A survey of surface imaging use in radiation oncology in the United States

Abstract

Surface imaging (SI) has been rapidly integrated into radiotherapy clinics across the country without specific guidelines and recommendations on its commissioning and use aside from vendor-provided information. A survey was created under the auspices of AAPM TG-302 to assess the current status of SI to identify if there is need for formal guidance. The survey was designed to determine the institutional setting of responders, availability and length of its use, commissioning procedures, and clinical applications. This survey was created in REDCap, and approved as IRB exempt to collect anonymized data. Questions were reviewed by multiple physicists to ensure concept validity and piloted by a small group of independent physicists to ensure process validity. All full members of AAPM self-identified as "therapy" or "other" were sent the survey link by email. The survey was active from February to March 2018. Of 3677 members successfully contacted, 439 completed responses; the summary of these responses provides insight on current surface imaging clinical practices, though they should not be assumed to be representative of radiation oncology as a whole. Results showed that 53.3% of respondents have SI in their clinics, mostly in treatment rooms, rarely in simulation rooms. Half of those without SI plan on purchasing it within 3 years. Over 10% have SI but do not use it clinically, 36.8% classify themselves as "expert" users, and 85.5% agreed/strongly agreed that SI guidelines are needed. Initial positioning with SI is most common for breast/chestwall and SRS/SBRT treatments, least common for pediatrics. Use of SI for intra-fraction monitoring follows a similar distribution. Gating with SI is most prevalent for breast/chestwall (66.0%) but also used in SBRT (33.0%), and non-SBRT lung/abdomen (<30%) treatments. SI is a rapidly growing technology in the field with widespread use for several anatomic sites. Guidelines and recommendations on commissioning and clinical use are warranted.

Recent advances in Surface Guided Radiation Therapy

“…breast and other skin-near targets [13,16,[21][22][23][24][25][26][27][28][29][30]. For deeper situated targets, surface imaging should be used with caution [13,22,31,32].…”

“…SGRT-based intra-fraction monitoring of pediatric treatments is not widely used [32] and literature is limited. In a case report [87] using SGRT in combination with a linac using the FFF mode, the palliative radiation treatment of an 18-month old boy with relapsed Wilms tumor was reported.…”

“…However, surface imaging achieved at least the same precision as laser alignment and was considered a valuable tool for initial patient setup and as a complement to conventional imaging modalities [ 13 , 22 , 38 ]. The lack of correlation between the surface and internal structure movement is not an argument against the use of SGRT [ 32 ], since SGRT does not provide contradictory but complementary information for image guidance. The choice of the ROI for the reference image influences the correlation between SGRT and image-guided positioning.…”

Technical Note: Development of 3D‐printed breast phantoms for end‐to‐end testing of whole breast volumetric arc radiotherapy

“…These phantoms were validated with hybrid plan measurements and an end-to-end test of a VMAT- The phantoms were fully compliant with the AlignRT surface scanning system, which is increasingly used for setup of breast cancer patients at radiotherapy departments. 5,19,20 The shape and red color of the PLA resulted in a stable surface registration result. During RTT training and hardware and software upgrade verification of the surface scanning system, we now use the E2E breasts compared to the vender-provided geometric phantom.…”

“…External features are also lacking in the thorax phantom of the Imaging and Radiation Oncology Core group (IROC) distributed for quality assurance (QA). 2 Moreover, all these phantoms have a shiny coating, cylindrical symmetry, or both, limiting the use of surface scanning technology used for patient setup, 3,4 which is increasingly being used for patient setup, 5 and whose positioning accuracy should be incorporated into commissioning.…”