Functional imaging-based assessment of TCP and NTCP in proton FLASH radiotherapy(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2026年第6期
- Page:
- 701-709
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- Functional imaging-based assessment of TCP and NTCP in proton FLASH radiotherapy
- Author(s):
- SHEN Shucheng1; 2; LI Mengyao2; SUN Song1; 2; WANG Ruozheng3; DAI Tianyuan2; YIN Yong2
- 1. Graduate School, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan 250117, China 2. Department of Radiation Physics and Technology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan 250117, China 3. Department of Radiation Oncology, Affiliated Tumor Hospital of Xinjiang Medical University, Urumuqi 830000, China
- Keywords:
- FLASH radiotherapy proton radiotherapy tumor control probability normal tissue complication probability oxygen depletion
- PACS:
- R318；R811.1
- DOI:
- DOI:10.3969/j.issn.1005-202X.2026.06.001
- Abstract:
- Abstract: Objective To develop an FMISO (Fluoromisonidazole)-PET functional imaging-guided framework for assessing tumor control probability (TCP) and normal tissue complication probability (NTCP) in proton FLASH radiotherapy, thereby providing a quantitative basis for efficacy prediction and clinical decision-making. Methods A FLASH effect evaluation model was established based on oxygen depletion kinetics to calculate the voxel-level FLASH sparing effect (FSE) factor under varying oxygen partial pressures (pO2) and dose rates. An SUV-pO2 mapping model was utilized to convert FMISO-PET uptake values into voxel-wise pO2 distributions. The FLASH physical dose (DFLASH) was converted to the equivalent dose at conventional dose rate (Deq) using the FSE, and further converted to the equivalent dose in 2 Gy. The generalized equivalent uniform dose was employed to integrate the biological dose distributions of target volumes and organs-at-risk for quantitative assessment of TCP and NTCP. The proposed framework was applied to non-small cell lung cancer (NSCLC) patients to predict the TCP and the risk of radiation pneumonitis (CTCAE grade≥2). Results (1) The FSE exhibited distinct oxygen dependence, reaching approximately 1.9 in well-oxygenated normal tissues (pO2≈40 mmHg) but close to 1.0 in hypoxic tumor tissues, demonstrating a significant differential response. (2) Under FLASH radiotherapy conditions (>40 Gy/s), NTCP was reduced by approximately 83% relative to conventional dose rates, while the reduction in TCP was not significant, resulting in wider therapeutic window. (3) Validation in two NSCLC patients showed that under FLASH conditions, the tumor TCP decreased by 1% to 21%. Regarding normal tissue sparing, the peripheral NSCLC case exhibited a relative reduction of approximately 83% in ipsilateral lung NTCP. For the central NSCLC case, the relative reductions were approximately 88% for the ipsilateral lung NTCP and 87% for the cardiac NTCP. The FLASH sparing benefit was more pronounced in central NSCLC owing to the larger irradiated volume of normal tissues. Conclusion The proposed method enables quantification of the FLASH effect and its integration with clinical prediction models, providing a feasible framework for the biological effect assessment and personalized optimization for proton FLASH radiotherapy.
Last Update: 2026-06-26