Motion Capture Pillow (MCP): A novel method to improve comfort and accuracy in radiotherapy

The delivery of radiotherapy has changed signi?cantly over the last few decades. Recent advances in radiotherapy practice may increase patient discomfort. A key challenge to improve patient comfort is the common use of a thermoplastic mask for patients with head and neck cancers. Patients suffer from discomfort and the claustrophobic effect of the mask, or as they lose soft tissue due to treatment and gain undesirable movement in the mask. A prototype system using a robotic motion capture pillow (MCP) is investigated for proof-of-concept and is pictorially presented for the potential replacement of thermoplastic masks

Head tracking using an optical soft tactile sensing surface

This research proposes a sensor for tracking the motion of a human head via optical tactile sensing. It implements the use of a fibrescope a non-metal alternative to a webcam. Previous works have included robotics grippers to mimic the sensory features of human skin, that used monochrome cameras and depth cameras. Tactile sensing has shown advantages in feedback-based interactions between robots and their environment. The methodology in this paper is utilised to track motion of objects in physical contact with these sensors to replace external camera based motion capture systems. Our immediate application is related to detection of human head motion during radiotherapy procedures. The motion was analysed in two degrees of freedom, respective to the tactile sensor (translational in z-axis, and rotational around y-axis), to produce repeatable and accurate results. The movements were stimulated by a robot arm, which also provided ground truth values from its end-effector. The fibrescope was implemented to ensure the device’s compatibility with electromagnetic waves. The cameras and the ground truth values were time synchronised using robotics operating systems tools. Image processing methods were compared between grayscale and binary image sequences, followed by motion tracking estimation using deterministic approaches. These included Lukas-Kanade Optical Flow and Simple Blob Detection, by OpenCV. The results showed that the grayscale image processing along with the Lukas-Kanade algorithm for motion tracking can produce better tracking abilities, although further exploration to improve the accuracy is still required

Residual Set-up Error for Canine Brain Radiation Therapy

When targeting a structure in three-dimensional space, the repositioning accuracy of the patient on the treatment table should be consistent among all radiation treatment sessions. Immobilization devices are used reposition the patients, and imaging systems built into the radiation machine are used to correct the patient’s position prior to treatment. Radiation oncologists usually treat a margin of normal tissue around the tumor called planning target volume (PTV) to account for interfraction (set-up errors) and intrafraction motion (such as motion due to respiration). The size of the PTV margin is an estimate of the targeting accuracy that can be achieved using immobilization devices and image guidance. The PTV margin reported for stereotactic radiation therapy (SRT) and stereotactic radiosurgery (SRS) to treat canine brain tumors ranges from 0-3 millimeters (Kelsey, Gieger, and Nolan 2018; Griffin et al. 2014; Dolera et al. 2017). An ideal margin would be a narrow margin to minimize the chance of toxicity to the normal brain and wide enough to cover the entire tumor target. The size of the PTV margin also depends on the radiation therapy delivery technique and the fractionation scheme (dose of radiation for each treatment session) planned for determined tumor types and locations. Accurate patient set-up and adequate PTV margin selection are required to minimize the chance of radiation side effects to the normal tissue surrounding the tumor region and to maximize tumor control. This is particularly relevant for SRS and SRT treatments, as higher doses of radiation are used to treat cancers compared to conventional radiation protocols

Contrasting Two Prophylactic Dysphagia Interventions for Patients with Head and Neck Cancer Treated with Radiotherpy with or without Adjunctive Chemotherapy

Many patients with head and neck cancer (HNC) suffer from dysphagia caused by organ preserving regimens of radiation therapy with or without adjunctive chemotherapy. Prior research has shown a benefit of prophylactic dysphagia intervention; however, prior studies vary in terms of timing, dosage, and types of treatments prescribed. Additionally, compliance to prophylactic swallowing exercises (PSEs) has been poor and anecdotal evidence points towards swallowing pain as a cause of poor compliance. This prospective study investigated exercise compliance, oral intake, self-perceived swallowing function, swallowing-related quality of life, and swallowing-related pain for patients who received two different types of prophylactic swallowing interventions. A total of 18 participants partook of the study. Nine patients completed only indirect swallowing exercises (exercises that do not require swallowing; ID-PSE group). The remaining nine patients completed a combination of indirect and direct swallowing exercises (exercises that require swallowing; C-PSE group). There were no significant differences between the groups at baseline or at any point during RT/CRT. The ID-PSE group performed significantly better than the C-PSE group at one month post-RT/CRT in swallowing function, as measured by the Eating Assessment Tool, and swallowing-related QOL, as measured by the MD Anderson Dysphagia Inventory. By three months post RT/CRT these differences were not present; however, at three months post the C-PSE group reported significantly less swallowing pain than the ID-PSE group. Between-group differences were not evident at any point in compliance or oral intake. Outcomes for both groups were comparable to prior PSE studies and better than outcomes reported in the literature in HNC patients who did not receive prophylactic intervention. This study is the first to investigate and provide preliminary evidence for the efficacy of a prophylactic swallowing intervention consisting solely of indirect swallowing exercises. Study limitations, clinical implications, and future directions are discussed

Principal Component Analysis-Based Anatomical Motion Models For Use In Adaptive Radiation Therapy Of Head And Neck Cancer Patients

Purpose: To develop standard and regularized principal component analysis (PCA) models of anatomical changes from daily cone beam CTs (CBCTs) of head and neck (H&N) patients, assess their potential use in adaptive radiation therapy (ART), and to extract quantitative information for treatment response assessment. Methods: Planning CT (pCT) images of H&N patients were artificially deformed to create “digital phantom” images, which modeled systematic anatomical changes during Radiation Therapy (RT). Artificial deformations closely mirrored patients’ actual deformations, and were interpolated to generate 35 synthetic CBCTs, representing evolving anatomy over 35 fractions. Deformation vector fields (DVFs) were acquired between pCT and synthetic CBCTs (i.e., digital phantoms), and between pCT and clinical CBCTs. Patient-specific standard PCA (SPCA) and regularized PCA (RPCA) models were built from these synthetic and clinical DVF sets. Eigenvectors, or eigenDVFs (EDVFs), having the largest eigenvalues were hypothesized to capture the major anatomical deformations during treatment. Modeled anatomies were used to assess the dose deviations with respect to the planned dose distribution. Results: PCA models achieve variable results, depending on the size and location of anatomical change. Random changes prevent or degrade SPCA’s ability to detect underlying systematic change. RPCA is able to detect smaller systematic changes against the background of random fraction-to-fraction changes, and is therefore more successful than SPCA at capturing systematic changes early in treatment. SPCA models were less successful at modeling systematic changes in clinical patient images, which contain a wider range of random motion than synthetic CBCTs, while the regularized approach was able to extract major modes of motion. For dose assessment it has been shown that the modeled dose distribution was different from the planned dose for the parotid glands due to their shrinkage and shift into the higher dose volumes during the radiotherapy course. Modeled DVHs still underestimated the effect of parotid shrinkage due to the large compression factor (CF) used to acquire DVFs. Conclusion: Leading EDVFs from both PCA approaches have the potential to capture systematic anatomical changes during H&N radiotherapy when systematic changes are large enough with respect to random fraction-to-fraction changes. In all cases the RPCA approach appears to be more reliable than SPCA at capturing systematic changes, enabling dosimetric consequences to be projected to the future treatment fractions based on trends established early in a treatment course, or, potentially, based on population models. This work showed that PCA has a potential in identifying the major mode of anatomical changes during the radiotherapy course and subsequent use of this information in future dose predictions is feasible. Use of smaller CF values for DVFs is preferred, otherwise anatomical motion will be underestimated

EQUIPMENT TO ADDRESS INFRASTRUCTURE AND HUMAN RESOURCE CHALLENGES FOR RADIOTHERAPY IN LOW-RESOURCE SETTINGS

Millions of people in low- and middle- income countries (LMICs) are without access to radiation therapy and as rate of population growth in these regions increase and lifestyle factors which are indicative of cancer increase; the cancer burden will only rise. There are a multitude of reasons for lack of access but two themes among them are the lack of access to affordable and reliable teletherapy units and insufficient properly trained staff to deliver high quality care. The purpose of this work was to investigate to two proposed efforts to improve access to radiotherapy in low-resource areas; an upright radiotherapy chair (to facilitate low-cost treatment devices) and a fully automated treatment planning strategy. A fixed-beam patient treatment device would allow for reduced upfront and ongoing cost of teletherapy machines. The enabling technology for such a device is the immobilization chair. A rotating seated patient not only allows for a low-cost fixed treatment machine but also has dosimetric and comfort advantages. We examined the inter- and intra- fraction setup reproducibility, and showed they are less than 3mm, similar to reports for the supine position. The head-and-neck treatment site, one of the most challenging treatment planning, greatly benefits from the use of advanced treatment planning strategies. These strategies, however, require time consuming normal tissue and target contouring and complex plan optimization strategies. An automated treatment planning approach could reduce the additional number of medical physicists (the primary treatment planners) in LMICs by up to half. We used in-house algorithms including mutli-atlas contouring and quality assurance checks, combined with tools in the Eclipse Treatment Planning System®, to automate every step of the treatment planning process for head-and-neck cancers. Requiring only the patient CT scan, patient details including dose and fractionation, and contours of the gross tumor volume, high quality treatment plans can be created in less than 40 minutes

An evaluation of a checklist in Musculoskeletal (MSK) radiographic image interpretation when using Artificial Intelligence (AI)

Background: AI is being used increasingly in image interpretation tasks. There are challenges for its optimal use in reporting environments. Human reliance on technology and bias can cause decision errors. Trust issues exist amongst radiologists and radiographers in both over-reliance (automation bias) and reluctance in AI use for decision support. A checklist, used with the AI to mitigate against such biases, may optimise the use of AI technologies and promote good decision hygiene. Method: A checklist, to be used in image interpretation with AI assistance, was developed. Participants interpreted 20 examinations with AI assistance and then re- interpreted the 20 examinations with AI and a checklist. The MSK images were presented to radiographers as patient examinations to replicate the image interpretation task in clinical practice. Image diagnosis and confidence levels on the diagnosis provided were collected following each interpretation. The participant perception of the use of the checklist was investigated via a questionnaire.Results: Data collection and analysis are underway and will be completed at the European Congress of Radiology in Vienna, March 2023. The impact of the use of a checklist in image interpretation with AI will be evaluated. Changes in accuracy and confidence will be investigated and results will be presented. Participant feedback will be analysed to determine perceptions and impact of the checklist also. Conclusion: A novel checklist has been developed to aid the interpretation of images when using AI. The checklist has been tested for its use in assisting radiographers in MSK image interpretation when using AI.<br/

Multimodality functional imaging in rectal cancer treated with radiotherapy

The successful treatment of locally advanced rectal cancer often relies upon the response to neoadjuvant radiotherapy to improve the chances of surgical resection. Diagnostic imaging is vital to determine appropriate patient management but there is a range of responses to radiation in those who undergo treatment. Multimodality functional imaging provides non-invasive assessment of several aspects of tumour pathophysiology such as hypoxia, perfusion and glucose metabolism, and can characterise heterogeneity within. This may be useful to determine suitable treatment strategy and to target tumour appropriately. Furthermore, it may guide to appropriate systemic radiosensitisers. Following neoadjuvant therapy, a complete response is possible in a minority of patients who could avoid major surgery if they could be confidently identified. Functional imaging may have a further role to play in this setting. In this thesis, the role of multimodality functional imaging is investigated in patients undergoing neoadjuvant chemoradiotherapy for locally advanced rectal cancer within two imaging studies, RIT and RHYTHM. Hypoxia, known to be an important cause of radioresistance, is assessed through static 18F-Fluoromisonidazole PET-CT and oxygen-enhanced MRI, which is compared with immunohistochemical markers of hypoxia. This process relies significantly on tumour perfusion, which is investigated through dynamic 18F-Fluoromisonidazole PET-CT. Dynamic contrast-enhanced MRI and perfusion CT provide a further indication of the effects of radiation on tumour perfusion. Within the heterogenous environment created, tumour metabolism is altered and this can be measured in order to evaluate appropriate treatment and response. 18F-Fluorodeoxyglucose PET-CT scanning is one method to assess glucose metabolism. A novel technique, glucoCEST MRI, may also provide this information with the anatomical superiority of this modality. It is explored further in BIOPIC, an imaging study of oropharyngeal squamous cell carcinoma patients undergoing radical radiotherapy. The results demonstrate that rectal tumours are heterogenous and a multitude of interacting pathophysiological factors likely affect the response to radiation. Defining complete response may require a multimodality solution in order to confidently avoid resection. Significant challenges in undertaking functional imaging are discussed and potential solutions considered

Translating the Evidence: Comprehensive Approaches for Head and Neck Cancer Prehabilitation

Head and neck cancer survivors experience significant changes to their health, well-being, and ability to participate in daily life activities as a result of cancer treatment. Oftentimes, these patients are left to their own devices without concrete instructions or strategies to mitigate, much less prevent, the sequelae they experience. Likewise, interdisciplinary teams lack an evidence-based framework in which to provide comprehensive supportive care for patients with head and neck cancer. Despite acknowledgement within the occupational therapy profession of the chronic nature of survivorship (Baxter et al., 2017) and the national public health initiatives to prevent and reduce the impact of secondary chronic disease burden (American Occupational Therapy foundation, n.d.; National Center for Chronic Disease Prevention and Health Promotion (U.S.) et al., 2004), there remains a critical gap in preventative services in head and neck cancer populations regarding known side effects of cancer treatment (Berkowitz et al., 2018; Fang & Heckman, 2016; Rogers et al., 2011). Therefore, a review and critical appraisal of the existing evidence surrounding prehabilitation as a model of care and the role of occupational therapy with head and neck cancer survivors was indicated. The evidence review and critical appraisal, which took place in the fall of 2021, provided the underpinning for three knowledge translation projects. The aims of this doctoral project are to increase awareness of head and neck cancer survivors’ needs and to share knowledge concerning evidence-based interventions and approaches to meet these needs. To accomplish these aims, I selected three different methods to translate knowledge. In the first project I sought to educate generalist practitioners and students in the context of a collaborative synchronous webinar series with the Minnesota Occupational Therapy Association about implications for practice. The second project involved a live webinar embedded within a semi-annual meeting of the Michigan Occupational Therapy Association Oncology Special Interest Section. Attendees in this project were assumed to have had at least minimal training or experience in oncology practice and included a range of practitioners and students. Attendees also participated in discussion pertaining to implementation. The third project was a scoping review article submitted to the interdisciplinary journal Archives of Physical Medicine and Rehabilitation. This article serves as a method to reach a wide audience in terms of discipline as well as geographic location. Together, these three projects provided a variety of opportunities to increase knowledge about prehabilitation and occupational therapy approaches in the supportive care of head and neck cancer survivors. In light of the vast scope of this project, future refinements of the recommended model are expected. Additional information and input from other disciplines would serve the usability of the model well. Future planned projects include a poster presentation at the American Congress of Rehabilitative Medicine Annual Conference in the fall of 2022, in addition to a critical issues article in the American Journal of Occupational Therapy to provide a call to action for occupational therapy practitioners to take their place on the interdisciplinary team