Radioembolisation with 90Y-microspheres: dosimetric and radiobiological investigation for multi-cycle treatment

Abstract

From a radiobiological perspective, multi-cycle treatments would allow administering higher activities with increased tumour irradiation and preserved radiation effects on NTL. Trials comparing single vs. multiple cycles are suggested.

OEDIPE, a software for personalized Monte Carlo dosimetry and treatment planning optimization in nuclear medicine: absorbed dose and biologically effective dose considerations

“…These radiobiological considerations, which enable one to take advantage of the differences in radiosensitivities and repair time constants between tumoral and healthy tissues, have been shown to be of interest to increase treatment efficacy while keeping a constant incidence and severity of toxicity (RCR, 2006). Recently, growing interest has been shown in radiobiological aspects involved in targeted radionuclide therapies (Sgouros et al, 2004;Cremonesi et al, 2008) because of their potential added value in improving the risk-to-benefit balance. Furthermore, the notion of Equivalent Uniform Biologically Effective Dose (EUD) (O'Donoghue, 1999) was introduced as a useful quantity to compare heterogeneous absorbed dose distributions with a homogeneous distribution that would have the same biological effects.…”

Fractionation protocol design for treatment planning optimization in SIRT using the OEDIPE software

“…In this study, this tolerance criterion was thus set to BED mean,NTL = 54 Gy 2.5 , which corresponds to 5% probability of causing severe hepatitis or liver failure within 5 years (Cremonesi et al, 2008) for standard fractionation protocols delivering a mean absorbed dose to NTL of 30 Gy in 15 fractions of 2 Gy; the "Gy 2.5 " unit denotes that the BED has been calculated considering α/β = 2.5 Gy for the NTL. Based on this BED mean tolerance criterion, the MIA was calculated for 4 fractionation protocols defined as 1 to 4 fractions with the total activity shared equally among the fractions.…”

“…As 99m Tc-MAA are injected to predict the 90 Y-microsphere distribution, predictive absorbed doses on the voxel scale were calculated with the MCNPX Monte Carlo code. For the present study, BED 3D distributions were calculated from these absorbed dose distributions using OEDIPE (Petitguillaume et al, 2014b) with standard values for radiobiological tissue-specific constants (Cremonesi et al, 2008), i.e. α/β = 10 Gy and T p = 1.5 h for hepatic lesions, and α/β = 2.5 Gy and T p = 2.5 h for healthy tissues.…”

“…Moreover, the Equivalent Uniform Biologically Effective Dose (EUD) (O'Donoghue, 1999), which enables one to compare heterogeneous absorbed dose distributions with a homogeneous distribution which would have the same biological effects, can be used to assess the levels of potential toxicity and tumor control achieved by a given heterogeneous absorbed dose distribution using, for example, normal tissue complication probability (NTCP) and tumor control probability (TCP) models. Cremonesi et al (2008) performed BED calculations to retrospectively study the potential of fractionation in SIRT. This study showed that considering multi-cycle treatments could lead to increasing the administered activity with an unvaried BED to NTL, thus demonstrating the potential of fractionation for treatment planning optimization in SIRT.…”

Biologically effective dose in fractionated molecular radiotherapy—application to treatment of neuroblastoma with131I-mIBG

“…The BED of a given treatment is defined as the hypothetical absorbed dose required to obtain the same biological effect if given with infinitesimal fractions or, for the case of protracted irradiation, with infinitely low absorbed-dose rate (Barendsen, 1982;Fowler, 1989). One aspect of BED is that it can be used to compare treatments given with different irradiation time-patterns with respect to the expected radiobiological response of tissues (Dale, 1990;Fowler, 1990;Howell et al, 1994;Dale and Carabe-Fernandez, 2005;Cremonesi et al, 2008). Since tumour and normal tissues typically respond differently to changes in the absorbed-dose rate or fractionation schedule, the irradiation time-pattern can be optimised using BED calculations (Dale, 1986;Millar, 1991).…”