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Managing radiotherapy patients with implanted cardiac devices (implantable cardiac pacemakers and implantable cardioverter‐defibrillators) has been a great practical and procedural challenge in radiation oncology practice. Since the publication of the AAPM TG‐34 in 1994, large bodies of literature and case reports have been published about different kinds of radiation effects on modern technology implantable cardiac devices and patient management before, during, and after radiotherapy. This task group report provides the framework that analyzes the potential failure modes of these devices and lays out the methodology for patient management in a comprehensive and concise way, in every step of the entire radiotherapy process. [ABSTRACT FROM AUTHOR]

Purpose: To assess the long‐term stability of the anchored radiofrequency transponders and compare displacement rates with other commercially available lung fiducial markers. We also sought to describe late toxicity attributable to fiducial implantation or migration. Materials and methods: The transponder cohort was comprised of 17 patients at our institution who enrolled in a multisite prospective clinical trial and underwent bronchoscopic implantation of three anchored transponders into small (2–2.5 mm) airways. We generated a comparison cohort of 34 patients by selecting patients from our institutional lung SBRT database and matching 2:1 based on the lobe containing tumor and proximity to the bronchial tree. Assessment of migration was performed by rigidly registering the most recent follow‐up CT scan to the simulation scan, and assessing whether the relative geometry of the fiducial markers had changed by more than 5 mm. Toxicity outcomes of interest were hemoptysis and pneumothorax. Results: The median follow‐up of patients in the transponder cohort was 25.3 months and the median follow‐up in the comparison cohort was 21.7 months. When assessing the most recent CT, all fiducial markers were within 5 mm of their position at CT simulation in 11 (65%) patients in the transponder group as compared to 23 (68%) in the comparison group (P = 0.28). One case of hemoptysis was identified in the transponder cohort, and bronchoscopy confirmed bleeding from recurrent tumor; no cases of hemoptysis were noted in the comparison cohort. No case of pneumothorax was noted in either group. Conclusion: No significant difference in the rates of fiducial marker retention and migration were noted when comparing patients who had anchored transponders placed into small airways and a 2:1 matched cohort of patients who had other commercially available lung fiducial markers placed. In both groups, no late or chronic toxicity appeared to be related to the implanted fiducial markers. [ABSTRACT FROM AUTHOR]

Background: For many years, the standard of care for radiosurgical thalamotomy has been a frame-based treatment, either on Gamma Knife or a linear accelerator with cones. Our institution has recently completed enrollment of phase I/II prospective clinical evaluating the safety and efficacy of a linear-accelerator based treatment with thermoplastic mask utilizing the linear accelerator’s native high-definition collimator to generate a similar rapid-falloff spherical dose distribution. In this study, we assessed the in-vivo accuracy of our treatments. Methods: We treated patients on an IRB-approved clinical trial (ClinicalTrials.gov Identifier: NCT03305588) using a Varian Edge™ (Palo Alto, CA) linear accelerator equipped with high-definition multi-leaf collimator and 10MV flattening-filter free beam using our previously described virtual-cone approach. Optical surface guidance was used to monitor the patient position during treatment. For 15 patients having follow-up imaging, the planned dose distribution was exported in the pre-treatment MPRAGE image space. The pre-treatment MPRAGE was coregistered to the 6-month post-treatment post-contrast T1 SPACE image using a two-stage linear registration (rigid followed by affine). The lesion was segmented using a semi-automated, threshold-based method. The centerof-gravity (COG) of the lesion and of the planned 65 Gy isodose volume were calculated. Results: The mean distances between the center coordinates of the lesion and target were less than 0.5 mm in all axes (mean ± standard deviation between lesion and target: x = -0.1 ± 0.3; y = -0.1 ± 0.5; z = -0.3 ± 0.7 mm). The mean Euclidean distance between the target and lesion COG was 0.86 mm (95% confidence interval 0.58 to 1.13 mm). The distance was significantly correlated with imaging signal-to-noise ratio (SNR), suggesting patients with greater head motion and poorer quality imaging resulted in a greater discrepancy between target and lesion. Conclusion: The distance between the target position and lesion position is consistent with sub-millimeter accuracy for frameless SRS thalamotomy. Imaging quality is a limiting factor when assessing the targeting accuracy. [ABSTRACT FROM AUTHOR]

Purpose/objective(s): Stereotactic radiosurgery (SRS) to ventral intermediate nucleus (VIM) is a storied & successful yet underutilized technique for tremor. High doses & small targets have historically necessitated treatment with stereotactic frame & either a GK platform or cone-mounted linear accelerator. We developed a coneless technique to replicate the dose distributions previously only attributable to GK on a linear accelerator (LINAC). We deployed this technique & tested it in a prospective clinical trial of safety & efficacy of SRS thalamotomy for non-DBS candidate patients with medically refractory essential or Parkinsonian tremor. Materials/methods: We assessed tremor pre- & posttreatment & QOL FTM/PROMIS scores. We obtained MPRAGE, FGATIR, diffusion-weighted tractographic, & resting-state fMRI sequences. We identified the VIM via both thalamic parcellation & classical stereotactic reference location, & targeted to 130Gy dmax dosimetrically equivalently to 4 mm GK shot with static MLC’s. We ensured 25Gy isodose line did not overlap the posterior limb of capsule. We delivered treatment on a LINAC with high-definition HDMLC & intrafraction optical surface monitoring (OSMS) to ensure patient immobility. We surveilled post-treatment imaging & tremor scores. Results: We accrued 43 patients. 1 withdrew & 1 elected to pursue previously declined DBS. At submission, 40 patients had been treated & 35 patients had ≥6 month follow-up. Median total treatment time was 32 minute. 31/35 (89%) exhibited meaningful tremor reduction (≥20% FTM reduction). Median maximum pre- & posttremor reduction was 59.6% (range: 9.8 - 100%). Time to tremor improvement ranged from 0.3 to 15 months. 1 patient experienced Grade 2 and 1 experienced reversible Grade 3 toxicity. Conclusion: Frameless, coneless MLC-based SRS thalamotomy on the LINAC is a safe, effective alternative workflow that may be preferable for some patients due to its efficient delivery. Data continue to mature, but current results are congruent to those of historical gamma knife & cone-based linac treatments. We have expanded the trial, and are beginning to integrate tractographic & functional imaging into target selection for future patients. [ABSTRACT FROM AUTHOR]