{"id":13991,"date":"2026-03-11T23:38:52","date_gmt":"2026-03-12T02:38:52","guid":{"rendered":"https:\/\/rtmedical.com.br\/tmp-en-1773283130135\/"},"modified":"2026-04-04T18:06:52","modified_gmt":"2026-04-04T21:06:52","slug":"lung-cancer-target-delineation","status":"publish","type":"post","link":"https:\/\/rtmedical.com.br\/en\/lung-cancer-target-delineation\/","title":{"rendered":"Lung Cancer: Target Delineation and Fields"},"content":{"rendered":"<p>Getting <strong>lung cancer target delineation<\/strong> right demands more than anatomical knowledge \u2014 it requires understanding respiratory motion, the nodal atlas, and how each clinical scenario changes your margin logic. Whether you are treating a 1.5 cm peripheral tumor with SBRT or a bulky N3 mediastinum with concurrent chemoradiation, the principles laid out by Wijetunga, Liao, and Gomez in <em>Target Volume Delineation and Field Setup, 2nd Edition<\/em> give you a reliable framework. This article distills that chapter into practical decision points.<\/p>\n<p>This detailed article is part of the <a href=\"https:\/\/rtmedical.com.br\/en\/target-volume-delineation-guide\/\">complete target volume delineation guide<\/a>, which covers lung, breast, esophagus, and other thoracic sites systematically. For comparison with nodal coverage in breast cancer, the article on <a href=\"https:\/\/rtmedical.com.br\/en\/regional-nodal-breast-irradiation\/\">regional nodal breast irradiation<\/a> covers adjacent anatomical territory in the supraclavicular and internal mammary regions.<\/p>\n<h2>How should I approach planning for lung cancer?<\/h2>\n<p>Start with the clinical scenario: early stage favors SBRT, locally advanced favors IMRT or 3D-CRT with chemotherapy, and postoperative cases use limited fields without a gross tumor volume. In every case, respiratory motion management is not optional \u2014 it is the variable that determines whether your margins are rational or arbitrary.<\/p>\n<p><img decoding=\"async\" data-src=\"https:\/\/rtmedical.com.br\/wp-content\/uploads\/2026\/04\/lung-cancer-lymph-node-stations-map-1.jpeg\" alt=\"Mediastinal lymph node station map for lung cancer planning\" class=\"alignright lazyload\" width=\"420\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 690px; --smush-placeholder-aspect-ratio: 690\/986;\" \/><\/p>\n<p>CT-based planning is the foundation. 4D CT captures the tumor motion envelope across the respiratory cycle and generates either the internal GTV (iGTV) or the internal target volume (ITV), depending on which margin approach you use. PET-CT adds metabolic information that is critical for distinguishing viable tumor from post-obstructive collapse \u2014 a common problem in lung. Mediastinoscopy and EBUS complete nodal staging when imaging is equivocal.<\/p>\n<p>OAR contouring includes both lungs, heart, spinal cord, esophagus, chest wall, great vessels, proximal bronchial tree (PBT), and brachial plexus for superior sulcus tumors. Dose constraints follow the QUANTEC publication (Marks et al., 2010).<\/p>\n<h2>Lymph node stations: the Michigan atlas as your reference<\/h2>\n<p>Every planner working in the thorax needs the Michigan nodal atlas internalized. Without that spatial map, decisions about involved-field versus elective coverage become guesswork.<\/p>\n<p>The stations are grouped into anatomical zones:<\/p>\n<ul>\n<li><strong>Supraclavicular:<\/strong> Station 1<\/li>\n<li><strong>Superior mediastinal:<\/strong> 2R, 2L, 3a, 3p, 4R, 4L<\/li>\n<li><strong>Aortic:<\/strong> 5, 6<\/li>\n<li><strong>Inferior mediastinal:<\/strong> 7, 8, 9<\/li>\n<li><strong>N1 (intrapulmonary):<\/strong> 10, 11, 12, 13, 14<\/li>\n<\/ul>\n<p>The table below, derived from Figure 13.1b data in the chapter, shows nodal involvement risk by station and primary tumor location. These percentages guide decisions about which regions to include or exclude.<\/p>\n<h3>Lymph node involvement risk by tumor lobe<\/h3>\n<table>\n<thead>\n<tr>\n<th>Station<\/th>\n<th>RUL (%)<\/th>\n<th>RML (%)<\/th>\n<th>RLL (%)<\/th>\n<th>LUL (%)<\/th>\n<th>LLL (%)<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>1 (Supraclavicular)<\/td>\n<td>11<\/td>\n<td>4<\/td>\n<td>3<\/td>\n<td>17<\/td>\n<td>3<\/td>\n<\/tr>\n<tr>\n<td>2R<\/td>\n<td>31<\/td>\n<td>26<\/td>\n<td>12<\/td>\n<td>5<\/td>\n<td>3<\/td>\n<\/tr>\n<tr>\n<td>2L<\/td>\n<td>3<\/td>\n<td>0<\/td>\n<td>2<\/td>\n<td>21<\/td>\n<td>7<\/td>\n<\/tr>\n<tr>\n<td>3a<\/td>\n<td>4<\/td>\n<td>7<\/td>\n<td>5<\/td>\n<td>3<\/td>\n<td>3<\/td>\n<\/tr>\n<tr>\n<td>4R<\/td>\n<td>64<\/td>\n<td>59<\/td>\n<td>26<\/td>\n<td>8<\/td>\n<td>4<\/td>\n<\/tr>\n<tr>\n<td>4L<\/td>\n<td>6<\/td>\n<td>4<\/td>\n<td>5<\/td>\n<td>56<\/td>\n<td>18<\/td>\n<\/tr>\n<tr>\n<td>5<\/td>\n<td>4<\/td>\n<td>0<\/td>\n<td>2<\/td>\n<td>71<\/td>\n<td>22<\/td>\n<\/tr>\n<tr>\n<td>6<\/td>\n<td>2<\/td>\n<td>0<\/td>\n<td>2<\/td>\n<td>32<\/td>\n<td>8<\/td>\n<\/tr>\n<tr>\n<td>7 (Subcarinal)<\/td>\n<td>20<\/td>\n<td>48<\/td>\n<td>35<\/td>\n<td>19<\/td>\n<td>33<\/td>\n<\/tr>\n<tr>\n<td>8<\/td>\n<td>2<\/td>\n<td>11<\/td>\n<td>15<\/td>\n<td>5<\/td>\n<td>50<\/td>\n<\/tr>\n<tr>\n<td>9<\/td>\n<td>2<\/td>\n<td>4<\/td>\n<td>5<\/td>\n<td>2<\/td>\n<td>17<\/td>\n<\/tr>\n<tr>\n<td>10 (Ipsilateral hilar)<\/td>\n<td>59<\/td>\n<td>63<\/td>\n<td>49<\/td>\n<td>56<\/td>\n<td>46<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><em>Source: Target Volume Delineation and Field Setup, 2nd Edition. RUL=right upper lobe, RML=right middle lobe, RLL=right lower lobe, LUL=left upper lobe, LLL=left lower lobe.<\/em><\/p>\n<p><img decoding=\"async\" data-src=\"https:\/\/rtmedical.com.br\/wp-content\/uploads\/2026\/04\/lung-lymph-node-risk-by-tumor-location.jpeg\" alt=\"Lymph node risk table by tumor location in lung cancer\" class=\"alignleft lazyload\" width=\"420\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 691px; --smush-placeholder-aspect-ratio: 691\/389;\" \/><\/p>\n<h2>Involved-field approach: why skip elective nodal irradiation?<\/h2>\n<p>Routine elective nodal irradiation was abandoned because studies showed low rates of elective nodal failure and unacceptable esophageal and pulmonary toxicity when large fields covered the entire mediastinum. The randomized trial comparing involved-field versus elective nodal irradiation demonstrated improved outcomes with the involved-field approach \u2014 consistent with the biology: irradiating clinically negative nodes adds dose without demonstrated benefit.<\/p>\n<p>The logic is straightforward: treat what you can see on imaging. GTV includes primary tumor and PET-positive or size-criteria lymph nodes on CT. Elective regions stay out unless there is a specific indication, such as limited-stage SCLC with hilar disease.<\/p>\n<h2>GTV to PTV expansions: two practical approaches<\/h2>\n<p>The chapter describes two approaches for incorporating respiratory motion into target expansions:<\/p>\n<p><strong>Approach 1 \u2014 iGTV-based:<\/strong> GTV \u2192 iGTV (motion envelope from 4D CT) \u2192 iCTV (isotropic expansion on iGTV) \u2192 PTV (setup margin). This is the preferred approach for SBRT, where precise iGTV definition is critical for respecting the peribronchial no-fly zone.<\/p>\n<p><strong>Approach 2 \u2014 Conventional CTV with ITV:<\/strong> GTV \u2192 CTV (microscopic expansion) \u2192 ITV (CTV moved by 4D CT motion envelope) \u2192 PTV. Preferred for postoperative cases without gross tumor volume and for locally advanced NSCLC with systematic IGRT.<\/p>\n<h2>SBRT for early-stage NSCLC: maximum precision, maximum BED<\/h2>\n<p>SBRT is the treatment of choice for stage I NSCLC in medically inoperable patients and is increasingly considered for high-risk operable patients. The goal is BED > 100 Gy to the tumor with minimum dose to surrounding normal tissue.<\/p>\n<p><img decoding=\"async\" data-src=\"https:\/\/rtmedical.com.br\/wp-content\/uploads\/2026\/04\/early-nsclc-sbrt-peripheral-tumor.jpeg\" alt=\"SBRT planning for early-stage peripheral NSCLC\" class=\"alignright lazyload\" width=\"420\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 510px; --smush-placeholder-aspect-ratio: 510\/264;\" \/><\/p>\n<p>The iGTV to iCTV expansion for early-stage disease is small: 0 to 0.2 cm. For a small peripheral tumor, microscopic extension is minimal and setup margin dominates the final PTV. The additional PTV margin depends on available IGRT technology.<\/p>\n<p>The proximal bronchial tree (PBT) \u2014 defined as the distal 2 cm of the trachea, carina, mainstem bronchi, lobar bronchi, and the first segments of segmental bronchi \u2014 is the most critical structure in SBRT planning. A no-fly zone (NFZ) extends 2 cm beyond the PBT. Tumors within or adjacent to the NFZ are classified as central and require less ablative fractionation.<\/p>\n<p>Dose schedules vary by location:<\/p>\n<ul>\n<li><strong>Peripheral:<\/strong> 54 Gy\/3fx (18 Gy\/fx), 48 Gy\/4fx (12 Gy\/fx), 50 Gy\/4fx, or 50 Gy\/5fx<\/li>\n<li><strong>Central:<\/strong> 50 Gy\/5fx, 70 Gy\/10fx, or 60 Gy\/8fx<\/li>\n<\/ul>\n<p>Maximum PBT point dose is constrained to 55 Gy in any schedule. Figure 13.2 in the chapter illustrates three early-stage cases: a classic peripheral tumor treated with 54 Gy\/3fx, a tumor near the PBT with 48 Gy\/4fx, and a central tumor with 50 Gy\/5fx.<\/p>\n<h2>Simulation setup: what to do before contouring<\/h2>\n<p>Reproducible positioning is the precondition for rational margins. Arms above the head reduces brachial plexus dose for superior tumors and moves the arms out of beam paths. An immobilization device \u2014 whether a custom mold or a flat board with arm poles \u2014 should be used consistently throughout the treatment course.<\/p>\n<p>4D CT acquisition requires adequate coaching for regular breathing. Irregular breathing during 4D CT creates artifacts in the motion-phase reconstruction that translate directly into inaccurate iGTV definition. If coaching is unavailable, slow CT (prolonged rotation time capturing average motion) is a reasonable fallback for non-SBRT cases.<\/p>\n<p>Contrast CT at the planning scan session is preferred for mediastinal contouring: it clarifies vessel boundaries at stations 4R, 4L, 5, and 6, where distinguishing lymph nodes from adjacent vascular structures can be genuinely difficult on non-contrast imaging. PET fusion further sharpens GTV definition when atelectasis is present. The atelectatic lung should be excluded from the GTV unless PET shows metabolic activity within the collapse.<\/p>\n<h2>Locally advanced NSCLC (stages II\u2013III): nodal control with chemoradiation<\/h2>\n<p>In locally advanced disease, the iGTV to iCTV expansion increases to 0.5\u20130.8 cm, reflecting histologic data showing significant microscopic extension in NSCLC. PTV margin depends on the level of motion management and IGRT implemented:<\/p>\n<ul>\n<li>1.0\u20131.5 cm without motion management or IGRT<\/li>\n<li>0.5\u20131.0 cm with 4D CT or CBCT, but not both<\/li>\n<li>0.3\u20130.5 cm with 4D CT + kV\/CBCT (preferred approach)<\/li>\n<\/ul>\n<p><img decoding=\"async\" data-src=\"https:\/\/rtmedical.com.br\/wp-content\/uploads\/2026\/04\/locally-advanced-nsclc-stage-iiib-planning.jpeg\" alt=\"Locally advanced NSCLC stage IIIB radiation planning\" class=\"alignleft lazyload\" width=\"420\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 691px; --smush-placeholder-aspect-ratio: 691\/698;\" \/><\/p>\n<p>The standard dose for stage II\u2013III NSCLC with concurrent chemotherapy is 60 Gy in 30 fractions (2 Gy\/fx). Dose escalation above 60 Gy has not shown benefit in randomized trials and increases toxicity. GTV includes primary tumor and involved lymph nodes visible on CT or PET.<\/p>\n<p>Figure 13.3 shows a cT1cN3M0 stage IIIB case: RUL tumor with right hilar, subcarinal, paratracheal, and right SCV nodes involved. The 60 Gy\/30fx plan covers all PET-positive sites while excluding contralateral elective chains. Figure 13.4 shows a cT4N3M0 stage IIIC case with bilateral SCV involvement and superior vena cava syndrome, requiring a field that covers the bilateral superior mediastinum.<\/p>\n<p><img decoding=\"async\" data-src=\"https:\/\/rtmedical.com.br\/wp-content\/uploads\/2026\/04\/nsclc-iiic-bilateral-supraclavicular.jpeg\" alt=\"NSCLC IIIC planning with bilateral supraclavicular involvement\" class=\"alignright lazyload\" width=\"420\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 461px; --smush-placeholder-aspect-ratio: 461\/859;\" \/><img decoding=\"async\" data-src=\"https:\/\/rtmedical.com.br\/wp-content\/uploads\/2026\/04\/nsclc-iiic-coronal-nodal-stations.jpeg\" alt=\"Coronal nodal stations for NSCLC IIIC planning\" class=\"alignleft lazyload\" width=\"420\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 691px; --smush-placeholder-aspect-ratio: 691\/759;\" \/><\/p>\n<h2>Postoperative NSCLC: limited fields are the new standard<\/h2>\n<p>Postoperative radiotherapy in NSCLC has evolved quickly. The historical approach used large fields covering the tumor bed, involved lymph nodes, bilateral mediastinum, ipsilateral stump, and supraclavicular fossa \u2014 with consequent pulmonary and cardiac toxicity. The Lung ART trial reshaped this paradigm.<\/p>\n<p><img decoding=\"async\" data-src=\"https:\/\/rtmedical.com.br\/wp-content\/uploads\/2026\/04\/postoperative-nsclc-radiation-planning.jpeg\" alt=\"Postoperative NSCLC radiation field planning\" class=\"alignright lazyload\" width=\"420\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 691px; --smush-placeholder-aspect-ratio: 691\/807;\" \/><\/p>\n<p>The current approach is limited: pathologically involved nodal regions plus the ipsilateral bronchial stump, with the option to extend one level above and below the positive levels. There is no GTV \u2014 delineation starts at the CTV. The standard sequence is CTV \u2192 ITV (respiratory motion) \u2192 PTV (~0.5 cm setup margin).<\/p>\n<p>Doses are stratified by surgical margin status:<\/p>\n<ul>\n<li><strong>R0 (clear margins):<\/strong> 50\u201354 Gy at 1.8\u20132.0 Gy\/fx<\/li>\n<li><strong>R1 (microscopically positive):<\/strong> 54\u201360 Gy at 1.8\u20132.0 Gy\/fx<\/li>\n<li><strong>R2 (gross residual disease):<\/strong> 60 Gy with concurrent chemotherapy<\/li>\n<\/ul>\n<p>Figure 13.5 shows a 5.8 cm LUL tumor with positive levels 5 and 10L. The limited field per Lung ART is used, with 54 Gy\/30fx.<\/p>\n<h2>SCLC: involved-field in both limited and extensive disease<\/h2>\n<p>Small cell lung cancer grows rapidly and is relatively radioresistant as a single modality, but responds well to combined chemoradiation. The involved-field approach is accepted in both stages.<\/p>\n<p><img decoding=\"async\" data-src=\"https:\/\/rtmedical.com.br\/wp-content\/uploads\/2026\/04\/small-cell-lung-cancer-radiation-planning.jpeg\" alt=\"Small cell lung cancer radiation therapy planning\" class=\"alignleft lazyload\" width=\"420\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 691px; --smush-placeholder-aspect-ratio: 691\/653;\" \/><\/p>\n<p>GTV to CTV expansion in SCLC is 0.5\u20131.0 cm, often including the ipsilateral hilum even without PET evidence, given lymphatic drainage patterns. CTV to PTV margins follow the same NSCLC guidelines, calibrated to available IGRT.<\/p>\n<p>Dose schedules differ by stage:<\/p>\n<ul>\n<li><strong>Limited stage:<\/strong> 45 Gy at 1.5 Gy twice daily (30 fractions) \u2014 the classic Turrisi regimen \u2014 or 66\u201370 Gy at 2.0 Gy daily as a higher-dose alternative<\/li>\n<li><strong>Extensive stage (consolidation):<\/strong> 30\u201345 Gy at 3.0 Gy\/fx to sites of bulky disease<\/li>\n<\/ul>\n<p>Figure 13.6 shows a cT2N2 limited-stage case with the involved field covering the primary tumor and involved mediastinal nodes but excluding elective chains. The schedule used was 45 Gy\/30fx BID.<\/p>\n<h2>Adaptive replanning: when the anatomy changes during treatment<\/h2>\n<p>Obstructive tumors causing atelectasis may partially resolve during treatment as radiotherapy reduces tumor volume and the lung re-aerates. This phenomenon, visible on verification CBCT, can expose previously collapsed lung tissue to doses intended for the tumor, dramatically altering the dose distribution.<\/p>\n<p><img decoding=\"async\" data-src=\"https:\/\/rtmedical.com.br\/wp-content\/uploads\/2026\/04\/lung-adaptive-replanning-metastatic.jpeg\" alt=\"Adaptive replanning due to lung re-aeration during treatment\" class=\"alignright lazyload\" width=\"420\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 344px; --smush-placeholder-aspect-ratio: 344\/339;\" \/><\/p>\n<p>Adaptive replanning should be considered whenever CBCT shows significant anatomical change \u2014 ipsilateral lung expansion, effusion resolution, or collapse reversal. The case in Figure 13.7 illustrates a metastatic lesion treated with 45 Gy\/15fx: pulmonary re-aeration during treatment required replanning to protect the newly aerated lung.<\/p>\n<p>There is no universal protocol for adaptive replanning triggers. Weekly CBCT review by both the dosimetrist and the physician is the minimum reasonable standard. Any visually significant change in the lung or mediastinal contour warrants DVH recalculation before continuing treatment.<\/p>\n<h2>iCTV editing and dose coverage<\/h2>\n<p><img decoding=\"async\" data-src=\"https:\/\/rtmedical.com.br\/wp-content\/uploads\/2026\/04\/nsclc-ictv-editing-dose-coverage.jpeg\" alt=\"iCTV editing and dose coverage in NSCLC planning\" class=\"alignleft lazyload\" width=\"420\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 691px; --smush-placeholder-aspect-ratio: 691\/880;\" \/><\/p>\n<p>The iCTV is edited from the iGTV with attention to anatomical barriers: pleura, chest wall, mediastinum, and great vessels limit microscopic extension and allow margin retraction in those directions. This editing reduces irradiated volume without compromising tumor control \u2014 provided the mean phase CT reconstruction from 4D CT is done rigorously.<\/p>\n<p>Adequate dose coverage is verified through DVHs: V95 \u2265 95% of PTV, Dmin \u2265 90% of prescribed dose. For SBRT, conformity is evaluated by the PITV index (ratio of prescription isodose volume to PTV volume) and the dose gradient index (GI). A tight isodose curve embracing the PTV with rapid falloff to surrounding normal tissue is the goal.<\/p>\n<h2>Dose schedule summary<\/h2>\n<table>\n<thead>\n<tr>\n<th>Scenario<\/th>\n<th>Total Dose<\/th>\n<th>Fractionation<\/th>\n<th>Notes<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>NSCLC stage I SBRT peripheral<\/td>\n<td>54 Gy \/ 48 Gy \/ 50 Gy \/ 50 Gy<\/td>\n<td>3 fx \/ 4 fx \/ 4 fx \/ 5 fx<\/td>\n<td>BED &gt;100 Gy; max PBT 55 Gy<\/td>\n<\/tr>\n<tr>\n<td>NSCLC stage I SBRT central<\/td>\n<td>50 Gy \/ 70 Gy \/ 60 Gy<\/td>\n<td>5 fx \/ 10 fx \/ 8 fx<\/td>\n<td>Within or adjacent to NFZ<\/td>\n<\/tr>\n<tr>\n<td>NSCLC stage II\u2013III<\/td>\n<td>60 Gy<\/td>\n<td>30 fx (2 Gy\/fx)<\/td>\n<td>Concurrent chemotherapy<\/td>\n<\/tr>\n<tr>\n<td>Postoperative R0<\/td>\n<td>50\u201354 Gy<\/td>\n<td>1.8\u20132.0 Gy\/fx<\/td>\n<td>Clear surgical margins<\/td>\n<\/tr>\n<tr>\n<td>Postoperative R1<\/td>\n<td>54\u201360 Gy<\/td>\n<td>1.8\u20132.0 Gy\/fx<\/td>\n<td>Microscopically positive margin<\/td>\n<\/tr>\n<tr>\n<td>Postoperative R2<\/td>\n<td>60 Gy<\/td>\n<td>2.0 Gy\/fx<\/td>\n<td>Concurrent chemotherapy<\/td>\n<\/tr>\n<tr>\n<td>SCLC limited stage<\/td>\n<td>45 Gy or 66\u201370 Gy<\/td>\n<td>1.5 Gy BID (30 fx) or 2.0 Gy daily<\/td>\n<td>Involved field<\/td>\n<\/tr>\n<tr>\n<td>SCLC extensive consolidation<\/td>\n<td>30\u201345 Gy<\/td>\n<td>3.0 Gy\/fx<\/td>\n<td>Bulky residual disease<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><em>Source: Target Volume Delineation and Field Setup, 2nd Edition \u2014 Chapter 13 (Wijetunga, Liao, Gomez).<\/em><\/p>\n<h2>OAR constraints and treatment plan evaluation<\/h2>\n<p>Dose constraints in lung radiation planning are not suggestions \u2014 exceeding them leads to measurable clinical events. The heart, lungs, esophagus, and spinal cord are the four structures that most frequently limit plan quality.<\/p>\n<p>For the lungs, the most widely used metrics are mean lung dose (MLD) and V20 (volume receiving 20 Gy or more). An MLD below 20 Gy and V20 below 35% are the conventional thresholds for conventionally fractionated treatment. For SBRT, V20 is less relevant; instead, V12.5 Gy (for single-fraction equivalent) and the contralateral lung mean dose become the key parameters. The ipsilateral lung receives substantial dose by design in lobar SBRT \u2014 the constraint work focuses on the contralateral side and the global lung minus GTV volume.<\/p>\n<p>Esophageal toxicity is the most treatment-limiting OAR in locally advanced NSCLC treated with concurrent chemotherapy. The QUANTEC mean esophageal dose constraint is under 34 Gy, with V50 below 40% and V60 below 30% as common thresholds. In practice, mediastinal node coverage often pushes the esophagus over these limits; when that happens, a frank discussion about toxicity risk versus local control benefit is necessary.<\/p>\n<p>The spinal cord constraint is straightforward in most lung cases: maximum dose under 45\u201350 Gy for conventional fractionation. Posterior mediastinal nodes at stations 8 and 9 occasionally push the cord, particularly in lower lobe tumors with posterior nodal involvement. In SBRT, the cord maximum is typically constrained to 18\u201322 Gy for multi-fraction regimens.<\/p>\n<p>Cardiac constraints include pericardial V30, mean heart dose, and \u2014 increasingly \u2014 specific chamber-level constraints. Large left lower lobe tumors irradiated with concurrent chemotherapy commonly produce mean heart doses above 20 Gy; there is growing evidence associating this with late cardiac events. When feasible, IMRT arc optimization to spare the cardiac base is worthwhile even if it requires a few extra beam angles.<\/p>\n<h2>Clinical integration and daily practice<\/h2>\n<p>Lung concentrates nearly every planning challenge in radiation oncology: tissue heterogeneity, motion, multiple nodal chains, proximity to critical structures, and scenarios ranging from ablative to palliative. The clinician who internalizes these principles can adapt the protocol to the real patient \u2014 not to the idealized trial participant.<\/p>\n<p>For those working across thoracic oncology and wanting to compare mediastinal delineation principles across primary sites, the article on <a href=\"https:\/\/rtmedical.com.br\/en\/esophageal-field-setup\/\">esophageal cancer field setup<\/a> provides complementary principles for the inferior mediastinum and gastroesophageal junction. The <a href=\"https:\/\/rtmedical.com.br\/en\/target-volume-delineation-guide\/\">complete delineation guide<\/a> offers systematic context for all sites, including head and neck, gynecological, and gastrointestinal primaries. For breast cancer with nodal involvement, the article on <a href=\"https:\/\/rtmedical.com.br\/en\/regional-nodal-breast-irradiation\/\">regional nodal breast irradiation<\/a> is the natural complement for understanding supraclavicular and internal mammary stations that anatomically overlap the superior mediastinum.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Lung cancer radiation planning: SBRT for early NSCLC, locally advanced chemoRT, postoperative fields, SCLC, and adaptive replanning with dose tables.<\/p>\n","protected":false},"author":1,"featured_media":16496,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"ngg_post_thumbnail":0,"fifu_image_url":"","fifu_image_alt":"","footnotes":""},"categories":[265,99,268],"tags":[],"class_list":{"0":"post-13991","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-delineamento-volumes","8":"category-radiotherapy","9":"category-delineamento-torax-gi"},"aioseo_notices":[],"rt_seo":{"title":"Lung Cancer RT: Target Volume Delineation","description":"Target volume delineation for lung cancer radiotherapy. GTV, CTV, ITV motion management, nodal coverage and SBRT for early-stage NSCLC.","canonical":"","og_image":"","robots":"default","schema_type":"MedicalWebPage","include_in_llms":false,"llms_label":"","llms_summary":"","faq_items":[{"q":"How is respiratory motion managed in lung RT delineation?","a":"Respiratory motion is managed using 4D-CT to generate an internal target volume (ITV) that encompasses tumor excursion throughout the breathing cycle. Alternatives include gating, breath-hold techniques, and real-time tumor tracking, each with specific margin implications."},{"q":"What are the CTV margins for locally advanced lung cancer?","a":"For locally advanced NSCLC, the CTV typically includes the GTV with a 6-8 mm margin for microscopic extension, excluding natural anatomic barriers such as bone and uninvolved mediastinal structures. Involved-field nodal irradiation based on PET\/CT staging is the current standard."},{"q":"How is SBRT delineated for early-stage lung cancer?","a":"SBRT for early-stage NSCLC uses a GTV-to-PTV approach without a separate CTV. The ITV is generated from 4D-CT, and a 5 mm isotropic PTV margin is added. No elective nodal irradiation is used, and typical prescriptions are 48-54 Gy in 3-5 fractions."}],"video":[],"gtin":"","mpn":"","brand":"","aggregate_rating":[]},"_links":{"self":[{"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/posts\/13991\/"}],"collection":[{"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/posts\/"}],"about":[{"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/types\/post\/"}],"author":[{"embeddable":true,"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/users\/1\/"}],"replies":[{"embeddable":true,"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/comments\/?post=13991"}],"version-history":[{"count":2,"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/posts\/13991\/revisions\/"}],"predecessor-version":[{"id":16551,"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/posts\/13991\/revisions\/16551\/"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/media\/16496\/"}],"wp:attachment":[{"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/media\/?parent=13991"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/categories\/?post=13991"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/tags\/?post=13991"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}