International Journal of Radiation Oncology Biology Physics最新文献

Purpose: There is limited evidence on quality-of-life (QoL) outcomes of stereotactic body radiation therapy (SBRT) compared with conventionally hypofractionated radiation therapy (CHRT) in patients with medically inoperable stage I (≤5 cm) non-small cell lung cancer (NSCLC).

Methods and materials: This phase 3 randomized trial was conducted across 16 Canadian centers, enrolling patients with medically inoperable stage I (≤5 cm) NSCLC. Participants were randomized in a 2:1 ratio to receive SBRT or CHRT. QoL was assessed over 2 years postrandomization using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 and the lung cancer-specific module 13 (LC-13), evaluating physical, symptom, functional, and social well-being. Differences in QoL between treatment groups at 2 weeks and 2 years were analyzed using linear mixed models, adjusting for baseline scores and stratification variables.

Results: Of the 233 patients, 154 received SBRT and 79 received CHRT. At 2 weeks, model estimated mean global health scores were higher in the SBRT group (68.93 vs 64.93), with an estimated mean difference of 4.00 (95% CI 3.12, 4.89, P < .01). At 24 months, global health scores were 59.96 for SBRT and 62.88 for CHRT, with a difference of -2.92, 95% CI: -3.73, -2.11, P < .01). Mean LC-13 symptom scores at 2 weeks were 15.70 for SBRT and 17.11 for CHRT, with a difference of -1.41 (95% CI: -1.87, -0.95, P < .01). Mean difference in LC-13 at 24 months was 0.14 (95% CI: -0.29, 0.57, P = .69).

Conclusions: SBRT offers modest benefit in acute QoL and similar benefit in long-term QoL compared with CHRT in patients with inoperable stage I NSCLC.

Purpose: This study evaluated the feasibility of a direct-to-unit stereotactic magnetic resonance imaging-guided adaptive radiation therapy (SMART) workflow for spine metastases.

Methods and materials: Ten patients with spinal metastases were prospectively enrolled. Preplans were created using diagnostic imaging, with patients proceeding directly to magnetic resonance imaging-guided adaptive treatment using online adaptation and bulk density override for dose calculation. Feasibility was defined as successful completion of the first fraction on the initial on-table attempt in ≥70% of patients. Toxicity, dosimetric outcomes, and clinical response were assessed.

Results: Delivery of first fraction on first attempt was successful 90% of the time. Of 36 total fractions, 10 required online adaptation. The median treatment time per fraction was 87 minutes. Acute toxicity was limited to grade 1 to 2 fatigue. At a median follow-up of 14 months, local control was 90% at 3 months and 67% at 6 months.

Conclusions: Direct-to-unit SMART is a feasible and safe approach for spine stereotactic body radiation therapy, allowing treatment without conventional simulation.

Purpose: Metachronous oligometastases may represent a favorable disease state for local therapy after prior curative treatment. Stereotactic Magnetic Resonance-Guided Adaptive Radiation Therapy (SMART) provides precise targeting of nodal and soft tissue metastases. The primary objective was to assess the feasibility and safety of SMART for abdominopelvic metachronous oligometastases. Secondary objectives included assessing rates of toxicities and evaluating local control (LC).

Methods and materials: Ten patients were enrolled with solid tumor metachronous abdominopelvic nodal or soft tissue metastases, ≤7 cm in maximal diameter, and ≤3 sites of active disease. All patients received 40 Gy in 5 fractions. Acute toxicities were graded per Common Terminology Criteria for Adverse Events v5 per-protocol follow-up over 1 year. Late toxicities and clinical outcomes were elucidated by chart review. LC, distant progression-free survival, and overall survival were analyzed using the Kaplan-Meier Method.

Results: Eight patients with prostate cancer and 2 with renal cell carcinoma were enrolled in the study. All patients were successfully treated with SMART per-protocol without complications. The median follow-up after SMART was 4.22 years. Three patients experienced acute grade 1 toxicities; there were no higher grade or late toxicities. Among these 10 patients, 4-year LC and overall survival were both 90%, and 4-year distant progression-free survival was 20%. Two patients (1 prostate cancer, 1 renal cell carcinoma) remain with no evidence of disease, each at over 4 years following SMART and without receiving further systemic or local therapies.

Conclusions: With 4 years median follow-up, this small prospective trial reports low toxicity, supporting the feasibility of SMART metastasis-directed therapy for metachronous oligometastases with minimal risk of acute or late toxicity.

Purpose: Functional magnetic resonance imaging (fMRI) localizes eloquent areas of the brain more accurately than structural imaging alone and minimizes the risk of neurosurgical injury. However, fMRI remains underutilized in stereotactic radiosurgery (SRS). We assessed the neuroanatomic relationship between SRS to brain metastases (BMs), nearby eloquent areas, identified using fMRI, and attributable symptoms of radionecrosis (RN). We then evaluated the advantage of a novel fMRI-guided SRS (fMRI-SRS) planning approach.

Methods and materials: Patients with an fMRI study within 3 months of SRS for BMs were included. The nearest eloquent area (NEA) was defined as the motor, language, or visual eloquent area on fMRI nearest to an irradiated BM. The primary outcome was focal symptomatic RN (FSRN), defined as radiographic RN with progressive neurologic symptoms localizable to the NEA. The relationship between dose to the NEA and risk of FSRN was assessed with logistic regression. Cases were replanned using fMRI-SRS, maximizing NEA avoidance while maintaining target coverage.

Results: Among 93 patients, 76 (82%) had resection prior to SRS. The most common SRS prescription was 30 Gy in 5 fractions. The NEA was a motor eloquent area in 71 cases (76%) and a language area in 18 cases (19%). Of 20 patients who developed radiographic RN, 4 (20%) were asymptomatic, 4 (20%) had nonlocalizable neurologic symptoms, and 12 (60%) had focal neurologic symptoms directly attributable to the NEA, consistent with FSRN. Among patients who received 5-fraction SRS with modern planning techniques, greater V14Gy (single-fraction equivalent) to the NEA predicted increased risk of FSRN at 18 months (odds ratio, 6.8/mL; P= .05). fMRI-SRS reduced NEA V14Gy in all cases replanned, with a mean reduction of 22.5%.

Conclusions: Focal neurologic symptoms of RN reflect SRS dose to nearby eloquent areas on fMRI. fMRI-SRS planning minimizes dose to eloquent areas without sacrificing target coverage and may mitigate neurologic toxicity.

Purpose: A combination of metastasis-directed ablative therapy and curative-intent treatment for oligometastatic breast cancer is an active area of research. We designed this prospective study to explore this approach in a homogenous population of patients with oligometastatic breast cancer with bone-only metastases.

Methods and materials: Patients with 1-5 bone-only metastases were included and received stereotactic body radiation therapy (SBRT) to the metastatic site, followed by curative-intent anthracycline and taxane-based chemotherapy and surgical excision of the primary tumor. Patients with vertebral metastases received SBRT as 30 Gy in 3 fractions over 3 days, and those with nonvertebral metastases received 24 Gy 2 two fractions over 2 days. Response assessment was done using PERCIST (PET response criteria in solid tumors). The study was designed to evaluate the progression-free survival (PFS), overall survival (OS), local control rate at the mestastatic site of SBRT, and impact of SBRT on pain control.

Results: Between June 2021 and April 2024, a total of 49 patients with a total of 84 metastatic sites were enrolled. After a median follow-up of 19.4 months (1.1-44.4 months), median PFS was 18.8 months (1.1-44.4 months; 95% CI, 26.512-36.349), whereas the 1- and 2-year PFS were 81.63% and 71.43%, respectively. Multivariate analysis for PFS revealed that patients who completed neoadjuvant chemotherapy (P = .05) and underwent surgical excision of the primary tumor (P = .02) experienced significantly improved PFS, and hormone receptor positivity approached significance (P = .07). The median OS for the entire cohort was 19.4 months (1.56-44.4 months), whereas the 1- and 2-year OS were 89% and 74%, respectively. Multivariate analysis for OS revealed significantly improved survival for patients completing neoadjuvant chemotherapy (P = .01), receiving locoregional radiation therapy (P = .038), and presence of vertebral metastasis (P = .038). With SBRT, a high proportion of patients (96.4%) experienced a reduction in their analgesic medication requirements. The median time to achieve a pain response was 2.3 months (IQR, 1.0-4.7 months). The treatment was well-tolerated, with no documented grade 3 to 4 toxicities reported throughout the follow-up period. The most frequently observed adverse event was a temporary exacerbation of pain, known as a pain flare, which occurred in 10.7% of the patient cohort.

Conclusions: Oligometastatic breast cancer is a very heterogeneous group of patients. This study demonstrates excellent outcomes in treatment-naïve, bone-only metastatic patients, emphasizing the need for patient selection. This finding underscores the critical importance of careful patient stratification and selection to achieve optimal therapeutic efficacy.

Purpose: Liver transplantation is the definitive treatment for hepatocellular carcinoma (HCC) in eligible patients with cirrhosis. Bridging liver-directed therapies are critical for maintaining transplant eligibility during long wait times. However, due to the fear of decompensation, many advanced cirrhotic patients are excluded from receiving liver-directed therapies. This prospective pilot clinical trial evaluated the feasibility, safety, and efficacy of stereotactic body radiation therapy (SBRT) as a bridging therapy in an advanced cirrhotic HCC population.

Methods and materials: HCC patients with Child-Pugh B8 or worse cirrhosis and eligible for liver transplant were enrolled. SBRT to 40 Gy in 5 fractions was delivered to a single HCC as a bridging strategy. The primary endpoint was the proportion of patients who were transplant eligible up to 1 year following SBRT. Secondary endpoints included disease control per modified Response Evaluation Criteria in Solid Tumors, proportion of patients that proceeded to transplant, incidence of nonclassical radiation-induced liver disease (RILD) within 1 week to 3 months after SBRT, and incidence of liver toxicity per Common Terminology Criteria for Adverse Events v5.0.

Results: Between 2019 and 2023, 9 patients with Child-Pugh B8 or worse cirrhosis were enrolled. Median follow-up was 11.2 months with a 22% death rate. Six patients (67%) were transplanted or remained transplant eligible 1 year after SBRT. Three patients (33%) failed to receive a liver transplantation: 2 due to factors unrelated to SBRT or tumor progression, and 1 patient experienced minimal tumor progression outside of Milan criteria. Per modified Response Evaluation Criteria in Solid Tumors, the local control rate was 100% and the incidence of intrahepatic and extrahepatic disease progression was 0%. Within 1 week to 3 months after SBRT, 1 patient (11%) experienced liver toxicity (Common Terminology Criteria for Adverse Events grade 4 acidosis, acute hepatic encephalopathy, and hepatic failure), but there were no instances of nonclassical RILD.

Conclusions: Bridging SBRT in patients with HCC and advanced cirrhosis may safely maintain transplant eligibility without increasing the risk of nonclassical RILD.

Purpose: In the early analysis of START-NEW-ERA phase 2 trial, SABR had optimal local control and promising overall survival without ≥G3 toxicity in patients with unresectable locally advanced non-small cell lung cancer (LA-NSCLC) unfit for concurrent chemoradiation therapy (ChT-RT). We report the 5-year outcomes with a focus on patterns of local recurrence (LR).

Methods and materials: SABR was delivered by volumetric-modulated arc therapy to the primary tumor and regional nodes based on positron emission tomography-computed tomography. When thoracic failures occurred, we matched the SABR planning with positron emission tomography-computed tomography images to accurately assess the LR location, precisely to determine in-field versus out-field recurrence, looking at the specific isodose line within which the LR occurred.

Results: Fifty patients with unresectable LA-NSCLC unfit for concurrent ChT-RT were enrolled. Median dose was 45 and 40 Gy in 5 daily fractions to tumor and regional nodes, respectively. After a median follow-up of 72 months (range, 10-108), the 3- and 5-year progression-free survival rates were 26% ± 6% and 26% ± 6%, respectively. The 3- and 5-year overall survival rates were 70% ± 6% and 46% ± 7%, respectively. No patients developed ≥G3 late toxicities. The 3- and 5-year LR-free survival rates were 64% ± 7% and 64% ± 7%, respectively. Multivariate analysis revealed squamous cell carcinoma (P = .016) and SABR dose <40 Gy (P = .044) as significant predictors of LR. Seventeen patients experienced LR; 14/17 had squamous cell carcinoma, and 13/17 had IIIA or IIIB. Tumors that recurred were all centrally or ultracentrally located. The LR was higher in patients receiving 35 Gy compared with those receiving at least 40 Gy (P = .037).

Conclusions: The 5-year outcomes of START-NEW-ERA trial confirm robust and sustained benefit in terms of safety and effectiveness of SABR in patients with LA-NSCLC unfit for concurrent ChT-RT.

Purpose: FLASH radiotherapy using high-energy X-rays combines ultra-high dose-rate irradiation with the physical characteristics of high-energy X-ray beams, achieving a significant reduction in normal tissue biological damage while maintaining sufficient tissue penetration, thereby presenting great potential for clinical translation. However, the absence of a traceable absolute dosimetry method for FLASH X-ray beams remains a substantial limitation to its clinical implementation. This study aims to establish a quasi-adiabatic water-controlled probe-type graphite calorimeter for the absolute measurement of absorbed dose to water in the 10 MV FLASH X-ray beam, to address the current lack of a traceable dosimetry standard for X-ray FLASH radiotherapy.

Methods and materials: A probe-type graphite calorimeter was developed, employing thermally stabilised water as the thermal control medium to precisely regulate the thermal equilibrium of the graphite core. This quasi-adiabatic system is designed to facilitate accurate absolute dose measurements under ultra-high dose rate conditions.

Results: The results indicate that for a single irradiation with a total dose exceeding 2 Gy, the mean Type A relative uncertainty, determined from five repeated measurements using the sample standard deviation, is less than 0.2%. By deriving the necessary correction factors for determining the absolute dose (i.e., in Gy) of FLASH photon radiotherapy, the uncertainty in water-absorbed dose measurement is determined to be 1.0% (1σ).

Conclusions: This study develops a probe-type graphite calorimeter for the absolute measurement of absorbed dose to water in 10 MV FLASH X-ray beams. The system is designed to address the current lack of a traceable dosimetric standard for X-ray FLASH radiotherapy, thereby supporting its clinical translation and application.

Purpose: To assess the impact of defacing-based deidentification techniques on reidentification risk and data utility across multimodal imaging in radiotherapy.

Materials and methods: We applied four defacing techniques: biometric_mask, quickshear, mri_reface, and Carina's deidentifier, to imaging from 88 brain patients (MRI, CT, and RTDose) and 97 head-and-neck (HN) patients (PET, CT, and RTDose) in The Cancer Imaging Archive (TCIA). Reidentification risk was assessed using ArcFace, a deep learning-based facial recognition model, by measuring cosine similarity scores and conducting receiver operating characteristic (ROC) analysis to distinguish between original and defaced images. Data integrity was evaluated by statistically comparing volume and image intensity changes between original and defaced images across nine critical organs and GTV.

Results: Quickshear provides the highest privacy protection, achieving the lowest AUC across imaging modalities (AUC: 0.61-0.74), followed by Carina (0.59-0.80). Mri_reface showed moderate protection (0.70-0.91), while biometric_mask offered the least (0.76-0.94). Carina preserved structure volumes, and mri_reface produced minor volumetric changes in the eyes (5%) and lens (9%). In contrast, biometric_mask substantially affected the mandible (39%) and oral cavity (69%), while quickshear significantly altered multiple structures (10.0%-86.6%). Median changes in mean CT intensity after defacing were -48.3% (IQR: 32%) with biometric_mask and -77.7% (IQR: 37.7%) with quickshear in the oral cavity. For eyes, Carina and mri_reface produced changes of +24.5% (IQR: 22.6%) and +54.9% (IQR: 66.1%), respectively. In the brain dataset, biometric_mask and quickshear decreased oral cavity D_mean by 0.72 Gy (IQR: 1.22) and 1.61 Gy (IQR: 2.84), respectively. Carina and mri_reface reduced Eyes D_max by 2.11 Gy (IQR: 3.44) and 1.05 Gy (IQR: 1.65), respectively. A similar trend was observed in the HN dataset with larger deviations.

Conclusions: Carina's deidentifier and mri_reface showed favorable privacy-utility trade-offs relative to facial removal; the optimal choice may vary by application priorities.

Background: Equitable access to high-quality cancer care depends on scalable, sustainable training initiatives, particularly in radiation oncology. This study evaluated whether gains in treatment planning competency, confidence, and knowledge among medical physicists were maintained two years after a virtual VMAT/IMRT training course.

Materials and methods: Medical physicists who completed a 15-week virtual training in 2022 were reassessed two years later via remote submission of a head and neck VMAT/IMRT plan, a multiple-choice knowledge test, and a confidence survey. Plan quality was assessed using automated scorecards (25-points) and expert rubrics (14-points), while knowledge and confidence were measured via surveys. Wilcoxon signed-rank tests compared pre-, post-, and follow-up outcomes. Effect sizes were calculated using Cohen's d.

Results: Nineteen of the 40 invited participants who had completed the prior post-course assignment (47.5%) enrolled in the follow-up study, representing 15 countries across four continents. Seventeen had complete data, defined as submitting pre-, post-, and follow-up responses for both objective and subjective assessments. Objective scores improved from 10.5/25 (±8.1) pre-training to 16.4/25 (±6.8) post-training and 18.6/25 (±6.4) at follow-up (p = 0.011 and p = 0.001), with no significant change from post-training to follow-up (p = 0.26). Subjective scores declined post-training (11.1/14 ± 5.9 to 8.5/14 ± 3.0; p = 0.021) but rebounded at follow-up (10.8/14 ± 3.4; p = 0.037), with no difference from baseline (p = 0.96). Among 18 participants with complete survey data, confidence improved from 3.18 ± 1.26 at baseline to 4.14 ± 0.95 post-training and was sustained at 4.12 ± 0.74 at follow-up, with a significant improvement from baseline to follow-up (p = 0.0023). Knowledge rose from 65.3% ± 29.9 at baseline to 83.3% ± 17.1 post-training and was sustained at 80.6% ± 20.2 at follow-up, with a significant improvement from baseline to follow-up (p = 0.026).

Conclusion: Remote VMAT/IMRT training led to lasting improvements in treatment planning, confidence, and knowledge, with objective scores continuing to rise over time. These findings support remote education as a sustainable model for building radiotherapy capacity in LMICs.