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PET/CT-Guided Biological Target Volume Delineation and Dose Optimization for Radioactive Seed Implantation Therapy in Malignant Tumors
Sponsor: Li Min
Summary
This prospective, open-label Phase I/II trial evaluates a PET/CT-guided planning strategy for radioactive seed implantation therapy in malignant solid tumors. The approach integrates metabolic information from PET/CT into brachytherapy planning to improve the accuracy of biological target volume delineation, enhance dose coverage, and support biologically informed dose delivery. Eligible participants are assigned to one of three arms: conventional CT-guided implantation, PET/CT-guided standard-dose implantation, or PET/CT-guided biologically optimized implantation. All participants undergo image-guided treatment followed by post-implant dosimetric verification and standardized clinical follow-up. Primary endpoints include technical success rate, dosimetric superiority, and 6-month local control. Secondary endpoints include dosimetric indices (D90, V100, conformity index, homogeneity index), pain relief, quality of life (EORTC QLQ-C30), treatment-related adverse events (CTCAE v5.0), progression-free survival (PFS), failure-free survival (FFS), and overall survival (OS). Exploratory analyses will evaluate associations between baseline PET metabolic parameters (SUVmax, metabolic tumor volume) and clinical outcomes, assess the feasibility of SUV-guided dose painting, and compare the performance of tumor-specific tracers (such as PSMA and FAPI) with FDG for target delineation and treatment response prediction. The central hypothesis is that PET/CT-guided planning-particularly when incorporating biological dose optimization-will achieve superior dosimetric performance and improved local control and survival outcomes compared with conventional CT-guided implantation.
Official title: A Phase I/II Study of PET/CT-Guided Biological Target Volume Delineation and Dose Optimization for Radioactive Seed Implantation Therapy in Malignant Tumors
Key Details
Gender
All
Age Range
18 Years - Any
Study Type
INTERVENTIONAL
Enrollment
90
Start Date
2026-01
Completion Date
2028-06-01
Last Updated
2026-01-08
Healthy Volunteers
No
Conditions
Interventions
CT-Guided Radioactive Seed Implantation
CT-guided implantation of 125I radioactive seeds for localized treatment of malignant tumors. The target area is delineated on contrast-enhanced CT images, and seeds are implanted according to a treatment planning system (TPS) with a prescribed dose of about 100 Gy. Post-procedure dosimetry will confirm D90, V100, and V150, as well as organ-at-risk (OAR) dose constraints.
PET/CT-Guided Radioactive Seed Implantation
PET/CT-guided 125I seed implantation performed using PET/CT fusion to support anatomical target delineation without SUV-based biological sub-volume definition. A standard uniform-dose treatment plan is implemented, and post-implant dosimetric evaluation is used to confirm target coverage and compliance with organ-at-risk constraints.
PET/CT-Guided Radioactive Seed Implantation (Biological Dose Optimization)
PET/CT-guided 125I seed implantation for the treatment of malignant tumors. The biological target volume (BTV) is defined using 18F-FDG PET/CT fused with planning CT to improve target accuracy and tumor coverage. The prescribed dose is approximately 100 Gy. Post-implant verification includes D90, V100, and OAR constraints.
Tumor-Specific PET/CT-Guided Radioactive Seed Implantation (PSMA/FAPI Subgroup)
125I seed brachytherapy guided by tumor-specific PET/CT imaging. Tracers such as PSMA (for prostate cancer) and FAPI (for pancreatic, colorectal, and fibrotic tumors) identify biologically active regions for targeted dose escalation. High-uptake areas (SUVmax \> threshold determined by tracer characteristics) receive escalated doses of approximately 120-150 Gy through increased seed density or activity, while normal tissues remain within tolerance limits.
Locations (1)
The 960th Hospital of People's Liberation Army (PLA)
Jinan, Shandong, China