IMRT is considered reasonable and medically necessary in instances where sparing the surrounding normal tissue is of added clinical benefit to the patient. Common clinical indications that frequently support the use of IMRT include:
Primary, metastatic or benign tumors of the central nervous system. Primary, metastatic tumors of the spine where spinal cord tolerance may be exceeded by conventional treatment.
Selected extracranial primary, metastatic or benign lesions.
Reirradiation that meets the requirements for medical necessity.
IMRT offers advantages as well as added complexity over conventional or three-dimensional conformal radiation therapy. Before applying IMRT techniques, a comprehensive understanding of the benefits and consequences is required. In addition to satisfying at least one of the four selection criteria noted above, the radiation oncologist’s decision to employ IMRT requires an informed assessment of benefits and risks including:
Determination of patient suitability for IMRT allowing for reproducible treatment delivery.
Adequate definition of the target volumes and organs at risk.
Equipment capability, including ability to account for organ motion when a relevant factor.
Physician and staff training.
Adequate quality assurance procedures.
On the basis of the above conditions demonstrating medical necessity, disease sites that may support the use of IMRT include the following:
• Primary, metastatic or benign tumors of the central nervous system including the brain, brain stem and spinal cord.
• Primary or metastatic tumors of the spine where the spinal cord tolerance may be exceeded with
• conventional treatment or where the spinal cord has previously been irradiated.
• Primary, metastatic, benign or recurrent head and neck malignancies including, but not limited to those involving:
• Skull base,
• Aero-digestive tract, and
• Salivary glands.
• Thoracic malignancies.
• Abdominal malignancies when dose constraints to small bowel or other normal tissue are exceeded and prevent administration of a therapeutic dose.
• Pelvic malignancies, including prostatic, gynecologic and anal carcinomas.
• Other pelvic or retroperitoneal malignancies.
Clinical scenarios that would not typically support the use of IMRT include:
Where IMRT does not offer an advantage over conventional or three-dimensional conformal radiation therapy techniques that deliver good clinical outcomes and low toxicity.
Clinical urgency, such as spinal cord compression, superior vena cava syndrome or airway obstruction.
Palliative treatment of metastatic disease where the prescribed dose does not approach normal tissue tolerances.
Inability to accommodate for organ motion, such as for a mobile lung tumor.
Inability of the patient to cooperate and tolerate immobilization to permit accurate and reproducible dose delivery.