- Dosimetric evaluation of the INTRABEAM system for breast intraoperative radiotherapy: A single-institution experience. [Journal Article]Med Dosim 2019MD
- Breast intraoperative radiotherapy (IORT) with the INTRABEAM system uses a 50 kV x-ray source to deliver a single fraction of radiation therapy to the lumpectomy cavity during breast-conserving surgery. We seek to perform a dosimetric analysis of the lumpectomy cavity for rigid spherical applicators. Water phantom measurements were acquired to validate the vendor-provided x-ray calibration. The p…
Breast intraoperative radiotherapy (IORT) with the INTRABEAM system uses a 50 kV x-ray source to deliver a single fraction of radiation therapy to the lumpectomy cavity during breast-conserving surgery. We seek to perform a dosimetric analysis of the lumpectomy cavity for rigid spherical applicators. Water phantom measurements were acquired to validate the vendor-provided x-ray calibration. The planning target volume (PTV) was defined as a 10 mm expansion beyond the spherical applicator, a dose-volume histogram (DVH) was generated and dose-volume parameters [Dmin, D1mm, V90, V80, V50, HI] were reported. Additionally, the therapeutic treatment depth using the 90 and 80% isodose level was computed [R90, R80]. When the percent depth dose (PDD) is normalized to the surface of the applicator, smaller applicators have a steeper PDD. For a prescription dose of 20 Gy to the surface of the applicator, the range of dose-volume parameters for the PTV was: 3.15 to 6.84 Gy for Dmin, 16.2 to 17.6 Gy for D1mm, 2.6 to 6.9% for V90, 5.5 to 15.1% for V80, and 21.1 to 55.6% for V50. For applicators 15 to 50 mm in diameter, the reported values were: 6.35 to 2.9 for HI, 0.53 to 0.85 mm for R90, and 1.18 to 1.85 mm for R80. Smaller applicators have reduced PTV coverage but elevated HI because the attenuation of the beam proximal to the source is more pronounced. Additionally, the presence of the aluminum filter for small applicators (≤30 mm) increases PTV coverage but reduces the dose rate on the applicator surface. The delivery of IORT is performed in the OR without the use of image-based planning. To overcome this limitation, we have generated sample DVH's and report dosimetric parameters to offer clinicians a unique dosimetric perspective.
- Off-axis dose distribution with stand-in and stand-off configurations for superficial radiotherapy treatments. [Journal Article]
- Current practice when delivering dose for superficial skin radiotherapy is to adjust the monitor units so that the prescribed dose is delivered to the central axis of the superficial unit applicator. Variations of source-to-surface distance due to patient's anatomy protruding into the applicator or extending away from the applicator require adjustments to the monitor units using the inverse squar…
Current practice when delivering dose for superficial skin radiotherapy is to adjust the monitor units so that the prescribed dose is delivered to the central axis of the superficial unit applicator. Variations of source-to-surface distance due to patient's anatomy protruding into the applicator or extending away from the applicator require adjustments to the monitor units using the inverse square law. Off-axis dose distribution varies significantly from the central axis dose and is not currently being quantified. The dose falloff at the periphery of the field is not symmetrical in the anode-cathode axis due to the heel effect. This study was conducted to quantify the variation of dose across the surface being treated and model a simple geometric shape to estimate a patient's surface with stand-in and stand-off. Isodose plots and color-coded dose distribution maps were produced from scans of GAFChromic EBT-3 film irradiated by a Gulmay D3300 orthovoltage x-ray therapy system. It was clear that larger applicators show a greater dose falloff toward the periphery than smaller applicators. Larger applicators were found to have a lower percentage of points above 90% of central axis dose (SA90). Current clinical practice does not take this field variation into account. Stand-in can result in significant dose falloff off-axis depending on the depth and width of the protrusion, while stand-off can result in a flatter field due to the high-dose region near the central axis being further from the source than the peripheral regions. The central axis also received a 7% increased or decreased dose for stand-in or stand-off, respectively.
- Reduced-volume tumor-bed boost is not associated with inferior local control and survival outcomes in high-risk medulloblastoma. [Journal Article]Pediatr Blood Cancer 2019; :e28027PB
- CONCLUSIONS: Reduced-volume radiotherapy boost to the TB does not appear to compromise LC or survival in patients with H-R medulloblastoma; it may reduce the risk of ototoxicity.
- Improving treatment efficiency via photon optimizer (PO) MLC algorithm for synchronous single-isocenter/multiple-lesions VMAT lung SBRT. [Journal Article]
- CONCLUSIONS: PO MLC algorithm improved treatment efficiency without compromising plan quality when compared to PRO algorithm for single-isocenter/multi-lesions VMAT lung SBRT. Shorter beam-on time can potentially reduce intrafraction motion errors and improve patient compliance. PO MLC algorithm is recommended for future clinical lung SBRT plan optimization.
- Radiosurgery for mesial temporal lobe epilepsy following ROSE trial guidelines - A planning comparison between Gamma Knife, Eclipse, and Brainlab. [Journal Article]
- CONCLUSIONS: Among the 4 SRS planning methods, VMAT with least PIV and acceptable maximum doses to brainstem and OA showed highest compliance with ROSE trial. Having the most conformal dose distribution and least dose inhomogeneity, VMAT scored higher than GK, Eclipse NCC, and Brainlab DCA plans.
- Gamma knife radiosurgery on the trigeminal ganglion for idiopathic trigeminal neuralgia: Results and review of the literature. [Journal Article]Surg Neurol Int 2019; 10:89SN
- CONCLUSIONS: GKS on TG appears to be a reasonable treatment option with short latency period, minor collateral effects, and high percentage of pain control. The mechanism of action of radiosurgery could be related to the inactivation of the satellite glial cells in the TG.
- Active-Scanned Protons and Carbon Ions in Cancer Treatment of Patients With Cardiac Implantable Electronic Devices: Experience of a Single Institution. [Journal Article]Front Oncol 2019; 9:798FO
- CONCLUSIONS: Treatment of CIED-patients with protons and carbon ions applied with active raster scanning technique was safe without any incidents in our single center experience. Monitoring after almost every fraction provided systematic and extensive data. Further investigations are necessary in order to form reliable guidelines, which should consider different modes of beam application, as active scanning supposedly provides a greater level of safety from malfunctions for patients with CIED undergoing particle irradiation.
- Hypofractionated radiosurgery plus bevacizumab for locally recurrent brain metastasis with previously high-dose irradiation. [Journal Article]World Neurosurg 2019WN
- CONCLUSIONS: Salvage FSRS with adjuvant bevacizumab treatment showed favorable clinical and radiologic control as a salvage treatment regimen. The diagnosis of RN and LR after salvage FSRS merit further study.
- Two-session Radiosurgery as Initial Treatment for Newly Diagnosed Large, Symptomatic Brain Metastases from Breast and Lung Histology. [Journal Article]Cureus 2019; 11(8):e5472C
- Introduction Surgery is considered the treatment of choice for patients with large, symptomatic brain metastases. This report describes a series of patients treated with upfront two-session radiosurgery rather than surgery for large brain metastases from breast and lung histology. Methods From October 2016 to January 2019, 10 consecutive patients with neurologic symptoms from large brain metastas…
Introduction Surgery is considered the treatment of choice for patients with large, symptomatic brain metastases. This report describes a series of patients treated with upfront two-session radiosurgery rather than surgery for large brain metastases from breast and lung histology. Methods From October 2016 to January 2019, 10 consecutive patients with neurologic symptoms from large brain metastases producing mass effects underwent two sessions of radiosurgical treatments 30 days apart. The response was assessed by imaging and clinical evaluations. Results Ten patients had a total of 36 tumors; of these, 22 lesions with a mean volume of 12.3 ml (range, 7-78.4 ml) underwent two-session radiosurgery. The mean prescription dose for the first treatment was 13 Gy (range, 9-18 Gy) to the 50% isodose line, and the intratumoral mean dose was 17.9 Gy (12-22.9). All 10 patients had neurological symptoms, with a mean Karnofsky physical score (KPS) of 60 (range, 50-70) on the day of treatment. None of these patients required neurosurgical or emergency consultation related to worsening of neurological symptoms between the first and second treatments. At 30 days, the mean KPS was 80 and maintained at 80 at the last follow-up (range, 60-100; P=0.002), and mean lesion volume was 4.1 ml (range, 1.3-70 ml). The mean prescription dose for the second treatment was 12 Gy (range, 9-18 Gy) to the 50% isodose line, and the intratumoral mean dose was 17.9 Gy (11-22.4). The mean overall survival was 24 months (range, 3-32 months). At last follow-up, three patients (30%) had died, two of systemic progression and one of tumor progression, and at one year, local tumor control was 91% and 19 (86%) lesions showed documented local control at last follow up. In those tumors that progressed, the mean time to progression was eight months (range, 5-20 months), and the mean time to surgery was nine months (range, 5-32 months). Conclusion Two-session radiosurgery proved to be a safe treatment for patients with large, symptomatic metastases in this series. Neurological worsening after radiosurgery for large lesions of breast and lung histology may be an infrequent event. This strategy in radiosurgery may have neurological benefits for these patients providing adequate local tumor control while reducing the need of upfront surgery at diagnosis.
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- Repeat stereotactic body radiation therapy (SBRT) for salvage of isolated local recurrence after definitive lung SBRT. [Journal Article]Radiother Oncol 2019RO
- CONCLUSIONS: Salvage SBRT for isolated local failures after initial SBRT appears safe, with low treatment-related toxicity and encouraging rates of tumor control.