We propose a Multi-Resonant Double-barrier Quantum-dot-in-a-Well (MR-DWELL) dosimeter with a tunable trade-off between sensitivity and radiation tolerance, realized through graphene-assisted electrostatic screening. The sensing mechanism relies on radiation-induced trapped charge that shifts and broadens resonant tunneling states in the DWELL heterostructure. The dimensionless capacitance ratio η=C_Q/C_geo is introduced as the universal design parameter: it controls the screening factor S=η/(1+η) and thereby the trade-off between sensitivity and radiation hardness. For η=2.09 the effective low-dose shift coefficient is reduced threefold (from 0.14~to 0.045 meV/mGy), while the screened architecture retains ∼83% of the peak tunneling current and a peak-to-valley ratio ∼10 after 1 MGy, thereby preserving the dosimetric sensitivity required for practical readout. The second-derivative spectroscopy d²I/dV² is identified as a robust experimental readout. A reduced-order Landauer model calibrated against literature data is employed for the screening physics, while a self-consistent NEGF-Poisson-trap framework is formulated for future quantitative validation. Explicit design rules for three operating regimes (high sensitivity, balanced, maximum hardness) are provided, together with a three-population trap model that conceptually enables dose-rate discrimination in the FLASH radiotherapy regime. A comparative analysis of model vintages and their methodological foundations is included to guide interpretation of numerical predictions.