Scalp and Cranium Radiation Therapy Using Modulation (SCRUM) and Bolus.

PURPOSE: A bolus is usually required to ensure radiation dose coverage of extensive superficial tumors of the scalp or skull. Oftentimes, these boluses are challenging to make and are nonreproducible, so an easier method was sought. METHODS AND MATERIALS: Thermoplastic sheets are widely available in radiation oncology clinics and can serve as bolus. Two template cutouts were designed for anterior and posterior halves to encompass the cranium of children and adults. RESULTS: The created bolus was imaged using computed tomography, which demonstrated good conformity and minimal air gaps. CONCLUSIONS: Although making a bolus for treating superficial tumors of the scalp or head and neck is challenging, the presented technique enables thermoplastic to be used as a bolus and is quick, easy, and reproducible.

Collision Risk Mitigation of Varian TrueBeam Linear Accelerator With Supplemental Live-View Cameras.

BACKGROUND: Noncoplanar radiation therapy techniques such as 4π have potential dosimetric advantages but introduce complexities in treatment delivery that increase the risk for collision. Direct or remote visual confirmation of clearance is a safeguard against collisions of the gantry, couch, and patient. With our institution's Varian TrueBeam system, we identified configurations that cannot be visualized with the included closed-circuit television cameras. At our practice, electronic, portal imaging device (EPID) collision risk also exists because of the routine deployment to capture exit-dose images for treatment quality assurance. We propose a simple, cost-effective solution using network cameras to help eliminate blind spots that permits safe, noncoplanar arrangements with an EPID-acquired exit dose. METHODS AND MATERIALS: Two Panasonic cameras were installed overhead while a third Panasonic camera was mounted onto the pedestal to monitor the couch undersurface. Live views from each camera were accessed with a web-based client. The EPID and gantry were visually assessed at 52 couch and gantry rotational angle configurations at 6 couch translational positions. Visibility was compared for the standard and supplemental camera setups at each configuration (χ2 test). RESULTS: Of the 294 assessable couch-gantry configurations, the standard camera setup had limited visibility of either gantry or EPID for 146 configurations compared with 72 configurations with additional cameras (51% blind-spot reduction; P < .01). An 87% blind-spot reduction was observed for our laterally centered, cranial-based, couch translational position (P < .01). CONCLUSIONS: The supplemental cameras were simple, effective additions for collision detection, especially for noncoplanar radiation therapy with EPID-acquired, exit-dose imaging. Over half of the assessable noncoplanar configurations had blind spots using standard cameras, which was reduced to <25% with additional cameras. In practice, there were almost no blind spots for patients with brain tumors who were treated with our templated beam arrangements. Using live-view camera feeds, vault re-entry to visually confirm clearance was reduced approximately 10-fold, which increased the treatment efficiency. In the most recent 12 months, no collision or near-collision events have been reported.

Eliminating Daily Shifts, Tattoos, and Skin Marks: Streamlining Isocenter Localization With Treatment Plan Embedded Couch Values for External Beam Radiation Therapy.

PURPOSE: The Radiation Oncology Incident Learning System demonstrated that incorrect or omitted patient shifts during treatment are common near-misses or incidents. This single pediatric hospital quality improvement experience evaluated a markless isocenter localization workflow to improve safety and streamline treatment, obviating the need for daily shifts. METHODS AND MATERIALS: Patients undergoing radiation therapy were simulated and treated with indexed immobilization devices. User origins were established at simulation based on a limited set of fixed couch-top references. In treatment planning, shifts from the user origin to the planned isocenter were converted to absolute couch parameters and embedded in the setup field parameters. Thus, the first fraction did not require any shifts. Before kilovoltage imaging, setup verification was often supplemented with surface-guided imaging. After image guidance and final couch adjustments, couch parameters could be reacquired and used for subsequent treatments. No skin marks were used. RESULTS: Over 3 years, approximately 300 patients were treated with over 5000 treatment fractions using this workflow. There were no wrong-site treatment errors. Approximately a dozen near-miss events related to the daily setup process occurred, largely on the first treatment. Root-cause analysis attributed errors to user origin misidentification, couch parameter miscalculation, incorrect immobilization device use, and immobilization device indexed at the wrong indexing position. Skin marks and tattoos were unnecessary. Continuous quality improvement added additional quality assurance checks, resulting in no near-miss incidents or adverse events in the preceding 12 months. CONCLUSION: We minimized near-miss incidents by using limited simulation user origins, converting user origin-to-isocenter shifts to absolute couch parameters, and enforcing restrictive tolerance tables to limit delivery parameter changes, coupled with surface guidance and quality assurance tools. This technique can be applied across institutions, age ranges, and tumor types and with or without surface guidance. This workflow has removed a common treatment setup error and the need for skin marks.

Re-irradiation of Recurrent Pineal Germ Cell Tumors with Radiosurgery: Report of Two Cases and Review of Literature.

Primary intracranial germ cell tumors are rare, representing less than 5% of all central nervous system tumors. Overall, the majority of germ cell tumors are germinomas and approximately one-third are non-germinomatous germ cell tumors (NGGCT), which include teratoma, embryonal carcinoma, yolk sac tumor (endodermal sinus tumor), choriocarcinoma, or mixed malignant germ cell tumor. Germ cell tumors may secrete detectable levels of proteins into the blood and/or cerebrospinal fluid, and these proteins can be used for diagnostic purposes or to monitor tumor recurrence. Germinomas have long been known to be highly curable with radiation therapy alone. However, many late effects of whole brain or craniospinal irradiation have been well documented. Strategies have been developed to reduce the dose and volume of radiation therapy, often in combination with chemotherapy. In contrast, patients with NGGCT have a poorer prognosis, with about 60% cured with multimodality chemoradiation. There are no standard approaches for relapsed germ cell tumors. Options may be limited by prior treatment. Radiation therapy has been utilized alone or in combination with chemotherapy or high-dose chemotherapy and transplant. We discuss two cases and review options for frameless radiosurgery or fractionated radiotherapy.