Radiosurgery Research Papers - Academia.edu (original) (raw)

BACKGROUND. The spine is the most common site of bony metastases in patients with osseous breast carcinoma metastases. Spine metastases are the source of significant pain and occasionally neurologic deficit in this patient population.

Abstract: Minimally invasive parathyroidectomy is an accepted treatment option for primary hyperparathyroidism. The need for intraoperative parathyroid hormone assays (iPTH) to confirm adenoma removal remains controversial. We studied... more

Abstract: Minimally invasive parathyroidectomy is an accepted treatment option for primary hyperparathyroidism. The need for intraoperative parathyroid hormone assays (iPTH) to confirm adenoma removal remains controversial. We studied minimally invasive radio-...

literature. This study was undertaken to provide a multi-institutional and multi-national summary of the current practice of spine SBRT / SRS. Materials/Methods: All 6 institutions are experienced in spine SBRT/SRS and are members of the... more

literature. This study was undertaken to provide a multi-institutional and multi-national summary of the current practice of spine SBRT / SRS. Materials/Methods: All 6 institutions are experienced in spine SBRT/SRS and are members of the Elekta Spine SBRT Group;

Optic nerve sheath meningiomas (ONSMs) represent the most challenging lesions involving the optic pathways: Microsurgery is not indicated and classical single-stage radiosurgery appears to be too risky due to the expected destruction of... more

Optic nerve sheath meningiomas (ONSMs) represent the most challenging lesions involving the optic pathways: Microsurgery is not indicated and classical single-stage radiosurgery appears to be too risky due to the expected destruction of the common blood supply with consequent loss of vision. Staged radiosurgery might be one treatment option because it exploits the ability of normal tissues to repair sub-lethal radiation-induced damage, offering a chance to control tumor growth while sparing function. Staged robotic radiosurgery was offered to 5 patients harboring ONSMs with the aim of sparing vision while achieving local growth control. Five patients with ONSM presenting with visual field deficits and loss of visual acuity were treated with staged CyberKnife radiosurgery, receiving 20 Gy in 4 stages (5 Gy per stage). Treatment planning was based on contrast-enhanced thin-slice CT (1.25 mm thickness for the first three cases, 0.5 mm for the last two) and volumetric MR imaging (1.5 T ...

A 26 year-old female experienced progressive left sided pulsatile tinnitus and conductive hearing loss for two years, which following an extensive clinical workup, was diagnosed as a left greater petrosal nerve schwannoma located within... more

A 26 year-old female experienced progressive left sided pulsatile tinnitus and conductive hearing loss for two years, which following an extensive clinical workup, was diagnosed as a left greater petrosal nerve schwannoma located within the petrous apex of the temporal bone. Between neurosurgical management and radiation therapy, multiple therapeutic options were presented to the patient, who ultimately chose stereotactic radiotherapy as an alternative to surgical resection due to the potential morbidity associated with surgery. The patient received three fractions of 600 cGy without subsequent worsening of her symptoms, new onset neurologic symptoms or radiation induced side effects reported at a 3, 6 and 12 month clinic visits. A follow-up MRI at 6 and 12 months post radiation administration demonstrated no further tumor growth.

Background Stereotactic radiosurgery is frequently used for the treatment of brain metastases. This study provides a retrospective evaluation of patients with secondary lesions of the brain treated with stereotactic radiosurgery (SRS) at... more

Background Stereotactic radiosurgery is frequently used for the treatment of brain metastases. This study provides a retrospective evaluation of patients with secondary lesions of the brain treated with stereotactic radiosurgery (SRS) at our institution. Aims To provide outcome data from a single institutional experience with SRS and identify any significant prognostic factors in the cohort. Methods Sixty-seven patients received first time SRS to 86 intracranial metastases between 2007 and 2010. Sixteen patients were excluded from this study due to the absence of post-treatment neuroimaging, resulting in 51 patients with 64 treated lesions. Of these patients, 37 (72.5 %) received SRS electively, while 14 (27.5 %) received salvage SRS after brain metastasis progression following whole brain radiotherapy. Results Median survival for the entire group was 15 months from the date of radiosurgery. Patients without active extracranial disease had statistically significant survival time than those with active extracranial disease (P = 0.03). 45 (70.3 %) lesions achieved local tumour control in 34 patients (66.7 %) with a mean follow-up period of 10.7 months (range 1.7-33.6 months, 95 % confidence interval 6.6-9.8 months). Conclusions The results reported in this study equate to those reported in other series consolidating SRS as an effective treatment option with few serious complications. Developments in systemic disease control will see further improvements in overall survival.

A highly individualized stereotactic body radiotherapy (SBRT) strategy was developed to allow a wide spectrum of patients with liver cancer to be treated. This phase I/II study encompasses individualization of immobilization, radiation... more

A highly individualized stereotactic body radiotherapy (SBRT) strategy was developed to allow a wide spectrum of patients with liver cancer to be treated. This phase I/II study encompasses individualization of immobilization, radiation planning, PTV margin determination, image guidance strategy and prescription dose. Active breathing control breath hold is used to immobilize the liver when feasible. Image guidance strategies include orthogonal MV images and orthogonal kV fluoroscopy using the diaphragm for a surrogate for the liver, and kV cone beam CT using the liver or tumour for guidance. The prescription dose is individualized to maintain the same estimated risk of radiation-induced liver disease (RILD), based on a normal tissue complication probability (NTCP) model, with a maximum permitted dose of 60 Gy in 6 fractions. Since August 2003, 79 patients with hepatocellular carcinoma (33), intrahepatic cholangiocarcinoma (12) and liver metastases (34) were treated. The median tumour volume was 293 cm3 (2.9-3 088 cm3). The median prescribed dose was 36.6 Gy (24.0 Gy-57.0 Gy) in 6 fractions. The median effective liver volume irradiated was 45% (9-80%). Sixty percent of patients were treated with breath hold to immobilize their liver. Intra-fraction reproducibility (sigma) of the liver with repeat breath holds was excellent (1.5 mm); however inter-fraction reproducibility (sigma) was worse (3.4 mm). Image guidance reduced the residual systematic and random setup errors significantly.

A method for extracranial Stereotactic radiosurgery (ESRS) is described. For this treatment method a stereotactic body frame was developed and is described here. The ESRS method uses a hypofractionation schedule with 2-3 fractions with... more

A method for extracranial Stereotactic radiosurgery (ESRS) is described. For this treatment method a stereotactic body frame was developed and is described here. The ESRS method uses a hypofractionation schedule with 2-3 fractions with 10-20 Gy/fraction to the periphery of the target volume, at the 65% isodose. The heterogeneous target dose is used as a means to increase the probability of killing the hypoxic tumor cells. It is argued from in vitro cell survival data that the dose increase used will give a reasonable probability to eradicate at least moderate concentrations of hypoxic cells. A high reproducibility of the target position with the ESRS method is based on the definition of the patient reference system to the stereotactic system and not to the bony anatomical reference points as used in conventional radiotherapy. Important to the ESRS method is that the target position is verified by computed tomography (CT) examinations. The positional accuracy of the target in the stereotactic system is 3.1 mm (mean deviation) in the transversal plane and 5.5 mm (mean deviation) in the longitudinal direction. The setup accuracy, i.e., the correct alignment of the stereotactic system to the isocenter of the treatment unit, is within I mm.

Purpose: Anterior callosotomy is a surgical option for the treatment of generalized tonic or atonic seizures associated with drop attacks. Besides open surgery, a radiosurgical callosal disconnection using the gamma knife (GK) also can be... more

Purpose: Anterior callosotomy is a surgical option for the treatment of generalized tonic or atonic seizures associated with drop attacks. Besides open surgery, a radiosurgical callosal disconnection using the gamma knife (GK) also can be performed, but reliable data about tolerability and efficacy are sparse.

The authors sought to assess the relationship between obliteration rate and different dose parameters following fractionated radiotherapy for arteriovenous malformations (AVMs). A comparison of the results of radiosurgery and radiotherapy... more

The authors sought to assess the relationship between obliteration rate and different dose parameters following fractionated radiotherapy for arteriovenous malformations (AVMs). A comparison of the results of radiosurgery and radiotherapy for AVMs was made to calculate the best fit alpha/beta value, which would then be used as a model for predicting the treatment outcome, independent of the number of fractions applied.

A 23-year-old Taiwanese female presented with intermittent twitching of the left eyelid and progressive left facial weakness for 10 months. Physical examination revealed grade II facial palsy on her left side. A white to pinkish mass with... more

A 23-year-old Taiwanese female presented with intermittent twitching of the left eyelid and progressive left facial weakness for 10 months. Physical examination revealed grade II facial palsy on her left side. A white to pinkish mass with blood vessels on its surface was found behind the left intact tympanic membrane . Contrast-enhanced coronal MRI showed that the main tumor, about 2 ϫ 1 cm in size, arose from the second genu and the mastoid segment of the facial nerve . An extended transmastoid approach was used to expose the tumor by microscope.

The capability of performing functional radiosurgery lesions in the brain using a dedicated linear accelerator (LINAC) have not yet been demonstrated. This study evaluates modern LINAC technology for the creation of a sharp, small and... more

The capability of performing functional radiosurgery lesions in the brain using a dedicated linear accelerator (LINAC) have not yet been demonstrated. This study evaluates modern LINAC technology for the creation of a sharp, small and functionally eloquent lesion in the thalamus. Three patients underwent thalamotomy using a dedicated linear accelerator to radiosurgery, 2 females and 1 male, ages were 52, 53, and 73 years. Two patients presented with unilateral poststroke central pain and 1 with unilateral upper extremity pain secondary to metastatic infiltration of the brachial plexus. Maximal doses varied from 150 to 200 Gy, delivered by a 5-mm diameter collimator and 5 to 8 noncoplanar arcs evenly distributed. All patients gained substantial relief of their pain. They were able to reduce their medications and improve their activity levels. The patient with end-stage metastatic disease died of his malignancy 2 weeks after the treatment. One patient presented with recurrence of the pain 4 months after the treatment. No clinical complications were noticed. A dedicated linear accelerator is able to perform a precise and circumscribed lesion in the thalamus for pain control. Moreover, it proved to be safe, because no complications were observed. For patients using chronic anticoagulant therapy or with severe disabilities caused by cardiac, pulmonary or malignant diseases, this technique represents an alternative of treatment to radiofrequency thalamotomy.

Purpose: The purpose of this work is to develop a framework to the inverse problem for radiosurgery treatment planning on the Gamma Knife V R Perfexion TM (PFX) for intracranial targets. Methods: The approach taken in the present study... more

Purpose: The purpose of this work is to develop a framework to the inverse problem for radiosurgery treatment planning on the Gamma Knife V R Perfexion TM (PFX) for intracranial targets. Methods: The approach taken in the present study consists of two parts. First, a hybrid grassfire and sphere-packing algorithm is used to obtain shot positions (isocenters) based on the geometry of the target to be treated. For the selected isocenters, a sector duration optimization (SDO) model is used to optimize the duration of radiation delivery from each collimator size from each individual source bank. The SDO model is solved using a projected gradient algorithm. This approach has been retrospectively tested on seven manually planned clinical cases (comprising 11 lesions) including acoustic neuromas and brain metastases. Results: In terms of conformity and organ-at-risk (OAR) sparing, the quality of plans achieved with the inverse planning approach were, on average, improved compared to the manually generated plans. The mean difference in conformity index between inverse and forward plans was À0.12 (range: À0.27 to þ0.03) and þ0.08 (range: 0.00-0.17) for classic and Paddick definitions, respectively, favoring the inverse plans. The mean difference in volume receiving the prescribed dose (V 100 ) between forward and inverse plans was 0.2% (range: À2.4% to þ2.0%). After plan renormalization for equivalent coverage (i.e., V 100 ), the mean difference in dose to 1 mm 3 of brainstem between forward and inverse plans was À0.24 Gy (range: À2.40 to þ2.02 Gy) favoring the inverse plans. Beam-on time varied with the number of isocenters but for the most optimal plans was on average 33 min longer than manual plans (range: À17 to þ91 min) when normalized to a calibration dose rate of 3.5 Gy=min. In terms of algorithm performance, the isocenter selection for all the presented plans was performed in less than 3 s, while the SDO was performed in an average of 215 min. Conclusions: PFX inverse planning can be performed using geometric isocenter selection and mathematical modeling and optimization techniques. The obtained treatment plans all meet or exceed clinical guidelines while displaying high conformity. V C 2012 American Association of Physicists in Medicine. [http://dx.

Purpose. This study sought to evaluate acute toxicity and local control in patients who underwent extracranial stereotactic body radiation therapy (SBRT) for paracardiac and cardiac metastatic lesions, defined as such when located at a... more

Purpose. This study sought to evaluate acute toxicity and local control in patients who underwent extracranial stereotactic body radiation therapy (SBRT) for paracardiac and cardiac metastatic lesions, defined as such when located at a maximum distance of 1 cm from the heart or inside its parenchyma. Materials and methods. Between January 2009 and May 2011, 16 patients with paracardiac and cardiac lesions were treated with SBRT. For dose specification, in 15 of 16 patients, the prescription dosage was 36 Gy in three fractions (70% isodose). In one patient, the target lesion was inside the heart, and the prescription dosage was 30 Gy in three fractions (70% isodose). Results. Regarding response to stereotactic radiotherapy, we recorded one (6%) complete response (CR), six (37%) partial responses (PR), five (32%) stable disease (SD) and four (25%) local failures. Median interval to local failure was 5.2 (range, 3-12) months. The cause of death was distant progression of disease in all four patients. Compliance to treatment was excellent; no patient developed cardiological symptoms or electrocardiographic abnormalities, even months after SBRT. Conclusions. Results of our retrospective study indicate that SBRT represents a safe and effective treatment option for patients with cardiac and paracardiac metastases. Keywords Cardiac metastases • Paracardiac metastases • Oligometastases • Stereotactic body radiotherapy • Radiotherapy Riassunto Obiettivo. Scopo di questo lavoro è valutare la tossicità acuta e il controllo locale nel trattamento di pazienti sottoposti a radioterapia stereotassica extracranica (SBRT) per lesioni metastatiche paracardiache e cardiache, definite come tali se localizzate entro 1 cm dal cuore o nel contesto del suo parenchima Materiali e metodi. Fra gennaio 2009 e maggio 2011, 16 pazienti con lesioni paracardiache e cardiache sono stati sottoposti a SBRT. In 15/16 pazienti la dose prescritta è stata di 36 Gy in 3 frazioni (all'isodose del 70%). In un paziente la lesione target era intracardiaca, e la dose di prescrizione è stata di 30 Gy in 3 frazioni (all'isodose del 70%). Risultati. Per quanto concerne la risposta alla radioterapia stereotassica, è stata registrata 1 (6%) risposta completa (CR), 6 (37%) risposte parziali (PR), 5 (32%) stabilità di malattia (SD) e 4 (25%) progressioni locali. L'intervallo mediano alla progressione locale è stato di 5,2 mesi (range 3-12 mesi). La tolleranza al trattamento è stata ottimale; nella serie di pazienti trattati nessuno ha sviluppato segni o sintomi di natura cardiologica in conseguenza della SBRT. Conclusioni. I risultati della nostra analisi retrospettiva indicano che la SBRT rappresenta una opzione terapeutica sicura ed efficace per metastasi cardiache e paracardiache. Parole chiave Metastasi cardiache • Metastasi paracardiache • Oligometastasi • Radioterapia stereotassica • Radioterapia RADIOTHERAPY RADIOTERAPIA

Studies of organs in the thorax and abdomen have shown that these organs can move as much as 40 mm due to respiratory motion. Without compensation for this motion during the course of external beam radiation therapy, the dose coverage to... more

Studies of organs in the thorax and abdomen have shown that these organs can move as much as 40 mm due to respiratory motion. Without compensation for this motion during the course of external beam radiation therapy, the dose coverage to target may be compromised. On the other hand, if compensation of this motion is by expansion of the margin around the target, a significant volume of normal tissue may be unnecessarily irradiated. In hypofractionated regimens, the issue of respiratory compensation becomes an important factor and is critical in single-fraction extracranial radiosurgery applications. CyberKnife is an image-guided radiosurgery system that consists of a 6-MV LINAC mounted to a robotic arm coupled through a control loop to a digital diagnostic x-ray imaging system. The robotic arm can point the beam anywhere in space with 6 degrees of freedom, without being constrained to a conventional isocenter. The CyberKnife has been recently upgraded with a real-time respiratory tracking and compensation system called Synchrony. Using external markers in conjunction with diagnostic x-ray images, Synchrony helps guide the robotic arm to move the radiation beam in real time such that the beam always remains aligned with the target. With the aid of Synchrony, the tumor motion can be tracked in three-dimensional space, and the motion-induced dosimetric change to target can be minimized with a limited margin. The working principles, advantages, limitations, and our clinical experience with this new technology will be discussed.

Task Group 101 of the AAPM has prepared this report for medical physicists, clinicians, and therapists in order to outline the best practice guidelines for the external-beam radiation therapy technique referred to as stereotactic body... more

Task Group 101 of the AAPM has prepared this report for medical physicists, clinicians, and therapists in order to outline the best practice guidelines for the external-beam radiation therapy technique referred to as stereotactic body radiation therapy ͑SBRT͒. The task group report includes a review of the literature to identify reported clinical findings and expected outcomes for this treatment modality. Information is provided for establishing a SBRT program, including protocols, equipment, resources, and QA procedures. Additionally, suggestions for developing consistent documentation for prescribing, reporting, and recording SBRT treatment delivery is provided.

Paragangliomas are rare neoplasms of neurological origin and account for 0.012% of all tumors. Only 10% of them have extraadrenal localization. Head and neck paragangliomas account for 0.33% neoplasms of that localization. Typically... more

Paragangliomas are rare neoplasms of neurological origin and account for 0.012% of all tumors. Only 10% of them have extraadrenal localization. Head and neck paragangliomas account for 0.33% neoplasms of that localization. Typically paragangliomas are benign tumors, but even 19% cases may have malignant potential. On the neck they are located typically closely to carotid artery bifurcation, jugular bulb and along the course of vagus nerve. Laryngeal localization is very rare. Nonspecific manifestation and wide spectrum of symptoms cause difficulty in diagnosis of paragangliomas. Presentation of the diagnostic process, performed treatment and obtained results of neck paragangliomas in the material of the Department of Otolaryngology of Warsaw Medical University in years 2001-2010. There was performed retrospective analysis, based on the medical documentation of 14 patients with neck paragangliomas (9 women and 5 men), age range 25-62 years, hospitalized in the Department of Otolaryngology of Warsaw Medical University during the last 10 years. The date from the history, physical examination, radiological evaluation and the method of performed treatment and post-treatment complications were studied. Out of 14 patients with neck paragangliomas, there were 9 cases of isolated tumors and 5 cases of synchronic, multicentric neoplasms. The most common and single symptom was nonspecific neck mass. Doppler ultrasonography was adequate diagnostic tool in carotid artery paragangliomas. To diagnose mulicentric paraganglioma, vagal or laryngeal paraganglioma more thorough radiological examination was necessary, including computed tomography, magnetic resonance and angiography. All patients had performed surgical treatment. There were observed very good results in patients with isolated paragangiomas of carotid artery or larynx. Surgical management of multicentric and vagal paragangliomas was exposed to higher risk of cranial nerve paresis. (1) Paragangliomas are rare tumors of nonspecific clinical manifestation, making the early diagnosis very difficult. (2) Precise radiological evaluation is necessary taking into consideration quite high incidence of multicentric paragangliomas. (3) There is higher risk of cranial nerve paresis after surgical treatment of multicentric paragangliomas, neoplasms larger then 5 centimeters in diameter and vagal paragangliomas then in isolated carotid artery paragangliomas.

Small-cell lung cancer (SCLC) has a high propensity to metastasize into the brain. Radiotherapy plays a major role in the treatment of brain metastases (BM) from SCLC. Whole-brain radiotherapy (WBRT) is the standard treatment of BM from... more

Small-cell lung cancer (SCLC) has a high propensity to metastasize into the brain. Radiotherapy plays a major role in the treatment of brain metastases (BM) from SCLC. Whole-brain radiotherapy (WBRT) is the standard treatment of BM from SCLC. However, the neurocognitive toxicity and modest efficacy of this approach have led to the increased use of stereotactic radiosurgery. We have no strong evidence for the use of different forms of radiation (WBRT vs. radiosurgery) in SCLC, because BM from this primary tumor were excluded from clinical trials. In this review, the use of radiation in form of WBRT or radiosurgery is discussed in distinct clinical indications: as a primary treatment and at relapse; without prior use of prophylactic cranial irradiation (PCI); and after PCI. Combinations of radiotherapy with chemotherapy are discussed as BM in SCLC occur rarely as a sole event.

It is difficult to estimate the fetal or ovarian radiation dosage for female patients undergoing Gamma Knife radiosurgery. Our goals are to determine the fetal and ovarian radiation dose at various distances from a cranial isocenter, to... more

It is difficult to estimate the fetal or ovarian radiation dosage for female patients undergoing Gamma Knife radiosurgery. Our goals are to determine the fetal and ovarian radiation dose at various distances from a cranial isocenter, to provide a reference for practitioners to estimate the fetal dose with respect to gestational age, and to identify the components of pelvic extracranial radiation.

Obwohl neurodestruktive Verfahren sehr effektiv in der Behandlung von Schmerzen malignen und nichtmalignen Ursprungs sein können, werden sie heute kaum noch durchgeführt. Dies liegt zum einen daran, dass sie in der Vergangenheit mit einer... more

Obwohl neurodestruktive Verfahren sehr effektiv in der Behandlung von Schmerzen malignen und nichtmalignen Ursprungs sein können, werden sie heute kaum noch durchgeführt. Dies liegt zum einen daran, dass sie in der Vergangenheit mit einer hohen Komplikationsrate verbunden waren. Diese Komplikationen beinhalteten das Auftreten neuer neurologischer Defizite und -bei entsprechend langer Nachbeobachtungszeit -das Wiederauftreten der früheren Schmerzen oder neuer Schmerzen durch eine Deafferentierung. Zum anderen gelingt es, mit weniger invasiven, z. B. neuromodulatorischen oder nichtinvasiven Verfahren (systemische, orale, transdermale Opioide, Koanalgetika) einen großen Teil dieser Schmerzen befriedigend zu reduzieren. Dennoch bestehen auch heute noch bestimmte, sehr eingeschränkte Indikationen für die Durchführung neurodestruktiver Verfahren.

ELSON syndrome is a rare clinical manifestation of an enlarging pituitary adenoma that can occur following bilateral adrenalectomy performed in the treatment of CD. It is characterized by skin and mucus membrane hyperpigmentation and... more

ELSON syndrome is a rare clinical manifestation of an enlarging pituitary adenoma that can occur following bilateral adrenalectomy performed in the treatment of CD. It is characterized by skin and mucus membrane hyperpigmentation and excess ACTH secretion. Diagnostic criteria for NS have been quite variable. Some authors 77 have defined NS as high levels of ACTH associated with skin hyperpigmentation after bilateral adrenalectomy regardless of pituitary enlargement, 80 whereas others consider the presence of an expanding pituitary adenoma causing visual field disturbance as a requirement for diagnosis. 114 With modern day imaging, and for the purposes of this review, corticotroph tumor progression and high ACTH have been proposed as a basis for the diagnosis of NS. 4 Historical Perspective The first suggestion that the adrenal gland was essential for life came from Brown-Séquard, who showed in the 1850s that bilateral adrenalectomy in animals caused death within a few days. 66 Harvey Cushing 13 was the first to link adrenal hypersecretion of cortisol to the presence of a pituitary tumor. The concept of the hypothalamic-pituitary-adrenal axis evolved further with the demonstration of the existence of ACTH-releasing factor in 1955 by Saffran and Schally. 98 The first case report of the characteristic triad of NS was published by Don Nelson in 1958. 78 He described a 33-year-old woman who developed marked skin hyperpigmentation, high plasma ACTH levels, and imaging evidence of a pituitary tumor (enlarged sella on skull radiographs) 3 years after bilateral adrenalectomy for CD. In 1960, Nelson and colleagues 79 formally described the syndrome of pituitary hypersecretion of ACTH and pituitary tumor enlargement, which has since become the eponymous syndrome. Corticotropin-releasing hormone was finally isolated and sequenced by Vale and coworkers in 1981, 113 and with the availability of radioimmunoassay, the elevation of plasma ACTH levels after bilateral adrenalectomy became diagnostic for NS. Historically, patients with CD were treated with bilateral

Purpose The authors tried to assess the treatment outcomes depending on the extent of resection in axial chordomas and compare the outcome of two adjunctive therapies (external beam radiation therapy vs. stereotactic radiosurgery)... more

Purpose The authors tried to assess the treatment outcomes depending on the extent of resection in axial chordomas and compare the outcome of two adjunctive therapies (external beam radiation therapy vs. stereotactic radiosurgery) following incomplete tumour resection in terms of local tumour control. Patients and methods We retrospectively reviewed 30 consecutive patients with chordoma involving skull base, sacrum and mobile spine between 1993 and 2008. Their initial treatments had different extent of resection. Wide resection was performed for 12 (40%), subtotal resection and adjunctive radiotherapy/radiosurgery for 12 (40%), while six patients (20%) were solely treated with radiotherapy/radiosurgery. For these three groups, overall and progression-free survival rate were compared. Results The overall survival rate was 96% at 5 years and 67% at 10 years. Tumour progression-free survival (PFS) rates were 73% and 43% at 5 and 10 years, respectively. Local tumour progression was seen in 67% in all patients, 58% in wide resection group, 67% in subtotal resection plus radiotherapy/radiosurgery group, and 75% in radiotherapy/radiosurgery group; however, this was not statistically significant (P=0.69). Neither the extent of resection nor tumour location significantly influenced overall and progression-free survival (P>0.05). With regard to the type of radiotherapy, tumour progression occurred in all lesions treated with external photon beam radiation therapy (EBRT) but only 38% of lesions treated with stereotactic radiosurgery (SRS) (P=0.003). Conclusions Adjunctive radiotherapy/radiosurgery following subtotal resection showed comparable local control and survival to wide resection. SRS offered superior local tumour control compared to EBRT.

Purpose: Flattening filter free (FFF) beams generated by medical linear accelerators have recently started to be used in radiotherapy clinical practice. Such beams present fundamental differences with respect to the standard filter... more

Purpose: Flattening filter free (FFF) beams generated by medical linear accelerators have recently started to be used in radiotherapy clinical practice. Such beams present fundamental differences with respect to the standard filter flattened (FF) beams, making the generally used dosimetric parameters and definitions not always viable. The present study will propose possible definitions and suggestions for some dosimetric parameters for use in quality assurance of FFF beams generated by medical linacs in radiotherapy.

To improve the quality of liver stereotactic body radiation therapy (SBRT) treatments, a novel 4π framework was developed with accompanying algorithms to optimize non-coplanar beam orientations and fluences. The dose optimization is... more

To improve the quality of liver stereotactic body radiation therapy (SBRT) treatments, a novel 4π framework was developed with accompanying algorithms to optimize non-coplanar beam orientations and fluences. The dose optimization is performed on a patient-specific deliverable beam geometry solution space, parameterized with patient and linear accelerator gantry orientations. Beams causing collision between the gantry and the couch or patient were eliminated by simulating all beam orientations using a precise computer assisted design model of the linear accelerator and a human subject. Integrated beam orientation and fluence map optimizations were performed on remaining beams using a greedy column generation method. Testing of the new method was performed on 10 liver SBRT cases previously treated with 50 to 60 Gy in 5 fractions using volumetric modulated arc therapy (VMAT). For each patient, both 14 and 22 non-coplanar fields were selected and optimized to meet the objective of ≥95% of the planning target volume (PTV) covered by 100% of the prescription dose. Doses to organs at risk, normal liver volumes receiving <15 Gy, integral dose, and 50% dose spillage volumes were compared against the delivered clinical VMAT plans. Compared with the VMAT plans, the 4π plans yielded reduced 50% dose spillage volume and integral dose by 22% (range 10%-40%) and 19% (range 13%-26%), respectively. The mean normal liver volume receiving <15 Gy was increased by 51 cc (range 21-107 cc) with a 31% reduction of the mean normal liver dose. Mean doses to the left kidney and right kidney and maximum doses to the stomach and spinal cord were on average reduced by 70%, 51%, 67%, and 64% (P≤.05). This novel 4π non-coplanar radiation delivery technique significantly improved dose gradient, reduced high dose spillage, and improved organ at risk sparing compared with state of the art VMAT plans.

The management of intracranial germinomas is controversial, with treatment options including conventional wide-field irradiation with or without chemotherapy or primary chemotherapy alone. The potential role of radiosurgery in the... more

The management of intracranial germinomas is controversial, with treatment options including conventional wide-field irradiation with or without chemotherapy or primary chemotherapy alone. The potential role of radiosurgery in the treatment of these lesions, although appealing, remains to be defined. We report a case whose initial management plan included radiosurgery to be followed by chemotherapy; however the patient subsequently refused chemotherapy. The presentation, diagnosis, treatment and results are discussed.

Purpose: Overprediction of the potency and toxicity of high-dose ablative radiotherapy such as stereotactic body radiotherapy (SBRT) by the linear quadratic (LQ) model led to many clinicians' hesitating to adopt this efficacious and... more

Purpose: Overprediction of the potency and toxicity of high-dose ablative radiotherapy such as stereotactic body radiotherapy (SBRT) by the linear quadratic (LQ) model led to many clinicians' hesitating to adopt this efficacious and well-tolerated therapeutic option. The aim of this study was to offer an alternative method of analyzing the effect of SBRT by constructing a universal survival curve (USC) that provides superior approximation of the experimentally measured survival curves in the ablative, high-dose range without losing the strengths of the LQ model around the shoulder. Methods and Materials: The USC was constructed by hybridizing two classic radiobiologic models: the LQ model and the multitarget model. We have assumed that the LQ model gives a good description for conventionally fractionated radiotherapy (CFRT) for the dose to the shoulder. For ablative doses beyond the shoulder, the survival curve is better described as a straight line as predicted by the multitarget model. The USC smoothly interpolates from a parabola predicted by the LQ model to the terminal asymptote of the multitarget model in the high-dose region. From the USC, we derived two equivalence functions, the biologically effective dose and the single fraction equivalent dose for both CFRT and SBRT. Results: The validity of the USC was tested by using previously published parameters of the LQ and multitarget models for non-small-cell lung cancer cell lines. A comparison of the goodness-of-fit of the LQ and USC models was made to a high-dose survival curve of the H460 non-small-cell lung cancer cell line. Conclusion: The USC can be used to compare the dose fractionation schemes of both CFRT and SBRT. The USC provides an empirically and a clinically well-justified rationale for SBRT while preserving the strengths of the LQ model for CFRT.

The CyberKnife Stereotactic Radiosurgery System is manufactured by Accuray, Inc. (570 Del Rey Avenue, Sunnyvale, CA 94085; telephone 1-888/522-3740 or 1-408/522-3740; http://www.accuray.com). It is currently available for purchase... more

The CyberKnife Stereotactic Radiosurgery System is manufactured by Accuray, Inc. (570 Del Rey Avenue, Sunnyvale, CA 94085; telephone 1-888/522-3740 or 1-408/522-3740; http://www.accuray.com). It is currently available for purchase (capital cost of US 3.2millionplusUS3.2 million plus US 3.2millionplusUS0.5 to 0.75 million for site setup), or in a revenue-sharing plan (US $0.5 to 0.75 million setup cost). [Figure: see text].

The ExacTrac X-Ray 6D image-guided radiotherapy (IGRT) system will be described and its performance evaluated. The system is mainly an integration of 2 subsystems: (1) an infrared (IR)-based optical positioning system (ExacTrac) and (2) a... more

The ExacTrac X-Ray 6D image-guided radiotherapy (IGRT) system will be described and its performance evaluated. The system is mainly an integration of 2 subsystems: (1) an infrared (IR)-based optical positioning system (ExacTrac) and (2) a radiographic kV x-ray imaging system (X-Ray 6D). The infrared system consists of 2 IR cameras, which are used to monitor reflective body markers placed on the patient's skin to assist in patient initial setup, and an IR reflective reference star, which is attached to the treatment couch and can assist in couch movement with spatial resolution to better than 0.3 mm. The radiographic kV devices consist of 2 oblique x-ray imagers to obtain high-quality radiographs for patient position verification and adjustment. The position verification is made by fusing the radiographs with the simulation CT images using either 3 degree-of-freedom (3D) or 6 degree-of-freedom (6D) fusion algorithms. The position adjustment is performed using the infrared system ...

This is an update of the Royal Adelaide Hospital radiosurgery experience between November 1993 and December 2004 comprising 165 patients with 168 intracranial lesions. Including re-treatment, there were 175 treatment episodes (163... more

This is an update of the Royal Adelaide Hospital radiosurgery experience between November 1993 and December 2004 comprising 165 patients with 168 intracranial lesions. Including re-treatment, there were 175 treatment episodes (163 radiosurgery and 12 stereotactic radiotherapy) at an average of 1.3 per month. The commonest lesions were acoustic neuroma (65), arteriovenous malformation (58), solitary brain metastasis (23) and meningioma . The clinical features, treatment details and outcome are described. Our results continue to be well within the range reported in the published work. Radiosurgery provides an elegant, non-invasive alternative to neurosurgery and conventional external beam radiotherapy for many benign and malignant brain tumours.

Purpose: Overprediction of the potency and toxicity of high-dose ablative radiotherapy such as stereotactic body radiotherapy (SBRT) by the linear quadratic (LQ) model led to many clinicians' hesitating to adopt this efficacious and... more

Purpose: Overprediction of the potency and toxicity of high-dose ablative radiotherapy such as stereotactic body radiotherapy (SBRT) by the linear quadratic (LQ) model led to many clinicians' hesitating to adopt this efficacious and well-tolerated therapeutic option. The aim of this study was to offer an alternative method of analyzing the effect of SBRT by constructing a universal survival curve (USC) that provides superior approximation of the experimentally measured survival curves in the ablative, high-dose range without losing the strengths of the LQ model around the shoulder. Methods and Materials: The USC was constructed by hybridizing two classic radiobiologic models: the LQ model and the multitarget model. We have assumed that the LQ model gives a good description for conventionally fractionated radiotherapy (CFRT) for the dose to the shoulder. For ablative doses beyond the shoulder, the survival curve is better described as a straight line as predicted by the multitarget model. The USC smoothly interpolates from a parabola predicted by the LQ model to the terminal asymptote of the multitarget model in the high-dose region. From the USC, we derived two equivalence functions, the biologically effective dose and the single fraction equivalent dose for both CFRT and SBRT. Results: The validity of the USC was tested by using previously published parameters of the LQ and multitarget models for non-small-cell lung cancer cell lines. A comparison of the goodness-of-fit of the LQ and USC models was made to a high-dose survival curve of the H460 non-small-cell lung cancer cell line. Conclusion: The USC can be used to compare the dose fractionation schemes of both CFRT and SBRT. The USC provides an empirically and a clinically well-justified rationale for SBRT while preserving the strengths of the LQ model for CFRT.

The requirement of an independent verification of the monitor units ͑MU͒ or time calculated to deliver the prescribed dose to a patient has been a mainstay of radiation oncology quality assurance. The need for and value of such a... more

The requirement of an independent verification of the monitor units ͑MU͒ or time calculated to deliver the prescribed dose to a patient has been a mainstay of radiation oncology quality assurance. The need for and value of such a verification was obvious when calculations were performed by hand using look-up tables, and the verification was achieved by a second person independently repeating the calculation. However, in a modern clinic using CT/MR/PET simulation, computerized 3D treatment planning, heterogeneity corrections, and complex calculation algorithms such as convolution/superposition and Monte Carlo, the purpose of and methodology for the MU verification have come into question. In addition, since the verification is often performed using a simpler geometrical model and calculation algorithm than the primary calculation, exact or almost exact agreement between the two can no longer be expected. Guidelines are needed to help the physicist set clinically reasonable action levels for agreement. This report addresses the following charges of the task group: ͑1͒ To re-evaluate the purpose and methods of the "independent second check" for monitor unit calculations for non-IMRT radiation treatment in light of the complexities of modernday treatment planning. ͑2͒ To present recommendations on how to perform verification of monitor unit calculations in a modern clinic. ͑3͒ To provide recommendations on establishing action levels for agreement between primary calculations and verification, and to provide guidance in addressing discrepancies outside the action levels. These recommendations are to be used as guidelines only and shall not be interpreted as requirements.

At this stage the patient first meet their radiation technologists, too (called " Therapists Radiation or Radiotherapy and radiology technicians "). The technician is trained to administer radiation dose prescribed by the doctor. It is... more

At this stage the patient first meet their radiation technologists, too (called " Therapists Radiation or Radiotherapy and radiology technicians "). The technician is trained to administer radiation dose prescribed by the doctor. It is also responsible for helping you achieve a comfortable position that will be the best to allow photons or electrons X-rays pass through the body part being treated. He or she will provide special accessories or foam supports for the patient to stay in the same position for each treatment. The patients also know his medical physicist. A medical physicist made the remarks on the physical aspects of the treatment plan.

Stereotactic radiosurgery (SRS) refers to a single radiation treatment delivering a high dose to an intra-cranial target localized in three-dimensions by CT and/or MRI imaging. Traditionally, immobilization of the patient's head has been... more

Stereotactic radiosurgery (SRS) refers to a single radiation treatment delivering a high dose to an intra-cranial target localized in three-dimensions by CT and/or MRI imaging. Traditionally, immobilization of the patient's head has been achieved using a rigid stereotactic head frame as the key step in allowing for accurate dose delivery. SRS has been delivered by both Cobalt-60 (Gamma Knife ®) and linear accelerator (linac) technologies for many decades. The focus of this review is to highlight recent advances and major innovations in SRS technologies relevant to clinical practice and developments allowing for non-invasive frame SRS.

A multidisciplinery Radiation Therapy Oncology Group (RTOG) task force has developed quality assurance guidelines for radiosurgery. The purpose of the guidelines are fourfold: (1) To ensure that participating institutions have the proper... more

A multidisciplinery Radiation Therapy Oncology Group (RTOG) task force has developed quality assurance guidelines for radiosurgery. The purpose of the guidelines are fourfold: (1) To ensure that participating institutions have the proper equipment and appropriate technique(s) to administer radiosurgery; (2) to outline a standard data set for each treated patient to assess protocol compliance; (3) to define minor and major deviations in protocol treatment; and (4) to set forth clinical data necessary to determine treatment efficacy, including failure patterns, and treatment toxicity. These guidelines are being implemented into active and developing radiosurgery protocols.

Single-fraction stereotactic radiosurgery (SRS) and hypofractionated stereotactic radiotherapy (SRT) are radiation planning and delivery techniques used for the treatment of intracranial and spine/spinal cord tumors and targets. For... more

Single-fraction stereotactic radiosurgery (SRS) and hypofractionated stereotactic radiotherapy (SRT) are radiation planning and delivery techniques used for the treatment of intracranial and spine/spinal cord tumors and targets. For cranial SRS and SRT, critical normal tissues/structures include the brainstem, cranial nerves, cochlea and normal brain parenchyma. For spine SRS/SRT, critical normal tissues/structures include the spinal cord, cauda equina as well as neighboring organs. This paper reviews clinical studies investigating central nervous system dose tolerances after cranial or spinal SRS/SRT. The impact of dose, volume, fractionation, and other relevant clinic-pathologic variables are discussed, as are limitations of the published data.

Task Group 101 of the AAPM has prepared this report for medical physicists, clinicians, and therapists in order to outline the best practice guidelines for the external-beam radiation therapy technique referred to as stereotactic body... more

Task Group 101 of the AAPM has prepared this report for medical physicists, clinicians, and therapists in order to outline the best practice guidelines for the external-beam radiation therapy technique referred to as stereotactic body radiation therapy ͑SBRT͒. The task group report includes a review of the literature to identify reported clinical findings and expected outcomes for this treatment modality. Information is provided for establishing a SBRT program, including protocols, equipment, resources, and QA procedures. Additionally, suggestions for developing consistent documentation for prescribing, reporting, and recording SBRT treatment delivery is provided.

To assess intra- and inter-fractional motions of liver and lung tumors using active breathing control (ABC). Nineteen patients with liver cancer and 15 patients with lung cancer treated with stereotactic body radiotherapy (SBRT) were... more

To assess intra- and inter-fractional motions of liver and lung tumors using active breathing control (ABC). Nineteen patients with liver cancer and 15 patients with lung cancer treated with stereotactic body radiotherapy (SBRT) were included in this retrospective study. All patients received a series of three CTs at simulation to test breath-hold reproducibility. The centroids of the whole livers and of the lung tumors from the three CTs were compared to assess intra-fraction variability. For 15 patients (8 liver, 7 lung), ABC-gated kilovoltage cone-beam CTs (kV-CBCTs) were acquired prior to each treatment, and the centroids of the whole livers and of the lung tumors were also compared to those in the planning CTs to assess inter-fraction variability. Liver intra-fractional systematic/random errors were 0.75/0.39 mm, 1.36/0.97 mm, and 1.55/1.41 mm at medial-lateral (ML), anterior-posterior (AP), and superior-inferior (SI) directions, respectively. Lung intra-fractional systematic/r...

Epilepsy surgery is an effective treatment for properly selected patients with intractable seizures. However, many patients with medically intractable epilepsy are not excellent candidates for surgical resection of the epileptogenic zone.... more

Epilepsy surgery is an effective treatment for properly selected patients with intractable seizures. However, many patients with medically intractable epilepsy are not excellent candidates for surgical resection of the epileptogenic zone. Due to recent advances in computer technology and bioengineering, several novel techniques are receiving increasing interest for their role in the care of people with epilepsy. Neuromodulation is an emerging surgical option to be used when conventional resective surgery is not indicated. We review the indications and expected outcomes of neuromodulatory treatments currently available for the treatment of refractory epilepsy, i.e., vagus nerve stimulation, deep brain stimulation, stereotactic radiosurgery, and multiple subpial transections.

Spinal metastases are associated with significant symptoms. From September 2005 to September 2007, 69 consecutive patients with 127 malignant spine metastatic lesions were treated at Wanfang Hospital with CyberKnife @ (CK) radiosurgery.... more

Spinal metastases are associated with significant symptoms. From September 2005 to September 2007, 69 consecutive patients with 127 malignant spine metastatic lesions were treated at Wanfang Hospital with CyberKnife @ (CK) radiosurgery. The radiosurgery dose ranged from 10 to 30 Gy (mean 15.5 Gy) prescribed to the 75-85% isodose line that encompassed at least 95% of the tumor volume. We used fiducials as tracking landmarks for CK treatment of the thoracic and lumbar spine. A torso anthropomorphic phantom and GafChromic MD-55 films were used to verify the accuracy of CK radiosurgery and 2D dose distribution, demonstrated high targeting accuracy with 2% average deviation of the measured dose from the estimated dose at the set-up center and less than 5% dose deviation in 2D isodose curve. Visual Analogue Scale and Oswestry Disability Index questionnaires were used to monitor functional outcome after radiosurgery. Local tumor control at 10 months was 96.8%. Mean pain scores decreased significantly from 65 to 30 after treatment (P = 0.001). Functional disability was significantly improved after treatment (P = 0.002). The most common treatment toxicities were nausea and fatigue. In conclusion, CK radiosurgery is a well-tolerated and effective treatment for spine tumors with good local tumor control and a favorable outcome on pain and functional improvement after treatment.

Single-fraction stereotactic radiosurgery (SRS) and hypofractionated stereotactic radiotherapy (SRT) are radiation planning and delivery techniques used for the treatment of intracranial and spine/spinal cord tumors and targets. For... more

Single-fraction stereotactic radiosurgery (SRS) and hypofractionated stereotactic radiotherapy (SRT) are radiation planning and delivery techniques used for the treatment of intracranial and spine/spinal cord tumors and targets. For cranial SRS and SRT, critical normal tissues/structures include the brainstem, cranial nerves, cochlea and normal brain parenchyma. For spine SRS/SRT, critical normal tissues/structures include the spinal cord, cauda equina as well as neighboring organs. This paper reviews clinical studies investigating central nervous system dose tolerances after cranial or spinal SRS/SRT. The impact of dose, volume, fractionation, and other relevant clinic-pathologic variables are discussed, as are limitations of the published data.

Stereotactic ablative radiotherapy is a modern cancer treatment strategy able to deliver highly focused radiation in one or a few fractions with a radical intent in several clinical settings. Young radiation oncologists need a constant... more

Stereotactic ablative radiotherapy is a modern cancer treatment strategy able to deliver highly focused radiation in one or a few fractions with a radical intent in several clinical settings. Young radiation oncologists need a constant and tailored update in this context to improve patient care in daily clinical practice. A recent meeting of AIRO Giovani (AIRO - Young Members Working Group) was specifically addressed to this topic, presenting state-of-the-art knowledge, based on the latest evidence in this field. Highlights of the congress are summarized and presented in this report, including thorough contributions of the speakers dealing with the role of stereotactic ablative radiotherapy in both oncological and non-oncological diseases, divided according to anatomical and clinical scenarios: intra-cranial settings (brain malignant primary tumors, metastases, benign tumors and functional disorders) and extra-cranial indications (lung primary tumors and metastases, thoracic re-irra...

Background: Spinal radiosurgery is a quickly evolving technique in the radiotherapy and neurosurgical communities. However, the methods of spine radiosurgery have not been standardized. This article describes the results of a survey about... more

Background: Spinal radiosurgery is a quickly evolving technique in the radiotherapy and neurosurgical communities. However, the methods of spine radiosurgery have not been standardized. This article describes the results of a survey about the methods of spine radiosurgery at five international institutions.