Prospective Evaluation of Implementation of a Tattoo-less Workflow for Non-Spine Bone SBRT

PURPOSE/OBJECTIVE(S)

Oligometastatic disease has expanded the clinical indications for non-spine bone (NSB) SBRT. Optical surface monitoring systems (OSMS) may reduce treatment time if it represents an effective surrogate for bone intrafraction motion monitoring. We aimed to identify whether OSMS could substitute for 2D-3D mid-imaging and enable a tattoo-less set up in NSB SBRT.

MATERIALS/METHODS

Beginning 11/2019, OSMS was incorporated in parallel with an existing workflow using CBCT and mid 2D-3D kV/kV imaging for pre- and mid-imaging for NSB SBRT. The ability of OSMS to detect both observed out-of-tolerance (>2mm/>2deg) shifts and manual couch shifts was analyzed. A workflow incorporating OSMS reference captures, CBCT for pre-treatment verification and OSMS/triggered imaging (TI) for intrafraction monitoring was developed and deployed for rib/sternum SBRT beginning 11/2021 and all NSB SBRT beginning 2/2022. All NSB SBRT treatment appointments were analyzed through statistical process control (SPC) with use of an XmR chart of average set up and total treatment time per quarter from 2/2019 to 2/2023. Special cause rules were based on IHI rules and conduced with spreadsheet software.

RESULTS

From 2/2019 to 2/2023, 1962 NSB SBRT fractions were delivered, including 337 rib, 150 sternum, 197 femur, 266 ilium, 222 multi-site. Over 104 femur and 87 ilium images, there were no over tolerance intra-fraction events detected with 2D-3D or OSMS. Over 20 manual shifts, OSMS could detect 2mm shifts to within 0.4mm 67% of the time and 0.8mm 95% of time. There was no difference in treatment set up time following adoption of an OSMS/TI workflow as a replacement for 2D-3D mid-imaging. A reduction in rib SBRT delivery and multi-site treatment set-up times was significantly associated with the adoption of OSMS/TI and OSMS, respectively, as assessed based on special cause variation with 8 consecutive points below the mean.

CONCLUSION

Integration of OSMS and triggered imaging has enabled the transition to a completely tattoo-less workflow, thus sparing patients the need for permanent tattoos whilst also allowing more continuous motion monitoring and reduced radiation exposure related to unnecessary 2D-3D or CBCT mid-imaging. Treatment times were significantly reduced for patients receiving rib SBRT or multi-site NSB SBRT with this workflow.

Deep Learning-Based Automated Quality Assurance for Palliative Spinal Treatment Planning in Radiotherapy

PURPOSE/OBJECTIVE(S)

Robustquality assurance (QA) for palliative spine radiation therapy (RT) remains critical due to the risk of wrong anatomic level treatment on account of human error in enumerating vertebral bodies accurately based on morphology with incomplete imaging of the spine and prevalence of anatomic variants (10%). We propose a rapid, fully automated deep learning-based QA (DL-QA) tool for segmenting and enumerating vertebral structures from image data, capable of identifying misalignment based on discrepancies in calculated dose coverage.

MATERIALS/METHODS

Ina retrospective cohort of 514 patients who received palliative spine radiation treatment at a single institution for spinal metastases, vertebral volumes for each individual spine level were automatically segmented on RT planning computed tomography scans using a publicly available deep learning algorithm, Total Segmentator (TS) deployed in the treatment planning system (Wasserthal et al, 2022). Departmental policy requires that the prescription/plan name include all spinal levels that receive a prescribed dosimetric threshold of V50% > 50%. By comparing the intended spine level target in the prescription and plan name against the TS volumes, the DL-QA flagged all cases for which any target vertebrae did not receive this threshold dose and/or any non-targeted vertebrae that received V50% > 50%. To detect spine anomalies, cases were also flagged if any vertebrae volume was not within ±1σ of the entire population of vertebrae volumes. Flagged cases were either categorized as: (1) wrong spine level RT error; (2) documentation error, in which treatment was correct but the prescription/plan name did not follow Departmental policy; or (3) potential spinal geometric error. All flagged cases were verified manually by checking the original images and treatment planning data.

RESULTS

Outof 514 patients, 29 cases were flagged as potential errors. Manual review revealed that one of these was a previously discovered true treatment error (due to anatomic variant with 4 lumbar bodies) while 10 were treated as intended but showed documentation errors due to variants in the number of vertebral bodies, kyphosis of the spine causing non-targeted vertebrae to appear in the treatment field, or improper observation of the Departmental plan naming policy. The remaining 18 cases were associated with flagged vertebrae volumes. Reviewing those patients, we identified spinal anomalies where TS attempted to account for extra or missing vertebrae (N = 9) and cases where TS made segmentation errors (N = 9).

CONCLUSION

Theproposed automated DL-QA system successfully identified patients with spine anomalies, flagged documentation errors, verified the correct target levels of spine RT treatments, and detected a known misadministration. The next phase will involve prospective testing of the system in a clinical setting upstream of treatment delivery.

Patient and Clinician Perspectives on Shared Decision Making in Vascular Access Selection: A Qualitative Study

RATIONALE & OBJECTIVE

Collaborative approaches to vascular access selection are being increasingly encouraged to elicit patients' preferences and priorities where no unequivocally superior choice exists. We explored how patients, their caregivers, and clinicians integrate principles of shared decision making when engaging in vascular access discussions.

STUDY DESIGN

Qualitative description.

SETTING & PARTICIPANTS

Semistructured interviews with a purposive sample of patients, their caregivers, and clinicians from outpatient hemodialysis programs in Alberta, Canada.

ANALYTICAL APPROACH

We used a thematic analysis approach to inductively code transcripts and generate themes to capture key concepts related to vascular access shared decision making across participant roles.

RESULTS

42 individuals (19 patients, 2 caregivers, 21 clinicians) participated in this study. Participants identified how access-related decisions follow a series of major decisions about kidney replacement therapy and care goals that influence vascular access preferences and choice. Vascular access shared decision making was strengthened through integration of vascular access selection with dialysis-related decisions and timely, tailored, and balanced exchange of information between patients and their care team. Participants described how opportunities to revisit the vascular access decision before and after dialysis initiation helped prepare patients for their access and encouraged ongoing alignment between patients' care priorities and treatment plans. Where shared decision making was undermined, hemodialysis via a catheter ensued as the most readily available vascular access option.

LIMITATIONS

Our study was limited to patients and clinicians from hemodialysis care settings and included few caregiver participants.

CONCLUSIONS

Findings suggest that earlier, or upstream, decisions about kidney replacement therapies influence how and when vascular access decisions are made. Repeated vascular access discussions that are integrated with other higher-level decisions are needed to promote vascular access shared decision making and preparedness.

A history of total mercury in edible muscle of fish from lakes in northern Canada

Subsistence fishing has been an important source of food for Native People in northern Canada since prehistoric time. Measurements of the levels of mercury in edible muscle of northern fish have been undertaken for over three decades in efforts to evaluate the risks of consuming northern fish. This report summarizes the data obtained from 7974 fish of 25 species from sites distributed from the Yukon to Labrador. The most abundant species were lake trout, lake whitefish, arctic char, walleye, northern pike and burbot. The question being asked was essentially "Are the fish safe to eat?" The results were used to support decisions on fishing and consumption of fish. They were sorted in several ways, into concentration ranges corresponding to human consumption guidelines, into political jurisdictions and into types of bedrock geology. Overall walleye, northern pike and lake trout, usually exceeded the subsistence consumption guideline of 0.2 microg g-1 total mercury and often exceeded the higher guideline of 0.5 microg g-1 total mercury for commercial sales of fish. Mercury in burbot, another facultative predator, was often lower but several still exceeding a guideline. Arctic char collections were mostly from anadromous populations and these had very low levels of mercury, presumably reflecting marine food sources. Lake whitefish were among the cleanest fish examined with 69 of 81 collections falling in the lowest range. Most collections were from sites in sedimentary rock. However a few sites were in metamorphic, intrusive or volcanic rocks and these, taken together, tended to have a higher proportion of sites in the higher ranges of mercury. These results indicate a widespread problem with mercury in subsistence fisheries for predator species of fish with the problem being most problematic for Nunavut.

Long survival and prognostic factors in hepatocellular carcinoma

We studied survival and prognostic factors in all cases of hepatocellular carcinoma seen at a Midwestern teaching hospital from 1947 through 1986. Of the 70 cases, 56 were diagnosed during life and 14 at autopsy. There were 47 males and 23 females with age at diagnosis ranging from 14 to 88. Median survival for the 56 patients diagnosed during life was 106 days. Only 11 patients lived longer than one year. Two patients were long survivors and presumed cured, one living 27 years after diagnosis and surgical treatment and the other 19 years. Cox regression model showed young age at diagnosis and low stage of disease at diagnosis to be significant predictors of long survival. White patients survived nearly twice as long as black patients but the difference was not significant. Gender and year of diagnosis did not appear to be important determinants of survival. Pathologic material was still available for one of the two long survivors and the histology was that of fibrolamellar carcinoma of young adults.

Cortisone-induced islet cell hyperplasia in hamsters

Pancreatic islet cell hyperplasia was studied in hamsters during one to eight weeks of cortisone treatment. Measurement of serum glucose and insulin; pancreatic insulin, glucagon, somatostatin, pancreatic polypeptide as well as islet tissue morphometry were performed. Serum glucose was highest at week 2, followed by mild to moderate hyperglycemia. Serum insulin was increasingly higher from week 1 to week 8. Pancreatic insulin was maximal at week 5 then declined through week 8 in the presence of beta cell neurosis in markedly hyperplastic islets. Pancreatic concentration of somatostatin and pancreatic polypeptide moderately increased more than the control levels; however, compared with the controls, glucagon was reduced by cortisone treatment. Effect of cortisone in the four types of islet cells is discussed, particularly on beta cell hyperplasia, which appears to be a response to decreased insulin binding to the target organs with no changes in receptor concentration.

The endocrine polypeptide cells of the human stomach, duodenum, and jejunum

Thirty specimens of stomach, duodenum, and jejunum, removed at operation, were examined by optical microscopical, cytochemical, and electron microscopical techniques. The overall distribution of four types of endocrine polypeptide cell in the stomach, and three in the intestine, was determined. The seven cell types are described by names and letters belonging to a scheme for nomenclature agreed upon at the 1969 Wiesbaden conference on gastrointestinal hormones. The gastrin-secreting G cell was the only cell for which firm identification with a known hormone was possible. Although there was wide variation in the distribution of the various cells, from one case to another, striking differences were nevertheless observable, with respect to the G cell, between antra from carcinoma and from ulcer cases.