Precision Radiation Oncology最新文献

Background: This study aimed to evaluate the differences between simultaneous integrated boost whole-brain radiotherapy (SIB-WBRT) and brain metastases local irradiation efficacy, and determine predictors of outcomes for lung cancer brain metastases patients in therapy.

Methods: This retrospective analysis evaluated patients with brain metastases treated with SIB-WBRT (whole brain at 40 Gy/20 fractions, tumor boosted to 56-60 Gy/20 fractions) and localized irradiation (prescribed doses ranging from 20-60 Gy over 2-25 fractions, typically administered as 30 Gy/5 fractions, with a biologically effective dose [BED] of 28-100.8 Gy) at PUMCH between September 2015 and December 2021. The primary outcome was intracranial progression-free survival (iPFS), with secondary outcomes encompassing overall survival (OS), development of new intracranial lesions, and tumor control. Propensity score matching was employed to compare the two retrospective groups. Survival curves for iPFS, OS, new intracranial lesions, and tumor control were generated and estimated using the Kaplan-Meier approach. Cox proportional hazards modeling was applied to examine the relationships between pertinent variables and clinical outcomes.

Results: After Propensity score matching, 59 patients were enrolled in each group (SIB-WBRT and local irradiation), with a total of 118 patients included in the analysis. No significant difference was observed between the 2 groups in iPFS (HR = 0.8, 95%CI: 0.4-1.3, P = 0.288), OS (HR = 1.1, 95%CI: 0.7-1.8, P = 0.653), or incidence of intracranial new lesions (HR = 0.6, 95%CI: 0.4-1.2, P = 0.144). However, a statistically significant difference was noted in local control time between the groups, with local irradiation brain metastases being superior (HR = 0.4, 95% CI: 0.2-0.8, P = 0.005). Tumor volume and other factors were related to local control.

Conclusion: Compared to local irradiation, SIB-WBRT did not significantly improve iPFS in patients with brain metastases. Compared to SIB-WBRT, local irradiation improved local control. Tumor volume and other factors may be associated with local control.

Background and purpose: Current evidence is insufficient to define the value of thoracic radiotherapy (TRT) following chemoimmunotherapy (CT-IO) in extensive-stage small-cell lung cancer (ES-SCLC). We aimed to ascertain whether incorporating immunotherapy (IO) could improve survival and explore the efficacy of TRT in combination with CT-IO among patients with ES-SCLC.

Methods: Clinical data were retrospectively analyzed. Patients were classified into two groups: IO and chemoradiotherapy (CRT). Within the IO group, we further defined two subgroups: CT-IO and chemoradioimmunotherapy (CRT-IO) groups.

Results: A total of 206 patients were enrolled in this study. The median overall survival was 22.2 months in the CRT-IO group, which was longer than the 16.0 months observed in the CT-IO group (P = 0.002) and 19.0 months noted in the CRT group (P = 0.208). The objective response rate (ORR) in the CRT-IO group (69.8%) was better than that in the CT-IO (68.9 %, P = 0.929) and CRT (59.3 %, P = 0.227) groups.

Conclusions: Considering the trend toward prolonged survival and a higher ORR in the CRT-IO group, TRT may be feasible in IO era. Considering the economic factors and physical conditions, CRT may be an option for patients with ES-SCLC.

Purpose: To evaluate the impact of different aperture shape controller (ASC) stratification strategies on the dosimetric quality and treatment efficiency of HyperArc plans for intracranial oligometastases.

Methods: This retrospective study analyzed 17 patients with 1-3 intracranial oligometastases. For each patient, the HyperArc plans were reoptimized using six ASC strength settings (off, very low, low, moderate, high, and very high). Evaluations encompassed planning target volume (PTV) and organ at risk (OAR) dosimetric parameters (Paddick Conformity Index [Paddick CI], Gradient Index [GI], D_2cm, OAR D_max/D_mean, Gamma passing rate), and treatment efficiency parameters (monitor units [MUs], segment number [SN], Modulation Complexity Score [MCS], Average Leaf Trajectory [ALT], and aperture irregularity [AI]).

Results: No statistically significant differences were observed in the PTV and OAR dosimetric parameters or gamma passing rates among the ASC strategy groups (p > 0.05), indicating a minimal impact of the ASC on plan dosimetric quality. In addition, SN, MCS, and ALT demonstrated no significant intergroup differences (p > 0.05). However, AI improved with moderate and high ASC strength. Critically, the total MUs differed significantly among the groups (F = 2.904, p < 0.05), with high ASC strength causing significantly lower MUs than ASC-off (p < 0.05), suggesting enhanced treatment efficiency.

Conclusions: ASC stratification strategies do not significantly compromise plan dosimetric quality in HyperArc treatment for intracranial oligometastases; however, these can markedly optimize treatment efficiency, particularly by reducing MUs. Considering both plan complexity and treatment efficiency, a moderate or high ASC strength is recommended to maintain high-quality radiotherapy while improving workflow efficiency.

Purpose: To quantify the detrimental impact of respiratory motion on the critical "peak-and-valley" dose distribution in lattice radiotherapy (LRT) for liver tumors, to thereby evaluate the necessity of motion management.

Methods: This study assessed the data of 24 patients with liver cancer who underwent free-breathing 4D-CT simulation, for which a 2×2×2 vertices LRT tree was constructed. Volumetric Modulated Arc Therapy (VMAT) plans were generated based on the results of free-breathing CT. The delivered dose distribution under respiratory motion was then simulated by dividing the planned dose into 10 equal subcomponents, applying phase-specific isocenter shifts derived from 4D-CT displacement measurements, and summing the deformed doses. The metrics analyzed included the vertex dose deviation, valley-to-peak dose ratio (VPDR), and low-dose bath volumes.

Results: The analysis revealed a mean 3D respiratory motion error of 8.59 mm, with predominant displacement in the superior-inferior (SI) direction (6.78±3.15 mm). Respiratory motion significantly degraded the LRT dose distributions; specifically, the vertices mean dose (D_mean) decreased from 50.19 Gy to 42.26 Gy, while the maximum dose (D_max) from 58.94 Gy to 52.63 Gy. Crucially, the VPDR increased in all directions, with the most pronounced increase observed in the SI direction (0.14±0.04 to 0.18±0.06, representing a 28.6% increase), escalating exponentially when motion error exceeded 8 mm. Increases in the left-right (LR) (0.41 to 0.44, increasing 7.3%) and antero-posterior (AP) (0.41 to 0.45, increasing 9.8%) directions were comparatively smaller. The motion also paradoxically altered the low-dose regions; while the absolute V_40%, V_20%, and V_10% volumes decreased by approximately 10 cm³ in the delivered plan, normalization to match the prescription coverage revealed significant increases in these volumes (minimum increases: V_40% by 3.59 cm³, V_20% by 15.85 cm³ and V_10% by 92.29 cm³).

Conclusion: Respiratory motion severely degrades essential spatial fractionation during liver LRT, particularly when exceeding 8 mm and occurring predominantly in the SI direction. This motion reduces peak vertex doses, increases the VPDR (homogenizing the dose distribution), and disrupts the low-dose bath volumes critical for normal tissue sparing and the bystander effect.

Objective: Spatially fractionated radiation therapy (SFRT) and stereotactic core ablative radiation therapy (SCART), two novel radiotherapy techniques, have demonstrated distinct advantages in the treatment of large-volume tumors. Both approaches allow precise delivery of high-dose radiation to the tumor core while sparing surrounding organs at risk. The objective of this study is to evaluate the efficacy and safety of these two techniques for the treatment of bone metastases accompanied by soft tissue formation.

Method: Patients with bone metastases accompanied by soft tissue formation will be recruited and assigned to the control or experimental groups. The control group will receive conventional radiotherapy (CRT) with 30 Gy delivered in 10 fractions, while the experimental group will undergo tumor core irradiation using SFRT or SCART with a single dose of 8-12 Gy, followed by whole-bone metastatic lesion radiotherapy with 25-40 Gy delivered in 5 fractions. The primary endpoint is the objective response rate, and secondary endpoints include the pain relief, safety, and local control rates.

Discussion: This study evaluates the efficacy and tolerability of using SFRT/SCART for treating bone metastases with soft tissue formation, with the expectation of improving local tumor control and reducing treatment-related toxicities.

Trial registration: The study was registered at ClinicalTrials.gov with the Identifier: NCT06987370 (Registered May 16, 2025).

Sinonasal teratocarcinosarcoma (SNTCS) is a rare and aggressive malignant tumor that is difficult to diagnose and lacks a standard therapeutic strategies. Here, we report a case of SNTCS harboring a SMARCA4 deletion and a CTNNB1 mutation. Following incomplete surgical resection, the patient received synchronous postoperative chemotherapy with tomotherapy (TOMO) radiation and achieved a complete response lasting for > 47 months with tolerated side effects. This case suggests that SMARCA4 deletion and CTNNB1 mutation may be key molecular events in the development of SNTCS, potentially providing valuable clues for its diagnosis. Moreover, to the best of our knowledge, this is the first case demonstrating that TOMO technology can be a beneficial option for SNTCS radiotherapy.

Purpose: This study aimed to improve the accuracy of the tumor radiotherapy dose and reduce the irradiation dose to the surrounding organs, by developing a versatile respiratory motion monitoring system with multi-scenario applications to enhance the clinical efficacy of radiotherapy for thoracic and abdominal tumors.

Methods: The respiratory motion monitoring system comprised an airbag structure integrated with a parallel-plate capacitive sensor. The airbag comprised a polymer balloon encapsulated in a nonelastic flexible membrane, and had a projected area of 120 mm × 120 mm. The capacitive sensor adopts a concentric configuration of beryllium copper (thickness: 0.1 mm, diameter: 10 mm) and oxygen-free copper (thickness: 1 mm, diameter: 10 mm) foils. Real-time monitoring of the respiratory motion was achieved by detecting the capacitance variations corresponding to changes in the internal air pressure within the airbag. The system performance was rigorously evaluated using a dynamic thorax phantom capable of simulating various patterns, including sinusoidal and fourth-power cosine waveforms.

Results: The capacitive sensor-based respiratory motion monitoring system demonstrated a displacement measurement range of up to 10 mm, capable of detecting movements as small as 0.1 mm (signal-to-noise ratio: 2.18). Real-time displacement conversion was performed using the fitted model y = ax+bx ³ (a = 26.105 ± 0.398, b = 285.868 ± 22.147). The system exhibited a high stability, with a standard deviation of only 0.0011 in capacitance measurements over 10 repeated tests with a 5 mm amplitude sinusoidal waveform, and further maintained the amplitude consistency within 2.25%-96.05% of the maximum value throughout 10 min of continuous operation. A reliable performance was confirmed across various respiratory waveforms, including sinusoidal and fourth-power cosine profiles. Furthermore, the non-metallic airbag structure enhances the adaptability to multiple clinical scenarios. However, two types of signal distortions were observed, originating from the airbag deformation and the limitations of the capacitive sensor electrode, both of which are thoroughly explained in the manuscript.

Conclusion: Overall, this study developed a capacitive sensor and airbag-based respiratory monitoring system that combines the advantages of abdominal pressure belts with infrared-based monitoring technologies. This integrated approach offers a cost-effective, structurally simple, and versatile solution for monitoring respiratory motion across multiple clinical scenarios.

Background: Ultra-high dose rate radiotherapy (typically defined >40 Gy/s) has shown promise for enhanced normal tissue sparing while maintaining tumor control, termed the FLASH effect when this biological response is observed. However, precise dose rate control remains a technical challenge in proton therapy systems, particularly for research applications investigating dose rate effects.

Purpose: To develop and validate a passive beam modulation technique using tungsten scatterers for controllable dose rate adjustment in a synchrotron-based proton therapy beamline without modifying accelerator parameters.

Methods: We investigated dose rate modulation using tungsten foils of varying thicknesses (0.1-3.5 mm) positioned upstream in an 87.2 MeV experimental proton beamline. Monte Carlo simulations using Geant4 were performed to model the dose rate variation as a function of the tungsten scatter's thickness. Experimental validation was conducted using an Advanced Markus ionization chamber for dose rate measurements and EBT-XD radiochromic films for lateral dose profile analysis. Five tungsten thicknesses were tested with full-spill deliveries (∼1400 monitor units (MUs), and ∼100 milliseconds (ms) pulse width).

Results: An inverse exponential relationship between dose rate and scatterer thickness was observed, with measured dose rates ranging from 288.9±0.7 Gy/s (0.1 mm tungsten) to 10.2±0.2 Gy/s (3.5 mm tungsten). Experimental measurements validated the accuracy of Monte Carlo predictions at the standard condition (1400 MU delivered in 100 ms) by falling within the 95% confidence intervals. Lateral beam profiles demonstrated progressive broadening with increased scatterer thickness, and the film measurements showed good agreements with Monte Carlo simulation (<2% difference at beam center).

Conclusions: Tungsten scatterer thickness modulation provides a practical, controllable method for dose rate adjustment spanning conventional to FLASH regimes. This passive approach enables precise dose rate control for preclinical radiobiological research without requiring modifications of accelerator structure and parameters.

Purpose: To characterize the newly released GafChromic^TM EBT4 film for transit dose measurement in high-dose rate brachytherapy (HDR-BT) surface applicators and to systematically investigate the relationship between transit dose and ¹⁹²Ir source activity.

Methods: EBT4 film was used to measure dose at 3 mm depth from a horizontally oriented Leipzig-style surface applicator connected to a ¹⁹²Ir HDR-BT remote afterloading unit. Transit dose was systematically characterized across eight different source activities ranging from 3.372 to 9.716 Ci (13,724 U to 39,544 U) using measurements with seven nominal dwell times (5-100 seconds, scaled to 10 Ci (40,700 U)). Transit dose was derived from linear extrapolation to zero dwell time and compared with dose calculated (10-Ci source with 100-s nominal dwell time, excluding transit contributions) using the treatment planning system (TPS) Eclipse (Version 16.1).

Results: EBT4 film demonstrated excellent dose-response linearity with nominal dwell time (adjusted R² > 0.99) across all source activities, confirming its suitability for transit dose measurement. Transit dose contributions ranged from 0.3% to 4.3% of TPS dose (100-s nominal dwell time at 10 Ci), with maximum contribution from the 9.543 Ci source (0.225±0.040 Gy) and minimum from the 5.502 Ci source (0.017±0.025 Gy). Transit dose showed poor linear correlation with source activity (adjusted R² = 0.497), indicating that factors beyond source activity influence transit dose magnitude.

Conclusions: This study validates EBT4 film as a reliable tool for transit dose measurement in surface brachytherapy. The observed non-linear relationship between transit dose and source activity reveals the critical influence of experimental setup variables, particularly source guide tube geometry, which affects the source-to-target distance during transit. These findings demonstrate that transit dose is impacted by multiple interdependent factors including source activity, guide tube configuration, and setup geometry. For clinical applications, this highlights the importance of standardized setup protocols and empirical measurement for accurate transit dose assessment.