Table 3.

Guidelines for use of active breathing coordinator

	ABC use guidelines
Central nervous-system
GI	For GI tumors susceptible to motion, 4DCT will be acquired. Treatment with free-breathing or abdominal-compression approach will be considered for all such patients. ABC is considered clinically necessary when treatment in free breathing or with abdominal compression leads to unacceptably high risk for toxicity (as defined by the treating doctor), and this risk would be substantially lowered with ABC. Specific considerations for the use of ABC include GI cases in which -Expanded lung volumes with ABC will reduce the risk of lung injury for patients with mediastinal disease. -Motion mitigation with ABC will lead to significant dose reductions in the abdomen or chest. In such cases, free-breathing or abdominal-compression approaches may be particularly useful alternatives.
Lymphoma	As per treatment guidelines for tumor location
Thoracic	ABC is clinically necessary for -Any reirradiation case where the anticipated toxicity will be reduced with ABC. -Any conventionally fractionated case where a plan that meets minimum safety requirements cannot be achieved except with ABC. -Any hypofractionated or SABR plan that cannot meet normal tissue safety objectives or will not be well visualized on cone beam computed tomography without the use of ABC.
Sarcoma	As per treatment guidelines for tumor location
Pediatrics	4DCT will be acquired in patients large enough for tracing to be obtained when there is a concern for susceptibility to motion. ABC will be considered clinically necessary and will be used in cooperative patients where ABC significantly reduces dose to organs at risk.
Breast	ABC technique will be used very judiciously and be considered clinically necessary only in cases with cardiac mean dose >4 Gy or lung V20 >40% when free-breathing techniques are used. In general, we should seek alternative approaches to ABC, including IMRT/VMAT, to meet dose objectives.

Abbreviations: 4DCT = 4-dimensional computed tomography; ABC = active breathing coordinator; GI = gastrointestinal; IMRT = intensity modulated radiation therapy; VMAT = volumetric modulated arc therapy.