A survey of practice patterns for real-time intrafractional motion-management in particle therapy

Background and purpose: Organ motion compromises accurate particle therapy delivery. This study reports on the practice patterns for real-time intrafractional motion-management in particle therapy to evaluate current clinical practice and wishes and barriers to implementation. Materials and methods: An institutional questionnaire was distributed to particle therapy centres worldwide (7/2020–6/2021) asking which type(s) of real-time respiratory motion management (RRMM) methods were used, for which treatment sites, and what were the wishes and barriers to implementation. This was followed by a three-round DELPHI consensus analysis (10/2022) to define recommendations on required actions and future vision. With 70 responses from 17 countries, response rate was 100% for Europe (23/23 centres), 96% for Japan (22/23) and 53% for USA (20/38). Results: Of the 68 clinically operational centres, 85% used RRMM, with 41% using both rescanning and active methods. Sixty-four percent used active-RRMM for at least one treatment site, mostly with gating guided by an external marker. Forty-eight percent of active-RRMM users wished to expand or change their RRMM technique. The main barriers were technical limitations and limited resources. From the DELPHI analysis, optimisation of rescanning parameters, improvement of motion models, and pre-treatment 4D evaluation were unanimously considered clinically important future focus. 4D dose calculation was identified as the top requirement for future commercial treatment planning software. Conclusion:  A majority of particle therapy centres have implemented RRMM. Still, further development and clinical integration were desired by most centres. Joint industry, clinical and research efforts are needed to translate innovation into efficient workflows for broad-scale implementation

A survey of practice patterns for adaptive particle therapy for interfractional changes

Background and purpose: Anatomical changes may compromise the planned target coverage and organs-at-risk dose in particle therapy. This study reports on the practice patterns for adaptive particle therapy (APT) to evaluate current clinical practice and wishes and barriers to further implementation. Materials and methods: An institutional questionnaire was distributed to PT centres worldwide (7/2020–6/2021) asking which type of APT was used, details of the workflow, and what the wishes and barriers to implementation were. Seventy centres from 17 countries participated. A three-round Delphi consensus analysis (10/2022) among the authors followed to define recommendations on required actions and future vision. Results: Out of the 68 clinically operational centres, 84% were users of APT for at least one treatment site with head and neck being most common. APT was mostly performed offline with only two online APT users (plan-library). No centre used online daily re-planning. Daily 3D imaging was used for APT by 19% of users. Sixty-eight percent of users had plans to increase their use or change their technique for APT. The main barrier was “lack of integrated and efficient workflows”. Automation and speed, reliable dose deformation for dose accumulation and higher quality of in-room volumetric imaging were identified as the most urgent task for clinical implementation of online daily APT. Conclusion: Offline APT was implemented by the majority of PT centres. Joint efforts between industry research and clinics are needed to translate innovations into efficient and clinically feasible workflows for broad-scale implementation of online APT

How to Cut the Electric Bill in Mobile Access Networks: A Mobile Operator's Perspective

One of the major challenges that mobile operators are facing is the increasing power consumption costs as a consequence of the network densication experienced in current and future mobile access networks. This power increase causes both financial and environmental concerns to operators, since both the operational expenses and the CO2 emissions are affected. This Master Thesis investigates and analyses various deployment architectures in urban and suburban areas, considering both the radio access and backhaul segments, as well as system solutions that are expected to increase the energy efficiency of Long Term Evolution (LTE) networks, such as Discontinuous Transmission - Discontinuous Reception (DTX-DRX) enhancement of future mobile networks. During this dissertation, it is investigated whether power efficient solutions can also be cost efficient in terms of Total Cost of Ownership (TCO) in urban environments. Additionally, the DTXDRX enhancement of HetNets is studied on a dense urban case, providing both nancial and environmental benefits by its utilization. The main results indicate that significant power and TCO savings can be achieved by the deployment of Heterogeneous Networks in urban environments. Fiber optics backhauling seems to be more attractive compared to Microwaves in these areas. Finally, DTX-DRX enhanced HetNets result in high power savings and can be financially attractive under particular conditions

Dosimetric Impact of Intrafraction Motion in Online-Adaptive Intensity Modulated Proton Therapy for Cervical Cancer

Purpose: A method was recently developed for online-adaptive intensity modulated proton therapy (IMPT) in patients with cervical cancer. The advantage of this approach, relying on the use of tight margins, is challenged by the intrafraction target motion. The purpose of this study was to evaluate the dosimetric effect of intrafraction motion on the target owing to changes in bladder filling in patients with cervical cancer treated with online-adaptive IMPT. Methods and Materials: In 10 patients selected to have large uterus motion induced by bladder filling, the intrafraction anatomic changes were simulated for several prefraction durations for online (automated) contouring and planning. For each scenario, the coverage of the primary target was evaluated with margins of 2.5 and 5 mm. Results: Using a 5- mm planning target volume margin, median accumulated D98% was greater than 42.75 GyRBE1.1 (95% of the prescribed dose) in the case of a prefraction duration of 5 and 10 minutes. For a prefraction duration of 15 minutes, this parameter deteriorated to 42.6 GyRBE1.1. When margins were reduced to 2.5 mm, only a 5-minute duration resulted in median target D98% above 42.75 GyRBE1.1. In addition, smaller bladders were found to be associated with larger dose degradations compared with larger bladders. Conclusions: This study indicates that intrafraction anatomic changes can have a substantial dosimetric effect on target coverage in an online-adaptive IMPT scenario for patients subject to large uterus motion. A margin of 5 mm was sufficient to compensate for the intrafraction motion due to bladder filling for up to 10 minutes of prefraction time. However, compensation for the uncertainties that were disregarded in this study, by using margins or robust optimization, is also required. Furthermore, a large bladder volume restrains intrafraction target motion and is recommended for treating patients in this scenario. Assuming that online-adaptive IMPT remains beneficial as long as narrow margins are used (5 mm or below), this study demonstrates its feasibility with regard to intrafraction motion

Tools for large-scale data analytics of an international multi-center study in radiation oncology for cervical cancer

Purpose: To develop and implement a software that enables centers, treating patients with state-of-the-art radiation oncology, to compare their patient, treatment, and outcome data to a reference cohort, and to assess the quality of their treatment approach. Materials and Methods: A comprehensive data dashboard was designed, which al- lowed holistic assessment of institutional treatment approaches. The software was tested in the ongoing EMBRACE-II study for locally advanced cervical cancer. The tool created individualized dashboards and automatic analysis scripts, verified pro- tocol compliance and checked data for inconsistencies. Identified quality assurance (QA) events were analysed. A survey among users was conducted to assess usability. Results: The survey indicated favourable feedback to the prototype and highlighted its value for internal monitoring. Overall, 2302 QA events were identified (0.4% of all collected data). 54% were due to missing or incomplete data, and 46% originated from other causes. At least one QA event was found in 519/1001 (52%) of patients. QA events related to primary study endpoints were found in 16% of patients. Sta- tistical methods demonstrated good performance in detecting anomalies, with precisions ranging from 71% to 100%. Most frequent QA event categories were Treatment Technique (27%), Patient Characteristics (22%), Dose Reporting (17%), Outcome 156 (15%), Outliers (12%), and RT Structures (8%). Conclusion: A software tool was developed and tested within a clinical trial in radia- tion oncology. It enabled the quantitative and qualitative comparison of institutional patient and treatment parameters with a large multi-center reference cohort. We demonstrated the value of using statistical methods to automatically detect implau- sible data points and highlighted common pitfalls and uncertainties in radiotherapy for cervical cancer

Clinical outcome of protocol based image (MRI) guided adaptive brachytherapy combined with 3D conformal radiotherapy with or without chemotherapy in patients with locally advanced cervical cancer

AbstractBackgroundTo analyse the overall clinical outcome and benefits by applying protocol based image guided adaptive brachytherapy combined with 3D conformal external beam radiotherapy (EBRT)±chemotherapy (ChT).MethodsTreatment schedule was EBRT with 45–50.4Gy±concomitant cisplatin chemotherapy plus 4×7Gy High Dose Rate (HDR) brachytherapy. Patients were treated in the “protocol period” (2001–2008) with the prospective application of the High Risk CTV concept (D90) and dose volume constraints for organs at risk including biological modelling. Dose volume adaptation was performed with the aim of dose escalation in large tumours (prescribed D90>85Gy), often with inserting additional interstitial needles. Dose volume constraints (D2cc) were 70–75Gy for rectum and sigmoid and 90Gy for bladder.Late morbidity was prospectively scored, using LENT/SOMA Score. Disease outcome and treatment related late morbidity were evaluated and compared using actuarial analysis.FindingsOne hundred and fifty-six consecutive patients (median age 58years) with cervix cancer FIGO stages IB–IVA were treated with definitive radiotherapy in curative intent. Histology was squamous cell cancer in 134 patients (86%), tumour size was >5cm in 103 patients (66%), lymph node involvement in 75 patients (48%). Median follow-up was 42months for all patients.Interstitial techniques were used in addition to intracavitary brachytherapy in 69/156 (44%) patients. Total prescribed mean dose (D90) was 93±13Gy, D2cc 86±17Gy for bladder, 65±9Gy for rectum and 64±9Gy for sigmoid.Complete remission was achieved in 151/156 patients (97%). Overall local control at 3years was 95%; 98% for tumours 2–5cm, and 92% for tumours >5cm (p=0.04), 100% for IB, 96% for IIB, 86% for IIIB. Cancer specific survival at 3years was overall 74%, 83% for tumours 2–5cm, 70% for tumours >5cm, 83% for IB, 84% for IIB, 52% for IIIB. Overall survival at 3years was in total 68%, 72% for tumours 2–5cm, 65% for tumours >5cm, 74% for IB, 78% for IIB, 45% for IIIB.In regard to late morbidity in total 188 grade 1+2 and 11 grade 3+4 late events were observed in 143 patients. G1+2/G3+4 events for bladder were n=32/3, for rectum n=14/5, for bowel (including sigmoid) n=3/0, for vagina n=128/2, respectively.Interpretation3D conformal radiotherapy±chemotherapy plus image (MRI) guided adaptive intracavitary brachytherapy including needle insertion in advanced disease results in local control rates of 95–100% at 3years in limited/favourable (IB/IIB) and 85–90% in large/poor response (IIB/III/IV) cervix cancer patients associated with a moderate rate of treatment related morbidity. Compared to the historical Vienna series there is relative reduction in pelvic recurrence by 65–70% and reduction in major morbidity. The local control improvement seems to have impact on CSS and OS. Prospective clinical multi-centre studies are mandatory to evaluate these challenging mono-institutional findings