PET/CT-Guided Biological Target Volume Delineation and Dose Optimization for Radioactive Seed Implantation Therapy in Malignant Tumors
A Phase I/II Study of PET/CT-Guided Biological Target Volume Delineation and Dose Optimization for Radioactive Seed Implantation Therapy in Malignant Tumors
1 other identifier
interventional
90
1 country
1
Brief 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.
Trial Health
Trial Health Score
Automated assessment based on enrollment pace, timeline, and geographic reach
participants targeted
Target at P50-P75 for not_applicable
Started Jan 2026
Typical duration for not_applicable
1 active site
Health score is calculated from publicly available data and should be used for screening purposes only.
Trial Relationships
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Study Timeline
Key milestones and dates
First Submitted
Initial submission to the registry
November 16, 2025
CompletedStudy Start
First participant enrolled
January 1, 2026
CompletedFirst Posted
Study publicly available on registry
January 8, 2026
CompletedPrimary Completion
Last participant's last visit for primary outcome
June 1, 2027
ExpectedStudy Completion
Last participant's last visit for all outcomes
June 1, 2028
January 8, 2026
January 1, 2026
1.4 years
November 16, 2025
January 2, 2026
Conditions
Keywords
Outcome Measures
Primary Outcomes (3)
Technical Success Rate
Technical success is defined as post-implant dosimetry achieving D90 ≥ 90 Gy and V100 ≥ 85% without major intraoperative or immediate postoperative complications (CTCAE Grade ≥3).
Within 24 hours after procedure
Dosimetric Superiority of PET/CT-Guided Implantation
Comparison of mean D90 between PET/CT-guided and CT-guided groups. Superiority is defined as a ≥10 Gy improvement in D90 or ≥5% increase in V100 coverage.
Immediately after implantation (dosimetric verification)
Local Control Rate at 6 Months
Local control is defined as complete response, partial response, or stable disease per RECIST 1.1 criteria at treated sites on follow-up imaging.
6 months ± 2 weeks after implantation
Secondary Outcomes (6)
Progression-Free Survival (PFS)
From the date of implantation until documented disease progression or death, whichever occurs first, assessed for up to 24 months
Failure-Free Survival (FFS)
From the date of implantation until the first documented treatment failure or death, assessed for up to 24 months
Overall Survival (OS)
From implantation until death from any cause, assessed for up to 24 months
Pain Relief Rate
Baseline, 1, 3, and 6 months post-treatment
Quality of Life (QoL)
Baseline, and 6 months
- +1 more secondary outcomes
Other Outcomes (5)
Comparison of PET-GTV and CT-GTV
Pre-treatment (baseline imaging)
Predictive Value of Baseline Tumor SUVmax on PET/CT for Treatment Outcomes
Baseline to 6 months
Early Metabolic Response
4-6 weeks post-treatment
- +2 more other outcomes
Study Arms (4)
CT-Guided Radioactive Seed Implantation
ACTIVE COMPARATORCT-guided 125I seed brachytherapy with a standard dose prescription. Target delineation based on contrast-enhanced CT. Post-implant dosimetry will verify D90, V100, V150, and organ-at-risk constraints.
PET/CT-Guided Radioactive Seed Implantation - Standard Dose
EXPERIMENTALPET/CT-guided 125I seed implantation using PET/CT to support anatomical target delineation without SUV-based biological sub-volume definition. A standard uniform-dose prescription is applied. Post-implant dosimetry verifies target coverage and organ-at-risk constraints.
PET/CT-Guided Radioactive Seed Implantation - Biological Dose Optimization
EXPERIMENTALPET/CT-guided 125I seed implantation incorporating SUV-based biological sub-volume identification. High-SUV regions receive selective dose escalation through adjustments in seed activity or spatial seed distribution while maintaining organ-at-risk constraints.
Specific PET/CT-Guided Radioactive Seed Implantation (PSMA/FAPI Subgroup)
EXPERIMENTALTumor-specific PET tracers such as PSMA and FAPI are used in selected subgroups to enhance lesion visualization and biological characterization for planning 125I seed implantation. Additional tracers are not currently in clinical use within the department but may be incorporated in future protocol amendments as availability allows.
Interventions
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 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.
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.
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.
Eligibility Criteria
You may qualify if:
- Age ≥ 18 years.
- Pathologically or clinically confirmed malignant tumor (solid tumor, lymphoma, or leukemia with a localized lesion suitable for radioactive seed implantation).
- Tumor site accessible for image-guided implantation, with a target lesion visible on CT or PET/CT.
- Life expectancy of at least 6 months.
- Ability to undergo PET/CT imaging (FDG or tumor-specific tracers such as PSMA or FAPI).
- Signed written informed consent.
You may not qualify if:
- Pregnant or breastfeeding women.
- Uncontrolled infection or active systemic inflammatory disease.
- Severe cardiopulmonary dysfunction that contraindicates interventional procedures (e.g., heart failure, severe COPD).
- Coagulation disorders (INR \> 1.5 or platelet count \< 50 × 10⁹/L).
- Known allergy or intolerance to radiopharmaceuticals or iodinated contrast media.
- Prior radiation therapy overlapping with the planned implantation area.
- Participation in another clinical trial within the past 30 days that may interfere with study results.
- Any medical or psychosocial condition considered unsuitable for study participation by the investigators (e.g., poor compliance, unstable clinical status).
Contact the study team to confirm eligibility.
Sponsors & Collaborators
- Li Minlead
Study Sites (1)
The 960th Hospital of People's Liberation Army (PLA)
Jinan, Shandong, 250031, China
MeSH Terms
Conditions
Study Officials
- STUDY DIRECTOR
Min Li, Dr.
Central Study Contacts
Study Design
- Study Type
- interventional
- Phase
- not applicable
- Allocation
- RANDOMIZED
- Masking
- SINGLE
- Who Masked
- OUTCOMES ASSESSOR
- Masking Details
- Due to the procedural nature of seed implantation, participants and treating clinicians cannot be blinded. However, independent radiologists and nuclear medicine physicians who evaluate imaging outcomes (e.g., tumor response, PET metabolic parameters, local control) will be blinded to group allocation and treatment details. Blinded image review will include: (1) PET/CT parameter assessment (SUVmax, MTV, TLG), (2) Radiographic response evaluation (RECIST 1.1 criteria), (3) Dosimetric verification (D90, V100, V150). All imaging data will be anonymized before evaluation to minimize potential bias in efficacy and dosimetric assessments.
- Purpose
- TREATMENT
- Intervention Model
- PARALLEL
- Sponsor Type
- OTHER
- Responsible Party
- SPONSOR INVESTIGATOR
- PI Title
- Vice Director
Study Record Dates
First Submitted
November 16, 2025
First Posted
January 8, 2026
Study Start
January 1, 2026
Primary Completion (Estimated)
June 1, 2027
Study Completion (Estimated)
June 1, 2028
Last Updated
January 8, 2026
Record last verified: 2026-01
Data Sharing
- IPD Sharing
- Will share
- Shared Documents
- STUDY PROTOCOL, ICF
- Time Frame
- Individual participant data (IPD) will be available beginning 6 months after publication of the primary study results and will remain available for 5 years following publication, or until the main study database is closed, whichever occurs first.
- Access Criteria
- Qualified researchers affiliated with academic institutions or recognized research organizations may request access to de-identified individual participant data (IPD), including imaging-derived parameters, dosimetric results, and clinical outcome data. Requests must include a brief research proposal describing the scientific rationale, objectives, and planned analyses. Approval will be granted by the study's principal investigator and institutional ethics committee. Data will be shared through secure institutional data transfer systems after execution of a formal data sharing agreement that ensures patient confidentiality and compliance with applicable privacy regulations.
De-identified individual participant data (IPD), including baseline demographics, PET/CT imaging parameters (SUVmax, MTV, TLG), dosimetric results, and clinical outcomes (local control, PFS, FFS, OS), will be shared upon reasonable request after publication of the main study results. Data will be available for qualified researchers conducting methodologically sound studies related to radiomics, brachytherapy, or PET-guided radiation optimization. Requests should be submitted to the principal investigator via institutional contact email. Access will require a data sharing agreement to ensure patient privacy and compliance with institutional and ethical standards.