RT Journal Article
SR Electronic
T1 Voxel-dosimetry as useful tool for optimized administered activity in radioembolization of liver tumors with 90Y-microspheres
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 131
OP 131
VO 52
IS supplement 1
A1 Di Dia, Giuseppina Amalia
A1 Botta, Francesca
A1 Cremonesi, Marta
A1 Ferrari, Mahila
A1 Wessels, Barry
A1 Orsi, Franco
A1 Bonomo, Guido
A1 De Cicco, Concetta
A1 Zheng, Yiran
A1 Paganelli, Giovanni
YR 2011
UL http://jnm.snmjournals.org/content/52/supplement_1/131.abstract
AB 131 Objectives To show the potentiality of voxel dosimetry in optimizing the treatment planning of liver radioembolisation. Methods Eleven patients with unresectable liver metastasis were treated with 90Y-resin-microspheres.Therapy was simulated by 99mTc-MAA distribution.The activity administered was based on patient-specific dosimetry using standard-method(MIRD16) on SPECT image, prescribing 40Gy as average dose limit(Dlim) to normal-liver.Retrospectively, voxel-dosimetry was performed.For voxel dose calculation, a software was developed and S-voxel factors for 90Y calculated by MonteCarlo simulation. Dose and Biological-Effective-Dose(BED) distribution were generated for normal-liver. Equivalent-Uniform-Biologically-Effective-Dose(EUBED)and Equivalent-Uniform-Dose (EUD) were assessed. Results The average dose from standard-method(Dlim=40Gy) differed slightly(within 10%) from the average dose among voxels (Dvoxdos).Conversely, Dlim vs. EUD differences were consistent (median 20 Gy;range 12-23). The EUD/Dvoxdos ratio was indicative of heterogeneous dose distribution (median 0.5;range 0.4-0.7).Consequently, a 40Gy prescription limit to normal-liver set as EUD instead of average dose would have increased the administrable activities.The median EUBED value was 24Gy(range18-39),lower than BED=64Gy from standard-method.These results were consistent with the absence of liver toxicity observed.Expressing the Normal-Tissue-Complication-Probability curves from external radiotherapy vs. BED,the liver injury probability would be 10% for BED=64Gy,negligible for the EUBED values derived. Conclusions Retrospective dose distribution analysis in treated patient offered useful information for future therapy optimization. The voxel-dosimetry gave evidence of dose inhomogeneities in normal-liver. Radiobiological estimations would suggest to replace the average dose by the EUD