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Unformatted text preview: G UO-LIANG JIANG, M.D., F.A.C.R. (HON.) Department of Radiation Oncology Cancer Hospital Fudan University Shanghai, China doi:10.1016/j.ijrobp.2006.08.007 1. Liang SX, Zhu XD, Xu ZR, et al. Radiation-induced liver disease in three-dimensional conformal radiotherapy for primary liver carcinoma. Int J Radiat Oncol Biol Phys 2006;65:426–434. 2. Lawrence TS, Ten Haken RK, Kessler ML, et al. The use of 3-D dose volume analysis to predict radiation hepatitis. Int J Radiat Oncol Biol Phys 1992;23:781–788. ADJUVANT MALIGNANT MESOTHELIOMA RADIOTHERAPY: HOW MANY DIFFICULTIES! IN REGARD TO: ALLEN ET AL. FATAL PNEUMONITIS ASSOCIATED WITH INTENSITY-MODULATED RADIATION THERAPY FOR MESOTHELIOMA ( INT J RADIAT ONCOL BIOL PHYS 2006;65:640–645) AND GUPTA ET AL. HEMITHORACIC RADIATION THERAPY AFTER PLEURECTOMY/DECORTICATION FOR MALIGNANT PLEURAL MESOTHELIOMA ( INT J RADIAT ONCOL BIOL PHYS 2005;63:1045–1052) We read with interest the articles by Allen et al. ( 1 ) and Gupta et al. ( 2 ). Adjuvant intensity-modulate radiotherapy (IMRT) in malignant mesothe- lioma provides greater local control than the conventional technique ( 2–4 ). However, Allen et al. ( 1 ) in their report recommend caution in using IMRT until a clearer understanding has been reached of the dose–volume effects created by IMRT for this patient population. At our institutions, we have adopted the Memorial Sloan-Kettering Cancer Center conventional technique ( 2, 3 ). Its implementation presents some problems, the solution of which requires some compromises. We provide some suggestions from Gupta et al. ( 2 ) that could be of interest to anyone wanting to adopt it. First, do the blocked areas, used to shield the organs at risk from photon irradiation, have the same X and Y dimensions and forms of the corre- sponding electron fields, or are the latter larger than the former to hold the penumbra situation in due consideration? Second, the peripheral penumbra regions of the blocked volumes, situ- ated on the same plane of opposite sites are principally caused by diver- gence of the opposed co-axial X-beams ( Fig. 1 ). They are technically difficult to compensate for with conformal electron beams. Therefore, how can we set up the noncoplanar posterior electron field, because we cannot see the posterior part of the thorax ( Fig. 2 ) and we cannot move the patient? We solved this problem adopting, whenever possible, two opposite co-axial mirror-like electron beams. Thus, we center the anterior electron beams and then rotate the gantry 180°, under the couch, after having positioned the symmetric mirror-like block on the collimator and moving the couch height to obtain a 100-cm source skin distance. Finally, when the two blocked volumes are not exactly opposite such as the blocked anterior cardiac volume, one needs to compensate for the retrocardiac region underdosage that, because of losing the dosimetric con- tribution of the blocked anterior X-beam, cannot be irradiated by compensating with the electron beam. In our practice, we accept this underdosage, becausewith the electron beam....
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