Fictive Field-based Feathering for Extended-SSD Total Body Irradiation: A Single-institution Planning and Dosimetric Analysis
Abstract
Purpose: 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. Materials and Methods: 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. Results: 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%. Conclusion: 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.
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BibTeX
@article{mogulagani2026fictive,
title = {{Fictive Field-based Feathering for Extended-SSD Total Body Irradiation: A Single-institution Planning and Dosimetric Analysis}},
author = {Vijay Kumar Mogulagani and Mohan Raj Uthiran and Ben Johnson Varghese and Siva Kumar Radhakrishnan and Lakshmana Perumal and Madhuri Dumpala},
journal = {Journal of Medical Physics},
year = {2026},
month = jul,
doi = {10.4103/jmp.jmp_87_26},
url = {https://doi.org/10.4103/jmp.jmp_87_26},
note = {CC BY-NC-SA},
}
RIS
TY - JOUR
TI - Fictive Field-based Feathering for Extended-SSD Total Body Irradiation: A Single-institution Planning and Dosimetric Analysis
AU - Vijay Kumar Mogulagani
AU - Mohan Raj Uthiran
AU - Ben Johnson Varghese
AU - Siva Kumar Radhakrishnan
AU - Lakshmana Perumal
AU - Madhuri Dumpala
PY - 2026
DA - 2026/07/01
JO - Journal of Medical Physics
DO - 10.4103/jmp.jmp_87_26
UR - https://doi.org/10.4103/jmp.jmp_87_26
AB - Purpose: 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. Materials and Methods: 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. Results: 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%. Conclusion: 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.
SN - 0971-6203
SN - 1998-3913
ER -