Experience With Normal Breathhold Planning Scans for Radiosurgery of Moving Targets With Live Tracking.

Purpose: Utilization of breathhold scans with live tracking has a long track record of good published outcomes for stereotactic body radiation therapy (SBRT) and is recommended by the manufacturer of the Synchrony tracking system. However, the popularity of four-dimensional computed tomography (4DCT) scans challenges the validity of the breathhold scan with live tracking technique. Although this study is not intended to prove the superiority of either method, we demonstrate the feasibility of using the breathhold scans with a phantom test and clinical examples.

Results from the AAPM Task Group 324 respiratory motion management in radiation oncology survey.

Purpose: To quantify the clinical practice of respiratory motion management in radiation oncology.

Methods: A respiratory motion management survey was designed and conducted based on clinician survey guidelines. The survey was administered to American Association of Physicists in Medicine (AAPM) members on 17 August 2020 and closed on 13 September 2020.

Contrast-Enhanced Ultrasound to Detect Early Microvascular Changes in Skeletal Muscle after High-Dose Radiation Treatment.

The biological response of normal tissue to high-dose radiation treatment remains poorly understood. Alterations to the microenvironment, specifically the microvasculature, have been implicated as a significant contributor to tumoral cytotoxicity. We used contrast-enhanced ultrasound (CEU) perfusion imaging, which is uniquely suited to assess functional status of the microcirculation, to measure microvascular blood flow after high-dose irradiation to normal skeletal muscle tissue in a murine model.

Safety and Efficacy of Accelerated Hypofractionation and Stereotactic Body Radiation Therapy for Hepatocellular Carcinoma Patients With Varying Degrees of Hepatic Impairment.

Purpose: To report the toxicities and outcomes for stereotactic body radiation therapy (SBRT) and accelerated hypofractionated radiation therapy (AHRT) in patients with Child-Pugh (CP) class A, B, or C and albumin-bilirubin (ALBI) score 1, 2, or 3 hepatocellular carcinoma.

Methods And Materials: We retrospectively reviewed the data from 146 patients with hepatocellular carcinoma who had undergone SBRT (50 Gy in 5 fractions) or AHRT (45 Gy in 18 fractions). The primary endpoint was liver toxicity, defined as an increase in the CP score of ≥2 within 6 months of radiation therapy.

The impact of anatomic tumor location on inter-fraction tumor motion during lung stereotactic body radiation therapy (SBRT).

Purpose: Narrow PTV margins and steep dose gradients underscore the importance of evaluating breathing-associated tumor motion for lung SBRT. The specific aim of this study was to determine the impact of anatomic tumor location on inter-fraction tumor motion.

Methods And Materials: Forty-one patients underwent standard free-breathing 4DCT simulation and daily image-guidance 4DCTs during lung SBRT.

Volumetric-modulated arc radiotherapy for pancreatic malignancies: dosimetric comparison with sliding-window intensity-modulated radiotherapy and 3-dimensional conformal radiotherapy.

Volumetric-modulated arc radiotherapy (VMAT) is an iteration of intensity-modulated radiotherapy (IMRT), both of which deliver highly conformal dose distributions. Studies have shown the superiority of VMAT and IMRT in comparison with 3-dimensional conformal radiotherapy (3D-CRT) in planning target volume (PTV) coverage and organs-at-risk (OARs) sparing. This is the first study examining the benefits of VMAT in pancreatic cancer for doses more than 55.

Electromagnetic navigational bronchoscopy-guided fiducial markers for lung stereotactic body radiation therapy: analysis of safety, feasibility, and interfraction stability.

Background: Embolization coils as fiducial markers for pulmonary stereotactic body radiation therapy (SBRT) are perceived to be the optimal marker type, given their ability to conform and anchor within the small airways. The aim of our study was to assess retention, placement, migration, feasibility, and safety of electromagnetic navigational bronchoscopy (ENB)-guided embolization coil markers throughout courses of SBRT.

Methods: Thirty-one patients with 34 nodules underwent ENB-guided fiducial placement of several 4 mm fibered platinum embolization coils before SBRT.

Real-time prostate motion assessment: image-guidance and the temporal dependence of intra-fraction motion.

Background: The rapid adoption of image-guidance in prostate intensity-modulated radiotherapy (IMRT) results in longer treatment times, which may result in larger intrafraction motion, thereby negating the advantage of image-guidance. This study aims to qualify and quantify the contribution of image-guidance to the temporal dependence of intrafraction motion during prostate IMRT.

Methods: One-hundred and forty-three patients who underwent conventional IMRT (n=67) or intensity-modulated arc therapy (IMAT/RapidArc, n=76) for localized prostate cancer were evaluated.

Circumferential or sectored beam arrangements for stereotactic body radiation therapy (SBRT) of primary lung tumors: effect on target and normal-structure dose-volume metrics.

To compare 2 beam arrangements, sectored (beam entry over ipsilateral hemithorax) vs circumferential (beam entry over both ipsilateral and contralateral lungs), for static-gantry intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) delivery techniques with respect to target and organs-at-risk (OAR) dose-volume metrics, as well as treatment delivery efficiency. Data from 60 consecutive patients treated using stereotactic body radiation therapy (SBRT) for primary non-small-cell lung cancer (NSCLC) formed the basis of this study. Four treatment plans were generated per data set: IMRT/VMAT plans using sectored (-s) and circumferential (-c) configurations.

Characterization of a gated fiber-optic-coupled detector for application in clinical electron beam dosimetry.

Purpose: Assessment of the fundamental dosimetric characteristics of a novel gated fiber-optic-coupled dosimetry system for clinical electron beam irradiation.

Methods: The response of fiber-optic-coupled dosimetry system to clinical electron beam, with nominal energy range of 6-20 MeV, was evaluated for reproducibility, linearity, and output dependence on dose rate, dose per pulse, energy, and field size. The validity of the detector system's response was assessed in correspondence with a reference ionization chamber.

Assessment of planning target volume margins for intensity-modulated radiotherapy of the prostate gland: role of daily inter- and intrafraction motion.

Purpose: To determine planning target volume margins for prostate intensity-modulated radiotherapy based on inter- and intrafraction motion using four daily localization techniques: three-point skin mark alignment, volumetric imaging with bony landmark registration, volumetric imaging with implanted fiducial marker registration, and implanted electromagnetic transponders (beacons) detection.

Methods And Materials: Fourteen patients who underwent definitive intensity-modulated radiotherapy for prostate cancer formed the basis of this study. Each patient was implanted with three electromagnetic transponders and underwent a course of 39 treatment fractions.

Performance characteristics of a gated fiber-optic-coupled dosimeter in high-energy pulsed photon radiation dosimetry.

Fiber-optic-coupled dosimeters (FOCDs) are a new class of in vivo dosimetry systems that are finding increased clinical applications. Utility of FOCDs has been limited in dosimetric applications due Cerenkov-ray signal contamination. The current study reports on the characterization of a novel FOCD, with a gated detection system for the discrimination and effective elimination of the direct contribution of Cerenkov radiation, for use in the radiotherapeutic realm.

Implications of a high-definition multileaf collimator (HD-MLC) on treatment planning techniques for stereotactic body radiation therapy (SBRT): a planning study.

Purpose: To assess the impact of two multileaf collimator (MLC) systems (2.5 and 5 mm leaf widths) on three-dimensional conformal radiotherapy, intensity-modulated radiotherapy, and dynamic conformal arc techniques for stereotactic body radiation therapy (SBRT) of liver and lung lesions.

Methods: Twenty-nine SBRT plans of primary liver (n=11) and lung (n=18) tumors were the basis of this study.

Stereotactic radiotherapy for unilateral orbital lymphoma and orbital pseudo-tumors: a planning study.

Orbital lymphoma and Grave's ophthalmopathy (GO) are successfully treated with radiation therapy. The lenses are blocked to prevent cataract formation. However, blocking of the lens by traditional methods can be difficult for tumors located anteriorly and extending into the retrobulbar space.

Volumetric image-guidance: does routine usage prompt adaptive re-planning? An institutional review.

Purpose: To investigate how the use of volumetric image-guidance using an on-board cone-beam computed tomography (CBCT) system impacts on the frequency of adaptive re-planning.

Material And Methods: Treatment courses of 146 patients who have undergone a course of external beam radiation therapy (EBRT) using volumetric CBCT image-guidance were analyzed. Target locations included the brain, head and neck, chest, abdomen, as well as prostate and non-prostate pelvis.

MOSFET sensitivity dependence on integrated dose from high-energy photon beams.

The ability of a commercially available dual bias, dual MOSFET dosimetry system to measure therapeutic doses reproducibly throughout its vendor-defined dose-based lifetime has been evaluated by characterizing its sensitivity variation to integrated/cumulative doses from,high-energy (6 and 15 MV) photon radiotherapy beams. The variation of sensitivity as a function of total integrated dose was studied for three different dose-per-fraction levels; namely, 50, 200, and 1200 cGy/fraction. In standard sensitivity mode (i.

Phantom investigation of 3D motion-dependent volume aliasing during CT simulation for radiation therapy planning.

Purpose: To quantify volumetric and positional aliasing during non-gated fast- and slow-scan acquisition CT in the presence of 3D target motion.

Methods: Single-slice fast, single-slice slow, and multi-slice fast scan helical CTs were acquired of dynamic spherical targets (1 and 3.15 cm in diameter), embedded in an anthropomorphic phantom.