Special Report
Rafael Martinez-Monge, MD
Patrick S. Fernandes, MD
Nilendu Gupta, PhD
Reinhard Gahbauer, MD
Cross-sectional Nodal Atlas:
A Tool for the Definition of
Clinical Target Volumes in
Three-dimensional Radiation
Therapy Planning1
Virtual three-dimensional clinical target volume definition requires the identification
of areas suspected of containing microscopic disease (frequently related to nodal
stations) on a set of computed tomographic (CT) images, rather than the traditional
approach based on anatomic landmarks. This atlas displays the clinically relevant
nodal stations and their correlation with normal lymphatic pathways on a set of CT
images.
When radiation is used with curative intent, the radiation volume usually encompasses the
detectable tumor and the anatomic areas thought to be at risk for metastatic spread. The
International Commission on Radiation Units and Measurements Report No. 50 (1) defines
gross tumor volume (GTV) as the gross palpable or visible or demonstrable extent and
location of the malignant growth. The same report defines clinical target volume (CTV) as a
volume that contains a demonstrable GTV and/or is considered to contain (only)
microscopic, subclinical extensions at a certain probability level. In clinical practice, the
determination of the extent of the CTV is based on the knowledge of the patterns of spread
for each specific disease presentation. Additional reliable information can be obtained from
patterns-of-failure analysis and necropsy series.
For most tumors, the CTV will encompass one or more nodal stations, usually near the
primary lesion. Traditionally, the location and boundaries of these nodal stations have
been established in reference to anatomic landmarks during the standard simulation setup.
Therefore, the radiation oncologist has been specifically trained to determine the bound-
aries of the different nodal stations on standard two-dimensional radiographs, especially in
the anteroposterior and posteroanterior views. With the advent of three-dimensional (3D)
virtual clinical target definition, the radiation oncologist faces the challenge of defining
the CTV on cross-sectional CT or magnetic resonance images. Unfamiliarity with this new
technique can make correlations with the known spatial references difficult to establish.
The present nodal atlas is intended to assist radiation oncologists who will use new 3D
virtual clinical target definition and treatment planning programs.
CLASSIFICATION AND NOMENCLATURE
The anatomic patterns of lymphatic drainage for different organs to their first echelon (or
efferent) nodal stations were taken from Rouviere’s Anatomy of the Human Lymphatic System
(2) and confirmed with other lymphatic anatomy textbooks (3,4). The main and accessory
lymphatic routes for different organs that are relevant in radiation oncology are summa-
rized in Tables 1–8, with an explanation of the abbreviations appearing in the Key Box.
When different subsites within an organ had unique drainage patterns, these were
individualized in the Tables as well. The classification of and nomenclature for the different
nodal areas usually followed the guidelines of Rouviere’s system (2). In the classification of
the mediastinal nodes, the widely used American Joint Committee on Cancer classification
Index terms:
Computed tomography (CT),
three-dimensional, 99.12917,
99.92
Lymphatic system, 99.12917, 99.92
Special reports
Treatment planning, 99.92
Radiology 1999; 211:815–828
Abbreviations:
CTV 5 clinical target volume
GTV 5 gross tumor volume
3D 5 three-dimensional
1 From the Division of Radiation Oncol-
ogy, the Arthur G. James Cancer Hospital,
Ohio State University, 300 W Tenth Ave,
Columbus, OH 43210. Received July 15,
1998; revision requested August 27;
revision received October 16; ac-
cepted November 23. Address re-
print requests to R.M.
r RSNA, 1999
Author contributions:
Guarantor of integrity of entire study,
R.M., R.G.; study design, R.M.; defini-
tion of intellectual content, R.M.; lit-
erature research, R.M., P.S.F.; data
acquisition and analysis, R.M., N.G.;
manuscript preparation, R.M.; manu-
script review, R.G.
815
was chosen instead (5). The nodal areas
represented are listed in the Key Box.
When clinically relevant, some nodal sta-
tions were further divided into sub-
groups, which are noted as lowercase
letters after the abbreviation codes pro-
vided in the Tables and the Figures. The
nonparenthesized lowercase letters indi-
cate differentiated subgroups, usually in
the direction of the zz8 axis. Parenthe-
sized letters indicate subgroup subdivi-
sion, usually in the direction of the xx8
axis (shown only for inguinal and exter-
nal iliac nodes).
LOCALIZATION OF NODAL
STATIONS
The different nodal stations were out-
lined and labeled on five different sets of
consecutive and equidistant CT images
(head and neck, thorax, abdomen, male
pelvis, and female pelvis) (Figs 1–6). We
elected to use CT images because they are
the customary image support in most 3D
virtual clinical target definition pro-
grams. The nodal stations on the cross-
sectional images were localized by ex-
Key Box for Abbreviations in Tables and Figures
Abbreviation Nodal Group Abbreviation Nodal Group
APWN Aortopulmonary window nodes PFL Pyriform fossa lymphatics
ATL Anterior tongue lymphatics PG&N Parotid gland and nodes
AxN Axillary nodes PHN Hilar nodes
BTL Base tongue lymphatics PL Parametrial lymphatic plexus
CIN Common iliac nodes PLN Prelaryngeal nodes
CN Celiac axis nodes PPL Periprostatic lymphatic plexus
CPN Cervical pretracheal nodes PRL Perirectal lymphatic plexus
DN Diaphragmatic nodes PSL Paranasal sinuses lymphatics
EIN
GL
External iliac nodes
Glottic lymphatics
PsRN Superior posterior pharyngeal wall lymphatics and retro-
pharyngeal nodes
HMN High mediastinal nodes PiL Inferior posterior pharyngeal wall lymphatics
HN Hepatic nodes PTrN Mediastinal pretracheal nodes
HPL Hard palate lymphatic plexus PVgL Paravaginal lymphatic plexus
IGL Infraglottic lymphatics PVL Perivesical lymphatic plexus
IIN Internal iliac nodes PVsN Prevascular nodes
IJN Internal jugular nodes RAN Retroaortic nodes
IMN Internal mammary nodes RCP Right cervical paratracheal nodes
IN Superficial inguinal nodes, deep inguinal RRH Right hilum renal nodes
nodes RLP Right lower paratracheal nodes
IPN Internal pudendal nodes RPN Right paraaortic nodes
IRN Inferior rectal nodes RUP Right upper paratracheal nodes
JVN Juxtavertebral nodes SAN Spinal accessory nodes
LCP Left cervical paratracheal nodes ScIN Supraclavicular nodes
LGN Left gastric nodes SCN Subcarinal nodes
LPN Left paraaortic nodes SGL Supraglottic lymphatic plexus
LRH Left renal hilum nodes SMaN Submandibular nodes
LUP Left upper paratracheal nodes SMeN Submental nodes
MN Mastoid nodes SMN Superior mesenteric nodes
NL Nasopharyngeal lymphatic plexus SN Sacral nodes
PAN Preaortic nodes SPL Soft palate lymphatics
PAuN Preauricular nodes SplN Splenic nodes
PCL Postcricoid lymphatic plexus SRN Superior rectal nodes
PecN Pectoral nodes SVL Seminal vesicles lymphatic plexus
PEN Paraesophageal nodes TL Tonsil lymphatic plexus
TABLE 1
Head and Neck Lymphatic System (I)
Anatomic Site First Echelon Nodal Group Subgroup Category Abbreviation
Lacrimal gland Preauricular nodes Main PAuN
Parotid nodes Main PG&N
Submandibular nodes Main SMaN
Eyelids, conjunctiva Preauricular nodes Main PAuN
Parotid nodes Main PG&N
Submandibular nodes Main SMaN
Pinna Preauricular nodes Main PAuN
Parotid nodes Main PG&N
Mastoid nodes Main MN
Internal jugular nodes Upper Main IJNu
External auditory canal Parotid nodes Main PG&N
Internal jugular nodes Upper Main IJNu
Middle ear Preauricular nodes Main PAuN
Retropharyngeal nodes Main PsRN
Internal jugular nodes Upper Main IJNu
External nose Submandibular nodes Main SMaN
Nasal cavity Retropharyngeal nodes Main PsRN
Internal jugular nodes Upper Main IJNu
Paranasal sinuses Retropharyngeal nodes Main PsRN
Internal jugular nodes Upper Main IJNu
Lip, upper Submandibular nodes Main SMaN
Submental nodes Accessory SMeN
Preauricular nodes Accessory PAuN
Lip, lower Submandibular nodes Main SMaN
Submental nodes Main SMeN
Cheek, cutaneous Submandibular nodes Main SMaN
Submental nodes Main SMeN
Parotid nodes Main PG&N
Buccal mucosa Submandibular nodes Main SMaN
Tongue, apex Submental nodes Main SMeN
Internal jugular nodes Upper, middle Main IJNu, m
Tongue, lateral and posterior Submandibular nodes Main SMaN
Internal jugular nodes Upper Main IJNu
816 x Radiology x June 1999 Martinez-Monge et al
Figure 1. CT images depict head and neck nodal stations at levels hn01 through hn09 on the topogram in Figure 7.
Volume 211 x Number 3 Cross-sectional Nodal Atlas for Definition of Clinical Target Volumes x 817
trapolating information from cross-
sectional anatomy atlases (6), lymphatic
atlases (3), and vascular atlases (4). To
allow easy correlation, the five sets of CT
images were connected with a recogniz-
able bone structure on a topogram (Fig 7).
REPRESENTATION OF THE
ANATOMY OF THE LYMPHATIC
SYSTEM IN THE NODAL ATLAS
The initial lymphatic system is composed
of capillary lymphatics, which originate
in the intima of the tissue and are im-
mersed in the ground substance of the
tissue space. These capillaries anastomose
in networks to form the peripheral lym-
phatic plexuses. These plexuses are only
represented in the atlas for certain organs
that are frequently irradiated while intact
(prostate, rectum, some head and neck
subsites, etc) to facilitate the recognition
of the organ or site and its spatial relation-
ship with the surrounding nodal stations.
The lymphatic plexuses drain to the
first echelon lymph nodal stations
through precollecting and collecting
ducts. Sometimes, there are intercalating
lymph nodes in the path of the collecting
ducts. In general, no intermediate paths
between the organ of interest and the first
echelon nodal station have been repre-
sented in the atlas to avoid unnecessary
complexity. However, some clinically rel-
evant intercalating nodes have been rep-
resented (superior and inferior rectal
nodes and internal pudendal nodes).
The first nodal station reached by the
lymphatic drainage of a given organ is
called the first echelon nodal group. The
first echelon lymph nodes connect to
each other through postlymphonodal col-
lecting ducts and finally drain to more
central efferent lymph nodes or directly
into the venous system through the main
lymphatic trunks, depending on ana-
tomic location. As a rule, the first echelon
nodal stations for all the different organs
of the head and neck, thorax, abdomen,
and pelvis are represented. These are listed
in the Tables 1–8. One exception to this
rule has been the case of the small bowel
and most of the large bowel. Due to the
TABLE 2
Head and Neck Lymphatic System (II)
Anatomic Site First Echelon Nodal Group Subgroup Category Abbreviation
Floor of mouth Submental nodes Main SMeN
Submandibular nodes Main SMaN
Internal jugular nodes Upper, middle Main IJNu, m
Lower gum Submandibular nodes Main SMaN
Submental nodes Main SMeN
Internal jugular nodes Upper, middle Main IJNu, m
Upper gum Submandibular nodes Main SMaN
Retropharyngeal nodes Main PsRN
Hard palate, soft Internal jugular nodes Upper Main IJNu
palate inferior Submandibular nodes Accessory SMaN
Retropharyngeal nodes Accessory PsRN
Soft palate, superior Retropharyngeal nodes Main PsRN
Internal jugular nodes Upper Main IJNu
Tonsil Internal jugular nodes Upper Main IJNu
Nasopharynx Retropharyngeal nodes Main PsRN
Internal jugular nodes Upper Main IJNu
Spinal accessory nodes Main SAN
Pyriform fossa Internal jugular nodes Upper, middle Main IJNu, m
Posterior cricoid Internal jugular nodes Upper, middle Main IJNu, m
Posterior pharyngeal Retropharyngeal nodes Main PsRN
wall, superior Internal jugular nodes Upper Main IJNu
Posterior pharyngeal
wall, inferior
Internal jugular nodes Middle Main IJNm
Supraglottic larynx Internal jugular nodes Upper, middle Main IJNu, m
Infraglottic larynx Internal jugular nodes Middle, lower Main IJNm, l
Cervical pretracheal nodes Cervical Main CPN
Prelaryngeal nodes Main PLN
Trachea Cervical pretracheal nodes Cervical Main CPN
Cervical paratracheal nodes Cervical Main LCP, RCP
Prelaryngeal nodes Accessory PLN
Thyroid Cervical pretracheal nodes Cervical Main CPN
Cervical paratracheal nodes Cervical Main LCP, RCP
Internal jugular nodes Upper, middle,
lower
Main IJNu, m, l
Retropharyngeal nodes Accessory PsRN
Parotid gland Parotid nodes Main PG&N
Submandibular nodes Main SMaN
Submandibular gland Submandibular nodes Main SMaN
Internal jugular nodes Upper Main IJNu
Sublingual gland Submandibular nodes Main SMaN
Internal jugular nodes Upper Main IJNu
818 x Radiology x June 1999 Martinez-Monge et al
Figure 2. CT images depict head and neck nodal stations at the levels hn10 through hn18 on the topogram in Figure 7.
Volume 211 x Number 3 Cross-sectional Nodal Atlas for Definition of Clinical Target Volumes x 819
anatomic mobility of these organs, the
efferent pre- and paraaortic nodal groups
(fixed structures with reproducible loca-
tion), rather than the first echelon nodal
groups (juxtaintestinal and paracolic), are
represented in the atlas. Patterns of
anomalous nodal spread, such as retro-
grade spread, are not shown in this atlas.
ERRORS IN LOCALIZATION
OF NODAL STATIONS
Lymphography is the technique of choice
to visualize nodal groups. However, its
decline in the field of diagnostic radiol-
ogy has led to the decline of its use as a
tool for radiation therapy planning, and
it has been virtually abandoned for both
purposes. However, currently used stan-
dard radiation ports still follow the bound-
aries determined during the lympho-
graphic era. During standard simulation,
the different nodal stations are not actu-
ally seen on the simulation radiographs;
therefore, a margin of normal tissue is
taken around the CTV to allow for any
localization uncertainties. Three-dimen-
sional virtual clinical target definition,
like standard simulation, lacks visualiza-
tion of nodal stations. However, because
localization errors on cross-sectional im-
ages are minimized (as are the associated
increases in CTV uncertainty and size of
the planning taget volume), this problem
is not as great. During 3D virtual clinical
target definition, only a few of the nodal
stations represented in the atlas are vis-
ible on a CT image. So, the exact location
of a given station in an individual is
difficult to determine. Furthermore, the
internal structure of the lymphatic sys-
tem (different normal variants among
subjects) precludes any categorical state-
ment (2–4). Therefore, we chose to out-
line wide areas rather than discrete loca-
tions for each nodal station to account
for the differences in normal anatomic
TABLE 3
Thoracic Lymphatic System
Anatomic Site First Echelon Nodal Group Subgroup Category Abbreviation
Lung; RUL antero-
medial
Right paratracheal nodes Upper, lower Main RUP, RLP
Lung; RUL postero-
lateral, RML, RLL
superior
Right paratracheal nodes
Right hilar nodes
Subcarinal nodes
Upper, lower Main
Main
Main
RUP, RLP
PHNr
SCN
Lung; RLL inferior Right hilar nodes Main PHNr
Subcarinal nodes Main SCN
Lung; LUL superior Left upper paratracheal
nodes
Main LUP
Prevascular nodes Main PVsN
Aortopulmonary window
nodes
Main APWN
Lung; LUL inferior,
LLL superior, LLL
middle
Left upper paratracheal
nodes
Prevascular nodes
Aortopulmonary window
nodes
Left hilar nodes
Subcarinal nodes
Main
Main
Main
Main
Main
LUP
PVsN
APWN
PHNl
SCN
Lung, LLL inferior Left hilar nodes Main PHNl
Subcarinal nodes Main SCN
Costal pleura, Supraclavicular nodes Main SclN
superior Internal jugular nodes Lower Main IJNl
Costal pleura, Juxtavertebral nodes Any level Main JVNs, m, i
middle Internal mammary nodes Any level Main IMNs, m, i
Costal pleura, Axillary nodes Main AxN
inferior Juxtavertebral nodes Any level Main JVNs, , m, i
Internal mammary nodes Any level Main IMNs, m, i
Right diaphragm, Diaphragmatic nodes Right lateral Main DNlat
subperitoneal Retroaortic nodes Suprarenal, thoracic Main RANsr, t
Left diaphragm, Paraesophageal nodes Inferior Main PENi
subperitoneal Retroaortic nodes Suprarenal, thoracic Main RANsr, t
Right and left dia-
phragm, sub-
pleural
Diaphragmatic nodes
Paraesophageal nodes
Retroaortic nodes
Anterior, lateral
Inferior
Suprarenal
Main
Main
Main
DNa, lat
PENi
RANsr
Breast Axillary nodes Main AxN
Internal mammary nodes Any level Main IMNs, m, i
Supraclavicular nodes Accessory SclN
Pectoral nodes Accessory PecN
820 x Radiology x June 1999 Martinez-Monge et al
Figure 3. CT images depict the nodal stations in the thorax (th).
Volume 211 x Number 3 Cross-sectional Nodal Atlas for Definition of Clinical Target Volumes x 821
TABLE 4
Gastrointestinal Lymphatic System (I)
Anatomic Site First Echelon Nodal Group Subgroup Category Abbreviation
Gastric cardia Left gastric nodes Juxtacardiac Main LGNc
Gastric lesser cur- Left gastric nodes Gastropancreatic Main LGNlc
vature Lesser curvature Main LGNlc
Gastric antrum Hepatic nodes Right gastroepiploic Main HNrg
and pylorus Infrapyloric Main HNp
Suprapyloric Main HNp
Greater omentum Hepatic nodes Right gastroepiploic Main HNrg
Infrapyloric Main HNp
Suprapyloric Main HNp
Gastric greater
curvature
Splenic nodes Suprapancreatic Main SplNs
Duodenum Hepatic nodes Infrapyloric Main HNp
Retropyloric Main HNp
Pancreaticoduodenal Main HNpd
Superior mesenteric nodes Postpancreaticoduodenal Main SMN
Pancreas Hepatic nodes Infrapyloric, suprapyloric Main HNp
Pancreaticoduodenal Main HNpd
Hepatic artery Main HNha
Splenic nodes Suprapancreatic Main SplNs
Splenic hilum Main SplNh
Left gastric nodes Gastropancreatic Main LGNlc
Superior mesenteric nodes Root of mesentery Main SMN
Middle colic Main SMN
Postpancreaticoduodenal Main SMN
Right paraaortic nodes Superior Main RPNs
Left paraaortic nodes Superior Main LPNs
Spleen Splenic nodes Splenic hilum Main SplNh
Liver Hepatic nodes Gallbladder, hepatic artery Main HNha
Celiac axis nodes Main CN
Left gastric nodes Lesser curvature Main LGNlc
Diaphragmatic nodes Anterior, lateral Main DNa, lat
Paraesophageal nodes Inferior Main PENi
Renal hilum nodes Main RRH, LRH
Gallbladder and Hepatic nodes Gallbladder Main HNha
cystic duct Foramen of Winslow Main HNha
Hepatic duct Hepatic nodes Foramen of Winslow Main HNha
Common bile
duct
Hepatic nodes Foramen of Winslow Main HNha
Postpancreaticoduodenal Main HNpd
TABLE 5
Gastrointestinal Lymphatic System (II)
Anatomic Site Efferent Nodal Group* Subgroup Category Abbreviation
Jejunum, ileum Superior mesenteric nodes Main SMN
Cecum and appendix Superior mesenteric nodes Main SMN
Ascending colon Superior mesenteric nodes Main SMN
Transverse colon, right Superior mesenteric nodes Main SMN
Transverse colon, left Superior mesenteric nodes Main SMN
Descending colon Left paraaortic nodes Any level Main LPNsr, s, m, i,
LRH
Superior mesenteric nodes Main SMN
Sigmoid colon Preaortic nodes Inferior mesenteric Main PANs, m
Left paraaortic nodes Superior, middle Main LPNs, m
Rectum Preaortic nodes Inferior mesenteric Main PANs, m
Internal iliac nodes Accessory IIN
Sacral nodes Accessory SN
* In the small and large intestine, the first echelon nodal group is represented by the juxtaintestinal
(small-bowel) or paracolic (large-bowel) nodes located in the mesenteric border of the organ.
Because of the mobility of these organs, the efferent nodal groups (fixed structures with
reproducible location), rather than the first echelon nodal groups, are represented in the atlas.
822 x Radiology x June 1999 Martinez-Monge et al
variability and nodal interconnection. An-
other difficult problem is the mobility of
the nodal stations located proximally in
the limbs (inguinal, axilla). The location
of these nodal groups will vary greatly,
depending on simulation positioning. The
cross-s