A pilot-stage device feasibility study investigating a mask-free motion-monitoring patient immobilisation system for use during radiation therapy treatment of head and neck cancer (HNC). This mask-free system combines the standard radiation therapy (RT) head rest to help the patient remain still with a surface guidance detection system that uses sensors to detect and track patient movement.

Patients who will have RT treatment for head and neck cancer involving an immobilisation mask will be asked to lie on the treatment couch for the normal treatment fraction time while the surface monitoring system is activated. We will then assess:

i) The level of acceptance of the system by HNC patients currently being treated with RT using an immobilisation mask, and ii) The ability of the surface guidance system to monitor movement of the patients

Radiation therapy (RT) is a central treatment modality for 74% of head and neck cancer (HNC) patients where preservation of the form and function of localised organs and tissue is of prime importance. Radiation therapy offers the possibility of organ preservation by providing a non-surgical approach to curative treatment, while helping to limit the extent of surgery in cases where definitive surgery is unavoidable. Radiation therapy also has an important role in maintaining quality of life in the palliative management of incurable HNC, where it can prevent and alleviate pain, bleeding, tumour fungation and difficulty with swallowing, breathing and speech.

State-of-the-art RT for HNC delivers lethal radiation doses to the cancer while sparing vital organs situated just a few millimetres away. To achieve this level of accuracy, tight-fitting thermoplastic head and neck masks are used to immobilise the patient in the desired treatment position for the duration of each of their RT treatments. These thermoplastic immobilisation devices are accepted internationally as the necessary standard and included in published guidelines. Open masks are an emerging immobilisation measure and a first step to reduce patient discomfort and anxiety. An open mask has a smaller visual restriction and fewer restraint points.

Although, thermoplastic immobilisation masks are the accepted clinical standard for HNC RT, it is widely recognised and acknowledged that there are several limitations with their use. Changes to the mask's fit may be needed due to patient weight loss, tumour shrinkage, or treatment related oedema. Thus, radiation therapists are required to monitor the mask for fit throughout the treatment course, undertake imaging at regular intervals and make corrections as per published guidelines and local protocols. There is also risk of movement of the patient within the mask, which may lead to under dosing of the target and overdosing of organs at risk. Court et al. reported that patients in their study needed to be repositioned in the immobilisation mask before treatment for 14% of fractions; 30% of the repositioning was for shoulder shifts of 1 cm or greater. Neubauer et al. observed shoulder motion of 2-5 mm in each direction on average (20 mm max). These shifts resulted in coverage loss (dose to 99% of the clinical target volume decreased by up to 1Gy) or increased dose to organs at risk (e.g., dose to brachial plexus increased by 0.7Gy).

The ACRF Image X Institute at the University of Sydney has developed a novel surface guidance system that can be mounted to any RT imaging and treatment couch. This system is currently being used in a clinical trial (NCT02881203) to guide breast cancer patients into a reproducible breath hold: the patient's chest position is measured via surface imaging and the system delivers visual feedback to the patient via a screen for the patient to correct their breath hold level if necessary (i.e., surface guidance). This system uses off-the-shelf electronics, most importantly a sensor which includes an optical and a depth camera, delivering frames at a rate of 30Hz and allowing the patient and operator to see an augmented reality video feed, including the surface depth information.

Similar to this, we will apply optical and depth cameras for head and neck surface monitoring by integrating a second sensor and adapting it to the different location of treatment

Pilot-stage, single-arm study investigating the technical feasibility and patient acceptance of a non-interventional, non-invasive, mask-free surface detection system.

Towards the end of their scheduled radiation therapy treatments, people being treated for HNC with RT using a thermoplastic immobilisation mask will be asked to lie in a treatment position on a treatment couch using a standard radiation therapy headrest without the mask, for the normal amount of time taken for individual radiation therapy treatments (20 minutes). During this time, the mask-free surface detection system will detect and record their location and movement. Data collected by the surface detection system during this couch session will be analysed to determine the feasibility of using the equipment to detect location and movement over this period. Data collected directly from the participants immediately before, during and following the couch session will be used to determine their acceptance of the system in terms of comfort and anxiety when compared with wearing the mask, and any suggestions for improvement of the system. Data collected directly from the radiation therapists following the couch session will be used to investigate their thoughts on the abilities of the system, ease of use and suggestions they may have.

To investigate the effect of changes in appearance due to weight loss over the course of HNC radiation therapy treatment, a 5-minute surface monitoring couch session conducted before the start of radiation therapy will record baseline surface-monitoring information only.

Data analysis will occur at the University of Sydney outside of participant sessions.

Inclusion Criteria

• A diagnosis of head and neck cancer, any stage
• ≥ 18 years of age
• ECOG performance status 0-2
• Receiving radiation therapy for HNC with a thermoplastic immobilisation mask
• Any other prior therapy allowed
• Willing and able to comply with all study requirements
• Must be able to read and complete questionnaires in English

Exclusion Criteria

• People with cognitive impairment which would preclude them from providing informed consent
• People who are unable to speak and read English and for whom obtaining consent would be difficult.

Withdrawal Criteria

• Participants may withdraw from the study at any time before, during or after participation, and do not have to provide a reason. They may do so by advising any member of the study team, research office or their treating team, by completing the withdrawal of consent form, verbally or in writing.
• Participants may be withdrawn from the study by the principal investigator, treating physician or attending clinician if they perceive the participant is experiencing or will likely experience physical or mental harm
• No additional study data will be collected for a participant after they withdraw from the study
• Withdrawing participants' data will be used unless the participant specifies they no longer give permission for the data to be stored or used, however, their data will not be removed from any analysis or publication that has already occurred, or from study databases once it has been de-identified
• Participant will be replaced if they withdraw or are withdrawn from the study prior to starting the second couch session. This will be done by recruitment of an additional participant.
• If a couch session is ended by the researcher or participant for reasons unrelated to the study (e.g. not related to equipment failure or participant non-acceptance), the session may be rescheduled, or participant replaced.
• Reasons for withdrawal will be reported in any outcome publications.

Non-identifiable individual participant data (IPD) may be shared with researchers for further scientific research. Facial images/photos identifying participants will not be shared.

Not before the study completion. For not more than 15 years after study completion, at which time the data sharing plan will be revised.