What are the Emami et al guidelines for dose constraints of the lung, heart, and spinal cord for planning 2D radiation therapy for breast cancer (CA breast)?

Emami et al Dose Constraints for 2D Breast Cancer Radiotherapy

Critical Note on Available Evidence

The provided evidence does not contain the specific Emami et al guidelines requested. The Emami et al tolerance dose publication (typically referring to the classic 1991 paper on normal tissue tolerance) is not included in the available sources. However, I can provide the relevant dose constraints from the available high-quality guidelines for lung, heart, and spinal cord in breast cancer radiotherapy.

Lung Dose Constraints for Breast Radiotherapy

For 2D planning of breast cancer, limit lung exposure to no more than 3-3.5 cm of lung tissue as projected on the radiograph at isocenter, with a minimum of 1-1.5 cm required. 1, 2, 3

Additional Lung Parameters (from modern guidelines):

• V20 (volume receiving ≥20 Gy) should be <40% for both lungs combined (total lungs minus clinical target volume) 1
• Mean lung dose should be ≤20 Gy as an alternative constraint 1
• Mean lung dose preferably <8.5 Gy when using advanced techniques 3

Heart Dose Constraints for Breast Radiotherapy

For left-sided breast lesions, minimize the amount of heart in tangential fields to the greatest extent possible. 1, 2

Specific Heart Dose Limits:

• 60 Gy to <1/3 of heart volume 1
• 45 Gy to <2/3 of heart volume 1
• 40 Gy to <100% of heart volume 1
• Total heart dose should be limited to 30 Gy for younger patients who are expected to be long-term survivors 1

Spinal Cord Dose Constraints

The available breast cancer guidelines do not specify spinal cord constraints for standard breast radiotherapy, as the spinal cord is typically not in the treatment field for tangential breast irradiation. 1

However, from thoracic radiotherapy guidelines applicable when treating regional nodes:

• Maximum spinal cord dose should be limited to 50 Gy for once-daily fractionation (including scatter) 1
• Maximum spinal cord dose should be limited to 41 Gy for twice-daily accelerated hyperfractionation 1

Standard 2D Breast Radiotherapy Dosing

Whole breast radiation should be delivered at 4,500-5,000 cGy using opposed tangential fields at 180-200 cGy per fraction. 1, 2, 4

Key Technical Requirements:

• Treatment fields delivered daily, Monday through Friday 1, 2
• Bolus should NOT be used for standard whole breast treatment 1, 3
• Higher energy photons (≥10 MV) indicated for large-breasted women to improve dose homogeneity 2, 4

Critical Pitfalls to Avoid

• Never exceed 3-3.5 cm of lung in the treatment field to prevent radiation pneumonitis 1, 2, 3
• Never use nodal irradiation for DCIS as it provides no benefit 1, 2
• Avoid excessive heart dose in left-sided lesions through careful field design 1, 3
• Do not use routine bolus as it increases skin reactions without improving outcomes 3

Planning Approach for 2D Technique

When using 2D planning for breast cancer:

• Use anterior-posterior and posterior-anterior ports weighted more anteriorly, or wedge pair technique 1
• Carefully review dose distribution to lungs, heart, and cord even with 2D techniques 1
• CT-based planning is strongly encouraged even for 2D delivery to identify organ volumes and minimize exposure 1