Annual Congress of the European Association of Nuclear MedicineOctober 17-21, 2026 I Austria, Vienna
Year: 2026
Type: article
Abstract: Aim/Introduction: Selective Internal Radiation Therapy (SIRT) using Yttrium-90 (90Y) microspheres, has emerged as an effective option in the locoregional management of primary and metastatic hepatic malignancies. Precise treatment planning is mandatory to maximize tumoricidal effects while sparing healthy tissues. CZT-based 360-degree ring SPECT systems offer enhanced sensitivity for pretreatment dosimetry; however, their limited axial field of view (FOV) often necessitates multi-bed acquisitions to cover both the lungs and liver. The present study investigates the hypothesis that hot lesions bisected by the overlap of two bed positions maintain quantitative parity with lesions captured within a single bed. The central question of this study is whether the stitching created at the bed interface introduces a significant bias in activity quantification. This potential bias could lead to discrepancies in tumour absorbed dose calculations and subsequent treatment planning. Materials and Methods: The experimental data were acquired using the Veriton-CT V400 (Spectrum Dynamics Medical) 360-degree CZT-based SPECT/CT system. To evaluate the impact of bed-stitching, the NEMA IEC body phantom, filled with 99mTc, was positioned so that the ‘hot’ spheres were centred at the intersection of two bed positions (with standard overlap of 4.92 mm). This was then compared with a reference single-bed acquisition, for which the phantom was fully encompassed within a single detector. The quantitative analysis included a visual inspection for artefacts, a comparison of standardised uptake values (SUVbw), and a determination of predicted absorbed doses and treatment activities using MIM SurePlan Liver (MIM Software Inc.). Results: Quantitative analysis revealed a consistent decrease in SUVbw for all spheres positioned at the bed overlap compared to the single-bed reference. The discrepancy was most pronounced in medium-sized spheres, with a maximum SUVbw reduction of 23.08 %. On average, the multi-bed acquisition underestimated activity concentration across all spheres by 12.88 %. These quantitative losses propagated directly to dosimetry, resulting in a significant underestimation of predicted absorbed doses and total treatment activity when lesions were bisected by the bed intersection. Conclusion: Our findings reject the hypothesis of quantitative parity between combinedbed and single-bed CZT-based SPECT imaging for 90Y pretreatment dosimetry. Significant discrepancies in SUVbw, absorbed doses and calculated treatment activities were observed when hot lesions were bisected by the field of view intersection. These results imply that discontinuities in bed stitching can be a significant factor affecting the accuracy of treatment planning for 360-degree ring SPECT systems.
Source: EANM Innovation
Language: English
Subfield: Radiology, Nuclear Medicine and Imaging
Field: Medicine
Domain: Health Sciences
Open Access status: hybrid
OpenAlex ID: W7214239302