Solitary plasmocytoma: improvement in critical organs sparing by means of helical tomotherapy.

Purpose: Helical tomotherapy (HT) was assessed in two patients with paramedullar solitary bone plasmocytoma. We compared doses delivered to critical organs, according HT plan or tridimensional conformal plan. Methods and materials: One male (patient no. 1), 67 yr-old and one female (patient no. 2), 37-yr-old, with histologically, biologically and radiological confirmed paramedullar solitary plasmocytoma have been treated in our department between November 2007 and February 2008 using HT. The prescription dose was 40 Gy in 20 fractions. This HT treatment planning was compared with a routine dosimetric work that was executed for a standard conformal radiotherapy treatment planning. Results: Treatment tolerance was excellent, without any side effects. Both patients achieved 9-month complete remission. HT resulted in substantial critical organs sparing. For patient no. 1, dose delivered to 20% of the total intestine volume was reduced from 28 Gy for conformal radiotherapy to 13 Gy for HT. Radiation dose delivered to 20% of the left kidney was reduced from 25 Gy to 7 Gy. For patient no. 2, volume of left lung that received at least 20 Gy was 12% for conformal radiotherapy vs. 6% for HT. Conclusions: For paramedullar solitary plasmocytoma, HT has the potential to significantly improve the quality of the dose distribution both in terms of better dose homogeneity within the planning target volume and more efficient sparing of critical organs. [ABSTRACT FROM AUTHOR]