{"id":13913,"date":"2026-03-11T23:27:27","date_gmt":"2026-03-12T02:27:27","guid":{"rendered":"https:\/\/rtmedical.com.br\/tmp-en-1773282444807\/"},"modified":"2026-04-04T18:06:47","modified_gmt":"2026-04-04T21:06:47","slug":"regional-nodal-breast-irradiation","status":"publish","type":"post","link":"https:\/\/rtmedical.com.br\/en\/regional-nodal-breast-irradiation\/","title":{"rendered":"Regional Nodal Irradiation for Breast Cancer"},"content":{"rendered":"<p><strong>Regional lymph node irradiation in breast cancer<\/strong> encompasses treatment of the axillary nodes (levels I through III), supraclavicular nodes, interpectoral (Rotter&#8217;s) nodes, and the internal mammary chain. When indicated \u2014 particularly after mastectomy with nodal involvement or in locally advanced disease \u2014 this approach improves locoregional control and may impact overall survival. Accurate target delineation requires mastery of lymphatic drainage anatomy and meticulous attention to adjacent critical structures.<\/p>\n<p>This article presents practical contouring guidelines for regional nodal irradiation based on the RADCOMP atlas and recommendations from Ho, Dunn, and Powell (Massachusetts General Hospital and Memorial Sloan Kettering Cancer Center), covering both unreconstructed and reconstructed chest wall scenarios. For a comprehensive overview across all anatomical sites, see our <a href=\"https:\/\/rtmedical.com.br\/en\/target-volume-delineation-guide\/\">complete guide to target volume delineation<\/a>.<\/p>\n<div class=\"toc\">\n<h2>In This Article<\/h2>\n<ul>\n<li><a href=\"#simulation\">1. Simulation and Positioning<\/a><\/li>\n<li><a href=\"#target-volumes\">2. Target Volumes: CTV and PTV<\/a><\/li>\n<li><a href=\"#nodal-levels\">3. Nodal Levels and Regional Coverage<\/a><\/li>\n<li><a href=\"#unreconstructed\">4. Unreconstructed Chest Wall<\/a><\/li>\n<li><a href=\"#reconstructed\">5. Reconstructed Chest Wall with Tissue Expander<\/a><\/li>\n<li><a href=\"#3d-conformal\">6. Conventional 3D Conformal Planning<\/a><\/li>\n<li><a href=\"#vmat-dosimetry\">7. VMAT\/IMRT Dosimetric Guidelines<\/a><\/li>\n<li><a href=\"#dibh\">8. DIBH and Laterality-Specific OAR Optimization<\/a><\/li>\n<\/ul>\n<\/div>\n<h2 id=\"simulation\">Simulation and Patient Positioning<\/h2>\n<p>CT simulation follows a standardized protocol: the patient is positioned with both arms raised above the head using breast board immobilization. This position abducts the scapula laterally, moving it away from the treatment field and improving access to axillary volumes. Intravenous contrast is optional but can help identify lymph nodes and vasculature \u2014 particularly the subclavian vein, which serves as the anatomical landmark for the transition between axillary levels II and III.<\/p>\n<p>When the breast is intact, the breast borders and lumpectomy scar are wired on the skin before scanning. This surface marking is essential for correlating clinical boundaries with CT images, especially when planning the boost. A common pitfall in practice is failing to wire the scar before the CT \u2014 this compromises tumor bed localization on axial slices and may lead to a misplaced boost field.<\/p>\n<p>The scan volume extends from the cricoid cartilage to 5 cm below the clinically marked inferior port edge. Complete inclusion of both lungs is mandatory \u2014 an often overlooked detail that can compromise bilateral lung DVH assessment and invalidate the entire plan. Without complete lung apices and bases in the scan, the contralateral $V_{20Gy}$ calculation becomes inaccurate.<\/p>\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" class=\"alignright lazyload\" data-src=\"https:\/\/rtmedical.com.br\/wp-content\/uploads\/2026\/04\/breast-regional-nodal-coronal-view-ptv-ctv.jpeg\" alt=\"Coronal view of regional nodal breast irradiation target delineation showing PTV, CTV, axillary levels I-III, supraclavicular and internal mammary nodes\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 461px; --smush-placeholder-aspect-ratio: 461\/548;\"><figcaption>Figure 12.1 \u2014 Coronal view: PTV (red), CTV (light orange), level I (blue), level II (light purple), level III (dark orange), supraclavicular (green), and IMN (yellow-green). Source: Target Volume Delineation and Field Setup, 2nd Edition.<\/figcaption><\/figure>\n<h2 id=\"target-volumes\">Target Volume Definition: CTV and PTV<\/h2>\n<p>The clinical target volume (CTV) for regional nodal irradiation encompasses: breast tissue or chest wall as defined by the RADCOMP Breast Atlas, ipsilateral regional lymph nodes, and interconnecting lymphatic drainage routes. In cases with a breast prosthesis, the CTV includes the prosthesis and the chest wall musculature\/skin deemed at risk for microscopic disease.<\/p>\n<p>The PTV receives asymmetric margins around the CTV \u2014 a critical aspect of this contouring approach that reflects the varying setup uncertainties in each direction:<\/p>\n<table>\n<thead>\n<tr>\n<th>Direction<\/th>\n<th>CTV \u2192 PTV Margin<\/th>\n<th>Note<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Medial<\/td>\n<td>3\u20135 mm<\/td>\n<td>\u2014<\/td>\n<\/tr>\n<tr>\n<td>Lateral<\/td>\n<td>5\u201310 mm<\/td>\n<td>Larger uncertainty from respiratory motion<\/td>\n<\/tr>\n<tr>\n<td>Posterior<\/td>\n<td>3\u20135 mm<\/td>\n<td>IMN: 0 mm posteriorly (spare lung)<\/td>\n<\/tr>\n<tr>\n<td>Superior \/ Inferior<\/td>\n<td>5\u201310 mm<\/td>\n<td>\u2014<\/td>\n<\/tr>\n<tr>\n<td>Anterior<\/td>\n<td>5\u201310 mm<\/td>\n<td>Include skin surface<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><em>Source: Target Volume Delineation and Field Setup, 2nd Edition (Table 12.1)<\/em><\/p>\n<p>The internal mammary nodes (IMN) receive zero posterior margin \u2014 this protects the underlying lung and is one of the key features distinguishing regional nodal contouring from breast-only treatment. The physician may trim lung inclusion at their discretion, but the reference is to keep lung within the PTV to the minimum necessary for target coverage.<\/p>\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" class=\"alignleft lazyload\" data-src=\"https:\/\/rtmedical.com.br\/wp-content\/uploads\/2026\/04\/breast-regional-nodal-sagittal-view-ptv.jpeg\" alt=\"Sagittal view of breast regional nodal irradiation planning showing PTV and axillary and supraclavicular nodal levels\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 461px; --smush-placeholder-aspect-ratio: 461\/576;\"><figcaption>Figure 12.2 \u2014 Sagittal view: PTV (red), CTV (light orange), levels I-III, supraclavicular (green), and IMN (yellow-green). Source: Target Volume Delineation and Field Setup, 2nd Edition.<\/figcaption><\/figure>\n<p>A 3 mm bolus is used daily over the chest wall for all VMAT\/IMRT plans. In inflammatory breast cancer, where the skin GTV dose must reach \u2265100% of the prescription dose, a thicker bolus (1 cm) may be applied. This ensures adequate skin coverage, which is a primary target in the inflammatory setting. In routine practice, the bolus must be checked daily \u2014 displacement or air bubbles significantly reduce the surface build-up effect.<\/p>\n<h2 id=\"nodal-levels\">Nodal Levels and Regional Coverage<\/h2>\n<p>The PTV for regional nodal irradiation includes all ipsilateral chains: axillary levels I, II, and III, supraclavicular nodes, interpectoral (Rotter&#8217;s) nodes, and internal mammary nodes. Each level has a distinct anatomical location and specific clinical relevance, and contouring errors at any level compromise the entire treatment.<\/p>\n<p>Level I lies lateral to the pectoralis minor, encompassing most clinically palpable axillary nodes. It contains the largest number of lymph nodes and is also most susceptible to surgical clip artifacts in patients after partial dissection. Level II sits behind the pectoralis minor \u2014 a region easily confused with axillary fat in obese patients \u2014 identifying the axillary vein as a superior landmark helps prevent under-contouring at this level.<\/p>\n<p>Level III is medial to the pectoralis minor, near the subclavian vein junction \u2014 its contouring requires attention to the transition into the supraclavicular field. The interpectoral (Rotter&#8217;s) nodes, located between the pectoralis major and minor, must also be included; despite their small number, omitting them can result in interpectoral space recurrence.<\/p>\n<p>The supraclavicular nodes are included as a contiguous superior volume, while the internal mammary nodes follow the internal mammary artery, typically in the first three intercostal spaces. In practice, IMN contouring tends to be the most controversial component: proximity to the heart (especially on the left side) demands careful balancing between coverage and cardiotoxicity. Nodal recurrence mapping studies, such as those published by DeSelm and colleagues, show that most regional recurrences concentrate in unirradiated stations \u2014 reinforcing the importance of including all indicated chains.<\/p>\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" class=\"alignright lazyload\" data-src=\"https:\/\/rtmedical.com.br\/wp-content\/uploads\/2026\/04\/breast-axial-slices-unreconstructed-chest-wall.jpeg\" alt=\"Axial slices of target volume and nodal delineation for unreconstructed right chest wall in cranio-caudal direction\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 690px; --smush-placeholder-aspect-ratio: 690\/658;\"><figcaption>Figure 12.3 \u2014 Axial slices (cranio-caudal) for unreconstructed right chest wall showing target volumes and nodal stations. Source: Target Volume Delineation and Field Setup, 2nd Edition.<\/figcaption><\/figure>\n<h2 id=\"unreconstructed\">Unreconstructed Right Chest Wall<\/h2>\n<p>In the post-mastectomy setting without reconstruction, the chest wall constitutes the primary CTV alongside the nodal volumes. Figures 12.1 and 12.2 (coronal and sagittal) and Figure 12.3 (axial slices) illustrate how the contours are distributed: the PTV follows the curvature of the remaining chest wall, with nodal stations contoured contiguously.<\/p>\n<p>Without a prosthesis or expander in the field, planning is more straightforward. The chest wall is relatively flat, allowing tangents with conventional angulation. The main challenge lies in ensuring uniform skin coverage and adequate retrosternal coverage where the IMN reside, without excessive ipsilateral lung dose. The absence of prosthetic volume reduces dosimetric complexity but does not eliminate the need for optimization \u2014 especially at the junction between tangential and supraclavicular fields.<\/p>\n<h2 id=\"reconstructed\">Reconstructed (Tissue Expander) Left Chest Wall<\/h2>\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" class=\"alignleft lazyload\" data-src=\"https:\/\/rtmedical.com.br\/wp-content\/uploads\/2026\/04\/breast-sagittal-reconstructed-tissue-expander.jpeg\" alt=\"Sagittal view of irradiation planning with tissue expander in reconstructed left chest wall showing PTV, nodal levels, and organs at risk\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 461px; --smush-placeholder-aspect-ratio: 461\/409;\"><figcaption>Figure 12.4 \u2014 Sagittal view: reconstructed left chest wall with tissue expander. PTV (red), CTV (light orange), levels I-III, supraclavicular (green), IMN (yellow-green), heart (yellow), contralateral breast (dark purple). Source: Target Volume Delineation and Field Setup, 2nd Edition.<\/figcaption><\/figure>\n<p>When the patient has tissue expander reconstruction, the planning geometry changes significantly. The expander protrudes the chest wall anteriorly, altering target depths and the spatial relationship with OARs. On the left side, the heart assumes a relatively more anterior position, requiring careful optimization. Figure 12.4 clearly shows the cardiac contour (yellow) in relation to the PTV in the sagittal view \u2014 this proximity explains the laterality-specific dosimetric limits.<\/p>\n<p>Figure 12.5 shows axial slices for the reconstructed left chest wall. Note how the PTV encompasses the expander bilaterally and how nodal stations maintain their standard contours despite the anatomical alteration. The prosthesis itself is included in the CTV \u2014 the IMRT\/VMAT criteria specify that the $D_{95\\%}$ inside the implant PTV should not exceed 120% of the prescription, an essential limit to avoid damage to the prosthetic material and capsular complications. In practice, hot spots above 120% over silicone or saline expanders can cause accelerated encapsulation and complicate subsequent reconstructive surgeries.<\/p>\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" class=\"alignright lazyload\" data-src=\"https:\/\/rtmedical.com.br\/wp-content\/uploads\/2026\/04\/breast-axial-slices-reconstructed-tissue-expander.jpeg\" alt=\"Axial slices of target delineation for reconstructed left chest wall with tissue expander showing volumes and nodal stations\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 690px; --smush-placeholder-aspect-ratio: 690\/738;\"><figcaption>Figure 12.5 \u2014 Axial slices (cranio-caudal) for reconstructed left chest wall with tissue expander. Source: Target Volume Delineation and Field Setup, 2nd Edition.<\/figcaption><\/figure>\n<h2 id=\"3d-conformal\">Conventional 3D Conformal Planning<\/h2>\n<p>Conventional 3D conformal planning for regional nodal irradiation typically employs a three-beam arrangement: a medial en face electron beam matched to two opposing lateral tangent fields. This classic configuration provides adequate chest wall and IMN coverage with the electron beam, while the tangents treat the lateral breast\/chest wall volume and the lower axillary nodes. The main advantage of this technique is its simplicity and reproducibility, although dosimetric homogeneity at the electron-photon junction remains a constant concern.<\/p>\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" class=\"alignleft lazyload\" data-src=\"https:\/\/rtmedical.com.br\/wp-content\/uploads\/2026\/04\/breast-3d-conformal-three-beam-arrangement.jpeg\" alt=\"Axial view showing three-beam arrangement for 3D conformal breast radiotherapy: medial en face electron beam and opposing lateral tangent fields\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 461px; --smush-placeholder-aspect-ratio: 461\/379;\"><figcaption>Figure 12.6 \u2014 Axial view: medial en face electron beam (red) matched to opposing lateral tangents (blue and green). Source: Target Volume Delineation and Field Setup, 2nd Edition.<\/figcaption><\/figure>\n<p>The supraclavicular field is planned separately as an anterior oblique or AP field, covering the level III and supraclavicular nodes. Figure 12.7 shows the coronal view of this field with the nodal targets overlaid \u2014 the junction between the supraclavicular field and the inferior tangents is one of the critical points of treatment, where overdose or underdose can occur if the geometry is not precise. The half-beam block technique (asymmetric jaw) minimizes divergence at the junction and reduces the risk of dose overlap.<\/p>\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" class=\"alignright lazyload\" data-src=\"https:\/\/rtmedical.com.br\/wp-content\/uploads\/2026\/04\/breast-coronal-supraclavicular-field-targets.jpeg\" alt=\"Coronal view of supraclavicular field with overlaid lymph node target volumes in breast radiotherapy\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 461px; --smush-placeholder-aspect-ratio: 461\/397;\"><figcaption>Figure 12.7 \u2014 Coronal view: supraclavicular field and lymph node targets. Source: Target Volume Delineation and Field Setup, 2nd Edition.<\/figcaption><\/figure>\n<p>For the tumor bed boost, an en face electron field with a custom cutout is typically used. Figure 12.8 demonstrates this setup in a 3D view: the electron field (blue) encompasses the tumor bed (maroon), surgical clips (light green), and the lumpectomy scar (gray). Electron energy selection depends on bed depth \u2014 in practice, 9\u201312 MeV covers most cases, following the rule that the 80% isodose reaches a depth in centimeters of approximately $E\/3$, where $E$ is the energy in MeV.<\/p>\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" class=\"alignleft lazyload\" data-src=\"https:\/\/rtmedical.com.br\/wp-content\/uploads\/2026\/04\/breast-3d-boost-tumor-bed-electron-field.jpeg\" alt=\"3D view of electron boost field to the tumor bed showing custom cutout, surgical clips, and lumpectomy scar in breast radiotherapy\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 461px; --smush-placeholder-aspect-ratio: 461\/389;\"><figcaption>Figure 12.8 \u2014 3D view: en face electron boost with custom cutout encompassing tumor bed, clips, and lumpectomy scar. Source: Target Volume Delineation and Field Setup, 2nd Edition.<\/figcaption><\/figure>\n<h2 id=\"vmat-dosimetry\">VMAT\/IMRT Dosimetric Guidelines<\/h2>\n<p>Dosimetric recommendations for regional nodal irradiation with VMAT follow rigorous criteria for both target coverage and organ-at-risk protection. The standard fractionation is 50 Gy in 25 fractions, maintaining the conventional 2 Gy per fraction scheme.<\/p>\n<h3>Target Criteria (50 Gy \/ 25 Fractions)<\/h3>\n<table>\n<thead>\n<tr>\n<th>Structure<\/th>\n<th>Parameter<\/th>\n<th>Objective<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>PTV<\/td>\n<td>$D_{95\\%}$<\/td>\n<td>\u2265 95%<\/td>\n<\/tr>\n<tr>\n<td>PTV<\/td>\n<td>$V_{95\\%}$<\/td>\n<td>\u2265 95%<\/td>\n<\/tr>\n<tr>\n<td>PTV<\/td>\n<td>$D_{05\\%}$<\/td>\n<td>\u2264 110%<\/td>\n<\/tr>\n<tr>\n<td>IMN<\/td>\n<td>$D_{95\\%}$<\/td>\n<td>\u2265 100%<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>The coverage criterion is twofold: both $D_{95\\%}$ and $V_{95\\%}$ must reach \u2265 95%, ensuring the volume is adequately covered in terms of both point dose and volumetric metrics. The hot spot limit ($D_{05\\%}$ \u2264 110%) is standard for breast fields and prevents dose concentrations that can cause skin fibrosis. For the IMN specifically, the $D_{95\\%}$ \u2265 100% target is more stringent than the general PTV, reflecting the oncological importance of this nodal station.<\/p>\n<h3>Normal Tissue Criteria \u2014 VMAT<\/h3>\n<table>\n<thead>\n<tr>\n<th>Organ at Risk<\/th>\n<th>Parameter<\/th>\n<th>Constraint<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Ipsilateral lung<\/td>\n<td>$V_{20Gy}$<\/td>\n<td>\u2264 33%<\/td>\n<\/tr>\n<tr>\n<td>Ipsilateral lung<\/td>\n<td>$V_{10Gy}$<\/td>\n<td>\u2264 68%<\/td>\n<\/tr>\n<tr>\n<td>Ipsilateral lung<\/td>\n<td>Mean dose<\/td>\n<td>\u2264 20 Gy<\/td>\n<\/tr>\n<tr>\n<td>Contralateral lung<\/td>\n<td>$V_{20Gy}$<\/td>\n<td>\u2264 25%<\/td>\n<\/tr>\n<tr>\n<td>Heart<\/td>\n<td>$V_{25Gy}$<\/td>\n<td>\u2264 25%<\/td>\n<\/tr>\n<tr>\n<td>Heart<\/td>\n<td>Mean dose<\/td>\n<td>\u2264 9 Gy (left) \/ \u2264 8 Gy (right)<\/td>\n<\/tr>\n<tr>\n<td>Heart<\/td>\n<td>$D_{max}$<\/td>\n<td>\u2264 50 Gy<\/td>\n<\/tr>\n<tr>\n<td>LAD<\/td>\n<td>$D_{max}$<\/td>\n<td>\u2264 50 Gy<\/td>\n<\/tr>\n<tr>\n<td>Contralateral breast (intact)<\/td>\n<td>Mean dose<\/td>\n<td>\u2264 5 Gy<\/td>\n<\/tr>\n<tr>\n<td>Contralateral breast (implant)<\/td>\n<td>Mean dose<\/td>\n<td>\u2264 8 Gy<\/td>\n<\/tr>\n<tr>\n<td>Esophagus<\/td>\n<td>$D_{max}$<\/td>\n<td>\u2264 50 Gy<\/td>\n<\/tr>\n<tr>\n<td>Thyroid<\/td>\n<td>Mean dose<\/td>\n<td>\u2264 20 Gy<\/td>\n<\/tr>\n<tr>\n<td>Brachial plexus<\/td>\n<td>$D_{max}$<\/td>\n<td>\u2264 55 Gy<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><em>Source: Target Volume Delineation and Field Setup, 2nd Edition (Table 12.2)<\/em><\/p>\n<p>Notice the mean heart dose differs between left breast (\u2264 9 Gy) and right (\u2264 8 Gy) \u2014 this asymmetry reflects the anatomical proximity and the differential risk of cardiotoxicity. The left anterior descending artery (LAD) receives the same $D_{max}$ limit of \u2264 50 Gy as the whole heart. In regional nodal irradiation, lung constraints are more permissive than in breast-only treatment ($V_{20Gy}$ \u2264 33% vs. typically \u2264 20-25% without nodal inclusion), acknowledging the trade-off required to cover the medial nodal volumes.<\/p>\n<h2 id=\"dibh\">DIBH and Laterality-Specific IMRT\/VMAT Criteria<\/h2>\n<p>Deep inspiratory breath hold (DIBH) increases the distance between the chest wall and the heart, significantly reducing cardiac dose. The guidelines distinguish non-DIBH and DIBH criteria, with more restrictive limits for DIBH reflecting the expected geometric gain. The addition of DIBH to VMAT in patients with implant reconstruction has been shown to further reduce the low-dose bath to normal tissue, as published by Dumaine and colleagues.<\/p>\n<table>\n<thead>\n<tr>\n<th>Structure<\/th>\n<th>Parameter<\/th>\n<th>Non-DIBH<\/th>\n<th>DIBH<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Ipsilateral lung<\/td>\n<td>$V_{20Gy}$<\/td>\n<td>30% (33%)<\/td>\n<td>27% (30%)<\/td>\n<\/tr>\n<tr>\n<td>Ipsilateral lung<\/td>\n<td>$V_{10Gy}$<\/td>\n<td>65% (68%)<\/td>\n<td>60% (63%)<\/td>\n<\/tr>\n<tr>\n<td>Ipsilateral lung<\/td>\n<td>Mean dose<\/td>\n<td>18 Gy<\/td>\n<td>18 Gy<\/td>\n<\/tr>\n<tr>\n<td>Contralateral lung<\/td>\n<td>$V_{20Gy}$<\/td>\n<td colspan=\"2\">5%<\/td>\n<\/tr>\n<tr>\n<td>Heart \u2014 left breast<\/td>\n<td>$V_{25Gy}$<\/td>\n<td colspan=\"2\">3%<\/td>\n<\/tr>\n<tr>\n<td>Heart \u2014 right breast<\/td>\n<td>$V_{25Gy}$<\/td>\n<td colspan=\"2\">0.5%<\/td>\n<\/tr>\n<tr>\n<td>Heart \u2014 left + IMN ($D_{95\\%}$ \u2265 90%)<\/td>\n<td>Mean dose<\/td>\n<td>7 Gy (8 Gy)<\/td>\n<td>6 Gy (7 Gy)<\/td>\n<\/tr>\n<tr>\n<td>Heart \u2014 right + IMN ($D_{95\\%}$ \u2265 90%)<\/td>\n<td>Mean dose<\/td>\n<td colspan=\"2\">4 Gy<\/td>\n<\/tr>\n<tr>\n<td>Heart \u2014 left + IMN ($D_{95\\%}$ \u2265 100%)<\/td>\n<td>Mean dose<\/td>\n<td>8 Gy (9 Gy)<\/td>\n<td>7 Gy (8 Gy)<\/td>\n<\/tr>\n<tr>\n<td>Heart \u2014 right + IMN ($D_{95\\%}$ \u2265 100%)<\/td>\n<td>Mean dose<\/td>\n<td colspan=\"2\">5 Gy<\/td>\n<\/tr>\n<tr>\n<td>Fallback (above not achievable)<\/td>\n<td>Mean dose<\/td>\n<td>10 Gy (12 Gy)<\/td>\n<td>9 Gy (10 Gy)<\/td>\n<\/tr>\n<tr>\n<td>LAD<\/td>\n<td>$D_{max}$<\/td>\n<td colspan=\"2\">25 Gy (35 Gy)<\/td>\n<\/tr>\n<tr>\n<td>Contralateral breast (intact)<\/td>\n<td>Mean dose<\/td>\n<td colspan=\"2\">6 Gy<\/td>\n<\/tr>\n<tr>\n<td>Contralateral breast (implant)<\/td>\n<td>Mean dose<\/td>\n<td colspan=\"2\">8 Gy<\/td>\n<\/tr>\n<tr>\n<td>Esophagus<\/td>\n<td>$D_{max}$<\/td>\n<td colspan=\"2\">35 Gy (40 Gy)<\/td>\n<\/tr>\n<tr>\n<td>Thyroid<\/td>\n<td>Mean dose<\/td>\n<td colspan=\"2\">20 Gy<\/td>\n<\/tr>\n<tr>\n<td>Brachial plexus<\/td>\n<td>$D_{max}$<\/td>\n<td colspan=\"2\">55 Gy<\/td>\n<\/tr>\n<tr>\n<td>Liver (right side)<\/td>\n<td>Mean dose<\/td>\n<td colspan=\"2\">8 Gy (10 Gy)<\/td>\n<\/tr>\n<tr>\n<td>Stomach<\/td>\n<td>Mean dose<\/td>\n<td>5 Gy<\/td>\n<td>3 Gy<\/td>\n<\/tr>\n<tr>\n<td>Cord<\/td>\n<td>$D_{max}$<\/td>\n<td colspan=\"2\">20 Gy<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><em>Source: Target Volume Delineation and Field Setup, 2nd Edition (Table 12.3). Values in parentheses represent maximum tolerance limits.<\/em><\/p>\n<p>This table warrants careful analysis. The mean cardiac dose limits vary according to the level of IMN coverage: when accepting $D_{95\\%}$ \u2265 90% for the IMN, cardiac constraints are tighter (7 Gy for left breast non-DIBH). If $D_{95\\%}$ \u2265 100% coverage is required, the limit relaxes to 8 Gy. A fallback tier exists \u2014 when no limit above is achievable, up to 10 Gy (12 Gy) without DIBH is accepted. In practice, this hierarchical scale allows the dosimetrist to trade IMN coverage against cardiac dose in a stepwise fashion, prioritizing cardiac protection when the anatomy does not cooperate.<\/p>\n<p>The LAD limit with IMRT\/VMAT is more restrictive (25 Gy, tolerance 35 Gy) compared to pure VMAT (50 Gy), reflecting the modulation capability to spare this critical structure. The $D_{95\\%}$ \u2264 120% criterion inside the implant PTV for reconstructed patients protects against hot spots that could cause capsular contracture or expander failure.<\/p>\n<p>For right-sided treatments, the liver becomes an additional OAR with mean dose \u2264 8 Gy (tolerance 10 Gy) \u2014 a detail that applies specifically to regional nodal irradiation, where inferior fields may graze the right hepatic lobe. The stomach is another OAR that differs with DIBH: 5 Gy without versus 3 Gy with breath hold. The spinal cord, with $D_{max}$ \u2264 20 Gy, is rarely dose-limiting but should be contoured in all cases where the supraclavicular field extends medially.<\/p>\n<p>For details on <a href=\"https:\/\/rtmedical.com.br\/en\/early-breast-fields\/\">early breast cancer tangent field setup and field-in-field technique<\/a>, see our dedicated article. When extensive supraclavicular nodal involvement is present, similar nodal coverage concepts apply in other sites \u2014 see also our article on <a href=\"https:\/\/rtmedical.com.br\/en\/lung-cancer-target-delineation\/\">lung cancer target delineation<\/a>, where mediastinal drainage shares similar anatomy.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Practical contouring guidelines for regional lymph node irradiation in breast cancer: CTV, PTV, axillary levels, and VMAT\/IMRT dosimetry.<\/p>\n","protected":false},"author":1,"featured_media":16499,"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":[265,267,99],"tags":[],"class_list":{"0":"post-13913","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-delineamento-volumes","8":"category-delineamento-mama","9":"category-radiotherapy"},"aioseo_notices":[],"rt_seo":{"title":"Regional Nodal Breast RT: Target Delineation","description":"Target volume delineation for regional nodal irradiation in breast cancer. Axillary, supraclavicular, and internal mammary node coverage.","canonical":"","og_image":"","robots":"default","schema_type":"MedicalWebPage","include_in_llms":false,"llms_label":"","llms_summary":"","faq_items":[{"q":"When is regional nodal irradiation indicated in breast cancer?","a":"Regional nodal irradiation is indicated for node-positive breast cancer, particularly with 4 or more positive axillary nodes. It is also considered for 1-3 positive nodes based on additional risk factors. The MA.20 and EORTC 22922 trials demonstrated improved outcomes with nodal RT."},{"q":"How are the internal mammary nodes contoured?","a":"Internal mammary nodes are contoured around the internal mammary vessels in the first three intercostal spaces. A 5 mm expansion around the vessels is typical. Coverage is particularly important for medially located tumors and node-positive disease."},{"q":"What are the key OARs in regional nodal breast RT?","a":"Heart, left anterior descending artery, lungs, brachial plexus, and contralateral breast are the primary OARs. Deep inspiration breath hold and prone positioning can significantly reduce cardiac dose, especially for left-sided breast cancer with nodal coverage."}],"video":[],"gtin":"","mpn":"","brand":"","aggregate_rating":[]},"_links":{"self":[{"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/posts\/13913\/"}],"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=13913"}],"version-history":[{"count":2,"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/posts\/13913\/revisions\/"}],"predecessor-version":[{"id":16587,"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/posts\/13913\/revisions\/16587\/"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/media\/16499\/"}],"wp:attachment":[{"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/media\/?parent=13913"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/categories\/?post=13913"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rtmedical.com.br\/en\/wp-json\/wp\/v2\/tags\/?post=13913"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}