Does Arc Therapy Have the Potential to Improve Radiation Treatment of Hodgkin's Lymphoma Patients ?
M Kunze-Busch1*, V Althof2, P van Kollenburg1, M ten Brinke2, J Woltman2, R van der Maazen1, (1) Radboud University Nijmegen Medical Centre, Nijmegen (2) Radiotherapeutic Institute RISO, DeventerSU-E-T-580 Sunday 3:00:00 PM - 6:00:00 PM Room: Exhibit Hall
Purpose: To evaluate whether arc therapy (helical Tomotherapy and volumetric arc therapy; VMAT) is superior to step and shoot IMRT regarding sparing of lungs while maintaining adequate planning target volume (PTV) coverage in Hodgkin's lymphoma patients .
Methods: Radiation treatment plans for eleven Hodgkin's lymphoma patients were created employing the following techniques: coplanar and noncoplanar Step & Shoot IMRT, VMAT and Tomotherapy, i.e., for every patient 4 different treatment plans were created. The IMRT and VMAT planning was performed with Pinnacle software (v. 8 and 9, Philips) suitable for delivery with an Elekta linear accelerator, Tomotherapy plans were calculated with Tomotherapy planning software (v. 3.4). Four patients received a single prescription dose of 30 or 36 Gy, and 7 patients received a simultaneous integrated boost (30 Gy/36 Gy). Treatment plans were optimized such that the normal tissue constraints for the lung [volume receiving more than 20 Gy (V20) is less than 30% and mean lung dose (MLD) is less than 14 Gy] were met, even if PTV coverage (V95%=99%) had to be sacrificed.
Results: All 4 techniques delivered clinically acceptable treatment plans. Tomotherapy achieved the highest dose homogeneity in the PTV and highest dose coverage of the boost volume (on average 98% versus 96% for the other 3 techniques). Since lung sparing was the first planning objective, all techniques scored equally well for V20 en MLD.
Conclusions: The strength of arc therapy lies in the large number of beamlets entering the patient from a high number of angles. For Hodgkin's lymphoma patients this does not automatically translate into a superior treatment due to the high weight on the lung objectives limiting the number of beamlets allowed to pass through the lung. This means that for Hodgkin's lymphoma arc therapy has no added value for sparing of the lungs.