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SU‐E‐T‐832: Segmental IMRT Treatment for Mycosis Fungoides of An Extremity
Author(s) -
Cadman P,
Mohamed M
Publication year - 2011
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3612796
Subject(s) - mycosis fungoides , nuclear medicine , dosimetry , imaging phantom , medicine , pinnacle , radiation treatment planning , linear particle accelerator , radiation therapy , radiology , lymphoma , beam (structure) , optics , physics , pathology
Purpose: Mycosis fungoides is a rare, but potentially lethal cutaneous T‐cell lymphoma that is traditionally treated with Total Skin Electron Irradiation, TSEI. We investigated the novel use of segmental IMRT for treatment of a patient with mycosis fungoides of the foot and report on dosimetric accuracy and clinical outcome. Methods: Pinnacle V9.0 was used to create a 9‐field segmental IMRT plan delivered using 6 MV photons on our Clinac 21EX with 120 leaf Millenium MLC. The target volume included the clinically assessed disease from the skin surface to a depth of 1 cm. The prescription dose was 30 Gy in 15 fractions. Planning objectives were chosen to create a uniform dose to the PTV while limiting dose to the underlying normal tissue as much as possible. The addition of a planning region of interest that extended 1 cm beyond the skin surface allowed the MLC leaves to open to create “skin flash”. A cylindrical dosimetry phantom was planned in the same manner to determine the accuracy of Pinnacle dose calculations. Gafchromic film placed in the axial plane of the phantom and subsequently analyzed in terms of absolute dose. Results: 92% of all film measurement points in the axial plane passed the gamma analysis criteria of 3% dose difference and 3 mm DTA. Measured doses near the surface (1 mm) were typically 85% of the prescription dose. Four months after completion of treatment the lesions in the foot had regressed completely and the patient was also able to walk unencumbered. Conclusions: Our results confirm that Pinnacle dose calculations are reasonable accurate for this type of IMRT delivery and that skin doses are within clinical range. Segtmental IMRT may be an excellent choice for treating extremities with mycosis fungoides when sparing of underlying tissues is a major concern.