Background/Objectives: Lung cancer is the leading cause of cancer-related mortality worldwide. Accurate radiotherapy (RT) planning alongside chemotherapy and immunotherapy is critical for improving treatment outcomes for inoperable non-metastatic cases. Conventional computed tomography (CT)-based planning may be inadequate for accurately identifying tumor margins and the location of nodal disease. We investigated whether ¹⁸F-labeled fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET-CT) imaging can assist in target volume delineation for primary, nodal, and metastatic disease in the RT planning and overall therapeutic planning of patients. Methods: In this single-center, prospective study, we recruited 34 patients with histologically confirmed locally advanced non-small-cell lung carcinoma (NSCLC). All patients underwent ¹⁸F-FDG PET-CT-based RT simulation. Two sequential RT plans were created by the same radiation oncologist: one based on CT alone and the other PET-CT. Planning target volumes (PTVs) and PET-CT-guided adjustments were analyzed to assess their impact. Standardized protocols for immobilization, imaging, target delineation, and dose prescription were applied. Results: A total of 34 patients (31 males and 3 females) were recruited in the study. ¹⁸F-FDG PET-CT detected distant metastases in 7/34 (20.6%) patients, altering the overall therapeutic plan in 4/34 (11.8%) and allowing radical RT in 3 of them who had oligometastatic disease (8.8%). It modified RT planning in 26/34 (76.5%) patients and clarified malignancy in atelectatic areas. Nodal involvement was identified in 3/34 patients (8.8%) and excluded in 3/34 cases, avoiding unnecessary nodal irradiation. Additional involved nodes were revealed in 12/34 (35.3%) patients, requiring dose escalation. Overall, changes to the tumor PTV were made in 23/30 (76.6%) and to the nodal PTV in 19/30 (63.3%) cases (p < 0.0001). Primary tumor and nodal PTVs increased in 20/34 (66.7%) and 13/34 (43.3%), respectively. Conclusions: ¹⁸F-FDG PET-CT significantly improves RT planning by more precisely defining tumor and nodal volumes, identifying undetected lesions, and guiding dose adaptation. Larger long-term studies are required to confirm potential locoregional control and survival improvements.

Background/Objectives: Precise staging and tumor delineation are essential for optimizing treatment and enhancing outcomes of radiotherapy (RT). While computed tomography (CT)-based RT remains standard, fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) offers improved detection of primary and nodal disease. This study investigates the role of PET/CT in RT planning of HNSCC. Methods: Fifty-one HNSCC patients underwent radical volumetric modulated arc RT with concurrent cisplatin chemotherapy in a prospective study. Two RT plans per patient were sequentially created by a single oncologist using CT-only and PET/CT data, respectively. Planning target volumes (PTVs) for primary and nodal regions were independently defined, and dose–volume histograms were analyzed and compared. Results: PET/CT significantly affected TNM staging, increasing the T-stage in 11.8% of patients and the N-stage in 33.3%. Distant metastases were found in 9.8% of patients, leading to a redefinition of the overall treatment policy. PET/CT-based planning improved primary tumor PTV coverage (PTV4) in 37.2% (19/51) of cases. The tumor areas excluded from the CT-based planning received an average of 85.6% of the prescribed PTV4 dose (range 18–93%), while in PET/CT planning, they received 95.4% (range 93–99%) (p < 0.0001). Nodal PTV areas requiring a booster dose (PTV2) were adjusted in 33.3% (17/51) of patients during PET-CT planning. These nodal areas received an average of 85.6% of the prescribed dose for PTV2 (range 18–93%) during CT planning, compared to 95.4% (range 93–99%) during PET/CT planning. There was no statistically significant difference in the dose received by organs at risk between CT- and PET/CT-RT planning. Conclusions: PET/CT improves target delineation for primary tumors and lymph nodes, also allowing for dose escalation in metabolically highly active lesions in patients with HNSCC. The method also reveals occult distant metastases in a subset of patients, enabling personalized treatment strategies.

Radiotherapy (RT)-induced lymphopenia may hinder the anti-tumor immune response. Preoperative RT or chemo-RT (CRT) for locally advanced rectal cancer is a standard therapeutic approach, while immunotherapy has been approved for mismatch repair-deficient rectal tumors. We retrospectively analyzed 98 rectal adenocarcinoma patients undergoing neoadjuvant CRT with VMAT (groups A, B, C) or IMRT (group D) techniques, with four different RT schemes: group A (n = 24): 25 Gy/5 Gy/fraction plus a 0.2 Gy/fraction rectal tumor boost; group B (n = 22): 34 Gy/3.4 Gy/fraction, with a 1-week treatment break after the first five RT fractions; group C (n = 20): 46 Gy/2 Gy/fraction plus a 0.2 Gy/fraction rectal tumor boost; group D (n = 32): 45 Gy/1.8 Gy/fraction followed by 5.4 Gy/1.8 Gy/fraction to the rectal tumor. We examined the effect of the time-corrected normalized total dose (NTD-T) to the BM on lymphopenia. Groups A and B (hypofractionated RT) had significantly higher lymphocyte counts (LCs) after RT than groups C and D (p < 0.03). An inverse association between the LCs after RT and NTD-T was demonstrated (p = 0.01). An NTD-T threshold of 30 Gy delivered to 30% of the BM volume emerged as a potential constraint for RT planning, which could be successfully integrated in the RT plan. Hypofractionated and accelerated RT schemes, and BM-sparing techniques may reduce lymphocytic damage and prove critical for immuno-RT clinical trials.

Background/Objectives: This study aimed to investigate the prognostic value of advanced techniques of magnetic resonance imaging (MRI) biochemical recurrence (BCR) after radiotherapy in patients with prostate cancer (PCa). Methods: A comprehensive literature review was conducted to evaluate the role of MRI in detecting BCR of PCa patients after external beam radiation therapy. Results: National guidelines do not recommend imaging techniques in clinical follow-up PCa. However, in 2021, the European Association of Urogenital Radiology (ESUR), the European Association of Urological Imaging (ESUI), and the PI-RADS Steering Committee introduced the Prostate Imaging for Recurrence Reporting (PI-RR) system. PI-RR incorporates the MRI biomarkers in the post-treatment process. In the last decade, a growing number of clinical researchers have investigated the role of various MRI techniques in BCR. Conclusions: The integration of advanced MRI technologies into clinical routine marks the beginning of a new era of BCR with accuracy.

This study provides an accurate assessment of radiotherapy-induced tissue changes in prostate cancer when relying solely on serum prostate-specific antigen kinetics. The current study aims to explore the role of quantitative magnetic resonance imaging and radiomic analyses. In this exploratory prospective study, 22 patients with histologically confirmed prostate cancer underwent multiparametric magnetic resonance imaging at three time points: pre-treatment, mid-treatment, and two months post-radiotherapy. Quantitative imaging analysis included total prostate volume, T2, apparent diffusion coefficient—ADC, and T2* mapping, alongside T2-weighted and diffusion-weighted radiomic feature extraction. Longitudinal changes and dose correlations were analyzed using repeated-measures ANOVA and linear mixed-effects models. Prostate volume increased from 44.22 ± 21.26 cm³ at baseline to 51.11 ± 22.36 cm³ mid-treatment (p < 0.001) and decreased to 37.98 ± 15.5626 cm³ post-treatment (p = 0.034), indicative of temporary radiation-induced glandular edema. T2 relaxation times decreased from 106.00 ± 23.74 ms to 93.33 ± 9.50 ms after therapy (p = 0.023), with androgen deprivation therapy influencing overall values (partial η² = 0.228, p = 0.028), while ADC and T2* remained largely stable (p > 0.05). Radiomic features, particularly from DWI, exhibited subtle time- and dose-dependent variations. Radiation dose was significantly associated with volume and T2, but not with ADC or T2*. These findings suggest that quantitative MRI biomarkers combined with radiomic analysis may provide objective, non-invasive measures of early prostate cancer radiotherapy-induced changes. These imaging-derived metrics may capture early treatment-related tissue alterations and could provide exploratory signals for early treatment evaluation in prostate cancer, although their relationship with biochemical markers requires further validation.

Solitary fibrous tumors (SFTs) are rare mesenchymal neoplasms that typically arise from the pleura but may occur in various extrathoracic sites. Primary intraparenchymal pulmonary SFTs without pleural attachment are exceptionally uncommon and often pose diagnostic and therapeutic challenges. We report the case of a middle-aged female patient presenting with progressive dyspnea and a large mass in the left lower lobe on imaging. Computed tomography revealed a well-circumscribed, hypervascular mass occupying the left lower lobe. Bronchoscopic and percutaneous biopsies were nondiagnostic, and surgical resection was pursued. Intraoperatively, the tumor was found to arise from the lung parenchyma without pleural involvement. Histopathological examination demonstrated a spindle-cell neoplasm with the typical “patternless pattern,” and immunohistochemistry confirmed nuclear STAT6 positivity, establishing the diagnosis of SFT. The postoperative course was uneventful apart from a transient pulmonary embolism, which was successfully treated. The patient was discharged in good condition and is under regular radiologic surveillance. SFTs of the lung are rare and often mimic more common pulmonary tumors radiologically. Histologic confirmation with STAT6 immunohistochemistry is crucial for accurate diagnosis. Complete surgical excision remains the mainstay of treatment. Given the risk of late recurrence—especially in large tumors—long-term imaging follow-up is mandatory. This case highlights the importance of considering SFT in the differential diagnosis of large pulmonary masses, the critical role of STAT6-based histopathologic confirmation, and the necessity for prolonged surveillance even after complete resection.