Hrvoje Kaučić

Ultrahypofractionated whole-breast radiotherapy reduces treatment burden but increases the importance of accurate dose delivery at each fraction. This retrospective single-center study evaluated cone-beam computed tomography-guided online adaptive radiotherapy in 55 patients with early-stage breast cancer treated with 26 or 27 Gy in five fractions. Dosimetric analysis was available for 52 patients and 259 paired scheduled and adapted fractions. Linear mixed-effects models with a patient-specific random intercept were used to account for repeated fractions within individual patients. The adapted plan was selected for 242 out of 260 delivered fractions (93.1%). Mean planning target volume V95% increased from 93.52 ± 2.94% with the scheduled plan to 98.13 ± 1.04% with adaptation (p < 0.001), with reduced interfraction variability. Ipsilateral lung V30% increased modestly from 13.94% to 14.96% (p < 0.001). In left-sided cases, no significant differences were observed for heart V25% (1.400% vs. 1.395%; p = 0.3825) or left anterior descending coronary artery D0.03 cm³ (1.771 vs. 1.873 Gy; p = 0.1390). Acute grade 1 toxicity occurred in five patients (9.1%), with no grade ≥ 2 events. Mean treatment-session duration was 28 min. Online adaptation significantly improved daily target coverage and was technically feasible within a five-fraction whole-breast workflow. Acute toxicity was limited in this cohort, while longer follow-up and cumulative dose analyses are needed to further define its impact on organ-at-risk exposure and clinical outcomes.

Background/Objectives: Metastatic melanoma increasingly includes clinical scenarios in which metastasis-directed treatment may complement systemic immunotherapy, particularly in oligometastatic disease. We evaluated outcomes of stereotactic body radiotherapy (SBRT) combined with immunotherapy in patients with metastatic melanoma, focusing on local control, survival, treatment sequencing, and safety. Methods: In this retrospective single-center study, 63 patients underwent SBRT for 97 extracranial metastatic lesions while receiving immune checkpoint inhibitors. The primary endpoint was local control (LC), while secondary endpoints included progression-free survival (PFS), overall survival (OS), and treatment-related toxicity. Results: LC rates at 12, 24, and 36 months were 95.9%, 89.7%, and 89.7%, respectively, demonstrating durable long-term control of treated lesions. Median OS was 47 months, while median PFS was not reached. A numerical trend toward longer PFS was observed among patients receiving SBRT during immunotherapy, although the differences were not statistically significant. No significant differences in LC were identified across oligometastatic disease subcategories. Combined treatment was well tolerated, with predominantly low-grade toxicity and no signal of increased immune-related adverse events. Conclusions: SBRT combined with immunotherapy appears to be a feasible and effective metastasis-directed treatment strategy in selected patients with metastatic melanoma. Durable local control, encouraging survival outcomes, and favorable tolerability support further prospective studies to optimize treatment sequencing and the integration of local and systemic therapies.

Online adaptive radiotherapy mitigates errors in absorbed dose delivery due to daily anatomical changes during hypofractionated breast treatment, particularly when comprehensive nodal therapy includes the internal mammary chain. To illustrate this, we present a case of a 65-year-old woman with left-sided luminal B invasive carcinoma, who underwent segmentectomy and level 1–2 dissection. Pathology revealed an 18 × 15 × 13 mm primary tumor with lymphovascular invasion, two of eleven axillary nodes positive, and intramammary metastasis, staged pT1cN1a. She received adjuvant docetaxel–cyclophosphamide followed by letrozole. Hypofractionated radiotherapy (40 Gy in 15 fractions) was administered in an inspiration breath-hold setting using a CBCT-guided online-adaptive platform. Adaptive planning improved V95% coverage over the planned treatment for all targets: on average, whole breast coverage increased from 88.4% to 96.3%, supraclavicular from 93.0% to 97.1%, axilla from 90.6% to 96.7%, and internal mammary from 91.8% to 95.9%. Organ-at-risk metrics remained within limits: the mean heart dose increased slightly (from an average of 0.12 Gy in scheduled to 0.15 Gy in adaptive plans). At the same time, the LAD D0.03 cm³ decreased, and the heart V4 Gy fell modestly (from 13.3% in the scheduled plan to 8.2% in the adaptive plan), reflecting low-dose redistribution without exceeding constraints. Lung and thyroid mean doses remained comparable. The patient tolerated treatment well, with no acute toxicity or local recurrence. This case highlights the importance of daily adaptation for complex left-sided radiation treatment involving internal mammary nodes, demonstrating target recovery without exceeding absorbed dose constraints and supporting future studies on control, toxicity, and quality of life.

Background: The aim of this retrospective, single-arm study was to present the technique and preliminary efficacy and safety results of a single-fraction SBRT for LAPC using total intravenous anaesthesia and optical surface guidance as motion management. Methods: Fifty-five patients with locally advanced pancreatic cancer were treated with SBRT with a single-fraction receiving a median BED₁₀ = 128.9 Gy. Forty-two patients received systemic treatment. End points were OS, FFLP, PFS, and toxicity. Actuarial survival analysis and univariate analysis were investigated. Results: The median follow-up was 15 months, mean OS was 18 months (95% CI: 16.7 to 19.3), and the one-year FFLP and 1-year OS were 100% and 90.9% (95% CI: ± 1.5%), respectively. Median PFS was 12 months (95% CI: 9.5 to 14.4), and 1-year PFS was 85.5% (95% CI: ± 1.4%). Thirty-five patients (63.6%) were alive at the time of analysis. No acute/late toxicity > G2/G1 was reported. Conclusions: SBRT for LAPC using total intravenous anaesthesia and optical surface guidance presented as an effective and safe treatment with very low toxicity.

Background: The aim of this study was to present the technique and preliminary results of efficacy and safety for single-fraction SBRT for LAPC using Total Intravenous Anaesthesia and Optical Surface Guidance as motion management. Methods: Fifty-five patients were treated with SBRT in a single-fraction receiving median BED₁₀ = 128.9 Gy. Forty-two patients received systemic treatment. End points were OS, FFLP, PFS, and toxicity. Actuarial survival analysis and univariate analysis were investigated. Results: Median follow-up was 15 months. Mean OS was 26.7 months. One-year FFLP and 1-year OS were 100% and 90.9%, respectively. Median PFS was 18 months, and 1-year PFS was 85.5%. Thirty-five patients (63.6%) were alive at the time of analysis. No acute/late toxicity > G2/G1 was reported. Conclusions: SBRT for LAPC using Total Intravenous Anaesthesia and Optical Surface Guidance presented as an effective and safe treatment with very low toxicity.

We present a patient treated with personalized ultra-fractionated stereotactic adaptive radiotherapy (PULSAR) for non-small cell lung cancer (NSCLC) using the adaptive Varian Ethos™ system equipped with the novel HyperSight imaging platform. Three pulses of 12 Gy were separated by a pause of four weeks during which the tumor was given enough time to respond to treatment. Only initial planning computed tomography (CT) was acquired on a CT simulator (Siemens Somatom Definition Edge), whereas other pulses were adapted using online cone beam computed tomography (CBCT) images (iCBCT Acuros reconstruction) acquired while the patient was lying on the treatment couch and delivered immediately. Significant tumor reduction was achieved between pulses, resulting in improved organs-at-risk sparing. In addition, the on-couch plan optimization based on CBCT greatly reduced the patient’s stay at the clinic and the duration of treatment preparation.

Image-guided radiotherapy supported by surface guidance can help to track lower lung lesions’ respiratory motion while reducing a patient’s exposure to ionizing radiation. However, it is not always clear how the skin’s respiratory motion magnitude and its correlation with the lung lesion’s respiratory motion vary between different skin regions of interest (ROI). Four-dimensional computed tomography (4DCT) images provide information on both the skin and lung respiratory motion and are routinely acquired for the purpose of treatment planning in our institution. An analysis of 4DCT images for 57 patients treated in our institution has been conducted to provide information on the respiratory motion magnitudes of nine skin ROIs of the torso, a tracking structure (TS) representing a lower lung lobe lesion, as well as the respiratory motion correlations between the nine ROIs and the TS. The effects of gender and the adipose tissue volume and distribution on these correlations and magnitudes have been analyzed. Significant differences between the ROIs in both the respiratory motion magnitudes and their correlations with the TS have been detected. An overall negative correlation between the ROI respiratory magnitudes and the adipose tissue has been detected for ROIs with rib cage support. A weak to moderate negative correlation between the adipose tissue volume and ROI-to-TS respiratory correlations has been detected for upper thorax ROIs. The respiratory magnitudes in regions without rib support tend to be larger for men than for women, but no differences in the ROI-to-TS correlation between sexes have been detected. The described findings should be considered when choosing skin surrogates for lower lung lesion motion management.

Image-guided radiotherapy supported by surface guidance can help track lower lung lesion respiratory motion while reducing a patient’s exposure to ionizing radiation. However, it is not always clear how skin respiratory motion magnitudes and correlations with lung lesion respiratory motion vary between different skin regions of interest (ROI). Four-dimensional Computed Tomography (4DCT) images provide information on both skin and lung respiratory motion and are routinely acquired for the purpose of treatment planning in our institution. Analysis of 4DCT images for 57 patients treated in our institution has been conducted to provide information on respiratory motion magnitudes of nine skin ROIs of the torso, a tracking structure (TS) representing lower lung lobe lesion, as well as respiratory motion correlations between nine ROIs and TS. The effects of gender and adipose tissue volume and distribution on these correlations and magnitudes have been analyzed. Significant differences between ROIs in both respiratory motion magnitudes and correlations to TS have been detected. An overall negative correlation between ROI respiratory magnitudes and the adipose tissue has been detected for ROIs with rib cage support. A weak to moderate negative correlation between adipose tissue volume and ROI-to-TS respiratory correlations has been detected for upper thorax ROIs. Respiratory magnitudes in regions without rib support tended to be larger for men than for women, but no differences in ROI-to-TS correlation between sexes have been detected. Described findings should be considered when choosing skin surrogates for lower lung lesion motion management.

Delivering focused radiation doses via linear accelerators is a crucial component of stereotactic radiosurgery (SRS) for brain metastases. The Varian Edge linear accelerator provides highly conformal radiation therapy through a high-definition multi-leaf collimator (HD120 MLC) and conical collimator (CC). HD120 MLC adapts to the shape of the target volume using movable tungsten leaves, while CC has a block of conical shape (cones). CC in SRS treatments of small brain metastases is preferred due to its mechanical stability and steeper dose fall-off, potentially sparing organs at risk (OARs) and the brain better than HD120 MLC. This study aims to determine if CC offers significant advantages over HD120 MLC for SRS treatments. For 116 metastatic lesions, CC and HD120 MLC treatment plans were created in Varian Eclipse TPS and compared based on various dose parameters, robustness tests, and QA measurements. The results indicate that CC provides no significant advantages over HD120 MLC, except for slight, clinically insignificant benefits in brain sparing and dose fall-off for the smallest lesions. HD120 MLC outperforms CC in almost every aspect, making it a better choice for irradiating brain metastases with 0.1 cm³ or higher volumes.

Purpose: To assess the efficacy and safety of stereotactic body radiotherapy for patients with unresectable, locally advanced pancreatic cancer using Optical Surface Management System – AlignRT (OSMS-AlignRT) as an optical body surface motion management in deep breath hold. Patients and Methods: Forty-five patients diagnosed with locally advanced pancreatic cancer were treated with stereotactic body radiotherapy in 3 or 5 fractions, and received varying BED₁₀ (median 79.5 Gy) from April 2017 to December 2020. All patients were treated in deep breath hold with OSMS-AlignRT used as optical body surface motion management. Thirty-three patients received systemic treatment before and/or after stereotactic body radiotherapy, and twelve patients received no systemic treatment. In this retrospective, observational, single-arm study, primary endpoints were overall survival and freedom from local progression (ie, local control). Secondary endpoints were progression-free survival and toxicity. Actuarial survival analysis and univariate analysis were investigated. Results: Data from forty-five patients were analyzed. Median follow-up was 15 months. One-year freedom from local progression and survival were 95.5% and 71.1%, respectively. Median progression-free survival was 14 months. Median overall survival from diagnosis for all patients was 17 months, and 19 months for patients alive at the time of analysis. No patient had >G2 toxicity. Conclusion: Stereotactic body radiotherapy for locally advanced pancreatic cancer using OSMS-AlignRT as optical body surface motion management in deep breath hold patients is an effective and safe local treatment option, with no >G2 toxicity, and could be a promising therapeutic option with acceptable toxicity, either as a single treatment or in a multimodal regimen. OSMS-AlignRT provided accurate and reliable body surface motion management during stereotactic body radiotherapy.