Lung Neoplasms, Radiation Pneumonitis
Conditions
Keywords
4DCT, Lung Ventilation Imaging, Functional Lung Imaging, Functional-Lung-Avoidance Radiotherapy (FLAR), IMRT, Organs at Risk (OARs), Radiation-Induced Lung Injury, Radiation Pneumonitis
Brief summary
This retrospective single-center study investigates whether four-dimensional CT (4DCT)-based lung ventilation imaging can guide functional lung avoidance radiotherapy (FLAR) for patients with primary lung cancer. Ventilation maps generated from planning 4DCT are used to identify well-ventilated lung regions, enabling paired comparison between functional lung avoidance radiotherapy plans and conventional anatomic radiotherapy plans. The study aims to assess whether incorporating functional lung information into radiotherapy planning can reduce radiation exposure to well-ventilated lung while maintaining adequate tumor coverage, and to explore its relationship with radiation-induced lung injury. All analyses are based on existing clinical imaging, treatment planning data, and follow-up records. No additional interventions, imaging, or procedures are performed as part of this study.
Detailed description
This study retrospectively evaluates a functional lung-guided radiotherapy planning workflow based on four-dimensional CT (4DCT) ventilation imaging in patients with primary lung cancer who previously underwent thoracic radiotherapy. High-quality 4DCT datasets acquired during routine simulation are processed to generate voxel-based lung ventilation maps using deformable image registration and Jacobian-based computational methods. These ventilation maps are spatially registered to planning CT images and incorporated into the treatment planning system to delineate high-function lung subregions. For each eligible patient, paired radiotherapy plans are retrospectively generated and analyzed: a conventional anatomic radiotherapy plan and a functional lung avoidance radiotherapy (FLAR) plan that incorporates ventilation-defined avoidance structures. Both plans are optimized to achieve comparable target coverage while differing in lung avoidance strategy. Dosimetric and clinical data are obtained from existing treatment planning records and routine clinical follow-up to support comparative analyses of functional lung sparing and associated pulmonary outcomes. All analyses are conducted retrospectively using data derived from standard clinical care. No prospective enrollment, additional imaging, or study-specific interventions are performed.
Interventions
None listed
Sponsors
The Second Affiliated Hospital of Chongqing Medical University
Study design
Observational model
COHORT
Time perspective
RETROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
18 Years to 85 Years
Healthy volunteers
No
Inclusion criteria
* Histologically confirmed primary lung cancer (adenocarcinoma, squamous cell carcinoma, or small-cell carcinoma) treated with thoracic radiotherapy. * High-quality 4DCT scans performed before radiotherapy, enabling generation of ventilation or perfusion maps. * Radiotherapy plans designed using IMRT. * Availability of both functional lung avoidance plans and conventional anatomical radiotherapy plans for paired analysis. * Complete treatment and follow-up records, including radiation-induced lung injury (e.g., radiation pneumonitis) and pulmonary function tests.
Exclusion criteria
* Incomplete or poor-quality imaging data preventing accurate ventilation/perfusion map generation. * Radiotherapy interrupted or incomplete for any reason. * Severe underlying lung diseases (e.g., extensive emphysema, pulmonary fibrosis, active tuberculosis) that may confound treatment outcomes or toxicity assessment. * Presence of other untreated primary malignancies during the study period. * Prior lung surgery or local therapies (e.g., ablation) that may affect evaluation of radiation-induced lung injury. * Missing follow-up data, making assessment of radiation-induced lung injury or long-term lung function changes impossible.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Incidence of Radiation-Induced Lung Injury (Grade ≥2) | Assessed at 3 months, 6 months, and 12 months after completion of radiotherapy. | Incidence of radiation-induced lung injury (RILI) of Grade ≥ 2, assessed using the Common Terminology Criteria for Adverse Events (CTCAE), Version 5.0. CTCAE grades range from Grade 1 (mild) to Grade 5 (death related to adverse event), with higher grades indicating more severe toxicity. The primary outcome is the proportion of patients experiencing CTCAE Grade ≥ 2 RILI. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Mean Dose to High-Function Lung (Gy) | At baseline treatment planning (prior to radiotherapy delivery). | DVH-derived mean dose to ventilation-defined high-function lung on paired plans (functional-lung-avoidance vs conventional plans). Lower dose indicates better sparing. |
| MLD for Whole Lung (Gy) | At treatment planning (baseline, pre-radiotherapy delivery). | DVH-derived mean lung dose (MLD) for whole lung on paired plans; absolute values reported separately for functional-lung-avoidance vs conventional plans. |
| V5 of High-Function Lung (%) | At baseline treatment planning (prior to radiotherapy delivery). | Percentage volume (%) of ventilation-defined high-function lung receiving ≥5 Gy, reported separately for functional-lung-avoidance and conventional radiotherapy plans. |
| V20 of High-Function Lung | At baseline treatment planning (prior to radiotherapy delivery). | DVH-derived V20 of ventilation-defined high-function lung, defined as the percentage of lung volume receiving ≥20 Gy, compared between functional-lung-avoidance and conventional radiotherapy plans. |
| Mean Dose to Heart (Gy) | At treatment planning (baseline, pre-radiotherapy delivery). | DVH-derived mean dose (Dmean) to the heart, compared between functional-lung-avoidance and conventional radiotherapy plans. |
| Maximum Dose to Esophagus (Gy) | At treatment planning (baseline, pre-radiotherapy delivery). | DVH-derived maximum dose (Dmax) to the esophagus, compared between functional-lung-avoidance and conventional radiotherapy plans. |
| Maximum Dose to Spinal Cord (Gy) | At treatment planning (baseline, pre-radiotherapy delivery). | DVH-derived maximum dose (Dmax) to the spinal cord, compared between functional-lung-avoidance and conventional radiotherapy plans. |
| Target Coverage (PTV D95) | At treatment planning (baseline, pre-radiotherapy delivery). | Percentage of planning target volume (PTV) receiving at least 95% of prescribed dose, compared between functional-lung-avoidance and conventional plans. |
| Conformity Index of Radiotherapy Plans | At treatment planning (baseline, pre-radiotherapy delivery). | Conformity Index (CI) of paired treatment plans, comparing functional-lung-avoidance and conventional anatomic radiotherapy plans. The Conformity Index is defined as the ratio of the prescription isodose volume to the target volume (CI = V\<sub\>RI\</sub\> / V\<sub\>T\</sub\>). The score ranges from 1.0 to \>2.0, where a value closer to 1.0 indicates better conformity and thus higher plan quality. |
| Homogeneity Index of Radiotherapy Plans | At treatment planning (baseline, pre-radiotherapy delivery). | Homogeneity Index (HI) of paired treatment plans, comparing functional-lung-avoidance and conventional anatomic radiotherapy plans. The Homogeneity Index is defined as (D\<sub\>2%\</sub\> - D\<sub\>98%\</sub\>) / D\<sub\>50%\</sub\>. The score typically ranges from 0 to 1.0, where lower values indicate more homogeneous dose distribution and better plan quality. |
Countries
China
Outcome results
None listed