Feasibility study of adaptive radiotherapy with Ethos for breast cancer

Purpose

The aim of this study was to assess the feasibility of online adaptive radiotherapy with Ethos for breast cancer.

Materials and methods

This retrospective study included 20 breast cancer patients previously treated with TrueBeam. All had undergone breast surgery for different indications (right/left, lumpectomy/mastectomy) and were evenly divided between these four cases, with five extended cone beam computed tomography (CBCT) scans per patient. The dataset was used in an Ethos emulator to test the full adaptive workflow. The contours generated by artificial intelligence (AI) for the influencers (left and right breasts and lungs, heart) and elastic or rigid propagation for the target volumes (internal mammary chain (IMC) and clavicular lymph nodes (CLNs)) were compared to the initial contours delineated by the physician using two metrics: Dice similarity coefficient (DICE) and Hausdorff 95% distance (HD95). The repeatability of influencer generation was investigated. The times taken by the emulator to generate contours, optimize plans, and calculate doses were recorded. The quality of the scheduled and adapted plans generated by Ethos was assessed using planning target volume (PTV) coverage, homogeneity indices (HIs), and doses to organs at risk (OARs) via dose-volume histogram (DVH) metrics. Quality assurance (QA) of the treatment plans was performed using an independent portal dosimetry tool (EpiQA) and gamma index.

Results

On average, the DICE for the influencers was greater than 0.9. Contours resulting from rigid propagation had a higher DICE and a lower HD95 than those resulting from elastic deformation but remained below the values obtained for the influencers: DICE values were 0.79 ± 0.11 and 0.46 ± 0.17 for the CLN and IMC, respectively. Regarding the repeatability of the influencer segmentation, the DICE was close to 1, and the mean HD95 was strictly less than 0.15 mm. The mean time was 73 ± 4 s for contour generation per AI and 80 ± 9 s for propagations. The average time was 53 ± 3 s for dose calculation and 125 ± 9 s for plan optimization. A dosimetric comparison of scheduled and adapted plans showed a significant difference in PTV coverage: dose received by 95% of the volume (D95%) values were higher and closer to the prescribed doses for adapted plans. Doses to organs at risk were similar. The average gamma index for quality assurance of adapted plans was 99.93 ± 0.38 for a 3%/3mm criterion.

Conclusion

This study comprehensively evaluated the Ethos® adaptive workflow for breast cancer and its potential technical limitations. Although the results demonstrated the high accuracy of AI segmentation and the superiority of adapted plans in terms of target volume coverage, a medical assessment is still required.

Cardiac protective techniques in left breast radiotherapy: rapid selection criteria for routine clinical decision making

OBJECTIVE

In left breast radiotherapy (RT) desired heart doses may be achieved without heart-sparing RT techniques in some patients. We aimed to examine the existence of predictive factors and cutoff points to determine which patients are the main candidates for heart-sparing RT techniques.

MATERIAL AND METHOD

Dosimetric data for left breast cancer was examined. RT plans were made at conventional doses to the breast and peripheral lymph nodes. Statistical analyses were performed using SPSS 22.0 (SPSS Inc., IBM Corp., Armonk, NY).

RESULT

114 cases were evaluated by ROC (Receiver operating characteristic) analysis in the breast-conserving surgery (BCS) and mastectomy groups. While only left lung volume (AUC: 0.74, 95% CI 0.61-0.87, p = 0.002) was significant in BCS cases, in cases with mastectomy, left lung volume (AUC: 0.81, 95% CI 0.69-0.94, p = 0.002) and lung/heart volume ratio (AUC: 0.83, 95% CI 0.70-0.96, p = 0.001) had a significant relationship with the relevance of heart doses. The cutoff point of 1.92 was selected for the lung/heart volume ratio for the mastectomized patients. Moreover, the cutoff point 1154 cc and 1208 cc was determined for the left lung volume for the BCS and mastectomized patients, respectively.

CONCLUSION

Various cutoff points in left breast RT can be used to predict whether RT plans will meet QUANTEC (Quantitative Analysis of Normal Tissue Effects in the Clinic) heart dose limits. Evaluating only these few cutoff points before planning makes it possible to eliminate 70% of patients with BCS and 40% of patients with mastectomy from respiratory-controlled methods, which require time and effort. Patients with lung volume and lung/heart volume ratio smaller than the cutoff values can be considered primary candidates for heart-sparing techniques.

Implementing dispersion measurement as part of scanning proton therapy commissioning and quality assurance

Introduction. Dispersion in an accelerator quantifies the deviation of the proton trajectory when there is a momentum deviation. We present for the first time a safe method of measuring dispersion in the clinic, using a scintillator detector and the momentum deviations within a spill. This is an important accelerator quantity as we found that this is the reason behind the large dose fluctuation in our absolute dosimetry measurement.Methods. Dispersions are measured for nine energies in a Hitachi ProBeat system at three locations (isocenter and at two profile monitors) and at two gantry angles (0 and 90 degrees) by first measuring the spot position and momentum drift within a spill. The spot position drift is measured by the XRV-4000 at the isocenter, and by the two profile monitors located at 0.57 and 2.27 m from the isocenter. The momentum drift is calculated from the intra-spill range drift which is measured using the Ranger accessory. The dispersion at isocenter and its gradient are calculated using the weighted least square regression on the measured dispersions at the three locations. A constraint is formulated on the dispersion and its gradient to ensure minimal intra-spill spot position deviation around the isocenter.Results. The measured intra-spill range and spot positional drift at isocenter are less than0.25mmand0.7mmrespectively. The momentum spread calculated from the range drift are less than 0.08%. The dispersion at the isocenter ranged from0.50to4.30mand the zero-crossing happens upstream of isocenter for all energies. 2 of the 9 energies (168.0 and 187.5 MeV) violated the constraint and has an intra-spill spot positional deviation greater than1.0within5cmfrom the isocenter.Conclusion. This measurement is recommended as part of commissioning and annual quality assurance for accelerator monitoring and to ensure intra-spill spot deviations remain low.

Alexithymia, Burnout, and Hopelessness in a Large Sample of Healthcare Workers during the Third Wave of COVID-19 in Italy

In the present study, we aimed to assess the frequency of and the relationships between alexithymia, burnout, and hopelessness in a large sample of healthcare workers (HCWs) during the third wave of COVID-19 in Italy. Alexithymia was evaluated by the Italian version of the 20-item Toronto Alexithymia Scale (TAS-20) and its subscales Difficulty in Identifying Feelings (DIF), Difficulty in Describing Feelings (DDF), and Externally Oriented Thinking (EOT), burnout was measured with the scales emotional exhaustion (EE), depersonalisation (DP), and personal accomplishment (PA) of the Maslach Burnout Test (MBI), hopelessness was measured using the Beck Hopelessness Scale (BHS), and irritability (IRR), depression (DEP), and anxiety (ANX) were evaluated with the Italian version of the Irritability' Depression' Anxiety Scale (IDA). This cross-sectional study recruited a sample of 1445 HCWs from a large urban healthcare facility in Italy from 1 May to 31 June 2021. The comparison between individuals that were positive (n = 214, 14.8%) or not for alexithymia (n = 1231, 85.2%), controlling for age, gender, and working seniority, revealed that positive subjects showed higher scores on BHS, EE, DP IRR, DEP, ANX, DIF, DDF, and EOT and lower on PA than the not positive ones (p < 0.001). In the linear regression model, higher working seniority as well as higher EE, IRR, DEP, ANX, and DDF scores and lower PA were associated with higher hopelessness. In conclusion, increased hopelessness was associated with higher burnout and alexithymia. Comprehensive strategies should be implemented to support HCWs' mental health and mitigate the negative consequences of alexithymia, burnout, and hopelessness.

Assessment of residual geometrical errors of clinical target volumes and their impact on dose accumulation for head and neck radiotherapy

PURPOSE

To assess the residual geometrical errors (dr) and their impact on the clinical target volumes (CTV) dose coverage for head and neck cancer (HNC) proton therapy patients.

METHODS

We analysed 28 HNC patients treated with 70 Gy (RBE) and 54.25 Gy (RBE) to the therapeutic CTV70 and prophylactic CTV54.25, respectively. Daily cone beam CTs were converted to high quality synthetic CTs (sCTs). The CTVs from the nominal CT were propagated to the corresponding sCTs using a hybrid deformable image registration (propagated CTVs) in RayStation 11B. For 11 patients, all propagated CTVs were reviewed by our HNC radiation oncologist (physician corrected CTVs). The residual geometrical error dr was quantified as a function of the daily CTVs volume overlap with the nominal plan CTV. The errors dr(propagated CTVs) and dr(physician corrected CTVs) and the difference in dice similarity coefficients (ΔDSC) were determined. Using clinical plans, dose coverage and the tumor control probability (TCP) for the nominal, accumulated and voxel-wise minimum scenarios were determined.

RESULTS

The difference in the residual geometrical error dr (propagated CTVs - physician corrected CTVs) and mean DSC (|ΔDSC|mean) were minor: Δdr(CTV70) = 0.16 mm, Δdr(CTV54.25) = 0.26 mm, |ΔDSC|mean < 0.9%. For all 28 patients, dr(CTV70) = 1.91 mm and dr(CTV54.25) = 1.90 mm. However, CTV54.25 above and below the cricoid cartilage differed substantially (1.00 mm c.f. 3.93 mm). The CTV54.25 coverage below the cricoid was then almost always lower, although the TCP of the accumulated dose was higher than the TCP of the voxel-wise minimum dose.

CONCLUSIONS

Setup uncertainty setting of 2 mm is possible. The feasibility of using propagated CTVs for error determination is demonstrated.

A Potential Pitfall and Clinical Solutions in Surface-Guided Deep Inspiration Breath Hold Radiation Therapy for Left-Sided Breast Cancer

Purpose

Deep inspiration breath hold (DIBH) is an effective technique to spare the heart in treating left-sided breast cancer. Surface-guided radiation therapy (SGRT) is increasingly applied in DIBH setup and motion monitoring. Patient-specific breathing behavior, either thoracically driven or abdominally driven (A-DIBH), should be unaltered, online identified, and monitored accordingly to ensure reproducible heart-sparing treatment.

Methods and Materials

Sixty patients with left-sided breast cancer treated with SGRT were analyzed: 20 A-DIBH patients with vertical chest elevation (VCE ≤ 5 mm) were prospectively identified, and 40 control patients were retrospectively and randomly selected for comparison. At simulation, both free-breathing (FB) and DIBH computed tomography (CT) were acquired, guided by a motion surrogate placed around the xiphoid process. For SGRT treatment setups, the region of interest (ROI) was defined on the CT chest surface, and the surrogate-based setup was a backup. For all 60 patients, the VCE was measured as the average of the FB-to-DIBH elevations at the breast and xiphoid process, together with abdominal elevation. In the 40-patient control group, A-DIBH patients (VCE ≤ 5 mm) were identified. Of the 20 A-DIBH patients, 10 were treated with volumetric modulated arc therapy plans, and 10 patients were treated with tangent plans. Clinical DIBH plans were recalculated on FB CT to compare maximum dose (DMax), 5% of the maximum dose (D5%), mean dose (DMean), and V30Gy, V20Gy, and V5Gy of the heart and lungs and their significance.

Results

In the 20 A-DIBH patients, VCE = 3 ± 2 mm, surrogate motion (9 ± 6 mm), and abdomen motion of 14 ± 5 mm are found. Heart dose reduction from FB to DIBH is significant (P < .01): ∆DMax = -8.4 ± 9.8 Gy, ∆D5% = -2.4 ± 4.4 Gy, and ∆DMean = -0.6 ± 0.9 Gy. Six out of 40 control patients (15%) are found to have VCE ≤ 5 mm.

Conclusions

A-DIBH (VCE ≤ 5 mm) patient population is significant (15%), and they should be identified in the SGRT workflow and monitored accordingly. A new abdominal ROI or an abdominal surrogate should be used instead of the conventional chest-only ROI. Patient-specific DIBH should be preserved for higher reproducibility to ensure heart sparing.

Impact of preoperative body composition in patients with renal cell carcinoma submitted to surgical treatment

Objective

To evaluate the impact of preoperative body composition in patients with renal cell carcinoma (RCC) undergoing surgical treatment.

Materials and Methods

This was a retrospective study of 52 patients with RCC undergoing total or partial nephrectomy. Body composition assessment was performed using the body mass index, together with computed tomography analysis at the level of the third lumbar vertebra to measure the area of visceral adipose tissue, as well as the area and density of skeletal muscle mass.

Results

Malnutrition, obesity and inadequate skeletal muscle gauge (SMG) were associated with higher hospital length of stay (p = 0.028, p = 0.02 and p = 0.012, respectively). Although the rates of postoperative symptoms and readmissions were low, survival was better among the patients with an adequate SMG than among those with an inadequate SMG (p = 0.003).

Conclusion

Among patients with RCC undergoing surgical treatment, preoperative body composition does not seem to be associated with the rates of perioperative complications, although an inadequate SMG seems to be associated with worse overall survival.

Process Modeling a Radiation Oncology Clinic Workflow From Therapeutic Simulation to Treatment: Identifying Impending Strain and Possible Treatment Delays

Purpose

The administration of safe, high-quality radiation therapy requires the systematic completion of a series of steps from computed tomography simulation, physician contouring, dosimetric treatment planning, pretreatment quality assurance, plan verification, and, ultimately, treatment delivery. Nevertheless, due consideration to the cumulative time required to complete each of these steps is often not given sufficient attention when determining patient start date. We set out to understand the systemic dynamics as to how varying patient arrival rate can affect treatment turnaround times using Monte Carlo simulations.

Methods and Materials

We developed a process model workflow for a single physician, single linear accelerator clinic that simulated arrival rates and processing times for patients undergoing radiation treatment using the AnyLogic Simulation Modeling software (AnyLogic 8 University edition, v8.7.9). We varied the new patient arrival rate from 1 to 10 patients per week to understand the effect of treatment turnaround times from simulation to treatment. We used processing-time estimates determined in prior focus studies for each of the required steps.

Results

Altering the number of patients simulated from 1 per week to 10 per week resulted in a corresponding increase in average processing time from simulation to treatment from 4 to 7 days. The maximum processing time for patients from simulation to treatment ranged from 6 to 12 days. To compare individual distributions, we used the Kolmogorov-Smirnov statistical test. We found that altering the arrival rate from 4 patients per week to 5 patients per week resulted in a statistically significant change in the distributions of processing times (P = .03).

Conclusions

The results of this simulation-based modeling study confirm the appropriateness of current staffing levels to ensure timely patient delivery while minimizing staff burnout. Simulation modeling can help guide staffing and workflow models to ensure timely treatment delivery while ensuring quality and safety.

Establishing a common metric for physical function: Linking SARC-F and PROMIS® physical function

INTRODUCTION

Aligned with the increasing need for standardized assessment of physical function in older individuals with cancer and other conditions, several patient-reported outcome measures (PROMs) have been developed and published. The aim of this study is to link the Strength, Assistance with walking, Rising from a chair, Climbing stairs, and Falls questionnaire (SARC-F), and the Patient-Reported Outcomes Measurement Information System® (PROMIS®) Physical Function Short Form 8c (PROMIS PF 8c), and make their scores convertible, in order to expand the use of both instruments in research and inform clinicians and researchers about the interchangeability of critical cut-off scores.

MATERIALS AND METHODS

The sample included 300 participants recruited from an online panel. Participants were included if they had received a cancer diagnosis from a clinician and reported receiving anti-cancer treatment. We conducted five linking procedures and selected an optimal one to generate the crosswalk table between the two measures.

RESULTS

The linked T scores of all five methods showed acceptably small mean differences from the observed T scores, and the standard deviation (SD), and root-mean-squared deviation (RMSD) of the differences were generally similar across all methods. After comparing across all statistics, the Stocking-Lord approach was considered as the optimal approach to compute the crosswalk table for converting SARC-F raw scores to PROMIS PF 8c scores. The crosswalk table shows that the SARC-F cut-off value of 4 between healthy versus symptomatic with a corresponding score of 37 fell in the range of moderate physical function limitation from 30 to 39 on the PROMI PF 8c T score metric.

DISCUSSION

The linkage in this study has potential for improving clinical and research activities for people with cancer and perhaps others with a similar range of physical function. It facilitates the interpretability in scores of both measures on a common metric anchored on general population for further group-level analysis. Researchers can use this crosswalk to harmonize data collected from either instrument without requiring all cohorts to administer the same instrument for a prospective data collection or retrospective data analysis purpose or for a cross-study effectiveness study.

Interim analysis of patient-reported outcome compliance and dosimetry in a phase 3 randomized clinical trial of oesophagus-sparing spinal radiotherapy

BACKGROUND

The randomized clinical trial ESO-SPARE investigates if oesophagus-sparing radiotherapy (RT) can reduce dysphagia in patients with metastatic spinal cord compression (MSCC). Patient-reported outcome (PRO) is the only follow-up measure. Due to the fragile patient population, low respondent compliance was anticipated. We performed a planned interim analysis of dosimetry and respondent compliance, to ensure that the protocol requirements were met.

METHODS

Patients >18 years referred for cervical/thoracic MSCC radiotherapy in 1-10 fractions were included from two centres. Patients were randomized (1:1) to standard RT or oesophagus-sparing RT, where predefined oesophageal dose constraints were prioritized over target coverage. Patients completed a trial diary with daily reports of dysphagia for 5 weeks (PRO-CTC-AE) and weekly quality of life reports for 9 weeks (QLQ-C30, EQ-5D-5L). According to power calculation, 124 patients are needed for primary endpoint analysis. The sample size was inflated to 200 patients to account for the fragile patient population. The co-primary endpoints, peak patient-reported dysphagia, and preserved ability to walk (EQ-5D-5L), are analysed at 5 and 9 weeks, respectively. The interim analysis was conducted 90 days after the inclusion of patient no 100. Respondent compliance was assessed at 5 and 9 weeks. In all RT plans, oesophagus and target doses were evaluated regarding adherence to protocol constraints.

RESULTS

From May 2021 to November 2022, 100 patients were included. Fifty-two were randomized to oesophagus-sparing RT. In 23% of these plans, oesophagus constraints were violated. Overall, the dose to both target and oesophagus was significantly lower in the oesophagus-sparing plans. Only 51% and 41% of the patients were evaluable for co-primary endpoint analysis at five and nine weeks, respectively. Mortality and hospitalization rates were significantly larger in patients who completed <4 days PRO questionnaires.

CONCLUSION

Compliance was lower than anticipated and interventions to maintain study power are needed.

Benchmarking Automated Machine Learning-Enhanced Planning With Ethos Against Manual and Knowledge-Based Planning for Locally Advanced Lung Cancer

Purpose

Currently, there is insufficient guidance for standard fractionation lung planning using the Varian Ethos adaptive treatment planning system and its unique intelligent optimization engine. Here, we address this gap in knowledge by developing a methodology to automatically generate high-quality Ethos treatment plans for locally advanced lung cancer.

Methods and Materials

Fifty patients previously treated with manually generated Eclipse plans for inoperable stage IIIA-IIIC non-small cell lung cancer were included in this institutional review board-approved retrospective study. Fifteen patient plans were used to iteratively optimize a planning template for the Daily Adaptive vs Non-Adaptive External Beam Radiation Therapy With Concurrent Chemotherapy for Locally Advanced Non-Small Cell Lung Cancer: A Prospective Randomized Trial of an Individualized Approach for Toxicity Reduction (ARTIA-Lung); the remaining 35 patients were automatically replanned without intervention. Ethos plan quality was benchmarked against clinical plans and reoptimized knowledge-based RapidPlan (RP) plans, then judged using standard dose-volume histogram metrics, adherence to clinical trial objectives, and qualitative review.

Results

Given equal prescription target coverage, Ethos-generated plans showed improved primary and nodal planning target volume V95% coverage (P < .001) and reduced lung gross tumor volume V5 Gy and esophagus D0.03 cc metrics (P ≤ .003) but increased mean esophagus and brachial plexus D0.03 cc metrics (P < .001) compared with RP plans. Eighty percent, 49%, and 51% of Ethos, clinical, and RP plans, respectively, were "per protocol" or met "variation acceptable" ARTIA-Lung planning metrics. Three radiation oncologists qualitatively scored Ethos plans, and 78% of plans were clinically acceptable to all reviewing physicians, with no plans receiving scores requiring major changes.

Conclusions

A standard Ethos template produced lung radiation therapy plans with similar quality to RP plans, elucidating a viable approach for automated plan generation in the Ethos adaptive workspace.

Anatomical changes in the male pelvis between the supine and upright positions-A feasibility study for prostate treatments in the upright position

Treating and imaging patients in the upright orientation is gaining acceptance in radiation oncology and radiology and has distinct advantages over the recumbent position. An IRB approved study to investigate the positions and orientations of the male pelvic organs between the supine and upright positions was conducted. The study comprised of scanning 15 male volunteers (aged 55-75 years) on a 0.6 T Fonar MRI scanner in the supine and upright positions with a full bladder and in the upright position with an empty bladder. The Pelvic study revealed that in the upright position the 1. Position and shape of the prostate are not impacted significantly by bladder fill. 2. Distance between the sacrum and the anterior bladder wall is significantly smaller. 3. Anterior-Posterior length and the bladder width is significantly larger. 4. Seminal vesicles are pushed down by the bladder. 5. Top of the penile bulb is further away from the apex of the prostate. These observed differences could positively impact upright prostate treatments by 1. Reducing the risk of small bowel approximating the treatment volume. 2. Prostate treatments can be done with a reduced focus on bladder fill. 3. Radiation beams for treating intermediate risk prostrate can be made smaller or a larger portion of the seminal vesicles can be treated with the same beam size than typically used for supine treatments. 4. Reducing the average dose to the penile bulb.

Time to consider the potential role of alternative resistance training methods in cancer management?

Exercise has emerged as fundamental therapeutic medicine in the management of cancer. Exercise improves health-related outcomes, including quality of life, neuromuscular strength, physical function, and body composition, and it is associated with a lower risk of disease recurrence and increased survival. Moreover, exercise during or post cancer treatments is safe, can ameliorate treatment-related side effects, and may enhance the effectiveness of chemotherapy and radiation therapy. To date, traditional resistance training (RT) is the most used RT modality in exercise oncology. However, alternative training modes, such as eccentric, cluster set, and blood flow restriction are gaining increased attention. These training modalities have been extensively investigated in both athletic and clinical populations (e.g., age-related frailty, cardiovascular disease, type 2 diabetes), showing considerable benefits in terms of neuromuscular strength, hypertrophy, body composition, and physical function. However, these training modes have only been partially or not at all investigated in cancer populations. Thus, this study outlines the benefits of these alternative RT methods in patients with cancer. Where evidence in cancer populations is sparse, we provide a robust rationale for the possible implementation of certain RT methods that have shown positive results in other clinical populations. Finally, we provide clinical insights for research that may guide future RT investigations in patients with cancer and suggest clear practical applications for targeted cancer populations and related benefits.

Barriers and Facilitators of Artificial Intelligence in Family Medicine: An Empirical Study With Physicians in Saudi Arabia

BACKGROUND

Artificial intelligence (AI) is a novel technology that has been widely acknowledged for its potential to improve the processes' efficiency across industries. However, its barriers and facilitators in healthcare are not completely understood due to its novel nature.

STUDY PURPOSE

The purpose of this study is to explore the intricate landscape of AI use in family medicine, aiming to uncover the factors that either hinder or enable its successful adoption.

METHODS

A cross-sectional survey design is adopted in this study. The questionnaire included 10 factors (performance expectancy, effort expectancy, social influence, facilitating conditions, behavioral intention, trust, perceived privacy risk, personal innovativeness, ethical concerns, and facilitators) affecting the acceptance of AI. A total of 157 family physicians participated in the online survey.

RESULTS

Effort expectancy (μ = 3.85) and facilitating conditions (μ = 3.77) were identified to be strong influence factors. Access to data (μ = 4.33), increased computing power (μ = 3.92), and telemedicine (μ = 3.78) were identified as major facilitators; regulatory support (μ = 2.29) and interoperability standards (μ = 2.71) were identified as barriers along with privacy and ethical concerns. Younger individuals tend to have more positive attitudes and expectations toward AI-enabled assistants compared to older participants (p < .05). Perceived privacy risk is negatively correlated with all factors.

CONCLUSION

Although there are various barriers and concerns regarding the use of AI in healthcare, the preference for AI use in healthcare, especially family medicine, is increasing.

Bridging the Communication Gaps: A Prospective Single-Arm Pilot Study Testing the Feasibility of Interdisciplinary Radiotherapy Planning in Locally Advanced Lung Cancer

RATIONALE AND OBJECTIVES

The treatment of locally advanced lung cancer (LALC) with radiotherapy (RT) can be challenging. Multidisciplinary collaboration between radiologists and radiation oncologists (ROs) may optimize RT planning, reduce uncertainty in follow-up imaging interpretation, and improve outcomes.

MATERIALS AND METHODS

In this prospective clinical treatment trial (clinicaltrials.gov NCT04844736), 37 patients receiving definitive RT for LALC, six attending ROs, and three thoracic radiologists were consented and enrolled across four treatment centers. Prior to RT plan finalization, representative computed tomography (CT) slices with overlaid outlines of preliminary irradiation targets were shared with the team of radiologists. The primary endpoint was to assess feasibility of receiving feedback no later than 4 business days of RT simulation on at least 50% of plans.

RESULTS

Thirty-seven patients with lung cancer were enrolled, and 35 of 37 RT plans were reviewed. Of the 35 patients reviewed, mean age was 69 years. For 27 of 37 plans (73%), feedback was received within 4 or fewer days (interquartile range 3-4 days). Thirteen of 35 cases (37%) received feedback that the delineated target potentially did not include all sites suspicious for tumor involvement. In total, changes to the RT plan were recommended for over- or undercoverage in 16 of 35 cases (46%) and implemented in all cases. Radiology review resulted in no treatment delays and substantial changes to irradiated volumes: gross tumor volume, -1.9 to +96.1%; planning target volume, -37.5 to +116.5%.

CONCLUSION

Interdisciplinary collaborative RT planning using a simplified workflow was feasible, produced no treatment delays, and prompted substantial changes in RT targets.

Intrafractional Diaphragm Variations During Breath-Hold Stereotactic Body Radiotherapy for a Liver Tumor Based on Real-Time Registration Between Kilovoltage Projection Streaming and Digitally Reconstructed Radiograph Images: A Case Report

In liver stereotactic body radiotherapy (SBRT), precise image guidance is paramount, serving as the foundation of this treatment approach. The accuracy of SBRT in liver cancer treatment heavily relies on meticulous imaging techniques. The diaphragm, situated adjacent to the liver, is a crucial anatomical structure susceptible to positional and motion variations, which can potentially impact the accuracy of liver tumor targeting. This study explores the application of real-time kilovoltage projection streaming images (KVPSI) in comparison to digitally reconstructed radiography (DRR) for assessing diaphragm position deviations during breath-hold liver tumor SBRT. A 76-year-old male diagnosed with cholangiocarcinoma underwent breath-hold SBRT using split arc volumetric modulated arc therapy (VMAT), where a full arc was split into six sub-arcs, each spanning 60 degrees. The diaphragm dome positions were continuously monitored through KVPSI during treatment. The intrafractional position deviations of the diaphragm were calculated and analyzed for each split arc. The case report revealed a mean diaphragm dome deviation of 0.47 mm (standard deviation: 4.47 mm) in the entire arc. This pioneering study showcases the feasibility of intrafractional diaphragm position variation assessment using real-time KVPSI during the breath-hold liver tumor VMAT-SBRT. Integrating real-time imaging techniques enhances our comprehension of the intra-breath-hold variations, thereby guiding adaptive treatment strategies and potentially improving treatment outcomes. Clinical validation through further research is essential.

A quick guide on implementing and quality assuring 3D printing in radiation oncology

As three-dimensional (3D) printing becomes increasingly common in radiation oncology, proper implementation, usage, and ongoing quality assurance (QA) are essential. While there have been many reports on various clinical investigations and several review articles, there is a lack of literature on the general considerations of implementing 3D printing in radiation oncology departments, including comprehensive process establishment and proper ongoing QA. This review aims to guide radiation oncology departments in effectively using 3D printing technology for routine clinical applications and future developments. We attempt to provide recommendations on 3D printing equipment, software, workflow, and QA, based on existing literature and our experience. Specifically, we focus on three main applications: patient-specific bolus, high-dose-rate (HDR) surface brachytherapy applicators, and phantoms. Additionally, cost considerations are briefly discussed. This review focuses on point-of-care (POC) printing in house, and briefly touches on outsourcing printing via mail-order services.

Clinical validation of SARC-F by proxy as a practical tool to evaluate sarcopenia in dependent older adults

INTRODUCTION

Sarcopenia is a prevalent disorder in older adults with significant adverse outcomes and regular screening is recommended for those at risk. The SARC-F questionnaire is the most commonly recommended screening tool for sarcopenia. However, as a self-reported tool, it cannot be applied to dependent individuals with communication problems. We hypothesized that implementation of the proxy-reported SARC-F (SARC-F by proxy) would be non-inferior in screening sarcopenia when compared with the standard SARC-F. Thus, we aimed to investigate the clinical validity of the SARC-F by proxy in identifying sarcopenia in older adults and to compare its performance with the standard SARC-F. Additionally, we aimed to determine the ideal cut-off of SARC-F by proxy in screening sarcopenia.

MATERIALS AND METHODS

This is a validation study including older adults aged ≥60 years without communication problems and their close proxies. The participants were recruited from a geriatric outpatient clinic of a tertiary health center and a nursing home. Standard SARC-F was transformed to SARC-F by proxy and administered to the proxies of older adults, and standard SARC-F was administered to the patients simultaneously in different rooms. We defined sarcopenia as probable and confirmed by the EWGSOP2 consensus report. We performed receiver operating characteristics (ROC) and sensitivity/specificity analyses of SARC-F by proxy for diagnosing sarcopenia and compared its performance with standard SARC-F by the DeLong test.

RESULTS

We included 172 older adults (median age: 72; 44.8% female) and 107 proxies in close contact (median age: 55, 63.2% female). The prevalence of probable and confirmed sarcopenia was 18.9% and 12.9%, respectively. For both definitions, area under the curve (AUC) values of SARC-F by proxy and standard SARC-F were moderate and similar [probable sarcopenia: 0.619 and 0.624 (p = 0.9); confirmed sarcopenia 0.613 and 0.645 (p = 0.7), respectively]. The best balance between sensitivity and specificity was achieved with a SARC-F by proxy score of ≥2 for both sarcopenia definitions (sensitivity levels were 74.7% and 77.8%, and specificity levels were 50.0% and 49.6%, for probable and confirmed sarcopenia, respectively).

DISCUSSION

SARC-F by proxy showed a similar, non-inferior performance compared to the standard SARC-F in the evaluation of sarcopenia. Our results suggest that it can be used instead of standard SARC-F to screen sarcopenia in older patients with communication problems. Further validation studies in different populations are warranted to support our findings.

Comparison and evaluation of different deep learning models of synthetic CT generation from CBCT for nasopharynx cancer adaptive proton therapy

BACKGROUND

Cone-beam computed tomography (CBCT) scanning is used for patient setup in image-guided radiotherapy. However, its inaccurate CT numbers limit its applicability in dose calculation and treatment planning.

PURPOSE

This study compares four deep learning methods for generating synthetic CT (sCT) to determine which method is more appropriate and offers potential for further clinical exploration in adaptive proton therapy for nasopharynx cancer.

METHODS

CBCTs and deformed planning CT (dCT) from 75 patients (60/5/10 for training, validation and testing) were used to compare cycle-consistent Generative Adversarial Network (cycleGAN), Unet, Unet+cycleGAN and conditionalGenerative Adversarial Network (cGAN) for sCT generation. The sCT images generated by each method were evaluated against dCT images using mean absolute error (MAE), structural similarity (SSIM), peak signal-to-noise ratio (PSNR), spatial non-uniformity (SNU) and radial averaging in the frequency domain. In addition, dosimetric accuracy was assessed through gamma analysis, differences in water equivalent thickness (WET), and dose-volume histogram metrics.

RESULTS

The cGAN model has demonstrated optimal performance in the four models across various indicators. In terms of image quality under global condition, the average MAE has been reduced to 16.39HU, SSIM has increased to 95.24%, and PSNR has increased to 28.98. Regarding dosimetric accuracy, the gamma passing rate (2%/2 mm) has reached 99.02%, and the WET difference is only 1.28 mm. The D95 value of CTVs coverage and Dmax value of spinal cord, brainstem show no significant differences between dCT and sCT generated by cGAN model.

CONCLUSIONS

The cGAN model has been shown to be a more suitable approach for generating sCT using CBCT, considering its characteristics and concepts. The resulting sCT has the potential for application in adaptive proton therapy.

Development of an age- and comorbidity- adjusted optimal radiotherapy utilisation rate for lung, rectal, prostate and cervical cancers

INTRODUCTION

Optimal radiotherapy utilisation (RTU) modelling estimates the proportion of people with cancer who would benefit from radiotherapy. Assessment of comorbidities is an important component of the assessment of suitability for radiotherapy in addition to chronological age and life expectancy. Comorbidities have not been considered in previous optimal RTU models. We aimed to develop an age- and comorbidity- adjusted optimal RTU model for patients with lung, rectal, prostate, and cervical cancer, and compare them to actual RTU rates, with a particular focus on those aged 80+ years, METHODS: New South Wales (NSW) Cancer Registry data (2010-2014) linked to radiotherapy data (2010-2015) and hospitalisation data (2008-2015) were used to determine the number of patients diagnosed with lung, rectal, prostate and cervical cancer. The Cancer Specific C3 'all sites' comorbidity index was calculated from hospital diagnosis data for each patient to determine suitability for radiotherapy. The index was then incorporated into a tumour site-specific decision tree model. The actual RTU was also calculated using the linked datasets.

RESULTS

14,696 patients were diagnosed with non-small cell lung cancer (NSCLC), 1839 with small cell lung cancer (SCLC), 5551 with rectal cancer, 30,935 with prostate cancer and 1216 with cervical cancer in New South Wales from 2010-2014. The proportion of patients aged 80+ years at cancer diagnosis was 25% (3603 patients), 15% (279 patients), 17% (943 patients), 12% (3745 patients), and 7% (88 patients) respectively. The age- and comorbidity- adjusted optimal RTU rates for patients aged 80+ years using the C3 index were 49% (NSCLC), 49% (SCLC), 43% (rectal), 51% (prostate) and 40% (cervical). The corresponding actual RTU rates for patients aged 80+ years were 25%, 32%, 27%, 16%, and 56%.

CONCLUSION

Even after adjusting for age and comorbidities, the actual radiotherapy utilisation rates were lower than optimal radiotherapy utilisation rates in patients aged 80+ years except for patients with cervical cancer. This warrants further assessment and research into reasons and solutions.

Plan robustness evaluation strategies in whole-pelvic proton therapy for high-risk prostate cancer patients within a randomised clinical trial

BACKGROUND

Inter-fractional anatomical changes challenge robust delivery of whole-pelvic proton therapy for high-risk prostate cancer. Pre-treatment robust evaluation (PRE) takes uncertainties in isocenter shifts and distal beam edge in treatment plans into account. Using weekly control computed tomography scans (cCTs), the aim of this study was to evaluate the PRE strategy by comparing to an off-line during-treatment robust evaluation (DRE) while also assessing plan robustness with respect to protocol planning constraints.

MATERIAL AND METHODS

Treatment plans and cCTs from ten patients included in the pilot phase of the PROstate PROTON Trial 1 were analysed. Treatment planning followed protocol guidelines with 78 Gy to the primary clinical target volume (CTVp) and 56 Gy to the elective target (CTVe) in 39 fractions. Recalculations of the treatment plans were performed for a total of 64 cCTs and dose/volume measures corresponding to clinical constraints were evaluated for this DRE against the simulated scenario interval from the PRE.

RESULTS

Of the 64 cCTs, 59 showed DRE CTVp measures within the robustness range from the PRE; this was also the case for 39 of the cCTs for the CTVe measures. However, DRE CTVe coverage was still within constraints for 57 of the 64 cCTs. DRE dose/volume measures for CTVp fulfilled target coverage constraints in 59 of 64 cCTs. All DRE measures for the rectum, bladder, and bowel were inside the PRE range in 63, 39, and 31 cCTs, respectively.

CONCLUSION

The PRE strategy predicted the DRE scenarios for CTVp and rectum. CTVe, bladder, and bowel showed more complex anatomical variations than simulated by the PRE isocenter shift. Both original and recalculated nominal treatment plans showed robust treatment delivery in terms of target coverage.

Geometric distortions in clinical MRI sequences for radiotherapy: insights gained from a multicenter investigation

BACKGROUND

As magnetic resonance imaging (MRI) becomes increasingly integrated into radiotherapy (RT) for enhanced treatment planning and adaptation, the inherent geometric distortion in acquired MR images pose a potential challenge to treatment accuracy. This study aimed to evaluate the geometric distortion levels in the clinical MRI protocols used across Danish RT centers and discuss influence of specific sequence parameters. Based on the variety in geometric performance across centers, we assess if harmonization of MRI sequences is a relevant measure.

MATERIALS AND METHODS

Nine centers participated with 12 MRI scanners and MRI-Linacs (MRL). Using a travelling phantom approach, a reference MRI sequence was used to assess variation in baseline distortion level between scanners. The phantom was also scanned with local clinical MRI sequences for brain, head/neck (H/N), abdomen, and pelvis. The influence of echo time, receiver bandwidth, image weighting, and 2D/3D acquisition was investigated.

RESULTS

We found a large variation in geometric accuracy across 93 clinical sequences examined, exceeding the baseline variation found between MRI scanners (σ = 0.22 mm), except for abdominal sequences where the variation was lower. Brain and abdominal sequences showed lowest distortion levels ([0.22, 2.26] mm), and a large variation in performance was found for H/N and pelvic sequences ([0.19, 4.07] mm). Post hoc analyses revealed that distortion levels decreased with increasing bandwidth and a less clear increase in distortion levels with increasing echo time. 3D MRI sequences had lower distortion levels than 2D (median of 1.10 and 2.10 mm, respectively), and in DWI sequences, the echo-planar imaging read-out resulted in highest distortion levels.

CONCLUSION

There is a large variation in the geometric distortion levels of clinical MRI sequences across Danish RT centers, and between anatomical sites. The large variation observed makes harmonization of MRI sequences across institutions and adoption of practices from well-performing anatomical sites, a relevant measure within RT.

Correlation between the setting of gating window width and setup accuracy in left breast cancer radiotherapy based on deep inspiration breath hold

Personalized precision irradiation of patients with left-sided breast cancer is possible by examining the setup errors of 3- and 4-mm gated window widths for those treated with deep inspiration breath-hold (DIBH) treatment. An observational study was performed via a retrospective analysis of 250 cone-beam computed tomography (CBCT) images of 60 left-breast cancer patients who underwent whole-breast radiotherapy with the DIBH technique between January 2021 and 2022 at our hospital. Among them, 30 patients had a gated window width of 3 mm, while the remaining 30 had a gated window width of 4 mm; both groups received radiotherapy using DIBH technology. All patients underwent CBCT scans once a week, and the setup errors in the left-right (x-axis), inferior-superior (y-axis), and anterior-posterior (z-axis) directions were recorded. The clinical-to-planning target volume (CTV-PTV) margins of the two gating windows were calculated using established methods. The setup error in the Y direction was 1.69 ± 1.33 mm for the 3-mm - wide gated window and 2.42 ± 3.02 mm for the 4-mm - wide gated window. The two groups had statistically significant differences in the overall mean setup error (Dif 0.7, 95% CI 0.15-1.31, t = 2.48, p= 0.014). The Z-direction setup error was 2.32 ± 2.12 mm for the 3-mm - wide gated window and 3.15 ± 3.34 mm for the 4-mm - wide gated window. The overall mean setup error was statistically significant between the two groups (Dif 0.8, 95% CI 0.13-1.53, t= 2.34, p = 0.020). There was no significant difference in the X-direction setup error (p > 0.05). Therefore, the CTV-PTV margin values for a 3-mm gated window width in the X, Y, and Z directions are 5.51, 5.15, and 7.28 mm, respectively; those for a 4-mm gated window width in the X, Y, and Z directions are 5.52, 8.16, and 10.21 mm, respectively. The setup errors of the 3-mm - wide gating window are smaller than those of the 4-mm - wide gating window in the three dimensions. Therefore, when the patient's respiratory gating window width is reduced, the margin values of CTV-PTV can be reduced to increase the distance between the PTV and the organs at risk (OARs), which ensures adequate space for the dose to decrease, resulting in lower dose exposure to the OARs (heart, lungs, etc.), thus sparing the OARs from further damage. However, some patients with poor pulmonary function or unstable breathing amplitudes must be treated with a slightly larger gating window. Therefore, this study lays a theoretical basis for personalized precision radiotherapy, which can save time and reduce manpower in the delivery of clinical treatment to a certain extent. Another potential benefit of this work is to bring awareness to the potential implications of a slightly larger gating window during treatment without considering the resulting dosimetric impact.

Pretreatment Masseter Muscle Volume Predicts Survival in Locally Advanced Nasopharyngeal Carcinoma Patients Treated with Concurrent Chemoradiotherapy

BACKGROUND AND PURPOSE

Muscle loss is a significant indicator of cancer cachexia and is associated with a poor prognosis in cancer patients. Given the absence of comparable studies, the current retrospective study sought to examine the correlation between the total masseter muscle volume (TMMV) before treatment and the survival outcomes in locally advanced nasopharyngeal cancer (LA-NPC) patients who received definitive concurrent chemoradiotherapy (CCRT).

METHODS

A three-dimensional segmentation model was used to determine the TMMV for each patient by analyzing pre-CCRT magnetic resonance imaging. The optimal TMMV cutoff values were searched using receiver operating characteristic (ROC) curve analyses. The primary and secondary endpoints were the relationship between the pre-CCRT TMMV measures and overall survival (OS) and progression-free survival (PFS), respectively.

RESULTS

Ninety-seven patients were included in this study. ROC curve analyses revealed 38.0 cc as the optimal TMMV cutoff: ≤38.00 cc (n = 42) and >38.0 cc (n = 55). Comparisons between the two groups showed that the TMMV>38.0 cc group had significantly longer PFS [Not reached (NR) vs. 28; p < 0.01] and OS (NR vs. 71; p < 0.01) times, respectively. The results of the multivariate analysis demonstrated that the T-stage, N-stage, number of concurrent chemotherapy cycles, and TMMV were independent associates of PFS (p < 0.05 for each) and OS (p < 0.05 for each) outcomes, respectively.

CONCLUSION

The findings of the current retrospective research suggest that pretreatment TMMV is a promising indicator for predicting survival outcomes in LA-NPC patients receiving definitive CCRT.

Dose-effect relationship of linear accelerator based stereotactic radiotherapy for brain metastases

OBJECTIVE

The purpose of this study is to reveal the dose-effect relationship of linear accelerator (LINAC)-based stereotactic radiotherapy (SRT) in patients with brain metastases (BM).

MATERIALS AND METHODS

The PubMed, Cochrane, and Web of Science databases were used to identify studies that reported local tumour control after LINAC-based SRT in patients with BMs. Studies of other approaches that could affect local tumour control, such as whole brain radiotherapy, targeted therapy, and immunotherapy, were excluded from the dose-effect relationship analysis. Data extracted included patient and treatment characteristics and tumour local control. Probit model in XLSTAT 2016 was used for regression analysis, and P < 0.05 was set as the statistically significant level.

RESULTS

After literature screening, 19 eligible studies involving 1523 patients were included in the probit model regression analysis. There was no significant dose-effect relationship between nominal BED10 and peripheral BED10 versus 12-month local control probability. There were significant dose effect relationships between the centre BED10 and the average BED10 versus the 12-month local control probability, with P values of 0.015 and 0.011, respectively. According to the model, the central BED10 and the average BED10 corresponding to probabilities of 90% 12-month local control were 109.2 GyBED10 (95% confidence interval (CI): 88.7-245.9 GyBED10) and 87.8 GyBED10 (95% CI: 74.3-161.5 GyBED10), respectively. A 12-month local control rate of 86.9% (95% CI: 81.7-89.7%) and 85.5% (95% CI: 81.2-89.2%) can be expected at a centre BED10 of 80 Gy and an average BED10 of 60 Gy, respectively.

CONCLUSION

For patients with BM treated with LINAC-based SRT, more attention should be given to the central and average doses of PTV. A clear definition of the dose prescription should be established to ensure the effectiveness and comparability of treatment.

Preventing Cardiotoxicity in Personalized Breast Irradiation

BACKGROUND

This study aims to assess the benefit of a deep inspiration breath hold (DIBH) over the standard irradiation technique, and eventually to identify anatomical and/or treatment preplanning characteristics correlated with the LAD dose.

METHODS

Patients with left-sided breast cancer undergoing whole breast radiotherapy with DIBH were analyzed. All patients included in the analysis had plans in DIBH and free-breathing (FB). Receiving operating characteristics (ROC analysis) were used to identify the cut-off point of parameters to predict the LAD maximum dose > 10 Gy and LAD mean dose > 4 Gy, and the areas under the curve (AUCs) were computed. Post-test probability has been performed to evaluate the effect of parameters' combination.

RESULTS

One hundred ninety-seven patients were analyzed. The LAD dose was significantly reduced in DIBH plans with the maximum and mean dose reduced by 31.7% (mean value 3.5 Gy vs. 4.8 Gy, p ≤ 0.001) and 28.1% (mean value 8.2 Gy vs. 12.8 Gy, p ≤ 0.001) in DIBH plans compared to FB plans. The strongest predictor of the LAD dose (maximum > 10 Gy and mean > 4 Gy) was the minimum distance of LAD from tangent open fields. Other parameters were lung volume and heart volume (LAD Dmax > 10 Gy) and lung volume, heart volume, and breast separation (LAD Dmean > 4 Gy).

CONCLUSION

The dosimetric advantage of DIBH is clear in all patients and DIBH should always be preferred.

Proton Therapy in the Treatment of Men with Breast Cancer

Purpose

Male breast cancer treatment involves multimodality therapy, including radiation therapy; nevertheless, few men have received proton therapy (PT) for it. Further, heart disease is an established leading cause of death in men, and radiation therapy heart dose correlates with cardiac toxicity, highlighting the need for cardiac-sparing radiation techniques. Thus, we provide a descriptive analysis of PT in a male breast cancer cohort.

Patients and Methods

Men who received PT for localized breast cancer between 2012 and 2022 were identified from a prospective database. Toxicities were prospectively recorded by using the Common Terminology Criteria for Adverse Events (CTCAE), version 4.0.

Results

Five male patients were identified. All had estrogen receptor (ER)-positive, Her2neu-negative disease and received adjuvant endocrine therapy. One had genetic testing positive for BRCA2, one had a variant of unknown significance (VUS) in the APC gene, and one had a VUS in MSH2. Median age was 73 years (range, 41-80). Baseline comorbidities included obesity (n = 1), diabetes (n = 1), hypertension (n = 4), history of deep vein thrombosis (n = 1), personal history of myocardial infarction (n = 3; 1 with a pacemaker), and a history of lung cancer (n = 1). All received PT to the left chest wall and comprehensive regional lymphatics. One received passive-scattering PT, and 4 received pencil beam scanning. One patient received a boost to the mastectomy incision via electrons. Median heart dose was 1 GyRBE (range, 0-1.0), median 0.1-cm3 dose to the left anterior descending artery was 7.5 GyRBE (range, 0-14.2), and median follow-up was 2 years (range, 0.75-6.5); no patient experienced a new cardiac event, and all remain free from breast cancer recurrence and progression.

Conclusion

In a small case series for a rare diagnosis, PT to the chest wall and regional lymphatics, including internal mammary nodes, resulted in low cardiac exposure, high local regional disease control rates, and minimal toxicity. Proton therapy should be considered for treating men with breast cancer to achieve cardiac sparing.

Surface-Guided Radiotherapy: Can We Move on from the Era of Three-Point Markers to the New Era of Thousands of Points?

The surface-guided radiotherapy (SGRT) technique improves patient positioning with submillimeter accuracy compared with the conventional positioning technique of lasers using three-point tattoos. SGRT provides solutions to considerations that arise from the conventional setup technique, such as variability in tattoo position and the psychological impact of the tattoos. Moreover, SGRT provides monitoring of intrafractional motion.

PURPOSE

This literature review covers the basics of SGRT systems and examines whether SGRT can replace the traditional positioning technique. In addition, it investigates SGRT's potential in reducing positioning times, factors affecting SGRT accuracy, the effectiveness of live monitoring, and the impact on patient dosage.

MATERIALS AND METHODS

This study focused on papers published from 2016 onward that compared SGRT with the traditional positioning technique and investigated factors affecting SGRT accuracy and effectiveness.

RESULTS/CONCLUSIONS

SGRT provides the same or better results regarding patient positioning. The implementation of SGRT can reduce overall treatment time. It is an effective technique for detecting intrafraction patient motion, improving treatment accuracy and precision, and creating a safe and comfortable environment for the patient during treatment.

Exploring the implications of modified advanced lung cancer inflammation index on outcomes in patients with advanced non-small cell lung cancer

Aim

Sarcopenia and skeletal muscle density (SMD) have been shown to be both predictive and prognostic marker in oncology. Advanced lung cancer inflammation index (ALI) has been shown to predict overall survival (OS) in small cell lung cancer (SCLC). Computed tomography (CT) enables skeletal muscle to be quantified, whereas body mass index (BMI) cannot accurately reflect body composition. The purpose was to evaluate the prognostic value of modified ALI (mALI) using CT-determined third lumbar vertebra (L3) muscle index beyond original ALI and see the interaction between sarcopenia, SMD, neutrophil-lymphocyte ratio (NLR), ALI and mALI at baseline and post 4 cycles of chemotherapy and their effects on OS and progress free survival (PFS) in patients with advanced non-SCLC (NSCLC).

Methods

This retrospective study consisted of a total of 285 advanced NSCLC patients. The morphometric parameters such as SMD, skeletal muscle index (SMI) and fat-free mass (FFM) were measured by CT at the L3 vertebra. ALI was defined as BMI × serum albumin/NLR and mALI was defined as SMI × serum albumin/NLR.

Results

Sarcopenia was observed in over 70% of patients across all BMI categories. Patients having sarcopenia suffered from a higher incidence of chemotherapeutic drug toxicities but this was not found to be statistically significant. Concordance was seen between ALI and mALI in the pre-treatment setting and this was statistically significant. A significant proportion of patients with poor ALI (90.9%), poor pre-chemotherapy mALI (91.3%) and poor post-chemotherapy mALI (89%) had poor NLR and each of them was statistically significant.

Conclusions

In both univariate and multivariate analyses, this study demonstrated the statistical significance of sarcopenia, SMD, and mALI as predictive factors for OS. Additionally, sarcopenia and SMD were also found to be statistically significant factors in predicting PFS. These biomarkers could potentially help triage patients for active nutritional intervention for better outcomes.

Clinical outcomes after online adaptive MR-guided stereotactic body radiotherapy for pancreatic tumors on a 1.5 T MR-linac

Introduction

Online adaptive magnetic resonance-guided radiotherapy (MRgRT) is a promising treatment modality for pancreatic cancer and is being employed by an increasing number of centers worldwide. However, clinical outcomes have only been reported on a small scale, often from single institutes and in the context of clinical trials, in which strict patient selection might limit generalizability of outcomes. This study presents clinical outcomes of a large, international cohort of patients with (peri)pancreatic tumors treated with online adaptive MRgRT.

Methods

We evaluated clinical outcomes and treatment details of patients with (peri)pancreatic tumors treated on a 1.5 Tesla (T) MR-linac in two large-volume treatment centers participating in the prospective MOMENTUM cohort (NCT04075305). Treatments were evaluated through schematics, dosage, delivery strategies, and success rates. Acute toxicity was assessed until 3 months after MRgRT started, and late toxicity from 3-12 months of follow-up (FU). The EORTC QLQ-C30 questionnaire was used to evaluate the quality of life (QoL) at baseline and 3 months of FU. Furthermore, we used the Kaplan-Meier analysis to calculate the cumulative overall survival.

Results

A total of 80 patients were assessed with a median FU of 8 months (range 1-39 months). There were 34 patients who had an unresectable primary tumor or were medically inoperable, 29 who had an isolated local recurrence, and 17 who had an oligometastasis. A total of 357 of the 358 fractions from all hypofractionated schemes were delivered as planned. Grade 3-4 acute toxicity occurred in 3 of 59 patients (5%) with hypofractionated MRgRT and grade 3-4 late toxicity in 5 of 41 patients (12%). Six patients died within 3 months after MRgRT; in one of these patients, RT attribution could not be ruled out as cause of death. The QLQ-C30 global health status remained stable from baseline to 3 months FU (70.5 at baseline, median change of +2.7 [P = 0.5]). The 1-year cumulative overall survival for the entire cohort was 67%, and that for the primary tumor group was 66%.

Conclusion

Online adaptive MRgRT for (peri)pancreatic tumors on a 1.5 T MR-Linac could be delivered as planned, with low numbers of missed fractions. In addition, treatments were associated with limited grade 3-4 toxicity and a stable QoL at 3 months of FU.

A spot-specific range uncertainty framework for robust optimization of proton therapy treatments

PURPOSE

An accurate estimation of range uncertainties is essential to exploit the potential of proton therapy. According to Paganetti's study, a value of 2.4% (1.5 standard deviation) is currently recommended for planning robust treatments with Monte Carlo dose engines. This number is based on a dominant contribution from the mean excitation energy of tissues. However, it was recently shown that expressing tissues as a mixture of water and "dry" material in the CT calibration process allowed for a significant reduction of this uncertainty. We thus propose an adapted framework for pencil beam scanning robust optimization. First, we move towards a spot-specific range uncertainty (SSRU) determination. Second, we use the water-based formalism to reduce range uncertainties and, potentially, to spare better the organs at risk.

METHODS

The stoichiometric calibration was adapted to provide a molecular decomposition (including water) of each voxel of the CT. The SSRU calculation was implemented in MCsquare, a fast Monte Carlo dose engine dedicated to proton therapy. For each spot, a ray-tracing method was used to propagate molecular I-values uncertainties and obtain the corresponding effective range uncertainty. These were then combined with other sources of range uncertainties, according to Paganetti's study of 2012. The method was then assessed on three head-and-neck patients. Two plans were optimized for each patient: the first one with the classical 2.4% flat range uncertainty (FRU), the second one with the variable range uncertainty. Both plans were then compared in terms of target coverage and OAR mean dose reduction. Robustness evaluations were also performed, using the SSRU for both plans in order to simulate errors as realistically as possible.

RESULTS

For patient 1, it was found that the median SSRU was 1.04% (1.5 standard deviation), yielding, therefore, a very large reduction from the 2.4% FRU. All three SSRU plans were found to have a very good robustness level at a 90% confidence interval while sparing OAR better than the classical plan. For instance, in nominal cases, average reductions in the mean dose of 15.7, 8.4, and 13.2% were observed in the left parotid, right parotid, and pharyngeal constrictor muscle, respectively. As expected, the classical plans showed a higher but unnecessary level of robustness.

CONCLUSIONS

Promising results of the SSRU framework were observed on three head-and-neck cases, and more patients should now be considered. The method could also benefit to other tumor sites and, in the long run, the variable part of the range uncertainty could be generalized to other sources of uncertainty in order to move towards more and more patient-specific treatments.

Evaluation of the clinical feasibility of cone-beam computed tomography guided online adaption for simulation-free palliative radiotherapy

Background and purpose

Simulation-free radiotherapy, where diagnostic imaging is used for treatment planning, improves accessibility of radiotherapy for eligible palliative patients. Combining this pathway with online adaptive radiotherapy (oART) may improve accuracy of treatment, expanding the number of eligible patients. This study evaluated the adaptive process duration, plan dose volume histogram (DVH) metrics and geometric accuracy of a commercial cone-beam computed tomography (CBCT)-guided oART system for simulation-free, palliative radiotherapy.

Materials and methods

Ten previously treated palliative cases were used to compare system-generated contours against clinician contours in a test environment with Dice Similarity Coefficient (DSC). Twenty simulation-free palliative patients were treated clinically using CBCT-guided oART. Analysis of oART clinical treatment data included; evaluation of the geometric accuracy of system-generated synthetic CT relative to session CBCT anatomy using a Likert scale, comparison of adaptive plan dose distributions to unadapted, using DVH metrics and recording the duration of key steps in the oART workflow.

Results

Auto-generated contours achieved a DSC of higher than 0.85, excluding the stomach which was attributed to CBCT image quality issues. Synthetic CT was locally aligned to CBCT anatomy for approximately 80% of fractions, with the remaining suboptimal yet clinically acceptable. Adaptive plans achieved a median CTV V95% of 99.5%, compared to 95.6% for unadapted. The median overall oART process duration was found to be 13.2 mins, with contour editing being the most time-intensive adaptive step.

Conclusions

The CBCT-guided oART system utilising a simulation-free planning approach was found to be sufficiently accurate for clinical implementation, this may further streamline and improve care for palliative patients.

Barrier films for the prevention of acute radiation dermatitis in breast cancer: A systematic review and meta-analysis of randomised controlled trials

PURPOSE

Radiation dermatitis (RD) is the most common side effect of adjuvant whole-breast or chest wall irradiation, majorly impacting quality of life in numerous patients. The use of barrier films (polyurethane dressings such as Hydrofilm® and Mepitel® film remaining on the skin for the duration of the radiation treatment) has been investigated as a prophylactic measure in several prospective trials. Here, we critically appraise the available evidence behind preventive barrier film application in the context of breast cancer treatment.

METHODS

International literature was reviewed and high-quality randomised controlled trials (RCTs) were included in this meta-analysis.

RESULTS

The results of 5 RCTs (663 patients; >90% Caucasian) were analysed. Overall, barrier films lead to improved clinician- and patient-reported outcomes: fewer grade ≥2 RD (11% vs. 42%; OR = 0.16; p < 0.001) and moist desquamation (2% vs. 16%; OR = 0.12; p = 0.006), as well as less patient-reported pain (standardised mean difference [SMD] -0.51; p < 0.001), itching (SMD -0.52; p = 0.001), burning (SMD -0.41; p = 0.011), and limitations in daily activities (SMD -0.20; p = 0.007). Furthermore, barrier films have a high acceptance rate among patients, as well as a favourable cost-benefit ratio. Possible side effects due to its application are mild and mostly self-limiting. Overall, there was a lack of information on the radiation treatment techniques used.

CONCLUSION

The evidence presented in this meta-analysis suggests that barrier films are an excellent tool in the prevention of RD among Caucasian patients receiving whole-breast or chest wall irradiation. Its use should therefore be considered routinely in these patients.

In silico trial of simulation-free hippocampal-avoidance whole brain adaptive radiotherapy

Background and Purpose

Hippocampal-avoidance whole brain radiotherapy (HA-WBRT) can be a time-consuming process compared to conventional whole brain techniques, thus potentially limiting widespread utilization. Therefore, we evaluated the in silico clinical feasibility, via dose-volume metrics and timing, by leveraging a computed tomography (CT)-based commercial adaptive radiotherapy (ART) platform and workflow in order to create and deliver patient-specific, simulation-free HA-WBRT.

Materials and methods

Ten patients previously treated for central nervous system cancers with cone-beam computed tomography (CBCT) imaging were included in this study. The CBCT was the adaptive image-of-the-day to simulate first fraction on-board imaging. Initial contours defined on the MRI were rigidly matched to the CBCT. Online ART was used to create treatment plans at first fraction. Dose-volume metrics of these simulation-free plans were compared to standard-workflow HA-WBRT plans on each patient CT simulation dataset. Timing data for the adaptive planning sessions were recorded.

Results

For all ten patients, simulation-free HA-WBRT plans were successfully created utilizing the online ART workflow and met all constraints. The median hippocampi D100% was 7.8 Gy (6.6-8.8 Gy) in the adaptive plan vs 8.1 Gy (7.7-8.4 Gy) in the standard workflow plan. All plans required adaptation at first fraction due to both a failing hippocampal constraint (6/10 adaptive fractions) and sub-optimal target coverage (6/10 adaptive fractions). Median time for the adaptive session was 45.2 min (34.0-53.8 min).

Conclusions

Simulation-free HA-WBRT, with commercially available systems, was clinically feasible via plan-quality metrics and timing, in silico.

Extensive clinical testing of Deep Learning Segmentation models for thorax and breast cancer radiotherapy planning

BACKGROUND

The performance of deep learning segmentation (DLS) models for automatic organ extraction from CT images in the thorax and breast regions was investigated. Furthermore, the readiness and feasibility of integrating DLS into clinical practice were addressed by measuring the potential time savings and dosimetric impact.

MATERIAL AND METHODS

Thirty patients referred to radiotherapy for breast cancer were prospectively included. A total of 23 clinically relevant left- and right-sided organs were contoured manually on CT images according to ESTRO guidelines. Next, auto-segmentation was executed, and the geometric agreement between the auto-segmented and manually contoured organs was qualitatively assessed applying a scale in the range [0-not acceptable, 3-no corrections]. A quantitative validation was carried out by calculating Dice coefficients (DSC) and the 95% percentile of Hausdorff distances (HD95). The dosimetric impact of optimizing the treatment plans on the uncorrected DLS contours, was investigated from a dose coverage analysis using DVH values of the manually delineated contours as references.

RESULTS

The qualitative analysis showed that 93% of the DLS generated OAR contours did not need corrections, except for the heart where 67% of the contours needed corrections. The majority of DLS generated CTVs needed corrections, whereas a minority were deemed not acceptable. Still, using the DLS-model for CTV and heart delineation is on average 14 minutes faster. An average DSC=0.91 and H95=9.8 mm were found for the left and right breasts, respectively. Likewise, and average DSC in the range [0.66, 0.76]mm and HD95 in the range [7.04, 12.05]mm were found for the lymph nodes.

CONCLUSION

The validation showed that the DLS generated OAR contours can be used clinically. Corrections were required to most of the DLS generated CTVs, and therefore warrants more attention before possibly implementing the DLS models clinically.

Investigation of Intra-fraction Stability and Inter-fraction Consistency of Active Breathing Coordinator (ABC)-Based Deep Inspiration Breath Holds in Left-Sided Breast Cancer

Background Deep inspiration breath-hold (DIBH) has been established as a standard technique to reduce cardiac dose. The part of the heart exposed to radiation can be significantly decreased using the DIBH technique during tangential left-sided breast cancer (LSBC) irradiation. Aim The objective of this study was to investigate the intra-fraction breath-hold stability and inter-fraction consistency of patient breath-hold against the threshold as a function of air volumes in the setting of active breathing coordinator (ABC)-based DIBH (ABC-DIBH) treatment to LSBC. Methods A total of 34 patients treated with external beam radiation therapy (EBRT) to the left breast using the ABC-DIBH device were included. The frequency of breath-holds per fraction and the entire course of treatment along with the total treatment time was evaluated for all patients. A prescription dose of either 200 cGy (conventional) or 267 cGy (hypofractionation) was administered during 649 fractions, resulting in a total of 4,601 breath-hold measurements being evaluated. The amplitude of deviation in terms of air volumes between the baseline threshold and the patient-specific measurement (during each breath-hold) per fraction was used to define the DIBH stability. Likewise, the consistency of the breathing amplitudes was used to define the compliance of patient breath-holds throughout the entire treatment period. Positional accuracy was evaluated using orthogonal (portal) images. Results The average number of breath-holds measured over the entire course of treatment for each patient was 144 inspirations (58-351). Similarly, the average number of breath-holds for each fraction during the course of treatment was 11 inspirations (7-21), which included setup imaging and treatment. The total number of breath-holds reduced significantly (p-value < 0.05) with hypofractionation (104 inspirations; range 58-170) as compared to conventional fractionation (145 inspirations; 58-351). The average breath-hold threshold in terms of air volume was 1.41 L (0.6-2.1 L) for all patients. The total treatment time reduced significantly after the third fraction (p-value < 0.05). The average deviation between the measured and baseline threshold breath-holds during the course of treatment was 0.5 L/sec (0.12-1.32 L/sec). The consistency of the breathing amplitudes were maintained within ±0.05 L during the entire treatment for all patients. The average translational shifts measured during setup were 0.28 cm ± 0.3 cm, 0.38 cm ± 0.4 cm, and 0.21 cm ± 0.3 cm in the lateral, longitudinal, and vertical directions, respectively. Conclusion The study has demonstrated the variations in intra-fraction breath-hold stability and inter-fraction breath-hold consistency in terms of air volumes for patients who were treated for LSBC. The frequency of breath-holds was observed to be higher with increased total treatment time for the first few fractions and reduced over the course of treatment.

Evaluation of a clinically introduced deep learning model for radiotherapy treatment planning of breast cancer

Deep learning (DL) models are increasingly studied to automate the process of radiotherapy treatment planning. This study evaluates the clinical use of such a model for whole breast radiotherapy. Treatment plans were automatically generated, after which planners were allowed to manually adapt them. Plans were evaluated based on clinical goals and DVH parameters. Thirty-seven of 50plans did fulfill all clinical goals without adjustments. Thirteen of these 37 plans were still adjusted but did not improve mean heart or lung dose. These results leave room for improvement of both the DL model as well as education on clinically relevant adjustments.

Impaired Cardiac and Skeletal Muscle Energetics Following Anthracycline Therapy for Breast Cancer

BACKGROUND

Anthracycline-related cardiac toxicity is a recognized consequence of cancer therapies. We assess resting cardiac and skeletal muscle energetics and myocyte, sarcomere, and mitochondrial integrity in patients with breast cancer receiving epirubicin.

METHODS

In a prospective, mechanistic, observational, longitudinal study, we investigated chemotherapy-naive patients with breast cancer receiving epirubicin versus sex- and age-matched healthy controls. Resting energetic status of cardiac and skeletal muscle (phosphocreatine/gamma ATP and inorganic phosphate [Pi]/phosphocreatine, respectively) was assessed with 31P-magnetic resonance spectroscopy. Cardiac function and tissue characterization (magnetic resonance imaging and 2D-echocardiography), cardiac biomarkers (serum NT-pro-BNP and high-sensitivity troponin I), and structural assessments of skeletal muscle biopsies were obtained. All study assessments were performed before and after chemotherapy.

RESULTS

Twenty-five female patients with breast cancer (median age, 53 years) received a mean epirubicin dose of 304 mg/m2, and 25 age/sex-matched controls were recruited. Despite comparable baseline cardiac and skeletal muscle energetics with the healthy controls, after chemotherapy, patients with breast cancer showed a reduction in cardiac phosphocreatine/gamma ATP ratio (2.0±0.7 versus 1.1±0.5; P=0.001) and an increase in skeletal muscle Pi/phosphocreatine ratio (0.1±0.1 versus 0.2±0.1; P=0.022). This occurred in the context of increases in left ventricular end-systolic and end-diastolic volumes (P=0.009 and P=0.008, respectively), T1 and T2 mapping (P=0.001 and P=0.028, respectively) but with preserved left ventricular ejection fraction, mass and global longitudinal strain, and no change in cardiac biomarkers. There was preservation of the mitochondrial copy number in skeletal muscle biopsies but a significant increase in areas of skeletal muscle degradation (P=0.001) in patients with breast cancer following chemotherapy. Patients with breast cancer demonstrated a reduction in skeletal muscle sarcomere number from the prechemotherapy stage compared with healthy controls (P=0.013).

CONCLUSIONS

Contemporary doses of epirubicin for breast cancer treatment result in a significant reduction of cardiac and skeletal muscle high-energy 31P-metabolism alongside structural skeletal muscle changes.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT04467411.

Genomic and Phenotypic Biomarkers for Precision Medicine Guidance in Advanced Prostate Cancer

OPINION STATEMENT

Prostate cancer (PCa) is the second most diagnosed malignant neoplasm and is one of the leading causes of cancer-related death in men worldwide. Despite significant advances in screening and treatment of PCa, given the heterogeneity of this disease, optimal personalized therapeutic strategies remain limited. However, emerging predictive and prognostic biomarkers based on individual patient profiles in combination with computer-assisted diagnostics have the potential to guide precision medicine, where patients may benefit from therapeutic approaches optimally suited to their disease. Also, the integration of genotypic and phenotypic diagnostic methods is supporting better informed treatment decisions. Focusing on advanced PCa, this review discusses polygenic risk scores for screening of PCa and common genomic aberrations in androgen receptor (AR), PTEN-PI3K-AKT, and DNA damage response (DDR) pathways, considering clinical implications for diagnosis, prognosis, and treatment prediction. Furthermore, we evaluate liquid biopsy, protein biomarkers such as serum testosterone levels, SLFN11 expression, total alkaline phosphatase (tALP), neutrophil-to-lymphocyte ratio (NLR), tissue biopsy, and advanced imaging tools, summarizing current phenotypic biomarkers and envisaging more effective utilization of diagnostic and prognostic biomarkers in advanced PCa. We conclude that prognostic and treatment predictive biomarker discovery can improve the management of patients, especially in metastatic stages of advanced PCa. This will result in decreased mortality and enhanced quality of life and help design a personalized treatment regimen.

Influence of air mapping errors on the dosimetric accuracy of prostate CBCT-guided online adaptive radiation therapy

PURPOSE

CBCT-guided online adaptive radiotherapy (oART) plans presently utilize daily synthetic CTs (sCT) that are automatically generated using deformable registration algorithms. These algorithms may have poor performance at reproducing variable volumes of gas present during treatment. Therefore, we have analyzed the air mapping error between the daily CBCTs and the corresponding sCT and explored its dosimetric effect on oART plan calculation.

METHODS

Abdominopelvic air volume was contoured on both the daily CBCT images and the corresponding synthetic images for 207 online adaptive pelvic treatments. Air mapping errors were tracked over all fractions. For two case studies representing worst case scenarios, dosimetric effects of air mapping errors were corrected in the sCT images using the daily CBCT air contours, then recalculating dose. Dose volume histogram statistics and 3D gamma passing rates were used to compare the original and air-corrected sCT-based dose calculations.

RESULTS

All analyzed patients showed observable air pocket contour differences between the sCT and the CBCT images. The largest air volume difference observed in daily CBCT images for a given patient was 276.3 cc, a difference of more than 386% compared to the sCT. For the two case studies, the largest observed change in DVH metrics was a 2.6% reduction in minimum PTV dose, with all other metrics varying by less than 1.5%. 3D gamma passing rates using 1%/1 mm criteria were above 90% when comparing the uncorrected and corrected dose distributions.

CONCLUSION

Current CBCT-based oART workflow can lead to inaccuracies in the mapping of abdominopelvic air pockets from daily CBCT to the sCT images used for the optimization and calculation of the adaptive plan. Despite the large observed mapping errors, the dosimetric effects of such differences on the accuracy of the adapted plan dose calculation are unlikely to cause differences greater than 3% for prostate treatments.

Hand grip strength, short physical performance battery, and gait speed: key tools for function in Non-Hodgkin Lymphoma

This study aimed to determine which performance assessment tools included in Comprehensive Geriatric Assessment (CGA) are the most sensitive for the functional approach in the initial evaluation and during the therapy of old adults diagnosed with Diffuse Large B-Cell Lymphoma (DLBCL). We prospectively recruited 31 patients aged 70 years or older presenting for an initial consultation in the Hematology Clinic of a tertiary hospital. We implemented an updated physical performance evaluation as part of CGA at baseline and during treatment. Baseline characteristics of the sample were compared according to age, Geriatric 8 (G8), frailty, Short Physical Performance Battery (SPPB), and sarcopenia measured by hand grip strength (HGS). Functional changes were monitored during the treatment period using HGS, gait speed (GS) and SPPB. The mean age was 79.0 (5.5) years and 51.6% of the sample was frail; 65,5% were treated with standard chemotherapy and 35,5% with a therapeutic regimen with attenuated doses. All the assessment tools included in CGA found functional differences at baseline when the sample was stratified and compared according to frailty, sarcopenia, and SPPB, but not according to G8 score and age. Only SPPB was able to detect functional differences between groups stratified by age at baseline. GS was the only score that identified clinically significant functional changes during the treatment. In conclusion, HGS and SPPB are appropriate performance scores to complete the functional approach in the initial hematologic evaluation, and GS is a promising option to detect functional decline during therapy in old adults with DLBCL.

Clinical Implementation and Evaluation of Auto-Segmentation Tools for Multi-Site Contouring in Radiotherapy

Background and purpose

Tools for auto-segmentation in radiotherapy are widely available, but guidelines for clinical implementation are missing. The goal was to develop a workflow for performance evaluation of three commercial auto-segmentation tools to select one candidate for clinical implementation.

Materials and Methods

One hundred patients with six treatment sites (brain, head-and-neck, thorax, abdomen, and pelvis) were included. Three sets of AI-based contours for organs-at-risk (OAR) generated by three software tools and manually drawn expert contours were blindly rated for contouring accuracy. The dice similarity coefficient (DSC), the Hausdorff distance, and a dose/volume evaluation based on the recalculation of the original treatment plan were assessed. Statistically significant differences were tested using the Kruskal-Wallis test and the post-hoc Dunn Test with Bonferroni correction.

Results

The mean DSC scores compared to expert contours for all OARs combined were 0.80 ± 0.10, 0.75 ± 0.10, and 0.74 ± 0.11 for the three software tools. Physicians' rating identified equivalent or superior performance of some AI-based contours in head (eye, lens, optic nerve, brain, chiasm), thorax (e.g., heart and lungs), and pelvis and abdomen (e.g., kidney, femoral head) compared to manual contours. For some OARs, the AI models provided results requiring only minor corrections. Bowel-bag and stomach were not fit for direct use. During the interdisciplinary discussion, the physicians' rating was considered the most relevant.

Conclusion

A comprehensive method for evaluation and clinical implementation of commercially available auto-segmentation software was developed. The in-depth analysis yielded clear instructions for clinical use within the radiotherapy department.

Technical note: Clinical evaluation of a newly released surface-guided radiation therapy system on DIBH for left breast radiation therapy

BACKGROUND

It has been shown that a significant reduction of mean heart dose and left anterior descending artery (LAD) dose can be achieved through the use of DIBH for left breast radiation therapy. Surface-guided DIBH has been widely adopted during the last decade, and there are mainly three commercially available SGRT systems. The reports of the performance of a newly released SGRT system for DIBH application are currently very limited.

PURPOSE

To evaluate the clinical performance of a newly released SGRT system on DIBH for left breast radiation therapy.

METHODS

Twenty-five left breast cancer patients treated with DIBH utilizing Varian's Identify system were included (total 493-fraction treatments). Four aspects of the clinical performance were evaluated: Identify offsets of free breathing post patient setup from tattoos, Identify offsets during DIBH, Identify agreement with radiographic ports during DIBH, and DIBH reference surface re-capture post patient shifts. The systematic and random errors of free breathing Identify offsets post patient setup were calculated for each patient, as well as for offsets during DIBH. Radiographic ports were taken when the patient's DIBH position was within the clinical tolerance of (± 0.3 cm, ± 30 ), and these were then compared with treatment field DRRs. If the ports showed that the patient alignment did not agree with the DRRs within 3 mm, a patient shift was performed. A new reference surface was captured and verification ports were taken.

RESULTS

The all-patient average systematic and random errors of Identify offsets for free breathing were within (0.4 cm, 1.50 ) post tattoo setup. The maximum per-patient systematic and random errors were (1.1 cm, 6.20 ) and (0.9 cm, 20 ), and the maximum amplitude of Identify offsets were (2.59 cm, 90 ). All 493-fraction DIBH treatments were delivered and successfully guided by the Identify SGRT system. The systematic and random errors of Identify offsets for DIBH were within (0.2 cm, 2.30 ). Seven patients needed re-captured surface references due to surface variation or position shifts based on the ports. All patient DIBH verification ports guided by Identify were approved by attending physicians.

CONCLUSION

This evaluation showed that the Identify system performed effectively for surface-guided patient setup and surface-guided DIBH imaging and treatment delivery. The feature of color-coded real-time patient surface matching feedback facilitated the evaluation of the patient alignment accuracy and the adjustment of the patient position to match the reference.

Impact of abdominal compression on intra-fractional motion and delivered dose in magnetic resonance image-guided adaptive radiation ablation of adrenal gland metastases

PURPOSE

The current study investigated the impact of abdominal compression on motion and the delivered dose during non-gated, magnetic resonance image (MRI)-guided radiation ablation of adrenal gland metastases.

METHODS

Thirty-one patients with adrenal gland metastases treated to 45-60 Gy in 3-8 fractions on a 1.5 T MRI-linac were included in the study. The patients were breathing freely (n = 14) or with motion restricted by using an abdominal compression belt (n = 17). The time-resolved position of the target in online 2D cine MR images acquired during treatment was assessed and used to estimate the dose delivered to the GTV and abutting luminal organs at risk (OAR).

RESULTS

The median (range) 3D root-mean-square target position error was significantly higher in patients treated without a compression belt [2.9 (1.9-5.6) mm] compared to patients using the belt [2.1 (1.2-3.5) mm] (P < 0.01). The median (range) GTV V95% was significantly reduced from planned 98.6 (65.9-100) % to delivered 96.5 (64.5-99.9) % due to motion (P < 0.01). Most prominent dose reductions were found in patients showing either large target drift or respiration motion and were mainly treated without abdominal compression. Motion did not lead to an increased number of constraint violations for luminal OAR.

CONCLUSIONS

Acceptable target coverage and dose to OAR was observed in the vast majority of patients despite intra-fractional motion during adaptive MRI-guided radiation ablation. The use of abdominal compression significantly reduced the target position error and prevented the most prominent target coverage degradations and is, therefore, recommended as motion management at MRI-linacs.

Does renal failure worsen radiation cystitis following radical prostatectomy?

OBJECTIVE

To investigate the impact of renal function on the risk, severity, and management of radiation cystitis in patients who underwent postoperative radiation therapy for prostate cancer.

METHODS

Retrospective data was assessed from patients treated with adjuvant/salvage radiation therapy at a single academic institution between 2006 and 2020. The incidence, severity, and management of radiation cystitis were compared between three groups: CKD 0-2, CKD 3-4, and CKD 5. Associations of clinicopathologic factors with radiation cystitis were assessed in univariate and multivariate Cox regression models.

RESULTS

A total of 110 patients who underwent radiation therapy following robot-assisted laparoscopic radical prostatectomy were included. The incidence of radiation cystitis following postoperative radiation therapy was 17% with a median presentation time of 34 months (interquartile range 16-65 months). The incidence of radiation cystitis was 100% in CKD 5 patients compared to 15% in CKD 0-2 and 17% in CKD 3-4 patients (p < 0.001). CKD 5 patients required more treatments, emergency department visits, and longer hospitalization times than CKD 0-4 patients (all p < 0.001). Multivariate analyses identified CKD 5 as the only significant factor associated with radiation cystitis (HR = 10.39, p = 0.026).

CONCLUSION

End-stage renal failure is associated with the risk and severity of radiation cystitis in patients receiving postoperative radiation therapy. Knowledge of the potential morbidity of this complication in this population could guide physicians and patients as they evaluate risks and benefits prior to selecting adjuvant or salvage radiation therapy.

Triggering daily online adaptive radiotherapy in the pelvis: Dosimetric effects and procedural implications of trigger parameter-value selection

BACKGROUND

Online adaptive radiotherapy (ART) can address dosimetric consequences of variations in anatomy by creating a new plan during treatment. However, ART is time- and labor-intensive and should be implemented in a resource-conscious way. Adaptive triggers composed of parameter-value pairs may direct the judicious use of online ART.

PURPOSE

This work analyzed our clinical experience using CBCT-based daily online ART to demonstrate how a conceptual framework based on adaptive triggers affects the dosimetric and procedural impact of ART.

METHODS

Sixteen patients across several pelvic sites were treated with CBCT-based daily online ART. Differences in standardized dose metrics were compared between the original plan, the original plan recalculated on the daily anatomy, and an adaptive plan. For each metric, trigger values were analyzed in terms of the proportion of treatments adapted and the distribution of metric values.

RESULTS

Target coverage metrics were compromised due to anatomic variation with the average change per treatment ranging from -0.90 to -0.05 Gy, -0.47 to -0.02 Gy, -0.31 to -0.01 Gy, and -12.45% to -2.65% for PTV D99%, PTV D95%, CTV D99%, and CTV V100%, respectively. These were improved using the adaptive plan (-0.03 to 0.01 Gy, -0.02 to 0.00 Gy, -0.03 to 0.00 Gy, and -4.70% to 0.00%, respectively). Increasingly strict triggers resulted in a non-linear increase in the proportion of treatments adapted and improved the distribution of metric values with diminishing returns. Some organ-at-risk (OAR) metrics were compromised by anatomic variation and improved using the adaptive plan, but changes in most OAR metrics were randomly distributed.

CONCLUSIONS

Daily online ART improved target coverage across multiple pelvic treatment sites and techniques. These effects were larger than those for OAR metrics, suggesting that maintaining target coverage was our primary benefit of CBCT-based daily online ART. Analyses like these can determine online ART triggers from a cost-benefit perspective.

Simulation as a tool to model potential workflow enhancements in radiotherapy treatment pathways - A systematic review

This systematic review aimed to synthesize and summarize the use of simulation of radiotherapy pathways. The objective was to establish the suitability of those simulations in modeling the potential introduction of processes and technologies to speed up radiotherapy pathways. A systematic literature search was carried out using PubMed and Scopus databases to evaluate the use of simulation in radiotherapy pathways. Full journal articles and conference proceedings were considered, and the search was limited to the English language only. To be eligible for inclusion, articles had to model multiple sequential processes in the radiotherapy pathway concurrently to demonstrate the suitability of simulation modeling in typical pathways. Papers solely modeling scheduling, capacity, or queuing strategies were excluded. In total, 151 potential studies were identified and screened to find 18 relevant studies in October 2022. Studies showed that various pathways could be modeled, including the entire pathway from referral to end of treatment or the constituent phases such as pre-treatment, treatment, or other subcomponents. The data required to generate models varied from study to study, but at least 3 months of data were needed. This review demonstrates that modeling and simulation of radiotherapy pathways are feasible and that model output matches real-world systems. Validated models give researchers confidence to modify models with potential workflow enhancements to assess their potential effect on real-world systems. It is recommended that researchers follow best practice guidelines when building models to ensure that they are fit for purpose and to enable decision makers to have confidence in their results.