International Journal of Radiation Oncology Biology Physics最新文献

Purpose/objectives: Radiation therapy treatment planning hinges on a critical factor: the prescribed dose. Surprisingly, there is no consistent, standardized global approach to evaluating the dosimetry of this prescription across different centers treating head and neck cancer (HNC). This study aimed to quantify global dose variations for identical prescriptions across international centers treating oropharyngeal cancer, to establish the foundation for future outcome-based studies and improve consistency of interpretation worldwide.

Materials and methods: The study included patients with oropharyngeal cancer who were consecutively treated from 2017 onward with intensity-modulated radiation therapy or volumetric modulated arc therapy at 8 globally recognized radiation therapy departments. These centers were categorized into 4 categories: North American, North European, Oceanic, and Asian.

Results: The study included 1514 patients from 8 centers and revealed 40 different dose prescriptions, ranging from 55 Gy in 20 to 70 Gy in 35 fractions. When normalized to a 70 Gy prescription, the mean clinical target volume dose showed a 4% median difference across centers. European and Oceania centers deviated by 0.4%, whereas North American and Asian centers had 2% variability. Near-minimum clinical target volume doses (D_98%) ranged from 68.7 to 71.4 Gy.

Conclusions: The study underscores the wide-ranging implementation of dose prescriptions in HNC. The lack of a standardized global approach to HNC treatment dose prescription carries potential implications for patient care, collaborative research, and treatment de-escalation or radiation therapy dose-painting strategies. This study highlights the need for careful interpretation of dose prescription standards across international centers, to analyze radiation therapy outcomes more accurately in light of their varied implementation.

Purpose: The Spinal Instability in Neoplasia Score (SINS) is the gold standard to determine if the metastatically involved spine is stable, potentially unstable, or frankly unstable. In potentially unstable spines, clarity is needed about the risk of post-stereotactic body radiation therapy (SBRT) vertebral compression fracture (VCF) and which patients may benefit from early stabilization. We aimed to identify predictors of VCF following spine SBRT in patients with potentially unstable SINS spinal metastases..

Methods and materials: A retrospective review of a prospectively maintained database of patients treated with SBRT for spinal metastases from January 2008 to December 2022 was performed. This analysis included only spine segments categorized as potentially unstable (SINS 7-12). The primary outcome was the rate of VCF. The cumulative incidence of VCF and the impact of covariates were estimated.

Results: Five hundred twenty-four patients with 976 treated spinal segments were SINS potentially unstable. Out of 976, 168 patients (17.2%) experienced a VCF after SBRT. Out of 168, 107 patients (63.7%) were iatrogenic and 61 (36.3%) concurrent with tumor progression. The 12-month incidence of iatrogenic VCF was 9.3% (95% CI, 7.4%-11.5%) as opposed to 23.4% (95% CI, 17.4%-29.9%) when concurrent with tumor progression (P < .0001). Multivariable analysis confirmed iatrogenic VCF associated with pre-existing VCF (hazard ratios [HR] = 1.83; 95% CI, 1.235-2.714; P = .003), no previous spine surgery (HR = 1.67; 95% CI, 1.024-2.710; P = .040), SINS total ≥10 (HR = 1.68; 95% CI, 1.122-2.512; P = . 012), and an increasing D90 clinical target volume in equivalent dose in 2 Gy (HR = 1.03; 95% CI, 1.010-1.055; P = .004). In the setting of concurrent tumor progression, only an increasing D90 to the clinical target volume in equivalent dose in 2 Gy fractions (HR = 1.04; 95% CI, 1.013-1.076; P = .005) predicted for VCF.

Conclusions: Tumor control outweighs the risk of VCF associated with spine SBRT in potentially unstable metastases. Prophylactic stabilization could be considered in segments with a total SINS ranging from 10 to 12, a pre-existing VCF, and when treating with high doses.

Deformable dose mapping and accumulation are essential tools in lung cancer stereotactic body radiation therapy (SBRT). Here, we provide a critical review of deformable image registration (DIR)-based dose mapping and accumulation techniques in SBRT for lung cancers, with emphasis on methodological principles, clinical applications, limitations, and guidance for practice. A broad appraisal of the literature was conducted, emphasizing DIR algorithms and related dose mapping strategies, including direct dose mapping, voxel warping, and energy/mass-congruent mapping. These methods were examined across key clinical scenarios for lung SBRT planning, including motion management, adaptive radiation therapy and reirradiation. Significant errors can occur when anatomic changes are large, such as tumor regression, mass and density variations, etc., as observed in reirradiation scenarios. These errors will propagate to the mapped and composite dose distributions, particularly in steep dose gradients, resulting in inaccuracies. Biomechanical models combined with energy/mass-congruent mapping better preserve physical principles under such conditions. Quality assurance remains challenging due to the absence of standardized benchmarks. Tools for validation of DIR and deformable dose accumulation accuracy in the clinic are severely lacking. The development of quality assurance frameworks is critical to safe implementation. Clinicians should apply DIR-based dose accumulation conservatively, particularly when anatomy changes considerably in reirradiation settings, given the potential for significant uncertainties in the composite doses. Each clinical case should be viewed carefully by assessing the risk/benefit, and clinical application should follow cooperative group guidelines. Standardization of methods for dose accumulation will enhance dose-volume-effect modeling.