The following is a summary of “Automated planning of stereotactic spine re-irradiation using cumulative dose limits,” published in the January 2024 issue of Oncology by Meyer et al.
Efficient review and planning for re-irradiation currently need more dedicated tools in commercial planning systems. This study aims to address this gap by developing an automated re-irradiation planning framework based on cumulative doses.
A retrospective study involved 14 patients who underwent spine SBRT re-irradiation near a previously treated site. The researchers introduced a fully automated workflow, DART (Dose Accumulation-based Re-irradiation Tool), within Eclipse, utilizing a combination of a dose accumulation script and a proprietary automated optimization algorithm. The prior treatment dose was converted into an equivalent dose in 2 Gy fractions (EQD2) and mapped to the current anatomy through deformable image registration. This process defined a series of optimization structures based on the intersection of EQD2 isodose lines with relevant organs at risk. The residual allowable dose at specified tissue tolerance was treated as a hard constraint during plan optimization.
All DART plans met institutional physical and cumulative constraints and passed plan checks by qualified medical physicists. DART demonstrated significant improvements in target coverage over clinical plans, with an average increase in PTV D99% and V100% of 2.3 Gy [range −0.3–––7.7 Gy] and 3.4 % [range −0.4 %−7.6 %] (p < 0.01, paired t-test), respectively. Additionally, high-dose spillage (>105 %) outside the PTV was reduced by up to 7 cm3. The homogeneity index for DART plans was improved by 19 % (p < 0.001).
DART provides a robust framework for generating more tailored re-irradiation plans by accounting for dose distributions from previous treatments. The superior plan quality achieved with DART has the potential to enhance the therapeutic ratio for re-irradiation patients, offering promising implications for clinical practice.
Source: sciencedirect.com/science/article/pii/S2405631624000174
