What do all those radiation treatment modality codes mean?

C. Matheson, RHIA, CCS Cancer Registry Leave a Comment

The regional treatment modality fields for radiation therapy can be tricky when deciding on the appropriate code to assign. The regional treatment modality field is used to record the dominant modality of radiation therapy used to deliver the most clinically significant regional dose to the primary volume of interest during the first course of treatment. Codes are assigned to evaluate patterns of radiation oncology care; therefore, it is important to know which radiation resources were used in the delivery of therapy.

Q: What radiation treatment modality code do I use for placement of gold seeds?

Answer: Use code 20-External Beam, NOS. Fiducial Markers Placement (gold seeds) is placed trans-rectal under guidance for patients receiving radiotherapy for prostate cancer. The gold fiducial markers are used to assess daily alignment and prostate motion during standard course of external beam radiation therapy. You want to code the external beam radiation therapy, not the markers. The exact modality of external beam should be confirmed with the radiation oncologist.

Q: What is the delivery method for IMRT therapy code 31?

Answer: Intensity modulated radiation therapy (IMRT) is an advanced form of external radiation therapy that uses photons. Computer programs are used to precisely map out the tumor in 3 dimensions. But along with aiming photon beams from several directions, the intensity of the beams can be adjusted. This gives even more control over decreasing the radiation reaching normal tissue while delivering a higher dose to the cancer. IMRT delivers radiation beams with a rotating device, similar to CT scanning. In CT, a beam rotates around the patient, creating a sequence of cross-sectional images. IMRT also delivers treatment one cross-section at a time. This rotating component allows for more specific targeting of the cancer. IMRT delivers radiation from every point on a helix, or spiral, in contrast to only a few points. The greater the number of beam directions, the more the dose will be confined to the target cancer cells, sparing normal cells from exposure. Because of its precision, it is important that a person remain in the right place and perfectly still during treatment. This usually requires a special cast or mold be made before treatment to keep the body in place.

Q: What is the difference between code 53 and 54 brachytherapy?

Answer: Code 53-Brachytherapy, Interstitial, LDR (low dose rate) code is used for Radioactive Palladium or Iodine Seed Implants. Radiation is delivered to the prostate in the form of dozens of tiny radioactive seeds implanted directly into the prostate gland. This approach has the advantage of delivering a high dose of radiation to tissues in the immediate area.

The radiation oncologist places metallic seeds (either Iodine 125 or Palladium 103) into the prostate gland guided by ultrasound to place the thin-walled needles through the skin of the perineum. Anywhere from 40-150 seeds are delivered through the needles and are permanently implanted throughout the entire prostate. The calculated volume of the prostate determines the exact number of seeds. Each seed emits a low level of radiation that can penetrate only a few millimeters of tissue, therefore primarily absorbed in the "target" tissue, and surrounding structures that can be damaged by radiation (such as bladder, urethra and rectum) are out of the seeds emission range. Although the prostate is implanted with permanent radioactive seeds, their energy is very low and become no longer useful after a period of months.

Answer: Code 54-Brachytherapy, Interstitial, HDR (high dose rate) is used for Radioactive Iridium Seed Implants. With this temporary implant technique, hollow needles are placed into the prostate gland and filled with radioactive material (iridium-192) for 5-15 minutes. After the treatment both the iridium and the needles are removed. This is repeated two to three times over the next several days. The greatest advantage of the temporary implant is the high degree of accuracy achieved by delivering the radiation to the exact location within the prostate. Radiation is given over a few minutes rather than many months, as in permanent implants.

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