Multifractionated image-guided and stereotactic intensity-modulated radiotherapy of paraspinal tumors: A preliminary report
ABSTRACT The use of image-guided and stereotactic intensity-modulated radiotherapy (IMRT) techniques have made the delivery of high-dose radiation to lesions within close proximity to the spinal cord feasible. This report presents clinical and physical data regarding the use of IMRT coupled with noninvasive body frames (stereotactic and image-guided) for multifractionated radiotherapy.
The Memorial Sloan-Kettering Cancer Center (Memorial) stereotactic body frame (MSBF) and Memorial body cradle (MBC) have been developed as noninvasive immobilizing devices for paraspinal IMRT using stereotactic (MSBF) and image-guided (MBC) techniques. Patients were either previously irradiated or prescribed doses beyond spinal cord tolerance (54 Gy in standard fractionation) and had unresectable gross disease involving the spinal canal. The planning target volume (PTV) was the gross tumor volume with a 1 cm margin. The PTV was not allowed to include the spinal cord contour. All treatment planning was performed using software developed within the institution. Isocenter verification was performed with an in-room computed tomography scan (MSBF) or electronic portal imaging devices, or both. Patients were followed up with serial magnetic resonance imaging every 3-4 months, and no patients were lost to follow-up. Kaplan-Meier statistics were used for analysis of clinical data.
Both the MSBF and MBC were able to provide setup accuracy within 2 mm. With a median follow-up of 11 months, 35 patients (14 primary and 21 secondary malignancies) underwent treatment. The median dose previously received was 3000 cGy in 10 fractions. The median dose prescribed for these patients was 2000 cGy/5 fractions (2000-3000 cGy), which provided a median PTV V100 of 88%. In previously unirradiated patients, the median prescribed dose was 7000 cGy (5940-7000 cGy) with a median PTV V100 of 90%. The median Dmax to the cord was 34% and 68% for previously irradiated and never irradiated patients, respectively. More than 90% of patients experienced palliation from pain, weakness, or paresthesia; 75% and 81% of secondary and primary lesions, respectively, exhibited local control at the time of last follow-up. No cases of radiation-induced myelopathy or radiculopathy have thus far been encountered.
Precision stereotactic and image-guided paraspinal IMRT allows the delivery of high doses of radiation in multiple fractions to tumors within close proximity to the spinal cord while respecting cord tolerance. Although preliminary, the clinical results are encouraging.
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ABSTRACT: Stereotactic body radiation therapy (SBRT) utilizes a three dimensional coordinate system to achieve more reproducible patient set-up [1, 2]. With SBRT, the margins for set-up uncertainty can be reduced, allowing greater volume sparing of the surrounding normal tissues. Since SBRT yields a reduced volume of normal tissue exposure, SBRT has been used to increase the fractional dose of radiation (hypofractionation) in an attempt to intensify the dose delivery without incrementally increasing the risk of normal tissue damage. This is becoming an important approach to treating discrete tumors, and has yielded impressive local control of treated tumors without significant toxicity. The benefit of SBRT is to achieve improved local control compared to conventional radiation, via improved target localization and more intense doles delivery, without the added toxicity. Arguably, SBRT can achieve similar or even improved outcome over surgical resection. One advantage that SBRT has over a limited resection (i.e. one that does not achieve wide margins) is that the penumbra dose around the target treats microscopic disease .
Article: Spinal Robotic Radiosurgery[Show abstract] [Hide abstract]
ABSTRACT: Spinal radiosurgery is a new class of procedures designed for primary or adjuvant treatment of certain spinal disorders [3, 6, 7, 9, 21, 23]. Because such large doses of radiation are administered, spinal radiosurgery, similar to its intracranial predecessor, requires extremely accurate targeting. In contrast, the lack of precision inherent in conventional external beam radiation therapy and the limitations of target immobilization techniques generally preclude large, single-fraction irradiation near radiosensitive structures, such as the spinal cord [5, 10, 23]. The frameless CyberKnife radiosurgery system has overcome these problems by using real-time image guidance, which allows the paraspinous target to be tracked even in the presence of occasional patient movement [12, 24]. Continuous tracking and correction for motion of the spine throughout treatment are prerequisites for spinal radiosurgery, because patients do move after set-up is complete . Until recently, clinicians surgically implanted fiducials into the spine to track the movement of the lesion during treatment [12, 14, 21]. In the first reported use of image-guided robotics to perform spinal radiosurgery, Ryu and coworkers demonstrated the safety and short-term efficacy for a variety of neoplastic and vascular lesions . Surgical implantation of fiducials into adjacent vertebral segments was necessary for tracking the ablated spinal lesion . However, this step introduces the added surgical risks associated with an invasive surgery, lengthens treatment time, and reduces patient comfort. It would be ideal if it were possible to track spinal lesions using bony landmarks (similar to tracking intracranial lesions based on skull anatomy) instead of fiducials. Recently, such a fiducial-free spinal tracking system has been introduced (Xsight-Spine Tracking System, Accuray Incorporated) [16, 20, 22].
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ABSTRACT: Die hypofraktionierte stereotaktische Bestrahlung erlaubt eine präzise hochdosierte und kleinvolumige Radiotherapie umschriebender Raumforderungen mit Tumorkontrollen größer 90% bei peripheren Lungentumoren. Berichtet wird über 70 Patienten mit 86 pulmonalen Läsionen in der Lunge (35 Bronchialkarzinome NSCLC, 51 Metastasen), die zwischen 1997 und 2005 an der Klinik für Strahlentherapie (Universität Würzburg) stereotaktisch bestrahlt wurden. Die Patienten wurden hypofraktioniert mit 3 x 10-12,5 Gy oder mit 1 x 26 Gy (Einzeitbestrahlung) therapiert. Die Morpholgie der pulmonalen Strahlenreaktion sowie deren zeitlicher Verlauf wurden ebenso wie das Tumoransprechen anhand von 346 Verlauf-CTs qualitativ und semiquantitativ ausgewertet. In der Diskussion wurden diese Ergebnisse mit Publikationen zu diesem Thema nach konventioneller Bestrahlung verglichen. Es zeigte sich eine günstiges Verhältnis zwischen Tumorwirksamkeit und Strahlenpneumonitis. The purpose was to evaluate the CT morphological pattern of tumor response and pulmonary injury after stereotactic body radiotherapy (SBRT) for early stage non-small cell lung cancer (NSCLC) and pulmonary metastases. Seventy patients (lesions n = 86) with pulmonary metastases (n = 51) or primary early stage NSCLC (n = 35) were analyzed. Patients were treated with hypofractionated SBRT (3 x 10-12,5 Gy; n = 53) or with radiosurgery (1 x 26 Gy; n = 33). The pattern and sequence of pulmonary injury and of tumor response was evaluated in 346 follow-up CT studies, 4.7 on average. No pulmonary reaction was observed in most patients six weeks after treatment. Spotted-streaky condensations were characteristic between three and six months. Dense consolidation and retraction started after nine months. At twelve months complete response was seen in 43% and the differentiation of residual tumor from pulmonary reaction was not possible in 33%.