Absorbed dose distribution of the auger emitters 67Ga and 125I and the β-emitters 67Cu, 90Y, 131I, and 186Re as a function of tumor size, uptake, and intracellular distribution

Absorbed dose estimates at the cellular level for 186Re and 188Re

“…We have calculated the total accumulated dose rates per unit accumulated activity supposing the medium to be water, without considering cell dimension. We have found similar results with NUDAT and from the work of Van Dieren for 186 Re (NUDAT (http://www-nds.iaea.org/htbin/nudat.cgi); Van Dieren et al, 1996). In the case of 188 Re, we found 0.4545 g-Gy/MBq-h.…”

Pulsed high intensity focused ultrasound increases penetration and therapeutic efficacy of monoclonal antibodies in murine xenograft tumors

“…The 90 Y-labeled antibody is capable of exerting its therapeutic effect at a distance from the antibody itself (mean penetration = 2.4 mm, max penetration=11 mm). The preferential accumulation in the tumor periphery may irradiate all tumor cells through the concept of “crossfire” where cells in the tumor center are irradiated by a distant source, which is likely with 90 Y [42]. However this approach may become more problematic with larger tumors with insufficient radiation crossfire.…”

[131I]- and [125I]metaiodobenzylguanidine therapy in macroscopic and microscopic tumors:A comparative study in SK-N-SH human neuroblastoma and PC12 rat pheochromocytoma xenografts

“…Not only are such mathematical models highly complex and include several assumptions [11,13,19,36], but for MIBG accurate information on intratumoral dose delivery is still lacking. Not only are such mathematical models highly complex and include several assumptions [11,13,19,36], but for MIBG accurate information on intratumoral dose delivery is still lacking.…”

“…This is in great contrast to 131 I, since for individual cells in a small tumor cell cluster, cross-doses from surrounding 131 I-labeled cells are more important than the self-dose because the highly energetic beta electrons deposit very little energy at the site of origin [11,13,38]. It is still a matter of debate, however, whether intracellular 125 I-labeled radiopharmaceuticals when localized outside the nucleus can deliver a significant dose of radiation to the nuclear DNA of the target cell [16,19,35,39,40] Table 4. The therapeutic outcome is known to depend on multiple (radio)biological factors, but intrinsic differences in radiosensitivity between the pheochromocytoma and neuroblastoma were excluded from the results with conventional irradiation used as an external reference.…”

“…More interesting, however, are the emitted internal-conversion and Auger electrons with ultrashort track lengths mostly within the range of granule sizes (<0.5 m). For spheres with diameters below 0.1 mm, a cytoplasmic 125 Iradioactive source was calculated to deliver at least as much radiation energy to the nucleus per disintegration than 131-radioiodine, up to at least a factor of 2 at the single cell level [10,[13][14][15]19]. Thus, the low-energy emission of [ 125 I]MIBG will be more fully absorbed in small target volumes with negligible radiation exposure of nontargeted neighboring cells and this radiopharmaceutical has therefore been advocated for treatment of microscopic neuroblastoma [10,[15][16][17].…”