International Journal of Radiation Oncology Biology Physics最新文献

Purpose: To collect national data from medical physicists on work effort, challenges, and job satisfaction in HDR brachytherapy as a function of procedure complexity.

Methods: A survey was administered in cooperation with IROC-Houston. Question topics included demographics, practice patterns, caseload, procedure complexity, relative time and effort required for simple and complex cases, and challenges/satisfaction associated with HDR.

Results: Of 429 completed responses, 365 performed HDR. The most commonly treated anatomic sites were gynecologic, prostate, and skin with 56% of respondents' clinics performing interstitial procedures. Respondents indicated that the median time and intensity ratios of a single channel HDR, relative to a weekly chart check (CPT77336), were 5 and 3, respectively implying a work ratio of 15. When comparing the most complex procedure to a single-channel treatment, the median time and intensity ratios reported were both 5, implying a work ratio of 25. The time and intensity ratios scaled with increasing complexity for gyne procedures (i.e., 1, 2-3, and ≥4 channels). Most respondents reported that it was more stressful to cover HDR versus EBRT (82%) and to switch between services (73%). Job satisfaction was impacted most positively by direct patient contact and the experience level of authorized users but most negatively by increased stress compared to other services and maintaining skill levels due to infrequent cases. Only the subset of respondents at clinics treating complex gyne with a high caseload (≥25 patients/year) indicated that staff allocation was inadequate or that a colleague had left their position due to HDR.

Conclusion: The results show a relationship between work effort and procedure complexity, which is currently not addressed in national staffing recommendations. To sustain a workforce capable of supporting HDR into the future, it is important that professional societies/leaders recognize the stress and intensity of complex cases and adjust staffing recommendations accordingly.

Purpose/objective: To evaluate the impact of radiotherapy on sexual health in women with gynecological cancers.

Material/methods: A comprehensive search of PubMed, Cochrane CENTRAL, Embase, CINAHL, APA PsycInfo, Scopus, and Web of Science was conducted using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies published from 01/2000 to 08/2025 were screened using MeSH terms and keywords related to "gynecological cancer and radiotherapy and sexual health." Inclusion criteria required studies assessing the impact of radiotherapy on sexual health in women with endometrial, cervical, and vulvar cancers using validated patient-reported outcome (PRO) questionnaires with baseline data. Reviews and studies on ovarian cancer were excluded. Two independent reviewers (LH, IV) performed data extraction.

Results: Of 1,402 records identified, 1,049 were screened, 26 studies met the inclusion criteria, comprising a total of 5,646 patients. Eleven studies focused on cervical cancer, seven on endometrial cancer, and eight included mixed gynecologic malignancies. The majority were prospective in design (n = 25), with one retrospective study identified. Commonly used patient-reported outcome (PRO) instruments included the EORTC QLQ-C30, QLQ-CX24, FSFI, LENT-SOMA, and SAQ. Radiation was consistently associated with long-term sexual dysfunction, including vaginal dryness, dyspareunia, and diminished sexual satisfaction. While sexual activity declined following treatment, it improved over time and then stabilized. Regular vaginal dilation was associated with maintained vaginal length and enhanced sexual function but had no effect on vaginal elasticity. Psychological, social, and cultural factors also influenced outcomes.

Conclusion: Radiotherapy for gynecologic cancers has enduring adverse effects on sexual health, shaped by both physical and psychosocial dimensions. Interventions like vaginal dilation and nurse-led programs may help preserve vaginal health, though adherence is low and benefits modest. Future research should prioritize diverse, longitudinal studies with standardized PRO tools, while clinical care should incorporate sexual health counseling, early pelvic rehabilitation, and psychosocial support into survivorship programs.

Purpose: Currently, on-board kV imaging systems on proton therapy machines typically employ scintillator-based energy-integrating detectors (EIDs) to acquire planar images or cone-beam CT (CBCT) scans. However, EID-based CBCT is limited by suboptimal image quality and poor quantification accuracy, falling short of the requirements for online adaptive proton therapy and other advanced imaging tasks for proton therapy. This study aims to experimentally demonstrate the feasibility of on-board photon-counting detector (PCD) CT imaging by integrating a PCD with a proton therapy gantry Methods and Materials: A CdTe-based PCD, featuring a pixel size of 100 μm and two energy channels, was mounted onto the surface of the existing flat-panel EIDs of an IBA Proteus ONE proton therapy system. The PCD-CT scans followed the same acquisition protocol as the clinical EID-CBCT for head imaging. Geometric distortions were estimated and corrected during image reconstruction. To assess non-spectral image quality, standardized phantoms with known material compositions were scanned under matched x-ray exposure and beam width conditions. The resulting PCD-CT images were compared to EID-CBCT in terms of modulation transfer function (MTF) and contrast-to-noise ratio (CNR), defined based on 15 different material inserts from two physical phantoms. In addition, spectral PCD-CT data were used to estimate the electron density ratio of each material relative to water. The estimated values were then compared to reference values.

Results: Compared to the EID, the PCD exhibits significantly higher detective quantum efficiency, especially at high spatial frequencies. When the MTFs of PCD-CT and EID-CBCT were matched by adjusting the reconstruction kernel, PCD-CT consistently achieved higher CNR across all material inserts tested. For electron density ratios estimated from spectral PCD-CT, the mean absolute percent error was 1.8%.

Conclusions: The feasibility of gantry-mounted PCD tomographic imaging for proton therapy has been demonstrated for the first time. The PCD-CT prototype provides superior non-spectral image quality compared to conventional EID-CBCT. Additionally, its spectral imaging capability enables accurate estimation of electron density ratios.

Purpose: To assess the dosimetric impact to organs-at-risk (OARs) and target coverage of a small margin weekly adaptive treatment for glioblastoma delivered on an MR-linac.

Methods: The UNIty-Based MR-Linac Guided AdapTive RadiothErapy for High GraDe Glioma (UNITED) phase 2 prospective trial utilized a 5 mm CTV margin compared to conventional 1.5 to 3 cm CTV margins. Margin reduction was supported by weekly administration of gadolinium contrast and adaptation to gross tumor volume (GTV) changes using onboard MR imaging. In the present study, dosimetric data from 29 patients with UNITED plans (P_UNITED) treated with 60 Gy in 30 fractions were retrospectively re-planned with conventional margins (P_Conv) and compared. For each patient, six weekly adapted and one conventional margin non-adapted plan were included in the analysis. Relevant OAR dose metrics were compared using Friedman tests followed by Nemenyi post-hoc analysis (α=0.005, corrected for multiple comparisons).

Results: A substantial and statistically significant reduction in irradiated normal brain volume was achieved with the median V60Gy lowered from 146.3-157.3 cm³ (range of median weekly values) with P_Convto 84.2-93.4 cm³ for P_UNITED (p<0.0001). The median max dose to the brainstem and optic chiasm was reduced from 56.1 Gy to 49.0 Gy (p=0.0001) and from 41.5 Gy to 38.4 Gy (p<0.0001), respectively. In addition to OAR sparing, 10 of 29 patients experienced suboptimal target coverage when conventional margin dose distributions were applied to weekly adapted contours, with five patients showing consistent under-dosing and CTV D98% below 50 Gy, highlighting the importance of adaptation for maintaining target coverage.

Conclusions: The UNITED small margin weekly adaptive treatment protocol for glioblastoma improves OAR sparing and reduces the irradiated normal brain volume while maintaining consistent target coverage.

Purpose: Based on bioeffect modeling of published outcomes after radiation therapy for head and neck squamous cell carcinoma with various time-dose-fractionation, we hypothesized that a 20-fraction hypofractionated (HFX) schedule delivering 55 Gy in 20 fractions, 5 fractions per week, over 4 weeks would be noninferior to a 33-fraction accelerated, normofractionated (NFX) 2 Gy per fraction schedule, delivering 66 Gy in 2-Gy fractions, 6 fractions per week over 5.5 weeks with respect to both local tumor control and late adverse events.

Methods and materials: The HYPNO (HYPo-fractionated vs NOrmo-fractionated radiation therapy for head and neck squamous cell carcinoma) trial was designed as a multicenter, pragmatic, embedded, 2-arm, unblinded, randomized controlled noninferiority trial with dual primary endpoints, loco-regional tumor control, and grade 3 or higher late adverse events with a 10% noninferiority margin for both endpoints. The trial was open for enrollment in 12 centers, each adhering to their standard of care to the extent that it was consistent with the requirements of the trial protocol. Concurrent chemoradiation therapy with 35 mg/m² cisplatin weekly was permitted.

Results: Between March 2014 and February 2020, 792 patients were centrally randomized: 395 to HFX and 397 to NFX. Accrual closed, with all outcome data still blinded, with 792 of a planned 836 patients (94.7%) enrolled, in part due to the emerging COVID-19 pandemic. The HYPNO test arm passed the separate noninferiority tests for both loco-regional tumor control (P = .04) and grade 3+ late adverse events (P = .004). At 3 years, the absolute difference in outcome between the 2 arms was ≤1.4 percentage points for overall survival, progression-free survival, loco-regional control, and grade 3+ late adverse events. The planned subgroup analyses showed no statistically significant heterogeneity of effect estimates for loco-regional control between the 2 trial arms.

Conclusions: The HYPNO test arm schedule was shown to be noninferior with respect to both loco-regional tumor control and grade 3+ late adverse events.

Introduction: Radiation-induced pneumonitis (RP) is a side effect after thoracic radiotherapy (RT). The ability to predict RP would facilitate treatment modifications. This study investigates the predictive capacity for symptomatic RP (CTCAE≥2) employing Radiomics and Dosiomics models.

Methods: Computed tomography (CT) scans, along with physical and 2-Gy equivalent dose volumes (EQD2), dose-volume histograms (DVH), and clinical parameters, were evaluated for 708 multicenter lung cancer patients, among whom 89 developed RP≥2. The training cohort consisted of 441 patients from the prospective RTOG 0617 trial. External validation was carried out on 267 patients from the prospective REQUITE study. A Random Forest classifier was employed, with feature selection executed within the inner loop of a 10x5-fold nested cross-validation (nCV) utilizing the minimum-redundancy-maximum-relevance algorithm. To address class imbalances, synthetic oversampling and undersampling were implemented using SMOTE-Tomek. The QUANTEC Normal Tissue Complication Probability (NTCP) model served as a reference. Additionally, the experiments were stratified by subgroups (standard/high-dose and 3D-conformal RT (3D-CRT)/intensity-modulated RT (IMRT)).

Results: The best radiomics model identified in the nCV was trained on the standard-dose subgroup achieved a test ROC-AUC of 0.56. The baseline NTCP model showed a predictive performance with a ROC-AUC of 0.56, which was largely dependent on radiation technique (ROC-AUCS: 3D-CRT: 0.75, IMRT: 0.50). The Dosiomics_EQD2 model, trained on the full training cohort, attained the second-best performance in the nCV, demonstrating the same technique-dependence (ROC-AUC of 0.75 vs. 0.39). Using a Dosiomics_EQD2 ensemble model trained separately on 3D-CRT and IMRT subgroups increased overall performance to a testing ROC-AUC of 0.61, outperforming other modeling strategies for IMRT, while being outperformed by clinical models for 3D-CRT.

Conclusion: This prospective trial-based study reveals an overall limited predictive capacity of radiomics and dosiomics models and a large influence of radiation technique. IMRT-specific models should be investigated further.

Purpose: Intensity-modulated radiation therapy (IMRT) is increasingly used for total body irradiation (TBI) due to its ability to deliver myeloablative doses while sparing radiosensitive organs. To enable consistent evaluation in future National Clinical Trials Network (NCTN) studies, the xxx Hematologic Malignancies Working Group (HMWG) convened IMRT-TBI experts and NCTN leaders to develop consensus recommendations for standardized multi-institutional implementation.

Methods: A 47-question survey was distributed to NRG institutions utilizing IMRT-TBI to characterize current planning and delivery practices. Responses were analyzed for commonalities and variations. A multidisciplinary working group reviewed survey findings, developed consensus-based technical and clinical recommendations, and created a standardized template for IMRT-TBI integration into NCTN protocols. Topics included simulation, contouring, planning, organ-at-risk (OAR) constraints, quality assurance (QA), image-guided radiotherapy (IGRT), commissioning, credentialing, and safeguards for clinical trial conduct.

Results: Eight institutions with collective experience treating more than 750 patients with IMRT-TBI responded. Most centers used VMAT to the upper body with anteroposterior/posteroanterior (AP/PA) fields to the lower body, 3-9 isocenters, lower dose rates for lung fields (100-200 MU/min), and no physical bolus. Common OAR constraints included lungs mean dose <8 Gy, kidneys mean dose <6-8 Gy, and lenses maximum dose <90% of prescription. All respondents used auto-segmentation; 50% used auto-planning. QA practices varied, but patient-specific QA passing rates were high (>95% with 3%/2 mm gamma). Consensus recommendations for clinical trial use were established, including standardized PTV definitions, OAR sparing goals, dosimetric constraints, QA requirements, and credentialing processes.

Conclusions: IMRT-TBI offers the potential for reduced toxicity and improved dose precision compared with 2D-TBI, but its complexity requires careful standardization in multi-institutional trials. The xxx HMWG and collaborating NCTN experts developed the consensus-based technical and clinical framework for incorporating IMRT-TBI into cooperative group protocols. Adoption of these recommendations will facilitate consistent implementation and enable rigorous evaluation of outcomes.

Purpose: Radiation dose selection for neoadjuvant chemoradiotherapy (nCRT) in esophageal squamous cell carcinoma (ESCC) varies widely in clinical practice, and prospective randomized data addressing this question are lacking. This trial compared two commonly used radiation dose regimens in nCRT for resectable thoracic ESCC.

Methods: This single-center, phase II prospective randomized controlled trial enrolled patients with locally advanced thoracic ESCC from February 22, 2018 to February 22, 2021. Patient were randomized 1:1 to receive nCRT with either 50.4Gy/28F or 41.4Gy/23F, concurrent with weekly paclitaxel and carboplatin. The primary endpoint was 2-year progression free survival (PFS).

Results: A total of 147 patients were randomized (50.4 Gy, n=72; 41.4 Gy, n=75), of whom 101 underwent surgical resection., Pathological complete response occurred in 23 of 46 patients (50.0%) in the 50.4-Gy group and 18 of 55 patients (32.7%) in the 41.4-Gy group (p=0.078). Using major pathological response (MPR) as an alternative endpoint, the 50.4Gy/28F regimen significantly increased the MPR rate to 73.9%, compared to 52.7% in the low-dose group (p=0.029). In the intention-to-treat population analysis, the 2-year PFS rates were 56.7% for the high-dose group and 49.3% for the low-dose group, with a hazard ratio (HR) of 0.72 (95% CI: 0.46-1.11, p=0.14). Two-year OS rates were similar between groups. Grade ≥2 radiation esophagitis occurred more frequently in the 50.4-Gy group, while postoperative complication rates were comparable.

Conclusions: Dose escalation from 41.4 to 50.4 Gy in nCRT for resectable ESCC did not improve PFS or OS but was associated with a higher MPR rate and increased esophagitis. These findings support current evidence that routine dose escalation does not confer a survival advantage, while providing randomized ESCC-specific data to inform individualized treatment decisions.

Purpose: ¹⁷⁷Lu-based radiopharmaceutical therapy (RPT) has shown increasing promise in the treatment of neuroendocrine and metastatic prostate cancer. Delivering optimal radiation dose to tumors while minimizing dose to organs-at-risk (OAR) remains an unmet need due to significant patient-to-patient heterogeneity in treatment response, necessitating multiple snapshots of the in vivo activity distribution. Towards this goal, here we present a high temporal-resolution activity reconstruction method demonstrated on preclinical prostate cancer models.

Methods: Utilizing a priori knowledge of tumor locations from a pretherapy scan (e.g. PET/CT), we have developed a low-cost, sparse sensor network to reconstruct the real-time tumor and OAR activity in preclinical cancer models. The proposed system was successfully validated¹ with a small custom phantom filled with [¹⁷⁷Lu]Lu-PSMA-617 and (2) with 4 mice models, bearing varying numbers of tumors from two human prostate cancer cell lines (PC3-PIP, PC3-flu), to which [¹⁷⁷Lu]Lu-PSMA-617 RPT was administered. Uncollimated γ counts using the developed network were acquired outside of the mouse at 10 minutes post-injection (m.p.i), 6 hours, 12 hours, 24 hours, and 48 hours post-injection (h.p.i).

Results: The developed system's total tumor activity and percent injected activity per milliliter of tissue (%IA/mL) reconstruction in tumors, kidneys, and bladders is highly linear with the total tumor activity (R²=0.991) and %IA/mL (R²=0.994) from state-of-art small-animal SPECT. Acquisition and reconstruction were performed at a 1-minute temporal resolution, greater than 30 times faster than conventional small-animal SPECT imaging, allowing for the ability to capture fast kinetics at early timepoints and create close-to continuous time-activity curves at a fraction of the cost of small-animal SPECT systems.

Conclusions: The system can be used for high temporal resolution preclinical activity reconstruction, and motivates clinical adaptation in order to improve ¹⁷⁷Lu-based RPT quality and safety through frequent activity distribution measurements of multiple tumors and OAR.

Purpose: This study reports the safety and efficacy outcomes of a Phase II prospective trial evaluating stereotactic body radiation therapy (SBRT) to the prostate bed in patients with high-risk features following radical prostatectomy.

Methods: Between May 2018 and May 2020, 49 patients were enrolled and stratified into three groups based on clinical context: Group I (adjuvant SBRT, PSA <0.2 ng/mL with adverse features such as positive margins, seminal vesicle invasion, or extraprostatic extension), Group II (salvage SBRT, PSA ≥0.2 and <2.0 ng/mL), and Group III (oligometastatic disease, ≤5 sites). Patients with PSA ≥0.2 ng/mL underwent staging with C11 PET; those with biochemical failure following treatment were restaged with PSMA PET. All patients received SBRT to the prostate bed to a total dose of 30-32 Gy in five fractions administered every other day. Patients in the salvage and oligometastatic groups received 6 and 18 months of androgen deprivation therapy (ADT), respectively. The primary endpoint was freedom from failure (FFF), defined as a PSA <0.5 ng/mL without clinical progression or re-initiation of ADT. Secondary endpoints included FFF with a PSA <0.2 ng/mL, toxicity rates (graded per CTCAE v5.0), clinical failure, and FFF in early salvage patients (PSA 0.2-<0.5 ng/mL).

Results: The median follow-up was 60 months. High-risk features included extraprostatic extension in 49%, seminal vesicle invasion in 10%, positive margins in 55%, and Gleason score 8-10 in 22%; no patients had nodal involvement at surgery. The median PSA at enrollment was 0.35 ng/mL (0.11 for Group I, 0.42 for Group II, and 0.39 for Group III). SBRT was well tolerated, with only two (4.1%) cases of grade ≥2 toxicity (one case of hematuria in Group I and one of rectal bleeding in Group II); no significant adverse events were observed in Group III. 5-year freedom from failure (FFF) rate was 60.9% (95% CI: 48.3%-76.9%). Improved FFF was observed in early salvage patients, at 5-years it was 74.7% (95% CI: 62.7-89.0%); hazard ratio [HR]: 0.33; 95% CI: 0.04-3.17). Overall survival was 95.5% (95% CI: 89.7-100%) for all cases.

Conclusions: Stereotactic body radiation therapy (SBRT) to the prostate bed was feasible and associated with a low incidence of treatment-related toxicity over long-term follow-up. The observed freedom-from-failure outcomes-particularly among patients treated in the early-salvage setting-were promising and appear comparable to historical results from conventionally fractionated post-prostatectomy radiation therapy.