Fictive Field-based Feathering for Extended-SSD Total Body Irradiation: A Single-institution Planning and Dosimetric Analysis.

Authors

Vijay Kumar Mogulagani, Mohan Raj Uthiran, Ben Johnson Varghese, Siva Kumar Radhakrishnan, Lakshmana Perumal, Madhuri Dumpala

Published in

Journal of medical physics. Volume 51. Issue 3. Pages 525-535. Epub Sep 23, 2026.

Abstract

The purpose of this study was to describe the planning, dosimetric evaluation, quality assurance (QA), and clinical implementation of a feathered junction technique for low-dose total body irradiation (TBI) using a common coordinate system and fictive field approach with an extended source-to-skin distance (SSD) anteroposterior/posteroanterior (AP/PA) couch-based linear accelerator technique.
Six patients treated with low-dose TBI for hematopoietic stem cell transplant conditioning were included. Two patients had aplastic anemia (2 Gy/1 fraction), two had myelodysplastic syndrome (4 Gy/2 fractions), and two had leukemia (2 Gy/1 fraction). Computed tomography (CT) simulation was performed in head-first supine and feet-first supine positions using a full-body Vac-Lok system, with a pelvic fiducial marker defining a common coordinate origin. Treatment planning was performed in the Monaco treatment planning system for an Elekta Synergy linear accelerator (6 MV, MLCi2). An extended-SSD AP/PA technique with jaw-based feathered junctions was used. Dosimetric evaluation included target coverage, junction dose characteristics, and organ-at-risk doses. QA included ionization chamber measurements and cone-beam CT verification.
Adequate target coverage was achieved. The mean planning target volume D95% and V95% were 92.9% ±2.05% and 94.03% ±1.47%, respectively. The mean maximum dose was 115.51% ±0.32%, mainly in peripheral regions. The mean lung doses were 103% ±1.2% and 104% ±0.8%, and kidney doses were 102% ±0.96% and 101.5% ±1.35%. Junction doses ranged from 102.5% ±0.5% to 105.5% ±0.6%.
The technique achieved acceptable dose homogeneity and controlled junction doses. It provides a reproducible and feasible approach for low-dose TBI using standard linear accelerator infrastructure without organ shielding.

PMID:
42891478
Bibliographic data and abstract were imported from PubMed on 18 Oct 2026.

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