et al. Int J Radiat Oncol Biol Phys. 2003 Feb 1;55(2):312-21.
** 165 pts. Parotid-sparing. Definitive or post-op. Used conventional anterior field to treat low neck.
** 17 LR failures. 9 of 17 (53%) were in-field. 5 (28%) were in lower neck field. Remaining were outside PTV1 but within PTV2 (2 pts) or outside PTV1 and PTV2 (1 pt).
** Target definition is adequate.
* Michigan; 2001 (1994-2000) - PMID 11395238 — "Xerostomia and its predictors following parotid-sparing irradiation of head-and-neck cancer." Eisbruch A et al. Int J Radiat Oncol Biol Phys. 2001 Jul 1;50(3):695-704.
** Purpose: to assess long-term xerostomia in pts receiving parotid-sparing RT and to find factors that affect its severity.
** 132 pts. One group of pts (n=84) received bilateral neck RT with a parotid-sparing technique (IMRT after 1996; modified 3-field technique with beam's eye view before 1996). Another group (controls; n=48) had smaller lateralized tumors and received RT only to the unilateral neck. Used self-reported questionnaires as well as measurements of salivary flow, unstimulated and stimulated, from each parotid duct orifice as well as for the submandibular and sublingual glands collectively. Contoured "oral cavity" to represent dose to the minor salivary glands.
** Dosimetry: Mean dose to contralateral (spared) parotid was 21.9 Gy for the bilateral RT group vs 4.1 Gy for unilateral RT. Contralateral submandibular gland could be spared with UNI RT (14.7 Gy) but not with BIL RT. Unilateral parotid could not be spared with either technique. Sialometry: contralateral parotid flow was decreased for BIL RT post-RT but rose steadily, approaching pre-RT levels by 12 mos; for UNI RT, no decrease post-RT, then rose to a higher level (to compensate). No output for unilateral irradiated parotid. Submandibular gland flow remained low in the BIL RT group.
** Conclusion: parotid sparing leads to an improvement in xerostomia over time. The uninvolved oral cavity should also be spared in order to reduce xerostomia (reflecting minor salivary gland contribution).
* Michigan; 2000 - PMID 10725621 — "Patterns of local-regional recurrence following parotid-sparing conformal and segmental intensity-modulated radiotherapy for head and neck cancer." Dawson LA et al. Int J Radiat Oncol Biol Phys. 2000 Mar 15;46(5):1117-26.
** 58 pts. 70.4 Gy (GTV), 61.2 Gy (post-operative neck), and 50.4 Gy (elective neck).
** Majority of LRR were in-field

### Oropharynx

* Johns Hopkins; 2009 (1998-2007) PMID 19131181 -- "Defining the risk of involvement for each neck nodal level in patients with early T-stage node-positive oropharyngeal carcinoma." (Sanguineti G, Int J Radiat Oncol Biol Phys. 2009 Aug 1;74(5):1356-64. Epub 2009 Jan 7.)
** Retrospective. 103 patients with T1-T2 clinically N+ oropharyngeal CA, who underwent neck dissection (radical LND 15%, modified radical LND 71%, selective LND 14%).
** Outcome: Positive Level IB 9%, Level II 91%, Level III 41%, Level IV 18%, and Level V 3%. If CT (-), then positive Level IB 3%, Level II 76%, Level III 17%, Level IV 6%, and Level V 1%. Can contour Level IB only posterior half
** Conclusion: Levels II and III should be included in high risk volumes regardless of imaging, Level IV should be low risk; Levels IB and V at very low risk and could be excluded from RT

## Brachial Plexus

Please see brachial plexus page

## Fields

* UTMB Galveston; 2004 PMID 15183476 -- "Are neck nodal volumes drawn on CT slices covered by standard three-field technique?" (Sanguineti G, Int J Radiat Oncol Biol Phys. 2004 Jul 1;59(3):725-42.)
** Treatment planning. 8 patients. Comparison of IMRT and standard 3-field technique for "medium larynx", "big larynx", and "tonsil"
** Conclusion: Dose-volume objectives of IMRT not consistent for some volumes with traditional 3F technique

## Axial CT Anatomy

* Axial CT
** Facial Nerve (CN VII)
** Cochlea and Temporal Bone
* Plain films
** Larynx

### Contouring examples

* See links at Radiation_Oncology/Head_&_Neck/General#Other_Resources (e.g., eContouring)