Table 4. Literature Review of Frameless Radiosurgery (Selected Series).
Ref = references; Pre-RT = pre-radiation therapy; HD = high definition; TPS = treatment planning system; IR = Infrared camera system with 4-6 reflectors or emitters mounted on bite-block tray; OSMS = optical surface monitoring system (AlignRT); kV = kilovoltage imaging; CBCT = cone beam CT; DOF = degrees of freedom; HD = high definition; MLC = multileaf collimator; SRS = stereotactic radiosurgery; VMAT = volumetric modulated arc therapy; FSRT = fractionated stereotactic radiotherapy; OBI = on-board imaging; GK = Gamma Knife; DCA = dynamic conformal arc; FFF = flattening fillter free; N = number; mets = metastases; OBI = on-board imager; AVM = arteriovenous malformation; CI = conformity index; HI = homogeneity index; GTV = gross target volume; PTV = planning target volume; IMRT = intensity modulate radiation therapy
| First Author [Ref], Institution, Publication year | Equipment | Image Guidance, Robotic Couch, Intrafraction Motion | Pre-RT Scans, Immobilization Devices | Patients | Technique, TPS | Notes, Results, or Conclusions |
| Mancosu [43] Milan-Rozzano 2016 | Varian Edge 120HD MLC | kV/CBCT 6-DOF couch OSMS | CT MRI | Phantom | - | Study of Edge linac with OSMS and CBCT. Tested ability of OSMS vs. CBCT ability to detect facial movements at isocenter, ability to recognize shifts, at different couch angles, and accuracy of OSMS when a camera is blocked. Submillimeter accuracy with rotational inaccuracy of 0.3 degrees. |
| Wen [44] Henry Ford 2015 | Varian Edge 120HD MLC | kV/CBCT 6-DOF couch OSMS | - | Commissioning | FFF VMAT Cones | Report of commissioning of Edge radiosurgery system. Deviation between OSMS and CBCT was -0.4, 0.1, and 0 mm in vertical, longitudinal, and lateral dimensions. Beam data and mechanical parameters similar to TrueBeam, with advanced imaging package, 6-DOF couch, and intracranial SRS accessory package. |
| Seravalli [45] MAASTRO 2015 | Elekta Synergy 10 mm MLC | kV/CBCT Pre- & post- CBCT | CT 1.2 mm MRI 1.2 mm Mask (BlueBAG) | N = 52 Brain mets | SRS Coplanar VMAT (Pinnacle) | Process of treatment. End-to-end test. GTV-PTV margin of 2.4 - 3.1 mm. Used Quantec constraints. |
| Li [29] MSK 2015 | Varian Trilogy kV/CBCT | OSMS | Bite block (PinPoint) vs Open Mask (Freedom) | N = 25 Bite block N = 8 Mask | FSRT Coplanar beams (iPlan) | Process of care diagram. Deliberate forced moves (15 volunteers) on ref Table 1. Study of volunteer comfort ref Table 2. |
| McTyre [40] Wake Forest 2015 | Gamma Knife Perfexion | No OBI | CT MRI Bite block (Extend) | N = 34 | Fractionated GK (GammaPlan) | Meningioma, schwannoma, metastases. GTV was treated without margin. 16-32 Gy to 50% isodose line over 4-5 fractions. Optic apparatus constrained to 4 Gy tangential to tumor. Daily repositioning errors < 1.2 mm. |
| Nanda [25] Emory 2014 | Novalis Tx HD MLC | kV/CBCT IR 6-DOF | CT 0.625 mm MRI | N = 5 Pediatric | SRS/FSRT Non-coplanar DCA IMRT 12 beams | GTV-PTV 1 mm 4/5 patients required anesthesia |
| Pan [41] UCSD 2012 | TrueBeam Trilogy | OSMS | CT 1.25 mm MRI 1.25 mm Open Mask (CIVCO) | N = 44 Adults | SRS/FSRT Multiple beams Cones or VMAT (Eclipse) | GTV-PTV 1 mm. Beam hold 1-2 mm and 1°. Treatment times – CBCT mean 11 min. Median shifts 1 mm, 2 mm, 1 mm vertical, longitudinal, lateral. Treatment time 15 min (shorter for TrueBeam). Compared local control to other series. |
| Schlesinger [39] UVA 2012 | Gamma Knife Perfexion | No OBI | CT MRI Bite block (Extend) | N = first 10 | Fractionated GK (GammaPlan) | Interfraction and intrafraction performance of Extend. Mean radial setup difference was 0.64 mm, SD 0.24 mm. Mean intrafractional positional difference was 0.47 mm. Cannot account for rotations. |
| Lu [35] BIDMC 2012 | Proton | Orthogonal kV Three 2 mm gold fiducial spheres | CT Frameless | N = 1 AVM | Proton | Description of novel technique with implanted fiducials to localize AVM identified on angiography and to transfer location information to CT for proton SRS planning. |
| Tryggestad [30] JHU 2011 | Elekta Synergy S | Pre- & post- CBCT | Mask - 4 types Nonrandom study Retrospective | N = 121 | FSRT/external RT | Demonstrated masks (ref. Figure 1). Best was type-S head and shoulder mask with head and shoulder cushion with mouthpiece. Can achieve intrafraction motion of 1 mm or less, and interfraction variability of less than 3 mm. |
| Ramakrishna [31] DFCI 2010 | Novalis | Stereoscopic kV (ExacTrac) IR | Frame (Radionics) Mask (BrainLAB) | N = 102 SRS N = 7 FSRT | SRS | End-to-end overall accuracy of Novalis Body ExacTrac is 0.7 mm ± 0.3 mm. Approximately 22% of mask-immobilized patients displayed intrafraction displacement of 1-2 mm. |
| Peng [49] UF Gainesville 2010 | Elekta Synergy Varian Trilogy | CT 2 mm Mask IR CBCT | N = 15 IR N = 18 Mask | - | Comparison of IR tracking system setup with CBCT. Setup with IR resulted in setup errors of 1.2 mm determined by CBCT, versus mask and laser setup errors of 3.2 mm. FSRT should not rely on IR alone. | |
| Mayo [34] U Mass 2010 | Varian Trilogy 5 mm MLC | kV/CBCT | CT 1.25 mm MRI 1.25 mm Mask (Alpha Cradle) | N = 12 Adults Brain mets | SRS Non-coplanar VMAT (Eclipse) | GTV-PTV 1-2 mm margin. Dosimetric details compared to CyberKnife, TomoTherapy, & IMRT. Reported on CI, gradient, & HI. Phantom end-to-end testing. Compared dose rate vs. survival in cell line (ref Figure 9). |
| Keshavarzi [50] UCSD 2009 | Varian Trilogy | IR | CT 1.25 mm MRI 1.5 mm Mask (AccuForm) | N = 12 Pediatric | SRS/FSRT MLC IMRT Cones (Eclipse) | GTV-PTV margin 1-3 mm |