Intensity modulated radiation therapy (IMRT) is an advanced form of three-dimensional conformal radiation therapy (3D CRT) that uses varying intensities of radiation to produce dose distributions that are more conformal than those possible with standard 3D CRT. The beam intensity is varied across the treatment field. That is, instead of using a single, large, uniform beam, the patient is treated with many very small beams of varying intensities. This method of irradiation delivers a more uniform dose of radiation to the tumor, while protecting surrounding tissue from unnecessarily high doses of radiation.

IMRT delivers radiation more precisely to a tumor while sparing the surrounding normal tissues and/or organs. When a tumor is not well separated from surrounding organs at risk (for example, when a tumor wraps itself around an organ), there may be no combination of radiation beams of the same intensity that will safely separate the tumor from the healthy organ and/or tissue. In such instances, IMRT allows more intense treatment directed to the tumor, while limiting the radiation dose to adjacent healthy organs and/or tissue.

IMRT is appropriate for treating tumors in various anatomic areas when sparing the surrounding normal tissue is essential and the patient has at least one of the following conditions:

• Critical organs and/or tissue adjacent to, but outside the planned treatment volume are sufficiently close and require IMRT to assure increased safety and morbidity reduction.
• An immediately adjacent volume has been irradiated and abutting portals must be established with high precision.
• Gross tumor volume margins are concave or convex and in close proximity to critical structures that must be protected to avoid unacceptable morbidity.
• Non-IMRT techniques would increase the probability of grade 2 or grade 3 radiation toxicity in greater than 15 percent of radiated similar cases.
• The volume of interest is in such location that its parameters can only be defined by MRI or CT.
• The tumor tissue lies in areas associated with target motion caused by cardiac and pulmonary cycles, and the IMRT is necessary to protect adjacent normal tissues.

The decision to use IMRT requires a clear understanding of accepted clinical practices that consider the risks and benefits of such therapy when compared to conventional and 3D conformal treatment. IMRT should not be used as a substitute for conventional radiation therapy methods.

The reason IMRT is chosen over other radiation therapy methods should be documented in the patient’s medical record by including the following information:

• the prescription, defining the goals and requirements of the treatment plan, including the specific dose constraints for the target(s) and nearby critical structures;
• a statement by the treating physician documenting the medical necessity for performing IMRT on the patient in question, rather than performing conventional or 3-dimensional treatment planning and delivery;
• a signed IMRT inverse plan that meets prescribed dose constraints for the planning target volume and surrounding normal tissue using either dynamic multi-leaf collimator or segmented multi-leaf collimator (average number of ‘steps’ required to meet IMRT delivery is 5) to achieve intensity modulation radiation delivery;
• the target verification methodology which must include the following:

  - documentation of the clinical treatment volume and the planning target volume
  - documentation of immobilization and patient positioning
  - means of dose verification and secondary means of verification;

• an independent check of the monitor units generated by the IMRT treatment plan, prior to the patient’s first treatment;
• fluence distributions re-computed in a phantom; and
• plan to account for structures moving in and out of high and low dose regions created by respiration. Voluntary breath holding is not considered appropriate and the solution for movement can best be accomplished with gating technology.

For reimbursement purposes, the treating physician (for example, radiation oncologist) must be on-site during treatment, in the event his or her personal assistance is required to care for the patient.

Code 77418 represents IMRT treatment delivery.

Intensity modulated radiotherapy treatment planning (code 77301) should be reported once for each treatment volume during a course of therapy. If code 77301 is reported more than once for the same tumor, the patient’s medical record must document the medical necessity for the additional service and be available for review upon request.

Simultaneous or planned sequential treatment of multiple targets within a region is considered a single treatment plan (for example, when multiple lesions of the brain or prostate and seminal vesicles are treated). Code 77301 should be reported using the date that the plan was approved by the radiation oncologist or physicist.

If the following services are reported on the same day as IMRT treatment planning (code 77301), they are not eligible for separate payment. A participating, preferred or network provider cannot bill the member for the denied service in this instance.

• CT guidance for replacement of radiation therapy fields (code 76370)
• Coronal, sagittal, multiplanar, oblique, 3-dimensional and/or holographic reconstruction (code 76375)
• Simulation-aided field setting (codes 77280, 77285, 77290, 77295)
• Teletherapy, isodose planning (codes 77305, 77310,77315)

NOTE:

This policy is designed to address medical guidelines that are appropriate for the majority of individuals with a particular disease, illness, or condition. Each person's unique clinical circumstances may warrant individual consideration, based on review of applicable medical records.

PRN References

02/2003, Intensity Modulated Radiation Therapy (IMRT)

Intensity Modulation Using Multileaf Collimators: Current Status, Medical Dosimetry, Volume 26, No. 2, Summer 2001

Treatment Planning and Delivery of Intensity-Modulated Radiation Therapy for Primary Nasopharynx Cancer, International Journal of Radiation Oncology, Biology, Physics, Volume 49, No. 3, March 2001

Intensity-Modulated Radiation Therapy (IMRT) for Prostate Cancer with the Use of a Rectal Balloon for Prostate Immobilization: Acute Toxicity and Dose-Volume Analysis, International Journal of Radiation Oncology, Biology, Physics, (Clinical Investigation), Volume 49, No. 3, March 2001

Intensity-Modulated Radiation Therapy in Head and Neck Cancers: The Mallinckrodt Experience, International Journal of Cancer, Volume 20, No. 2, April 2000

The Theory & Practice of Intensity Modulated Radiation Therapy, A Monograph by Edward S. Sternick, Ph.D., Editor, Advanced Medical Publishing, Madison, WI.

Medicare Medical Policy