Laser-free pelvic alignment in an online adaptive radiotherapy environment.
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ABSTRACT:
SUBMITTER: Barnes H
PROVIDER: S-EPMC7042150 | biostudies-literature | 2020 Mar
REPOSITORIES: biostudies-literature
Publications
Laser-free pelvic alignment in an online adaptive radiotherapy environment.
Barnes Helen H Mohajer Jonathan J Dunlop Alex A Adair Smith Gillian G Herbert Trina T Lawes Rebekah R Tree Alison A McNair Helen H
Technical innovations & patient support in radiation oncology 20200217
The MR-Linac (MRL) provides a novel treatment modality that enables online adaptive treatments, but also creates new challenges for patient positioning in a laser-free environment. The accuracy and duration of prostate patient set-up on the MRL using two different methods for patient alignment was determined to establish standard of practice on the MRL. Differences in set-up accuracy were significant in the longitudinal direction and are accounted for in online plan adaption. Both methods record ...[more]
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Project description:Background and purposeStudies have demonstrated the potential of online adaptive radiotherapy (oART). However, routine use has been limited due to resource demanding solutions. This study reports on experiences with oART in the pelvic region using a novel cone-beam computed tomography (CBCT)-based, artificial intelligence (AI)-driven solution.Material and methodsAutomated pre-treatment planning for thirty-nine pelvic cases (bladder, rectum, anal, and prostate), and one hundred oART simulations were conducted in a pre-clinical release of Ethos (Varian Medical Systems, Palo Alto, CA). Plan quality, AI-segmentation accuracy, oART feasibility and an integrated calculation-based quality assurance solution were evaluated. Experiences from the first five clinical oART patients (three bladder, one rectum and one sarcoma) are reported.ResultsAuto-generated pre-treatment plans demonstrated similar planning target volume (PTV) coverage and organs at risk doses, compared to institution reference. More than 75% of AI-segmentations during simulated oART required none or minor editing and the adapted plan was superior in 88% of cases. Limitations in AI-segmentation correlated to cases where AI model training was lacking. The five first treated patients complied well with the median adaptive procedure duration of 17.6 min (from CBCT acceptance to treatment delivery start). The treated bladder patients demonstrated a 42% median primary PTV reduction, indicating a 24%-30% reduction in V45Gy to the bowel cavity, compared to non-ART.ConclusionsA novel commercial oART solution was demonstrated feasible for various pelvic sites. Clinically acceptable AI-segmentation and auto-planning enabled adaptation within reasonable timeslots. Possibilities for reduced PTVs observed for bladder cancer indicated potential for toxicity reductions.
| S-EPMC8057957 | biostudies-literature
Project description:Label-free quantification using precursor-based intensities is a versatile workflow for large-scale proteomics studies. The method however requires extensive computational analysis and is therefore in need of robust quality control during the data mining stage. We present a new label-free data analysis workflow integrated into a multiuser software platform. A novel adaptive alignment algorithm has been developed to minimize the possible systematic bias introduced into the analysis. Parameters are estimated on the fly from the data at hand, producing a user-friendly analysis suite. Quality metrics are output in every step of the analysis as well as actively incorporated into the parameter estimation. We furthermore show the improvement of this system by comprehensive comparison to classical label-free analysis methodology as well as current state-of-the-art software.
| S-EPMC3650348 | biostudies-literature
Project description:Magnetic Resonance-guided Radiotherapy (MRgRT) allows direct monitoring of treated volumes. The aim of this study was to investigate the feasibility of a new gating strategy consisting in using an isodose as boundary. Forty-four patients treated for thoracic and abdominal lesions using MRgRT were enrolled. The accuracy of the new strategy was compared to the conventional one in terms of area improvement available for gating without compromising target coverage. A mean increase of 24% for lung, 15% for liver and 11% for pancreas was observed, demonstrating how the new method can be useful in challenging situations with low dose conformality.
| S-EPMC8254198 | biostudies-literature
Project description:PurposeThe Ethos (Varian Medical Systems) radiotherapy device combines semi-automated anatomy detection and plan generation for cone beam computer tomography (CBCT)-based daily online adaptive radiotherapy (oART). However, CBCT offers less soft tissue contrast than magnetic resonance imaging (MRI). This work aims to present the clinical workflow of CBCT-based oART with shuttle-based offline MR guidance.MethodsFrom February to November 2023, 31 patients underwent radiotherapy on the Ethos (Varian, Palo Alto, CA, USA) system with machine learning (ML)-supported daily oART. Moreover, patients received weekly MRI in treatment position, which was utilized for daily plan adaptation, via a shuttle-based system. Initial and adapted treatment plans were generated using the Ethos treatment planning system. Patient clinical data, fractional session times (MRI + shuttle transport + positioning, adaptation, QA, RT delivery) and plan selection were assessed for all fractions in all patients.ResultsIn total, 737 oART fractions were applied and 118 MRIs for offline MR guidance were acquired. Primary sites of tumors were prostate (n = 16), lung (n = 7), cervix (n = 5), bladder (n = 1) and endometrium (n = 2). The treatment was completed in all patients. The median MRI acquisition time including shuttle transport and positioning to initiation of the Ethos adaptive session was 53.6 min (IQR 46.5-63.4). The median total treatment time without MRI was 30.7 min (IQR 24.7-39.2). Separately, median adaptation, plan QA and RT times were 24.3 min (IQR 18.6-32.2), 0.4 min (IQR 0.3-1,0) and 5.3 min (IQR 4.5-6.7), respectively. The adapted plan was chosen over the scheduled plan in 97.7% of cases.ConclusionThis study describes the first workflow to date of a CBCT-based oART combined with a shuttle-based offline approach for MR guidance. The oART duration times reported resemble the range shown by previous publications for first clinical experiences with the Ethos system.
| S-EPMC10969008 | biostudies-literature
Project description:BACKGROUND:To compare online adaptive radiation therapy (ART) to a clinically implemented plan selection strategy (PS) with respect to dose to the organs at risk (OAR) for rectal cancer. METHODS:The first 20 patients treated with PS between May-September 2016 were included. This resulted in 10 short (SCRT) and 10 long (LCRT) course radiotherapy treatment schedules with a total of 300 Conebeam CT scans (CBCT). New dual arc VMAT plans were generated using auto-planning for both the online ART and PS strategy. For each fraction bowel bag, bladder and mesorectum were delineated on daily Conebeam CTs. The dose distribution planned was used to calculate daily DVHs. Coverage of the CTV was calculated, as defined by the dose received by 99% of the CTV volume (D99%). The volume of normal tissue irradiated with 95% of the prescribed fraction dose was calculated by calculating the volume receiving 95% of the prescribed fraction or more dose minus the volume of the CTV. For each fraction the difference between the plan selection and online adaptive strategy of each DVH parameter was calculated, as well as the average difference per patient. RESULTS:Target coverage remained the same for online ART. The median volume of the normal tissue irradiated with 95% of the prescribed dose dropped from 642?cm3 (PS) to 237?cm3 (online-ART)(p <?0.001). Online ART reduced dose to the OARs for all tested dose levels for SCRT and LCRT (p <?0.001). For V15Gy of the bowel bag the median difference over all fractions of all patients was -?126?cm3 in LCRT, while the average difference per patient ranged from -?206?cm3 to -?40?cm3. For SCRT the median difference was -?62?cm3, while the range of the average difference per patient was -?105?cm3 to -?51?cm3. For V15Gy of the bladder the median difference over all fractions of all patients was 26% in LCRT, while the average difference per patient ranged from -?34 to 12%. For SCRT the median difference of V95% was -?8%, while the range of the average difference per patient was -?29 to 0%. CONCLUSIONS:Online ART for rectal cancer reduces dose the OARs significantly compared to a clinically implemented plan selection strategy, without compromising target coverage. TRIAL REGISTRATION:Medical Research Involving Human Subjects Act (WMO) does not apply to this study and was retrospectively approved by the Medical Ethics review Committee of the Academic Medical Center (W19_357 # 19.420; Amsterdam University Medical Centers, Location Academic Medical Center, Amsterdam, The Netherlands).
| S-EPMC7371470 | biostudies-literature
Project description:Purpose: The purpose of this work was to propose an online replanning algorithm, named intensity field projection (IFP), that directly adjusts intensity distributions for each beam based on the deformation of structures. IFP can be implemented within a reasonably acceptable time frame. Methods and Materials: The online replanning method is based on the gradient-based free form deformation (GFFD) algorithm, which we have previously proposed. The method involves the following steps: The planning computed tomography (CT) and cone-beam CT image are registered to generate a three-dimensional (3-D) deformation field. According to the 3-D deformation field, the registered image and a new delineation are generated. The two-dimensional (2-D) deformation field of ray intensity in each beam direction is determined based on the 3-D deformation field in the region of interest. The 2-D ray intensity distribution in the corresponding beam direction is deformed to generate a new 2-D ray intensity distribution. According to the new 2-D ray intensity distribution, corresponding multi-leaf collimator (MLC), and jaw motion data are generated. The feasibility and advantages of our method have been demonstrated in 20 lung cancer intensity modulated radiation therapy (IMRT) cases. Results: Substantial underdosing in the CTV is seen in the original and the repositioning plans. The average prescription dose coverage (V100%) and D95 for CTV were 100% and 60.3 Gy for the IFP plans compared to 82.6% (P < 0.01) and 44.0 Gy (P < 0.01) for original plans, 86.7% (P < 0.01), and 58.5 Gy (P < 0.01) for repositioning plans. On average, the mean total lung doses were 12.2 Gy for the IFP plan compared to the 12.4 Gy (P < 0.01) and 12.6 Gy (P < 0.01) for the original and the repositioning plans. The entire process of IFP can be completed within 3 min. Conclusions: We proposed an online replanning strategy for automatically correcting interfractional anatomy variations. The preliminary results indicate that the IFP method substantially increased planning speed for online adaptive replanning.
| S-EPMC7063069 | biostudies-literature
Project description:BackgroundOnline adaptive radiotherapy has the potential to reduce toxicity for patients treated for rectal cancer because smaller planning target volumes (PTV) margins around the entire clinical target volume (CTV) are required. The aim of this study is to describe the first clinical experience of a Conebeam CT (CBCT)-based online adaptive workflow for rectal cancer, evaluating timing of different steps in the workflow, plan quality, target coverage and patient compliance.MethodsTwelve consecutive patients eligible for 5 × 5 Gy pre-operative radiotherapy were treated on a ring-based linear accelerator with a multidisciplinary team present at the treatment machine for each fraction. The accelerator is operated using an integrated software platform for both treatment planning and delivery. In all directions for all CTVs a PTV margin of 5 mm was used, except for the cranial/caudal borders of the total CTV where a margin of 8 mm was applied. A reference plan was generated based on a single planning CT. After aligning the patient the online adaptive procedure started with acquisition of a CBCT. The planning CT scan was registered to the CBCT using deformable registration and a synthetic CT scan was generated. With the support of artificial intelligence, structure guided deformation and the synthetic CT scan contours were adapted by the system to match the anatomy on the CBCT. If necessary, these contours were adjusted before a new plan was generated. A second and third CBCT were acquired to validate the new plan with respect to CTV coverage just before and after treatment delivery, respectively. Treatment was delivered using volumetric modulated arc treatment (VMAT). All steps in this process were defined and timed.ResultsOn average the timeslot needed at the treatment machine was 34 min. The process of acquiring a CBCT, evaluating and adjusting the contours, creating the new plan and verifying the CTV on the CBCT scan took on average 20 min. Including delivery and post treatment verification this was 26 min. Manual adjustments of the target volumes were necessary in 50% of fractions. Plan quality, target coverage and patient compliance were excellent.ConclusionsFirst clinical experience with CBCT-based online adaptive radiotherapy shows it is feasible for rectal cancer. Trial registration Medical Research Involving Human Subjects Act (WMO) does not apply to this study and was retrospectively approved by the Medical Ethics review Committee of the Academic Medical Center (W21_087 # 21.097; Amsterdam University Medical Centers, Location Academic Medical Center, Amsterdam, The Netherlands).
| S-EPMC8305875 | biostudies-literature
Project description:BACKGROUND:The function of the pelvic bones is to transfer load generated by body weight. Proper function of the pelvic bones can be disturbed by alignment changes that occur during pregnancy. Further, misalignment of the pelvic bones can lead to pain, urinary incontinence, and other complications. An understanding of the timing and nature of pelvic alignment changes during pregnancy may aid in preventing and treating these complications. OBJECTIVE:To investigate the changes in pelvic alignment during pregnancy and one month after childbirth. METHODS:This is a prospective, longitudinal cohort study. Pelvic measurements were obtained for 201 women at 12, 24, 30, and 36 weeks of pregnancy, and 1 month after childbirth. The anterior and posterior width of the pelvis (the distance between the bilateral anterior superior iliac spines and the bilateral posterior superior iliac spines), the anterior pelvic tilt, and pelvic asymmetry (the mean left and right pelvic tilt degrees and the bilateral difference of the anterior pelvic tilt) were measured. For the change in pelvic alignment, a Friedman test was conducted to determine any significant difference in the measurements over time. RESULTS:The anterior and posterior width of the pelvis became significantly wider with pregnancy progress and the anterior width of the pelvis at 1 month after childbirth remained wider than that at 12 weeks of pregnancy (p < 0.001). The anterior pelvic tilt increased during pregnancy and decreased after childbirth (p < 0.05). CONCLUSION:Some changes in pelvic alignment occur continuously during the perinatal period. Changes in the anterior width of the pelvis are not recovered at one month post-childbirth. Understanding these perinatal changes may help clinicians avert complications due to pelvic misalignment.
| S-EPMC6799872 | biostudies-literature
Project description:IntroductionOnline MRI guided adaptive radiotherapy (MRIgRT) is resource intensive. To maintain and increase uptake traditional roles and responsibilities may need refining. This novel study aims to provide an in-depth understanding and subsequent impact of the roles required to deliver on-line adaptive MRIgRT by exploring the current skills and knowledge of radiographers.MethodA purposive sampling approach was used to invite radiographers, clinicians and physicists from centres with experience of MRIgRT to participate. Focus Group Interviews were conducted with two facilitators using a semi-structure interview guide (Appendix 1). Four researchers independently familiarised themselves and coded the data using framework analysis. A consensus thematic framework of ptive Radiotherapy codes and categories was agreed and systematically applied.ResultsThirty participants took part (Radiographers: N = 18, Physicists: N = 9 and Clinicians: N = 3). Three key themes were identified: 'Current MRIgRT', 'Training' and 'Future Practice'. Current MRIgRT identified a variation in radiographers' roles and responsibilities with pathways ranging from radiographer-led, clinician-light-led and MDT-led. The consensus was to move towards radiographer-led with the need to have a robust on-call service heavily emphasised. Training highlighted the breadth of knowledge required by radiographers including MRI, contouring, planning and dosimetry, and treatment experience. Debate was presented over timing and length of training required. Future Practice identified the need to have radiographers solely deliver MRIgRT, to reduce staff present which was seen as a main driver, and time and resources to train radiographers seen as the main barriers.ConclusionRadiographer-led MRIgRT is an exciting development because of the potential radiographer role development. A national training framework created collaboratively with all stakeholders and professions involved would ensure consistency in skills and knowledge.Implications for practiceRole development and changes in education for therapeutic radiographers.
| S-EPMC8497277 | biostudies-literature
Project description:The purpose of this study was to characterize the motion and define the required treatment margins of the pathological mesorectal lymph nodes (GTVln) for two online adaptive MRI-guided strategies for sequential boosting. Secondly, we determine the margins required for the primary gross tumor volume (GTVprim). Twenty-eight patients treated on a 1.5T MR-Linac were included in the study. On T2-weighted images for adaptation (MRIadapt) before and verification after irradiation (MRIpost) of five treatment fractions per patient, the GTVln and GTVprim were delineated. With online adaptive MRI-guided radiotherapy, daily plan adaptation can be performed through the use of two different strategies. In an adapt-to-shape (ATS) workflow the interfraction motion is effectively corrected by redelineation and the only relevant motion is intrafraction motion, while in an adapt-to-position (ATP) workflow the margin (for GTVln) is dominated by interfraction motion. The margin required for GTVprim will be identical to the ATS workflow, assuming each fraction would be perfectly matched on GTVprim. The intrafraction motion was calculated between MRIadapt and MRIpost for the GTVln and GTVprim separately. The interfraction motion of the GTVln was calculated with respect to the position of GTVprim, assuming each fraction would be perfectly matched on GTVprim. PTV margins were calculated for each strategy using the Van Herk recipe. For GTVln we randomly sampled the original dataset 20 times, with each subset containing a single randomly selected lymph node for each patient. The resulting margins for ATS ranged between 3 and 4 mm (LR), 3 and 5 mm (CC) and 5 and 6 mm (AP) based on the 20 randomly sampled datasets for GTVln. For ATP, the margins for GTVln were 10-12 mm in LR and AP and 16-19 mm in CC. The margins for ATS for GTVprim were 1.7 mm (LR), 4.7 mm (CC) and 3.2 mm anterior and 5.6 mm posterior. Daily delineation using ATS of both target volumes results in the smallest margins and is therefore recommended for safe dose escalation to the primary tumor and lymph nodes.
| S-EPMC9953931 | biostudies-literature