Ye, Jason C.

Objectives: This practice parameter was revised collaboratively by the American College of Radiology (ACR), and American Radium Society (ARS). Image-guided radiation therapy (IGRT) uses various imaging modalities to maximize the accuracy and precision of radiation treatment delivery. Methods: This practice parameter was developed according to the process described under the heading The Process for Developing ACR Practice Parameters and Technical Standards on the ACR website (https://www.acr.org/Clinical-Resources/Practice-Parameters-and-Technical-Standards) by the Committee on Practice Parameters–Radiation Oncology of the ACR Commission on Radiation Oncology in collaboration with the ARS. Results: This practice parameter for IGRT addresses qualifications and responsibilities of personnel, clinical IGRT implementation, documentation, quality control and improvement, safety, and patient education. Since the publication of the ACR–ASTRO Practice Parameter in 2019, there is now more clarity as to what criteria and parameters need to be documented in the medical record, a better appreciation of the large amount of imaging data, how to interpret such data, as well as the complex interactions of multiple systems in the implementation of IGRT. Conclusions: This practice parameter assists practitioners in the clinical use of IGRT. IGRT should complement and be used in combination with other quality assurance processes. IGRT is a rapidly evolving field, and practitioners should have a thorough understanding of its strengths and potential limitations.

Abstract INTRODUCTION DSC-MRI perfusion methods are commonly used to evaluate both primary and metastatic brain cancer with the creation of maps of relative cerebral blood volume (rCBV). Recently, guidelines were established to ensure a standard DSC-MRI acquisition protocol that reduces inter-site variability. The purpose of this study was to initiate the determination of rCBV benchmark values using the DSC-MRI consensus protocol in treatment-naïve brain metastases. METHODS Patients from three sites with treatment-naïve, contrast-enhancing brain metastases on MRI were considered for inclusion in this retrospective study. The MRIs included pre- and post-contrast T1w(T1+C) images obtained after administration of gadolinium-based contrast agent (GBCA) (0.1 mmol/kg), which serves as the recommended preload for the DSC-MRI data collection. A 2nd GBCA dose (0.1 mmol/kg) was administered 40-60sec after the collection of baseline GRE-EPI images using recommended settings (FA=60o, TE/TR=30ms/1100-1250ms) for 120s. Calibrated pre/post T1w difference maps (dT1) were used for delineation of enhancing lesion, and standardized (calibrated) rCBV (sRCBV) created. Mean sRCBV for metastases were compared to normal appearing white matter (NAWM) and treatment-naive glioblastoma (GBM) from a previous study. Pairwise comparisons were performed using the Mann-Whitney nonparametric test. RESULTS N=52 patients with primary histology of lung (n=27); breast (n=6); skin (n=7); gastrointestinal (GI: n=3) and genitourinary (GU: n=9) cancers were included in comparison to GBM (n=31). The mean sRCBV for all metastases (1.77+/-1.05) is significantly lower (p=0.0003) than for GBM (2.67+/-1.34) but with both statistically greater (p< 0.0001) than NAWM (0.706+/-0.163). Individually, lung (1.47+/- 0.61), breast (2.275+/-0.87), skin (2.10+/-1.22), GI (1.91+/- 0.64) and GU (2.01+/-0.63) mean sRCBV are statistically greater than for NAWM. CONCLUSION Using the consensus DSC-MRI acquisition protocol confirms use of sRCBV to identify biologically active, treatment-naive brain metastases setting benchmark values for future applications.

Abstract Stereotactic Radiosurgery ( SRS ) is considered standard of care for patients with 1–3 brain metastases ( BM ). Recent observational studies have shown equivalent OS in patients with 5+ BM compared to those with 2–4, suggesting SRS alone may be appropriate in these patients. We aim to review outcomes of patients treated with SRS with 2–4 versus 5+ BM . This analysis included consecutive patients from 1994 to 2015 treated with SRS . Of 1017 patients, we excluded patients with a single BM and patients without adequate survival data, resulting in 391 patients. All risk factors were entered into univariate analysis using Cox proportional hazards model, and significant factors were entered into multivariate analysis ( MVA ). We additionally analyzed outcomes after excluding patients with prior surgery or whole‐brain radiotherapy ( WBRT ). Median follow‐up was 7.1 months. Median KPS was 90, mean age was 59, and most common histologies were melanoma and lung. Median tumor volume was 3.41 cc. Patients with 2–4 BM had a median OS of 8.1 months compared to 6.2 months for those with 5+ BM ( P = 0.0136). On MVA , tumor volume, KPS , and histology remained significant for OS , whereas lesion number did not. Similar results were found when excluding patients with prior surgery or WBRT . Rather than lesion number, the strongest prognostic factors for patients undergoing SRS were tumor volume >10 cc, KPS , and histology. BM number may therefore not be the most important criterion for candidacy for SRS . Patients with 5 or more BM should be considered for SRS .