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Updated: May 16, 2025
Dynamic Lung Tumor Tracking for Stereotactic Ablative Body Radiation Therapy
Published on: June 7, 2015
Proton stereotactic centralized ablative radiation therapy for treating bulky tumor: a treatment plan study
Tengxiang Li1,2, Xinsen Yao3, Ruimin He1,4
1School of Nuclear Science and Technology, University of South China, Hengyang, China.
Objective:
Stereotactic centralized/core ablative radiation therapy (SCART) is a novel radiotherapy approach. This study investigates the potential benefits of proton-based SCART (pSCART) by leveraging the dosimetric advantages of protons and integrating them with the SCART technique.
Methods:
Five clinical cases previously treated with conventional proton therapy were selected for this study. The pSCART plans utilized a relative biological effectiveness (RBE) prescription dose of 24 Gy (RBE) × 3 fractions, with each plan consisting of three to five fields. The prescribed dose for the CyberKnife SCART was the highest value meeting the organs-at-risk (OARs) dose limits and the tumor edge dose limits. The dose distributions of the CyberKnife-based SCART and pSCART plans were compared using five criteria: i) prescription dose; ii) 80% prescription dose volume, targets coverage at 80% and 20% dose levels, and the 80%/20% ratio; iii) volume receiving >5 Gy outside the tumor edge; iv) dose tolerance limits to OARs; and v) mean dose to OARs.
Results:
pSCART can deliver a higher prescription dose of 24 Gy × 3 fractions versus SCART's 15 Gy × 2-3 fractions or 18 Gy × 2 fractions. Specifically, pSCART outperforms SCART in terms of the 80% prescription dose volume and 80% dose level coverage of stereotactic centralized/core target volumes (SCTV) achieving 69.77%-100.00% versus SCART's 43.6%-99.5%. The 20% dose level coverage for gross target volume (GTV) is slightly lower for pSCART, achieving 88.96%-98.64% versus SCART's 90.1%-99.9%. The maximum point dose outside the target volume is lower for pSCART at 4.58-6.19 Gy versus SCART's 4.78-6.67 Gy; additionally, the V5Gy at the tumor edge is significantly smaller for pSCART at 5.93-23.72 cm3 versus SCART's 6.85-151.66 cm3. The average dose to most OARs in the pSCART plan is lower than in the SCART plan.
Conclusions:
This work provides initial insights into evaluating treatment plans for bulky tumors using pSCART. Compared to the CyberKnife SCART, pSCART generates significantly higher prescription doses and larger high-dose regions within the GTV while delivering lower doses at the tumor edge, enhancing normal tissue sparing.
