A planning comparison of 3-dimensional conformal multiple static field, conformal arc, and volumetric modulated arc therapy for the delivery of stereotactic body radiotherapy for early stage lung cancer.

The primary objective of this study was to compare dosimetric variables as well as treatment times of multiple static fields (MSFs), conformal arcs (CAs), and volumetric modulated arc therapy (VMAT) techniques for the treatment of early stage lung cancer using stereotactic body radiotherapy (SBRT). Treatments of 23 patients previously treated with MSF of 48Gy to 95% of the planning target volume (PTV) in 4 fractions were replanned using CA and VMAT techniques. Dosimetric parameters of the Radiation Therapy Oncology Group (RTOG) 0915 trial were evaluated, along with the van׳t Riet conformation number (CN), monitor units (MUs), and actual and calculated treatment times. Paired t-tests for noninferiority were used to compare the 3 techniques. CA had significant dosimetric improvements over MSF for the ratio of the prescription isodose volume to PTV (R100%, p < 0.0001), the maximum dose 2cm away from the PTV (D2cm, p = 0.005), and van׳t Riet CN (p < 0.0001). CA was not statistically inferior to MSF for the 50% prescription isodose volume to PTV (R50%, p = 0.05). VMAT was significantly better than CA for R100% (p < 0.0001), R50% (p < 0.0001), D2cm (p = 0.006), and CN (p < 0.0001). CA plans had significantly shorter treatment times than those of VMAT (p < 0.0001). Both CA and VMAT planning showed significant dosimetric improvements and shorter treatment times over those of MSF. VMAT showed the most favorable dosimetry of all 3 techniques; however, the dosimetric effect of tumor motion was not evaluated. CA plans were significantly faster to treat, and minimize the interplay of tumor motion and dynamic multileaf collimator (MLC) motion effects. Given these results, CA has become the treatment technique of choice at our facility.

A Comparative Planning Analysis and Integral Dose of Volumetric Modulated Arc Therapy, Helical Tomotherapy, and Three-dimensional Conformal Craniospinal Irradiation for Pediatric Medulloblastoma.

INTRODUCTION: The purpose of this study was to compare volumetric modulated arc therapy (VMAT) with helical tomotherapy (HT) and three-dimensional conformal radiation therapy (3D-CRT) for craniospinal irradiation (CSI) in children with medulloblastoma. METHODS: Five children treated with 3D-CRT were retrospectively replanned with HT and VMAT. Tomotherapy plans used a single helical arc, thereby eliminating field junctions. VMAT plans used two arcs rotating alternatively clockwise and counterclockwise, respectively. Conformity and homogeneity indices, dose-volume histograms, integral doses, monitor units delivered, and beam-on times were compared. RESULTS: VMAT showed an improved mean conformity index of 1.05 in comparison with 3D-CRT (1.58, P = .04) and HT (1.34, P = .04). The mean homogeneity index of VMAT (1.13) was not significantly different from 3D-CRT (1.16) but higher than HT (1.08, P = .04). For normal tissues, VMAT resulted in a lower mean dose to the skin, eyes, lenses, optic nerves, cochlea, esophagus, heart, peritoneal cavity, bladder, and rectum compared with 3D-CRT (all P = .04). There were few significant differences in dose-volume statistics for normal tissues between VMAT and HT. The mean nontarget tissue integral dose for VMAT of 80.8 J was significantly lower than for 3D-CRT (91.5 J, P = .04) and HT (95.6 J, P = .04). Body and nontarget tissue integral doses were lowest with VMAT in every patient. CONCLUSIONS: For CSI, VMAT provides comparable normal tissue sparing with tomotherapy and may reduce the integral dose. Compared with 3D-CRT, VMAT improved normal tissue sparing at higher doses despite larger volumes receiving lower doses. These findings have potential implications in the risk of the development of late adverse effects and radiation-related second malignancies in children with curable primary disease.

International Atomic Energy Agency Randomized Phase III Study of Radiation Therapy in Elderly and/or Frail Patients With Newly Diagnosed Glioblastoma Multiforme.

PURPOSE: The optimal radiotherapy regimen for elderly and/or frail patients with newly diagnosed glioblastoma remains to be established. This study compared two radiotherapy regimens on the outcome of these patients. PATIENTS AND METHODS: Between 2010 and 2013, 98 patients (frail = age ≥ 50 years and Karnofsky performance status [KPS] of 50% to 70%; elderly and frail = age ≥ 65 years and KPS of 50% to 70%; elderly = age ≥ 65 years and KPS of 80% to 100%) were prospectively randomly assigned to two arms in a 1:1 ratio, stratified by age (< and ≥ 65 years old), KPS, and extent of surgical resection. Arm 1 received short-course radiotherapy (25 Gy in five daily fractions over 1 week), and arm 2 received commonly used radiotherapy (40 Gy in 15 daily fractions over 3 weeks). RESULTS: The short-course radiotherapy was noninferior to commonly used radiotherapy. The median overall survival time was 7.9 months (95% CI, 6.3 to 9.6 months) in arm 1 and 6.4 months (95% CI, 5.1 to 7.6 months) in arm 2 (P = .988). Median progression-free survival time was 4.2 months (95% CI, 2.5 to 5.9) in arm 1 and 4.2 months (95% CI, 2.6 to 5.7) in arm B (P = .716). With a median follow-up time of 6.3 months, the quality of life between both arms at 4 weeks after treatment and 8 weeks after treatment was not different. CONCLUSION: There were no differences in overall survival time, progression-free survival time, and quality of life between patients receiving the two radiotherapy regimens. In view of the reduced treatment time, the short 1-week radiotherapy regimen may be recommended as a treatment option for elderly and/or frail patients with newly diagnosed glioblastoma.

A pseudoisochromatic test of color vision for human infants.

Despite the development of experimental methods capable of measuring early human color vision, we still lack a procedure comparable to those used to diagnose the well-identified congenital and acquired color vision anomalies in older children, adults, and clinical patients. In this study, we modified a pseudoisochromatic test to make it more suitable for young infants. Using a forced choice preferential looking procedure, 216 3-to-23-mo-old babies were tested with pseudoisochromatic targets that fell on either a red/green or a blue/yellow dichromatic confusion axis. For comparison, 220 color-normal adults and 22 color-deficient adults were also tested. Results showed that all babies and adults passed the blue/yellow target but many of the younger infants failed the red/green target, likely due to the interaction of the lingering immaturities within the visual system and the small CIE vector distance within the red/green plate. However, older (17-23 mo) infants, color- normal adults and color-defective adults all performed according to expectation. Interestingly, performance on the red/green plate was better among female infants, well exceeding the expected rate of genetic dimorphism between genders. Overall, with some further modification, the test serves as a promising tool for the detection of early color vision anomalies in early human life.