Planning Target Research Articles

Hypofractionated versus Conventional Postmastectomy Irradiation for Breast Cancer: Comparison of Acute Skin Toxicity.

Breast cancer is the leading cause of cancer mortality among women. Radiotherapy can reduce recurrence and prolong survival of patients accepting breast-conserving surgery (BCS). This study aims to compare acute skin reactions in patients receiving hypofractionated versus conventional radiotherapy at a single institution and to summarize the relevant influencing factors. This study analyzed 152 patients who underwent either hypofractionated or conventional whole-breast irradiation (WBI) after BCS. Acute skin toxicity was assessed according to the Radiation Therapy Oncology Group (RTOG) criteria. Predictive factors for acute skin toxicity were identified using multivariate analysis and visualized using a forest spot. Grade 0 reactions occurred in 75.34% vs 70.89%, grade 1 in 16.44% vs 15.19%, grade 2 in 8.22% vs 12.66%, and grade 3 in 0% vs 1.27% of patients receiving hypofractionated and conventional WBI, respectively. There was no statistically significant difference in acute skin reaction in patients treated with hypofractionated radiation compared with conventional radiation (P = 0.62). Multivariate analysis revealed that metastatic lymph nodes (P = 0.021), whole-breast planning target volume (PTV-WB) (P < 0.001), and tumor bed planning target volume (PTV-TB) (P = 0.002) were significantly correlated with higher rates of acute skin toxicity. Hypofractionated WBI demonstrated similar acute skin adverse reactions compared to conventional WBI. These findings indicate that hypofractionated radiotherapy offers comparable tolerance, equivalent curative effect, convenience, andeconomic benefits, supporting its clinicalpromotion.

Ultrahypofractionation in postoperative radiotherapy for breast cancer: A single-institution retrospective cohort series.

The 'FAST-forward', study published in April 2020, demonstrated the effectiveness of an extremely hypofractionated radiotherapy schedule, delivering the total radiation dose in five sessions over the course of 1 week. We share our department's experience regarding patients treated with this regimen in real-world clinical settings, detailing outcomes related to short-term toxicity and efficacy. A descriptive observational study was conducted on 160 patients diagnosed with breast cancer. Between July 2020 and December 2021, patients underwent conservative surgery followed by a regimen of 26 Gy administered in five daily fractions. The median age was 64 years (range: 43-83), with 82 patients (51.3%) treated for left-sided breast cancer, 77 patients (48.1%) for right-sided breast cancer, and 1 instance (0.6%) of bilateral breast cancer. Of these, 66 patients had pT1c (41.3%), 70.6% were infiltrative ductal carcinomas, and 11.3% were ductal carcinoma insitu. Most tumours exhibited intermediate grade (41.9%), were hormone receptor positive (81.3%), had low Ki-67 (Ki-67 < 20%; 51.9%) and were Her 2 negative (85%). The majority of surgical margins were negative (99.4%). Among the patients, 72.5% received hormonotherapy, and 23.8% received chemotherapy. Additionally, 26 patients (16.3%) received an additional tumour boost following whole breast irradiation (WHBI) of 10 Gy administered in five sessions of 2 Gy over a week. The median planning target volume (PTV) was 899 cm3 (range: 110-2509 cm3). Early toxicity was primarily grade I radiodermatitis, affecting 117 patients (73.1%). During a median follow-up of 15 months (range: 3.9-28.77), only one patient experienced a local relapse, which required mastectomy. The implementation of this highly hypofractionated regimen in early-stage breast cancer appears feasible and demonstrates minimal early toxicity. However, a more extended follow-up duration would be required to evaluate long-term toxicity and efficacy accurately.

Philosophical and practical understanding of the quality of medical education in the Russian Federation: analysis of the opinions of students and practicing doctors

Introduction. The transformation of higher medical education, caused by the rapid development of medical technologies and growing social demands on the healthcare system, requires research into students’ ideas about quality education, their assessments and expectations, since students’ understanding of the learning process can have a significant impact on the development of student motivation and medical professionalism. The purpose of the study is to analyze the current system of higher medical education in the Russian Federation based on survey data from senior students, residents, and practicing doctors. Materials and methods. The survey involved 350 respondents (senior students, residents, practicing physicians) mainly from Moscow medical higher education institutions. Statistical analysis was carried out using the software StatTech v. 3.0.4. Methods of mathematical statistics: U-Mann-Whitney, Kruskal-Wallis, χ2 -Pearson tests. Results. It was revealed that only 52% of respondents consider the amount of theoretical knowledge acquired at a higher education institution under a specialty program to be sufficient. Students and graduates of the pediatric faculty more often consider the amount of theoretical training sufficient compared to respondents from the medical and dental faculties (p &lt; 0.001). Only half of the respondents are satisfied with the quality of the education received. Students and graduates of the Faculty of Pediatrics more often stated that they use the knowledge and skills acquired during practical training in their professional activities (p &lt; 0.001). Students and graduates of medical faculties of non-core Moscow universities and Russian National Research Medical University named after N.I. Pirogov are most satisfied with the amount of theoretical knowledge received within the framework of the specialty program compared to students and graduates of other higher education institutions (p &lt; 0.001). Conclusion. The results of this study may be valuable for government agencies that determine strategies for the development of higher medical education in Russia, as well as for university leaders who plan targets for the development of educational activities with an emphasis on involving students in the educational process.

Survival outcomes and failure patterns for oropharyngeal cancers treated with simultaneous integrated boost in intensity modulated radiotherapy (SIB-IMRT) and concurrent chemotherapy.

Intensity modulated radiotherapy (IMRT) has become a standard radiotherapy treatment delivery option owing to the advantages it offers in terms of target coverage and organ sparing. Furthermore, the ability to introduce different fractionation for different targets lets us deliver higher doses to the high-risk areas and lower doses to the elective volumes at the same sitting, referred to as simultaneous integrated boost (SIB). In the current study, we intended to retrospectively analyze the clinical outcomes and patterns of the failure of oropharyngeal cancers treated with SIB-IMRT and concurrent chemotherapy at our centre and analyze the factors contributing to poorer outcomes. Data of oropharyngeal cancer patients treated with SIB-IMRT and concurrent chemotherapy were retrieved from the institutional database. Patient demographic details, histopathological features, staging, treatment details, failure patterns and outcomes were documented. All potential factors were evaluated for outcomes. Radiation was delivered by using the SIB-IMRT technique. High-risk planning target volume (PTV) received 66 Gy in 2.2 Gy/fraction, intermediate and low-risk PTV received 60 Gy and 54 Gy, respectively. Primary endpoint was to assess local control (LC), regional control (RC) and loco-regional control (LRC) rates and secondary end point was to evaluate the survival outcomes - overall survival (OS) and cancer-specific mortality. All survival analyzes were performed using the Kaplan-Meier method. A total of 169 cases were included in the final analysis. The median age was 55 years (range 20-78) with 95.3% males. The base of tongue was the most common primary site. Around 54% cases were node negative with 38% patients having stage IV disease. The local control rates for N0 vs. N+ cases were 74.1 vs. 62.3% (P = 0.046), respectively. Similarly, the 4-year RC rates for N0 vs. N+ cases were 94.4 vs. 83.5% (P = 0.024), respectively. On multivariate analysis, only 4-year RC rates showed significant difference between the two (P = 0.039). No differences were found between T stages in LRC and OS. The 4-year LRC rates for stages 1, 2 vs. 3, 4 were non-significant (69.2 vs. 66.3%; P = 0.178). The 4-year OS rate was 81.3%. The 4-year LC and LRC rates were 67.8 and 89.5%, respectively. There were 54 local and 17 regional failures. The median time to failure was 13 months (range 3.6-82.9). SIB-IMRT provides comparable outcomes for oropharyngeal cancers. OS and loco-regional recurrences were significantly worse for nodal positive disease.

Dosimetric impact of respiratory motion on proximal bronchial tree during lung cancer stereotactic body radiation therapy: A patient-specific phantom study

IntroductionThe respiratory motion of the proximal bronchial tree (PBT) adjacent to the tumor is not taken into consideration in the treatment plan, and there is a risk that the PBT may be irradiated with a higher dose. Therefore, this study aimed to measure the PBT dose directly using patient-specific phantoms of patients treated with SBRT for a centrally located lung tumor and to determine the dose variation with the respiratory motion of the PBT. Materials and methodsThis study included 10 patients who received SBRT for central lung tumors. We utilized patient-specific tumor phantoms fabricated with a three-dimensional printer using the patient's computed tomography (CT) data to analyze the dose variation in PBT owing to respiratory motion. Two SBRT plans were generated: a full-phase plan and a 30−70 gating plan. Dose measurements were performed using glass dosimeters. We measured the dose three times for each plan, with the phantom either in motion or fixed at the 50% phase. ResultsWe analyzed the target volumes and measured doses for each SBRT plan. Compared with the gross tumor volume on the 50% phase CT image, the internal target volume was larger by approximately 13.1% and 45.9% during the 30−70% phase and full phases CT images, respectively. Similarly, the planning target volumes increased by 9.3% and 34.4%, respectively. The average variations in the measured dose of the glass dosimeter owing to patient-specific motion were 3.85% for the full-phase plans and 1.92% for the 30−70 gating plans. ConclusionRespiratory motion can affect the absorbed dose of the PBT, and this effect is particularly pronounced when the PBT is near the tumor. The gating method reduces the degree of dose variation. This study highlights the importance of understanding the respiratory motion of the PBT in SBRT for centrally located lung tumors.

Predicting treatment response in multicenter non-small cell lung cancer patients based on federated learning

BackgroundMulticenter non-small cell lung cancer (NSCLC) patient data is information-rich. However, its direct integration becomes exceptionally challenging due to constraints involving different healthcare organizations and regulations. Traditional centralized machine learning methods require centralizing these sensitive medical data for training, posing risks of patient privacy leakage and data security issues. In this context, federated learning (FL) has attracted much attention as a distributed machine learning framework. It effectively addresses this contradiction by preserving data locally, conducting local model training, and aggregating model parameters. This approach enables the utilization of multicenter data with maximum benefit while ensuring privacy safeguards. Based on pre-radiotherapy planning target volume images of NSCLC patients, a multicenter treatment response prediction model is designed by FL for predicting the probability of remission of NSCLC patients. This approach ensures medical data privacy, high prediction accuracy and computing efficiency, offering valuable insights for clinical decision-making.MethodsWe retrospectively collected CT images from 245 NSCLC patients undergoing chemotherapy and radiotherapy (CRT) in four Chinese hospitals. In a simulation environment, we compared the performance of the centralized deep learning (DL) model with that of the FL model using data from two sites. Additionally, due to the unavailability of data from one hospital, we established a real-world FL model using data from three sites. Assessments were conducted using measures such as accuracy, receiver operating characteristic curve, and confusion matrices.ResultsThe model’s prediction performance obtained using FL methods outperforms that of traditional centralized learning methods. In the comparative experiment, the DL model achieves an AUC of 0.718/0.695, while the FL model demonstrates an AUC of 0.725/0.689, with real-world FL model achieving an AUC of 0.698/0.672.ConclusionsWe demonstrate that the performance of a FL predictive model, developed by combining convolutional neural networks (CNNs) with data from multiple medical centers, is comparable to that of a traditional DL model obtained through centralized training. It can efficiently predict CRT treatment response in NSCLC patients while preserving privacy.

Simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) combined with nimotuzumab for locally advanced esophageal squamous cell carcinoma (ESCC): A phase II clinical trial

ObjectiveTo evaluate the feasibility, safety and efficacy of concurrent simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) combined with nimotuzumab in the treatment of locally advanced esophageal squamous cell cancer (ESCC).MethodsEligible patients were histologically proven to have locally advanced ESCC, and were unable to tolerate or refuse concurrent chemoradiotherapy (CCRT). Enrolled patients underwent concurrent SIB-IMRT in combination with nimotuzumab. SIB-IMRT: For the planning target volume of clinical target volume (PTV-C), the prescription dose was 50.4 Gy/28fractions, 1.8 Gy/fraction, 5fractions/week, concurrently, the planning target volume of gross tumor (PTV-G) undergone an integrated boost therapy, with a prescription dose of 63 Gy/28fractions, 2.25 Gy/fraction, 5 fractions/week. Nimotuzumab was administered concurrently with radiotherapy, 200 mg/time, on D1, 8, 15, 22, 29, and 36, with a total accumulation of 1200 mg through intravenous infusion. The primary endpoint of the study was the safety and efficacy of the combined treatment regimen, and the secondary endpoints were 1-year, 2-year, and 3-year local control and survival outcomes.Results(1) From December 2018 to August 2021, 35 patients with stage II-IVA ESCC were enrolled and 34 patients completed the full course of radiotherapy and the intravenous infusion of full-dose nimotuzumab. The overall completion rate of the protocol was 97.1%. (2) No grade 4–5 adverse events occurred in the entire group. The most common treatment-related toxicity was acute radiation esophagitis, with a total incidence of 68.6% (24/35). The incidence of grade 2 and 3 acute esophagitis was 25.7% (9/35) and 17.1% (6/35), respectively. The incidence of acute radiation pneumonitis was 8.6% (3/35), including one case each of Grades 1, 2, and 3 pneumonitis. Adverse events in other systems included decreased blood cells, hypoalbuminemia, electrolyte disturbances, and skin rash. Among these patients, five experienced grade 3 electrolyte disturbances during the treatment period (three with grade 3 hyponatremia and two with grade 3 hypokalemia). (3) Efficacy: The overall CR rate was 22.8%, PR rate was 71.4%, ORR rate was 94.2%, and DCR rate was 97.1%.(4) Local control and survival: The 1-, 2-, and 3-year local control (LC) rate, progression-free survival(PFS) rate, and overall survival(OS) rate for the entire group were 85.5%, 75.4%, and 64.9%; 65.7%, 54.1%, and 49.6%; and 77.1%, 62.9%, and 54.5%, respectively.ConclusionsThe combination of SIB-IMRT and nimotuzumab for locally advanced esophageal cancer demonstrated good feasibility, safety and efficacy. It offered potential benefits in local control and survival. Acute radiation esophagitis was the primary treatment-related toxicity, which is clinically manageable. This comprehensive treatment approach is worthy of further clinical exploration (ChiCTR1900027936).

Clinical effects of re-evaluating a lung SBRT failure mode and effects analysis in a radiotherapy department.

The increasing complexity of radiation treatments can hinder its clinical success. This study aimed to better understand evolving risks by re-evaluating a Failure Mode and Effects Analysis (FMEA) in lung SBRT. An experienced multidisciplinary team conducted an FMEA and made a reassessment 3years later. A process map was developed with potential failure modes (FMs) identified. High-risk FMs and their possible causes and corrective actions were determined. The initial FMEA analysis was compared to gain a deeper perspective. We identified 232 FMs. The high-risk processes were plan approval, target contouring, and patient evaluation. The corrective measures were based on stricter standardization of plan approval, pre-planning peer review, and a supporting pretreatment checklist, which substantially reduced the risk priority number in the revised FMEA. In the FMEA reassessment, we observed that the increased complexity and number of patients receiving lung SBRT conditioned a more substantial presence of human factors and communication errors as causal conditions and a potential wrong dose as a final effect. Conducting a lung SBRT FMEA analysis has identified high-risk conditions that have been effectively mitigated in an FMEA reanalysis. Plan approval has shown to be a weak link in the process. The increasing complexity of treatments and patient numbers have shifted causal factors toward human failure and communication errors. The potential of a wrong dose as a final effect augments in this scenario. We propose that digital and artificial intelligence options are needed to mitigate potential errors in high-complexity and high-risk RT scenarios.

Preoperative radiosurgery for brain metastases (PREOP-1): A feasibility trial

PurposePreoperative radiosurgery (SRS) of brain metastases (BM) aims to achieve cavity local control with a reduction in leptomeningeal relapse (LMD) and without additional radionecrosis compared to postoperative SRS. We present the final results of a prospective feasibility trial of linac-based stereotactic radiosurgery (SRS) prior to neurosurgical resection of a brain metastasis (PREOP-1). MethodsEligibility criteria included a BM up to 4 cm in diameter for elective resection. The primary endpoint was the feasibility of delivering linac-based preoperative SRS in all patients prior to anticipated gross tumour resection. Secondary endpoints included rates of LMD, local control and overall survival. Exploratory endpoints were the level of expression of immunological and proliferative markers. ResultsThirteen patients of median age 65 years (range 41–77) were recruited. Twelve patients (92 %) received preoperative radiosurgery and metastasectomy and one patient went directly to surgery and received postoperative SRS, thus the primary endpoint was not met. The median time between referral and preoperative SRS was 6.5 working days (1–10) and from SRS to neurosurgery was 1 day (0–5). The median prescribed dose was 16 Gy (14–19) to a median planning target volume of 12.7 cm3 (5.9–26.1). Five patients completed 12-month follow-up after preoperative SRS without local recurrence or leptomeningeal disease. The patient who received postoperative FSRT developed LMD after six months. There was one transient toxicity (grade 2 alopecia) and nine patients have died from extracranial causes. Patients reported significant improvement in motor weakness at 6 months (P = 0.04). No pattern in changes of marker expression was observed. ConclusionIn patients with large brain metastasis without raised intracranial pressure, linac-based preoperative SRS was feasible in 12/13 patients and safe in 12/12 patients without any surgical delay or intracranial complications.

Comparative Analysis of Recurrent Glioblastoma Target Contours via 11C-Methionine, 68Ga-Prostate-Specific Membrane Antigen Positron Emission Tomography, and Magnetic Resonance Imaging: Implications for Precision Radiotherapy Planning

PurposeGlioblastoma (GBM) recurrence poses challenges in radiotherapy treatment planning as reirradiation has limited leeway needing for precise target delineation. Though effective radiotracers are emerging for treatment planning, comparisons of 11C-methionine positron emission tomography (MET-PET), 68Ga-prostate-specific membrane antigen PET (PSMA-PET), and magnetic resonance imaging (MRI) for contouring recurrent GBMs are lacking in the literature. This case study aims to highlight the differences and similarities in target contours delineated from three examinations, aiming to raise doubts about the adequacy of current radiotherapy planning practices. Methods and MaterialsA 37-year-old female patient with recurrent IDH1/2 wild-type GBM underwent MRI, MET-PET, and PSMA-PET scans. Target delineations were performed, and volumes were compared using the Dice Similarity Coefficient (DSC), Conformity Index (CI), and Overlap Volume (OV), considering different planning target volume (PTV) margins. ResultsWe found that MET-PET and MRI volumes showed superior agreement compared to PSMA-PET across all similarity parameters, indicating a more marked discrepancy between PSMA-PET and other modalities. Increasing PTV margins demonstrated progressive convergence in inter-volume discrepancies. Notably, PSMA-PET delineated larger volumes extending beyond MRI-based volumes. ConclusionsThus, MRI alone may not suffice for target delineation in recurrent GBMs. PET imaging modalities offer complementary insights. Combined PET-MRI guidance could improve tumor boundary detection in target delineation for reirradiation. Prospective trials are necessary to ascertain its impact on patient outcomes.

Stereotactic Radiosurgery with Volumetric Modulated Arc Radiotherapy: Final Results of a Multi-arm Phase I Trial (DESTROY-2)

AimsTo present the final results of a phase I trial on stereotactic radiosurgery (SRS) delivered using volumetric modulated arc therapy (VMAT) in patients with primary or metastatic tumors in different extracranial sites. Materials and methodsThe DESTROY-2 trial, planned as a prospective dose escalation study in oligometastatic (one to five lesions) cancer patients relied on the delivery of a single high dose of radiation utilizing high-precision technology. The primary study endpoint was the definition of the maximum tolerated dose (MTD) of SRS-VMAT. The secondary objectives of the study were the evaluation of safety, efficacy, and long-term outcomes. All patients consecutively observed at our radiotherapy unit matching the inclusion criteria were enrolled. Each enrolled subject was included in a different phase I study arm, depending on the tumor site and the disease stage (lung, liver, bone, other), and sequentially assigned to a particular dose level. ResultsTwo hundred twenty seven lesions in 164 consecutive patients (male/female: 97/67, median age: 68 years; range: 29–92) were treated. The main primary tumors were: prostate cancer (60 patients), colorectal cancer (47 patients), and breast cancer (39 patients). The maximum planned dose level was achieved in all study arms, and the MTD was not exceeded. 34 Gy, 32 Gy, 24 Gy, and 24 Gy were established as the single-fraction doses for treating lung, liver, bone, and other extracranial lesions, respectively. The prescribed BED 2Gyα/β:10 to the planning target volume ranged from 26.4 Gy to 149.6 Gy. Twenty-seven patients (16.5%) experienced grade 1–2 and only one grade 3 acute toxicity, which was a pulmonary one. In terms of late toxicity, we registered only 5 toxicity>G2: a G3 gastro-intestinal one, three G3 bone toxicity, and a G3 laryngeal toxicity. The overall response was available for 199 lesions: 107 complete response (53.8%), 50 partial response (25.1%), and 31 stable disease (15.6%), leading to an overall response rate of 94.5%. Progression was registered only in 11 cases (5.5%). The overall response rate in each arm ranged from 88.6% to 96.4%. The overall two-year local control, distant metastasis free survival, disease free survival, and overall survival were 81.7%, 33.0%, 25.4%, and 78.7% respectively. ConclusionIn conclusion, the planned doses of 34 Gy, 32 Gy, 24 Gy, and 24 Gy were successfully administered as single-fractions for the treatment of lung, liver, bone, and other extracranial lesions, respectively, in a prospective SRS dose-escalation trial. No dose-limiting toxicities were registered, and minimal acute and late toxicity were reported. New indications for SRS are currently being studied in oligoprogressive patients receiving targeted drugs or in combination with immunotherapy. The DESTROY-2 trial represents, in our opinion, a credible starting point for future modern radiosurgery trials.

Prognostic nomogram for overall survival in patients with stage IV non-small cell lung cancer treated with chemotherapy combined with high-dose thoracic radiotherapy.

e20607 Background: Although the targeted therapy and immunotherapy have become the first line options for selected stage IV non-small cell lung cancer (NSCLC) patients. However, there are instances where certain patients are not administered targeted therapy or immunotherapy due to a variety of factors, chemotherapy and radiotherapy remain the main way to treat such patients. This study aimed to construct a prognostic nomogram for patients with stage IV NSCLC treated with chemotherapy combined with high-dose (≥ 60 Gy) thoracic radiotherapy. Methods: The nomogram was based on a retrospective study of 335 patients with stage IV NSCLC who treated with chemotherapy combined with high-dose (≥ 60 Gy) thoracic radiotherapy were hospitalized between January 2010 and January 2018(patient did not receive TKI therapy or immunotherapy). The patients were randomly assigned to either a primary cohort (n = 234) or a validation cohort (n = 101) at a ratio of 7 : 3. In the primary cohort, a univariate analysis of the clinical or therapeutic factors that may predict OS was performed using a Cox regression model, with P &lt; 0.05 indicating statistical significance. The variables from the univariate analysis that affected OS significantly were included in the Cox regression model for the multivariate analysis. A nomogram was then created based on the results of multivariate analysis and using the “rms,” “foreign,” and “survival” R version 4.0.3 software packages. The discriminatory ability of the nomogram was measured using the area under the curve (AUC) of a receiver operating curve (ROC). Results: Multivariate logistic regression analysis revealed that malignant pericardial effusion, adrenal metastasis, elevated lactate dehydrogenase levels, and excessive planning target volume were independent risk factors for poorer 1–3 year overall survival (OS), while a higher radiotherapy dose for the primary lesion was associated with better OS. Nomogram prediction models were constructed using these five variables. The AUC of the ROC for 1-year, 2-year, and 3-year OS in the primary cohort were 0.685, 0.729, and 0.816, respectively. In the validation cohort, the AUC of the ROC for 1-year, 2-year, and 3-year OS were 0.706, 0.749, and 0.797, respectively. The Kaplan-Meier survival analysis showed that differentiation between the high-risk group and low-risk group using the prediction model had a direct, significant effect on survival in both the primary cohort ( P &lt; 0.001) and validation cohort ( P = 0.004). Conclusions: The nomogram model constructed in this study may be used to objectively predict the prognosis and OS of patients with stage IV NSCLC treated with chemotherapy and high-dose thoracic radiotherapy. Identify patients who may not benefit from high-dose thoracic radiotherapy prior to treatment to avoid overtreatment.

Evaluating intra-fractional tumor motion in lung stereotactic radiotherapy with deep inspiration breath-hold.

To evaluate the intra-fractional tumor motion in lung stereotactic body radiotherapy (SBRT) with deep inspiration breath-hold (DIBH), and to investigate the adequacy of the current planning target volume (PTV) margins. Twenty-eight lung SBRT patients with DIBH were selected in this study. Among the lesions, twenty-three were at right or left lower lobe, two at right middle lobe, and three at right or left upper lobe. Post-treatment gated cone-beam computed tomography (CBCT) was acquired to quantify the intra-fractional tumor shift at each treatment. These obtained shifts were then used to calculate the required PTV margin, which was compared with the current applied margin of 5mm margin in anterior-posterior (AP) and right-left (RL) directions and 8mm in superior-inferior (SI) direction. The beam delivery time was prolonged with DIBH. The actual beam delivery time with DIBH (Tbeam_DIBH) was compared with the beam delivery time without DIBH (Tbeam_wo_DIBH) for the corresponding SBRT plan. A total of 113 treatments were analyzed. At six treatments (5.3%), the shifts exceeded the tolerance defined by the current PTV margin. The average shifts were 0.0±1.9mm, 0.1±1.5mm, and -0.5±3.7mm in AP, RL, and SI directions, respectively. The required PTV margins were determined to be 4.5, 3.9, and 7.4mm in AP, RL, and SI directions, respectively. The average Tbeam_wo_DIBH and Tbeam_DIBH were 2.4±0.4 min and 3.6±1.5 min, respectively. The average treatment slot for lung SBRT with DIBH was 25.3±7.9 min. Intra-fractional tumor motion is the predominant source of treatment uncertainties in CBCT-guided lung SBRT with DIBH. The required PTV margin should be determined based on data specific to each institute, considering different techniques and populations. Our data indicate that our current applied PTV margin is adequate, and it is possible to reduce further in the RL direction. The time increase of Tbeam_DIBH, relative to the treatment slot, is not clinically significant.

Dose-Painting Proton Radiotherapy Guided by Functional MRI in Non-enhancing High-Grade Gliomas

AimsThis study aimed to demonstrate the feasibility and evaluate the dosimetric effect and clinical impact of dose-painting proton radiotherapy (PRT) guided by functional MRI in non-enhancing high-grade gliomas (NE-HGGs). Materials and methodsThe 3D-ASL and T2 FLAIR MR images of ten patients with NE-HGGs before radiotherapy were studied retrospectively. The hyperintensity on T2 FLAIR was used to generate the planning target volume (PTV), and the high-perfusion volume on 3D-ASL (PTV-ASL) was used to generate the simultaneous integrated boost (SIB) volume. Each patient received pencil beam scanning PRT and photon intensity-modulated radiotherapy (IMRT). There were five plans in each modality: (1) Uniform plans (IMRT60 vs. PRT60): 60Gy in 30 fractions to the PTV. (2)–(5) SIB plans (IMRT72, 84, 96, 108 vs. PRT72, 84, 96, 108): Uniform plan plus additional dose boost to PTV-ASL in 30 fractions to 72, 84, 96, 108 Gy. The dosimetric differences between various plans were compared. The clinical effects of target volume and organs at risk (OARs) were assessed using biological models for both tumor control probability (TCP) and normal tissue complication probability (NTCP). ResultsCompared with the IMRT plan, the D2 and D50 of the PRT plans with the same prescription dose increased by 1.27–4.12% and 0.64–2.01%, respectively; the R30 decreased by > 32%; the dose of brainstem and chiasma decreased by > 27% and >32%; and the dose of normal brain tissue (Br-PTV), optic nerves, eyeballs, lens, cochlea, spinal cord, and hippocampus decreased by > 50% (P < 0.05). The maximum necessary dose was 96GyE to achieve >98% TCP for PRT, and it was 84Gy to achieve >91% TCP for IMRT. The average NTCP of Br-PTV was 1.30% and 1.90% for PRT and IMRT at the maximum dose escalation, respectively. The NTCP values of the remaining OARs approached zero in all PRT plans. ConclusionThe functional MRI-guided dose escalation using PRT is feasible while sparing the OARs constraints and demonstrates a potential clinical benefit by improving TCP with no or minimal increase in NCTP for tissues outside the PTV. This retrospective study suggested that the use of PRT-based SIB guided by functional MRI may represent a strategy to provide benefits for patients with NE-HGGs.

A machine learning-based approach to predict energy layer for each field in spot-scanning proton arc therapy for lung cancer: A feasibility study.

Determining the optimal energy layer (EL) for each field, under considering both dose constraints and delivery efficiency, is crucial to promoting the development of proton arc therapy (PAT) technology. This study aimed to explore the feasibility and potential clinical benefits of utilizing machine learning (ML) technique to automatically select EL for each field in PAT plans of lung cancer. Proton Bragg peak position (BPP) was employed to characterize EL. The ground truth BPPs for each field were determined using the modified ELO-SPAT framework. Features in geometric, water-equivalent thicknesses (WET) and beamlet were defined and extracted. By analyzing the relationship between the extracted features and ground truth, a polynomial regression model with L2-norm regularization (Ridge regression) was constructed and trained. The performance of the regression model was reported as an error between the predictions and the ground truth. Besides, the predictions were used to make PAT plans (PAT_PRED). These plans were compared with those using the ground truth BPPs (PAT_TRUTH) and the mid-WET of the target volumes (PAT_MID) in terms of relative biological effectiveness-weighted dose (RWD) distributions. One hundred ten patients with lung cancer, a total of 7920 samples, were enrolled retrospectively, with 5940 cases randomly selected as the training set and the remaining 1980 cases as the testing set. Nine patients (648 samples) were collected additionally to evaluate the regression model in terms of plan quality and robustness. With regard to the prediction errors, the root mean squared errors and mean absolute errors between the ML-predicted and ground truth BPPs for the testing set were 9.165 and 6.572mm, respectively, indicating differences of approximately two to three ELs. As for plan quality, the PAT_TRUTH and PAT_PRED plans performed similarly in terms of plan robustness, target coverage and organs at risk (OARs) protection, with differences smaller than 0.5Gy(RBE). This trend was also observed for dose conformity and uniformity. The PAT_MID plans produced the lowest robustness index and lowest doses to OARs, along with the highest heterogeneity index, indicating better protection for OARs, improved plan robustness, but compromised dose homogeneity. Additionally, for relatively small tumor sizes, the PAT_MID plan demonstrated a notably poor dose conformity index. Within this cohort under investigation, our study demonstrated the feasibility of using ML technique to predict ELs for each field, offering a fast (within 2 s) and memory-efficient reduced way to select ELs for PAT plan.

Comparison of plan quality and robustness using VMAT and IMRT for breast cancer

Abstract To evaluate the plan quality and robustness of volumetric modulated arc therapy (VMAT) and intensity modulated radiation therapy (IMRT) for breast cancer, 50 patients, including 25 patients who received radiotherapy after breast-conserving surgery (BCR) and 25 patients who received postmastectomy radiotherapy (PRT), were selected for this study. Nominal VMAT and IMRT plans were generated for each patient on Eclipse treatment planning system (version 15.6). The dosimetric metrics, dose distribution, gamma passing rate, and delivery time were compared. In addition, 12 uncertainty plans with plan isocenter uncertainty and CT density uncertainty were recalculated based on the nominal plans for each patient. The dose volume histogram (DVH) band width (DVHBW) was adopted to quantify the plan robustness of the nominal plans for the perturbed scenarios in this study. For BCR, the dosimetric metrics except planning target volume (PTV) conformal index (CI) and ipsilateral lung V 5 were not statistically different for IMRT and VMAT plans. PTV CI of VMAT plans was better than that of IMRT plans (VMAT: 0.923 ± 0.024, IMRT: 0.855 ± 0.032, p = 0.003). The ipsilateral lung V 5 of VMAT plan was higher than that of IMRT plan (VMAT: 42.4% ± 2.8%, IMRT: 40.5% ± 4.0%, p = 0.045). The VMAT plans save more than 1.20 min compared to the IMRT plans (VMAT: 0.87 min, IMRT: 2.08 min, p &lt; 0.001). The gamma passing rates of VMAT plans were better than those of IMRT plans (3 mm/3%, VMAT: 99.7% ± 0.2%, IMRT: 99.4% ± 0.4%, p &lt; 0.001; 2 mm/2%, VMAT: 97.2% ± 1.0%, IMRT: 96.9% ± 0.6%, p = 0.108). For PRT, the dosimetric metrics of VMAT plans, including PTV D mean, homogeneity index (HI), CI, and D max of spinal cord, were significantly better than those of IMRT plans. The VMAT plans save more than 45% time compared with IMRT plans (VMAT: 1.54 min, IMRT: 2.81 min, p &lt; 0.001). The difference in gamma passing rates between VMAT plans and IMRT plans was not statistically significant. For the plan robustness, the DVHBW of VMAT plans and IMRT plans for BCR were 2.09% ± 0.23% and 2.98% ± 0.40%, respectively (p &lt; 0.05). For PRT, the DVHBW of VMAT plans was significantly better than those of IMRT plans (VMAT: 3.05% ± 0.26%, IMRT: 3.57% ± 0.27%, p &lt; 0.05). The results show that the dosimetric metrics of VMAT plans were comparable to those of IMRT plans. More importantly, the VMAT plans had excited dose distribution and fast execution efficiency. The plan robustness of VMAT plans were superior.

Comparative analysis of simultaneous integrated boost and sequential boost radiotherapy in node-positive cervical cancer: dosimetric and radiobiological considerations.

For locally advanced cervical cancer, the standard therapeutic approach involves concomitant chemoradiation therapy, supplemented by a brachytherapy boost. Moreover, an external beam radiotherapy (RT) boost should be considered for treating gross lymph node (LN) volumes. Two boost approaches exist with Volumetric Intensity Modulated Arc Therapy (VMAT): Sequential (SEQ) and Simultaneous Integrated Boost (SIB). This study undertakes a comprehensive dosimetric and radiobiological comparison between these two boost strategies. The study encompassed ten patients who underwent RT for cervical cancer with node-positive disease. Two sets of treatment plans were generated for each patient: SIB-VMAT and SEQ-VMAT. Dosimetric as well as radiobiological parameters including tumour control probability (TCP) and normal tissue complication probability (NTCP) were compared. Both techniques were analyzed for two different levels of LN involvement - only pelvic LNs and pelvic with para-aortic LNs. Statistical analysis was performed using SPSS software version 25.0. SIB-VMAT exhibited superior target coverage, yielding improved doses to the planning target volume (PTV) and gross tumour volume (GTV). Notably, SIB-VMAT plans displayed markedly superior dose conformity. While SEQ-VMAT displayed favorable organ sparing for femoral heads, SIB-VMAT appeared as the more efficient approach for mitigating bladder and bowel doses. TCP was significantly higher with SIB-VMAT, suggesting a higher likelihood of successful tumour control. Conversely, no statistically significant difference in NTCP was observed between the two techniques. This study's findings underscore the advantages of SIB-VMAT over SEQ-VMAT in terms of improved target coverage, dose conformity, and tumour control probability. In particular, SIB-VMAT demonstrated potential benefits for cases involving para-aortic nodes. It is concluded that SIB-VMAT should be the preferred approach in all cases of locally advanced cervical cancer.

Evaluation of the offset couch parameter between kilovoltage on-board imaging and cone-beam computed tomography in patients with prostate cancer

Background: External Beam Radiation Therapy (EBRT) is a curative therapy technique for prostate cancer. Since the prostate is unstable and surrounded by the bladder and rectum, precision of the target location is critical. Image Guided Radiation Therapy (IGRT) can improve treatment precision. The bladder and rectum may alter volume during IGRT, shifting the prostate’s position and resulting in missed target volume doses and extra organs at risk (OARs) doses. Objective: To assess setup error and residual error during patient positioning, as well as the current IGRT protocol efficiency, in prostate cancer patients while recommending a planning target volume (PTV) margin. Materials and methods: The offset couch parameter of on-board imaging (OBI) and cone-beam computed tomography (CBCT) was computed to determine the error distribution, magnitude, and error difference between treatment phases. The systematic and random errors were calculated using the van Herk equation to determine the planning target volume (PTV) margin. Results: The setup error was -0.86 to 0.25 mm, and the residual error was -0.15 to 0.32 mm. The couch displacement percentage for OBI was 29.44% to 58.89%, and for CBCT was 8.10% to 34.12%. The systematic error was 1.65 to 3.21. The random error was 1.78 to 3.29. The setup error was greatest in the longitudinal (Lng) direction, residual error was greatest in the vertical (Vrt) direction, and systematic and random error were greatest in the Vrt and lateral (Lat) direction, respectively. The PTV margin was greatest in the Vrt direction, while the Lng direction was the narrowest margin for every treatment phase. Conclusion: The highest setup error occurs in the Lng direction for all treatment phases. For the 46 Gy and 60 Gy phases, the highest residual error is in the Vrt direction. However, in the 78 Gy phase, the error is relatively close to 0.01mm in every direction. The current IGRT protocol is effective in detecting setup and residual errors. The 78 Gy phase has the greatest PTV margin, whereas the 46 Gy phase shows the narrowest margins in all directions.

Introducing a new national tool to monitor the carbon footprint of inhalers

Abstract Introduction The Welsh Government launched its National Health Service (NHS) Wales decarbonisation strategic delivery plan in March 2021.[1] The plan includes a number of actions related to the carbon footprint of inhalers. The National Prescribing Support Unit was requested to provide data for the carbon footprint of inhalers, and develop an analysis tool to measure progress in reducing the carbon footprint and movement towards the all Wales target of 20,000 carbon dioxide (CO2) tonnes per annum. Aim To introduce a new tool for monitoring the carbon footprint of inhalers used in Wales. Methods The data requirements for the tool were determined using a nominal group technique. A literature search was conducted to identify any available sources of inhaler carbon footprint values that would be used to inform the required analyses. A collaborative approach with specialist groups was adopted to develop and pilot the dashboard. Results The nominal group technique identified the essential minimal dataset required. These were data relating to quantity, cost, and carbon footprint of the inhalers prescribed. Data for quantity and cost of inhalers used were already available to the unit. A literature search revealed a reliable source of inhaler carbon footprint values for developing the initial dashboard, and any updating required as additional inhalers are presented within the dataset.[2] Through the collaborative approach with specialist groups, a dashboard was developed and piloted with selected individuals within Wales. Feedback was then attained and actioned upon where appropriate, before the dashboard was made readily available to all NHS Wales employees. Conclusion The new monitoring tool went live in January 2022 and provides data on inhaler quantity, spend and carbon footprint at an all Wales, Health Board, cluster and GP practice level. This enables reporting at a national and organisational level, as well as lower down to specific geographies. Ongoing work involves the addition of new inhalers, refreshing with the most recent data, and updating the background carbon footprint values held within the tool. These are instigated on an issuing of changes in the supporting reference data values.[2] The availability of a tool to report on the carbon footprint of inhalers used within Wales provides a consistent data source to support the strategic delivery plan targets. A strength of this work has been to deliver a meaningful tool in support of this aim. Whilst a limitation is that we do not know the exact impact of the tool in making the change happen, we are aware that the tool is used on a regular basis by stakeholders.

Rapid Plan Module Applying to Optimize the Planning Process for Treatment of Head and Neck and Rectal Cancer

In situations where the number of patients is large, it may be necessary to quickly create dosimetry plan without compromising the quality of the final plan. With the help of the modern technologies, it is possible to optimize and standardize the dosimetry planning process. The Varian Eclipse planning system has a Rapid Plan module, which is an automated system for creating plans based on the database of clinical plans (1-4). Knowledge-based planning is a promising method that can improve plan quality and speed up treatment planning. In this study the performance of volume modulated radiotherapy planning optimization (VMAT) for head and neck and rectal cancer was examined. Plans were compared based on dose statistics for critical organs and planning target volume using dose-volume histograms. Each model is configured on more than 50 real plans. The plans made using the RapidPlan had dose distributions no worse than the dose distributions of clinical plans. No statistically significant differences were found regarding planning target volume (PTV) coverage. The model was used for already treated patients with different types of localizations. The results indicate that automation of dosimetry planning is possible using the Rapid Plan module, and this may facilitate its use in clinical practice.