Quality of patient positioning during cerebral tomotherapy irradiation using different mask systems

Randomized self-controlled study comparing open-face vs. closed immobilization masks in fractionated cranial radiotherapy

PURPOSE

To compare patient discomfort and immobilisation performance of open-face and closed immobilization masks in cranial radiotherapy.

MATERIAL AND METHODS

This was a single-center randomized self-controlled clinical trial. At CT simulation, an open-face and closed mask was made for each patient and treatment plans with identical dose prescription were generated for each mask. Patients were randomised to start treatment with an open-face or closed mask. Masks were switched halfway through the treatment course; every patient was their own control. Patients self-reported discomfort, anxiety and pain using the visual analogue scale (VAS). Inter- and intrafraction set-up variability was measured with planar kV imaging and a surface guided radiotherapy (SGRT) system for the open-face masks.

RESULTS

30 patients with primary or metastatic brain tumors were randomized - 29 completed radiotherapy to a median total dose of 54 Gy (range 30-60 Gy). Mean discomfort VAS score was significantly lower with open-face masks (0.5, standard deviation 1.0) vs. closed masks (3.3, standard deviation 2.9), P < 0.0001. Anxiety and pain VAS scores were significantly lower with open-face masks (P < 0.0001). Closed masks caused more discomfort in infraorbital (P < 0.001) and maxillary (P = 0.02) areas. Two patients and 27 patients preferred closed or open-face masks, respectively. Interfraction longitudinal shifts and roll and yaw rotations were significantly smaller and lateral shifts were significantly larger with closed masks in combination with the laser system (P < 0.05) compared to open masks in combination with a SGRT system. Intrafraction variability did not differ between the masks.

CONCLUSIONS

Open-face masks are associated with decreased patient discomfort without compromising patient positioning and immobilisation accuracy.

A review of Image Guided Radiation Therapy in head and neck cancer from 2009-201 - Best Practice Recommendations for RTTs in the Clinic

Radiation therapy (RT) is beneficial in Head and Neck Cancer (HNC) in both the definitive and adjuvant setting. Highly complex and conformal planning techniques are becoming standard practice in delivering increased doses in HNC. A sharp falloff in dose outside the high dose area is characteristic of highly complex techniques and geometric uncertainties must be minimised to prevent under dosage of the target volume and possible over dosage of surrounding critical structures. CTV-PTV margins are employed to account for geometric uncertainties such as set up errors and both interfraction and intrafraction motion. Robust immobilisation and Image Guided Radiation Therapy (IGRT) is also essential in this group of patients to minimise discrepancies in patient position during the treatment course. IGRT has evolved with increased 2-Dimensional (2D) and 3-Dimensional (3D) IGRT modalities available for geometric verification. 2D and 3D IGRT modalities are both beneficial in geometric verification while 3D imaging is a valuable tool in assessing volumetric changes that may have dosimetric consequences for this group of patients. IGRT if executed effectively and efficiently provides clinicians with confidence to reduce CTV-PTV margins thus limiting treatment related toxicities in patients. Accumulated exposure dose from IGRT vary considerably and may be incorporated into the treatment plan to avoid excess dose. However, there are considerable variations in the application of IGRT in RT practice. This paper aims to summarise the advances in IGRT in HNC treatment and provide clinics with recommendations for an IGRT strategy for HNC in the clinic.

3D-Printed masks as a new approach for immobilization in radiotherapy - a study of positioning accuracy

We developed a new approach to produce individual immobilization devices for the head based on MRI data and 3D printing technologies. The purpose of this study was to determine positioning accuracy with healthy volunteers.

3D MRI data of the head were acquired for 8 volunteers. In-house developed software processed the image data to generate a surface mesh model of the immobilization mask. After adding an interface for the couch, the fixation setup was materialized using a 3D printer with acrylonitrile butadiene styrene (ABS). Repeated MRI datasets (n=10) were acquired for all volunteers wearing their masks thus simulating a setup for multiple fractions. Using automatic image-to-image registration, displacements of the head were calculated relative to the first dataset (6 degrees of freedom).

The production process has been described in detail. The absolute lateral (x), vertical (y) and longitudinal (z) translations ranged between −0.7 and 0.5 mm, −1.8 and 1.4 mm, and −1.6 and 2.4 mm, respectively. The absolute rotations for pitch (x), yaw (y) and roll (z) ranged between −0.9 and 0.8°, −0.5 and 1.1°, and −0.6 and 0.8°, respectively. The mean 3D displacement was 0.9 mm with a standard deviation (SD) of the systematic and random error of 0.2 mm and 0.5 mm, respectively.

In conclusion, an almost entirely automated production process of 3D printed immobilization masks for the head derived from MRI data was established. A high level of setup accuracy was demonstrated in a volunteer cohort. Future research will have to focus on workflow optimization and clinical evaluation.

A focus group consultation round exploring patient experiences of comfort during radiotherapy for head and neck cancer

Purpose

The aim of this study was to consult patients about their experiences of comfort while wearing a thermoplastic mask during head and neck radiotherapy before designing a study to develop a comfort scale for radiotherapy.

Methods

A qualitative method using a focus group of patients receiving radiotherapy for head and neck cancer was deployed. Five patients were invited and agreed to participate. Semi-structured questions guided the focus group interview. Thematic analysis was used to identify themes.

Findings

Three patients participated in the focus group. Three main themes were identified: Physical comfort, Mental perception, Passivity. Physical comfort derived from feelings of pressure, unpleasantness, and generally being uncomfortable. Mental perception derived from how the physical comfort was perceived and derived from feelings of shock, anxiety, indifference and sensory systems. Passivity arose from feelings such as the ‘doctor knows best’, ‘putting up with it’, and ‘being taken for a ride’.

Conclusion

The insight of patient’s comfort and experiences are valuable for clinicians to provide patient-centred care. Findings of this study implicate further investigation of how the themes of patient comfort can be measured in radiotherapy to improve the patient experience.