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Purpose: To assess the impact of a multidisciplinary approach for treatment of patients with metastatic epidural spinal cord compression in terms of feasibility, local control, and survival., Methods and Materials: Eighty-nine consecutive patients treated between January 2004 and December 2007 were included. The most common primary cancers were lung, breast, and kidney cancers. Ninety-eight surgical procedures were performed. Radiotherapy was performed within the first month postoperatively. Clinical outcome was evaluated by modified visual analog scale for pain, Frankel scale for neurologic deficit, and magnetic resonance imaging or computed tomography scan. Nearly all patients (93%) had back pain before treatment, whereas major or minor preoperative neurologic deficit was present in 62 cases (63%)., Results: Clinical remission of pain was obtained in the vast majority of patients (91%). Improvement of neurologic deficit was observed in 45 cases (72.5%). Local relapse occurred in 10%. Median survival was 11 months (range, 0-46 months). Overall survival at 1 year was 43.6%. Type of primary tumor significantly affected survival., Conclusions: In patients with metastatic epidural spinal cord compression, the combination of surgery plus radiotherapy is feasible and provides clinical benefit in most patients. The discussion of each single case within a multidisciplinary team has been of pivotal importance in implementing the most appropriate therapeutic approach., (Copyright © 2010 Elsevier Inc. All rights reserved.)

Background: To report about early clinical experience in radiation treatment of head and neck cancer of different sites and histology by volumetric modulated arcs with the RapidArc technology., Methods: During 2009, 45 patients were treated at Istituto Clinico Humanitas with RapidArc (28 males and 17 females, median age 65 years). Of these, 78% received concomitant chemotherapy. Thirty-six patients were treated as exclusive curative intent (group A), three as postoperative curative intent (group B) and six with sinonasal tumours (group C). Dose prescription was at Planning Target Volumes (PTV) with simultaneous integrated boost: 54.45 Gy and 69.96 Gy in 33 fractions (group A); 54.45 Gy and 66 Gy in 33 fractions (group B) and 55 Gy in 25 fractions (group C)., Results: Concerning planning optimization strategies and constraints, as per PTV coverage, for all groups, D98% > 95% and V95% > 99%. As regards organs at risk, all planning objectives were respected, and this was correlated with observed acute toxicity rates. Only 28% of patients experienced G3 mucositis, 14% G3 dermitis 44% had G2 dysphagia. Nobody required feeding tubes to be placed during treatment. Acute toxicity is also related to chemotherapy. Two patients interrupted the course of radiotherapy because of a quick worsening of general clinical condition., Conclusions: These preliminary results stated that volumetric modulated arc therapy in locally advanced head and neck cancers is feasible and effective, with acceptable toxicities.

Background: To report acute toxicity, initial outcome results and planning therapeutic parameters in radiation treatment of advanced lung cancer (stage III) with volumetric modulated arcs using RapidArc (RA)., Methods: Twenty-four consecutive patients were treated with RA. All showed locally advanced non-small cell lung cancer with stage IIIA-IIIB and with large volumes (GTV:299 ± 175 cm3, PTV:818 ± 206 cm3). Dose prescription was 66Gy in 33 fractions to mean PTV. Delivery was performed with two partial arcs with a 6 MV photon beam., Results: From a dosimetric point of view, RA allowed us to respect most planning objectives on target volumes and organs at risk. In particular: for GTV D1% = 105.6 ± 1.7%, D99% = 96.7 ± 1.8%, D5%-D95% = 6.3 ± 1.4%; contra-lateral lung mean dose resulted in 13.7 ± 3.9Gy, for spinal cord D1% = 39.5 ± 4.0Gy, for heart V45Gy = 9.0 ± 7.0Gy, for esophagus D1% = 67.4 ± 2.2Gy. Delivery time was 133 ± 7s. At three months partial remission > 50% was observed in 56% of patients. Acute toxicities at 3 months showed 91% with grade 1 and 9% with grade 2 esophageal toxicity; 18% presented grade 1 and 9% with grade 2 pneumonia; no grade 3 acute toxicity was observed. The short follow-up does not allow assessment of local control and progression free survival., Conclusions: RA proved to be a safe and advantageous treatment modality for NSCLC with large volumes. Long term observation of patients is needed to assess outcome and late toxicity.

Purpose: It has been shown that in cases of lung tumors close to the liver cupola, the four dimensional (4D)-CT postprocessing maximum intensity projection (MIP) algorithm does not fully recover the radiotherapy internal gross tumor volume (IGTV). In this work, a semiautomatic technique was evaluated by which the residual IGTV that was not included into the IGTV by MIP algorithm was actually added., Methods: A moving phantom and five selected patients were considered. The various IGTVs produced by the semiautomatic approach were compared to those generated by 4D-CT manual contouring., Results: In all cases, the radiation oncologist qualitatively concurred with the semiautomatic IGTV. A quantitative difference in volume of 2.6% was found in the phantom study, whereas a mean difference of 0.1 +/- 4.6% was obtained in the patient studies., Conclusions: A semiautomatic technique to include the residual part of IGTV covered by liver/spleen cupola when using MIP algorithm was validated on phantom and on selected patients, revealing the possibility of defining the IGTV for patients with lesions located near liver/spleen cupola by performing only the contours on the MIP series.

Purpose: The cylindrical symmetry of vertebrae favors the use of volumetric modulated are therapy in generating a dose "hole" on the center of the vertebrae limiting the dose to the spinal cord. The authors have evaluated if collimator angle is a significant parameter for dose distribution optimization in vertebral metastases., Methods: Three patients with one-three vertebrae involved were considered. Twenty-one differently optimized plans (nine single-arc and 12 double-arc plans) were performed, testing various collimator angle positions. Clinical target volume was defined as the whole vertebrae, excluding the spinal cord canal. The planning target volume (PTV) was defined as CTV+5 mm. Dose prescription was 5 x 4 Gy(2) with normalization to PTV mean dose. The dose at 1 cm(3) of spinal cord was limited to 11.5Gy., Results: The best plans in terms of target coverage and spinal cord sparing were achieved by two arcs and Arcl-80 degrees and Arc2-280 degrees collimator angles for all the cases considered (i.e., leaf travel parallel to the spinal cord primary orientation). If one arc is used, only 80 degrees reached the objectives., Conclusions: This study demonstrated the role of collimation rotation for the vertebrae metastasis irradiation, with the leaf travel parallel to the spinal cord primary orientation to be better than other solutions. Thus, optimal choice of collimator angle increases the optimization freedom to shape a desired dose distribution.

Purpose: A planning study was performed to evaluate RapidArc (RA), a volumetric modulated arc technique, on malignant pleural mesothelioma. The benchmark was conventional fixed-field intensity-modulated radiotherapy (IMRT)., Methods and Materials: The computed tomography data sets of 6 patients were included. The plans for IMRT with nine fixed beams were compared against double-modulated arcs with a single isocenter. All plans were optimized for 15-MV photon beams. The dose prescription was 54 Gy to the planning target volume. The planning objectives for the planning target volume were a minimal dose of >95% and maximal dose of <107%. For the organs at risk, the parameters were as follows: contralateral lung, percentage of volume receiving 5 Gy (V(5 Gy)) <60%, V(20 Gy) < 10%, mean <10.0 Gy; liver, V(30 Gy) <33%, mean <31 Gy; heart, V(45 Gy) <30%, V(50 Gy) <20%, dose received by 1% of the volume (D(1%)) <60 Gy; contralateral kidney, V(15 Gy) <20%; spine, D(1%) <45 Gy; esophagus, V(55 Gy) <30%; and spleen, V(40 Gy) <50%. The monitor units (MUs) and delivery time were scored to measure the treatment efficiency. The pretreatment portal dosimetry scored delivery to the calculation agreement with the Gamma Agreement Index., Results: RA and IMRT provided equivalent coverage and homogeneity. Both techniques fulfilled objectives on organs at risk with a tendency of RA to improve sparing. The conformity index was 1.9 +/- 0.1 for RA and IMRT. The number of MU/2 Gy was 734 +/- 82 for RA and 2,195 +/- 317 for IMRT. The planning vs. delivery agreement revealed a Gamma Agreement Index for IMRT of 96.0% +/- 2.6% and for RA of 95.7% +/- 1.5%. The treatment time was 3.7 +/- 0.3 min for RA and 13.4 +/- 0.1 min for IMRT., Conclusion: RA demonstrated compared with conventional IMRT, similar target coverage and better dose sparing to the organs at risks. The number of MUs and the time required to deliver a 2-Gy fraction were much lower for RA, allowing the possibility to incorporate this technique in the treatment options for mesothelioma patients., ((c) 2010 Elsevier Inc. All rights reserved.)

Mechanical stabilization of oncological vertebral fractures with cement augmentation is the first mechanism of pain relief, with or without restoration of vertebral body height. The aim of this study was to assess the safety and efficacy of vertebroplasty for painful vertebral body fractures in patients with multiple myeloma, in each phase of the disease. The authors reviewed a consecutive group of patients with multiple myeloma who underwent vertebroplasty at our Institute between November 2003 and December 2005. Twenty-eight levels were performed on 11 patients during 14 treatment sessions. All patients suffered from intractable back pain, and presented various lesion types (with and without fractures of posterior wall, and with and without epidural disease). The preoperative median visual analog scale (VAS) score was 7. The median duration of symptoms was 1.1 months. Eight patients were ambulating with orthopaedic devices (57%) in the pre-treatment period. Improvement or complete pain relief was observed in all patients (immediately in 8 cases, and after 2 days in 6 cases). The median VAS pain score decreased to 2. There was no symptomatic procedure-related complication. There were three cases (21%) of PMMA leakage: in the disc space in one case (7%), and in the anterior spinal canal in two cases (14%). Complete removal of orthopaedic devices was obtained in five patients (36%). No new deformation or collapse of the treated vertebrae was observed during the follow-up (range 1 day-25 months). In conclusion, vertebroplasty is a safe and efficient procedure in the treatment of painful vertebral body fractures in patients with multiple myeloma, without potential contraindications, such as fractures of the posterior wall or epidural disease. We also treated three and more levels in 28% of cases in a single session without complications. Due to the early pain relief and the low complication rate, it is possible to expand the indication to vertebroplasty for the prophylactic augmentation of those vertebral bodies at risk of fracture in which significant neoplastic substitution of the body is present.

Introduction: The radiation oncology process along with its unique therapeutic properties is also potentially dangerous for the patient, and thus it should be delivered under a systematic risk control. To this aim incident reporting and analysis are not sufficient for assuring patient safety and proactive risk assessment should also be implemented. The paper accounts for some methodological solutions, lessons learned and opportunities for improvement, starting from the systematic application of the failure mode effects and criticality analysis (FMECA) technique to the radiotherapy process of an Italian hospital., Materials and Methods: The analysis, performed by a working group made of experts of the radiotherapy unit, was organised into the following steps: (1) complete and detailed analysis of the process (integration definition for function modelling); (2) identification of possible failure modes (FM) of the process, representing sources of adverse events for the patient; (3) qualitative risk assessment of FMs, aimed at identifying priorities of intervention; (4) identification and planning of corrective actions., Results: Organisational and procedural corrective measures were implemented; a set of safety indexes for the process was integrated within the traditional quality assurance indicators measured by the unit. A strong commitment of all the professionals involved was observed and the study revealed to be a powerful "tool" for dissemination of patient safety culture., Conclusion: The feasibility of FMECA in fostering radiotherapy safety was proven; nevertheless, some lessons learned as well as weaknesses of current practices in risk management open to future research for the integration of retrospective methods (e.g. incident reporting or root cause analysis) and risk assessment., ((c) 2010 Elsevier Ireland Ltd. All rights reserved.)

When local recurrences arise within an irradiated region involving metastatic spinal cord compression, the dose limit to the spinal cord reduces the chance to re-treat the patient by 3D-conformational RT technique. The possibility of using volumetric modulated arc RT by RapidArc was evaluated for dose sparing at spinal cord level and preserving target coverage. A clinically satisfactory PTV coverage and dose sparing to the spinal cord were obtained. An upcoming trial on patients will provide clinical outcomes., (Copyright 2009 Elsevier Ireland Ltd. All rights reserved.)

Aims and Background: The hairy/enhancer of split (E(spl))-related family of transcription factors (HES and HEY) are established targets of the notch signaling pathway, which has been implicated in different developmental processes, tumor formation and the self-renewal of neural stem cells. We determined the expression of HEY1 in human malignant gliomas to investigate whether its expression might be related to prognosis., Methods: The expression of HEY1 was studied by in situ hybridization on 62 cases of glioblastoma. Patients were treated with surgery followed by chemotherapy and radiotherapy. We considered as end points of the study the overall survival time and progression-free interval. Correlations between HEY1 expression and tumor grade/patient overall survival and free interval before recurrence were analyzed using univariate analysis., Results: Based on the in situ hybridization results, HEY1 expression rate was reported as negative staining in 13 cases (20.6%), as weak staining in 11 cases (17.3%), as moderate staining in 21 cases (33.3%), and as strong staining in 17 cases. We considered in the analysis the cumulative expression of HEY1 at in situ hybridization (Hey Index) as negative in 13 cases and positive in 49 cases (77.78%). The overall survival (P = 0.002) and the free-interval (P = 0.012) were significantly longer in patients who were negative for HEY1 expression., Conclusions: Our data suggest that expression of HEY1 might be used as a marker to distinguish glioblastoma patients with a relatively good prognosis from those at high-risk, and that, in the future, HEY1 might represent a therapeutic target.

Purpose: A planning study was performed comparing volumetric modulated arcs, RapidArc (RA), fixed beam IMRT (IM), and conformal radiotherapy (CRT) with multiple static fields or short conformal arcs in a series of patients treated with hypofractionated stereotactic body radiation therapy (SBRT) for solitary or oligo-metastases from different tumors to abdominal lymph nodes., Methods and Materials: Fourteen patients were included in the study. Dose prescription was set to 45 Gy (mean dose to clinical target volume [CTV]) in six fractions of 7.5 Gy. Objectives for CTV and planning target volume (PTV) were as follows: Dose(min) >95%, Dose(max) <107%. For organs at risk the following objectives were used: Maximum dose to spine <18 Gy; V(15Gy) <35% for both kidneys, V(36Gy) <1% for duodenum, V(36Gy) <3% for stomach and small bowel, V(15Gy) <(total liver volume--700 cm(3)) for liver. Dose-volume histograms were evaluated to assess plan quality., Results: Planning objectives on CTV and PTV were achieved by all techniques. Use of RA improved PTV coverage (V(95%) = 90.2% +/- 5.2% for RA compared with 82.5% +/- 9.6% and 84.5% +/- 8.2% for CRT and IM, respectively). Most planning objectives for organs at risk were met by all techniques except for the duodenum, small bowel, and stomach, in which the CRT plans exceeded the dose/volume constraints in some patients. The MU/fraction values were as follows: 2186 +/- 211 for RA, 2583 +/- 699 for IM, and 1554 +/- 153 for CRT. Effective treatment time resulted as follows: 3.7 +/- 0.4 min for RA, 10.6 +/- 1.2 min for IM, and 6.3 +/- 0.5 min for CRT., Conclusions: Delivery of SBRT by RA showed improvements in conformal avoidance with respect to standard conformal irradiation. Delivery parameters confirmed logistical advantages of RA, particularly compared with IM.

Aim: To evaluate the efficacy of different radiotherapy treatment modalities in radioresistant brain metastasis., Patients and Methods: A retrospective analysis was conducted on 78 patients with brain metastases from melanoma, sarcoma, or renal cell carcinoma primary tumours who underwent radiosurgery (20 Gy) and/or hypofractionated stereotactic radiotherapy (6x4 Gy or 7x4 Gy) with or without whole-brain radiotherapy at our Center., Results: The actuarial median survival times for melanoma, renal cell carcinoma and sarcoma were 23, 22 and 7 months respectively, with a significant correlation to recursive partitioning analysis class., Discussion: Our results show that these treatments were effective both in symptom palliation and in improving survival, suggesting that although outcomes generally remained poor in this study population, it is possible and important to control intracranial brain metastases.

Background: Zoledronic acid belongs to the new generation of bisphosphonates with demonstrated clinical benefit for the treatment of bone metastases from different kinds of neoplasms. Hypocalcemia and serum creatinine elevation are expected adverse events during this therapy. The monitoring of serum calcium and creatinine is therefore recommended. The primary aim of this study was to establish the actual incidence of hypocalcemia and serum creatinine elevation during treatment with zoledronic acid. Skeletal-related events and side effects were also assessed., Methods: Serum creatinine and calcium levels were evaluated in 240 consecutive patients (83 males, 157 females; mean age, 62 years) with metastatic bone lesions from different solid tumors treated with zoledronic acid., Results: Overall, 93 of 240 patients (38.8%) developed hypocalcemia, which was grade (G)1 in 45 patients (48.4%), G2 in 37 patients (39.8%), G3 in 10 patients (10.8%), and G4 in one patient (1.1%). The median time to occurrence of hypocalcemia (any grade) was 2.3 months after the beginning of the treatment (range, 0-34.9 months). Increased serum creatinine was observed in 33 of 240 patients (13.7%), of whom 19 had G1 (57.6%), 11 had G2 (33.3%), and three had G3 (9.1%). The median time to serum creatinine increase (for any grade) was 4.7 months (range, 0-29.2 months)., Conclusions: Our analysis shows a high incidence of hypocalcemia and increased serum creatinine level during treatment with zoledronic acid. These results strongly support the need for accurate monitoring of plasma calcium and creatinine levels.

Objective: To describe the technique and the surgical outcome of laparoscopic resection of bulky lymph nodes before adjuvant treatment., Design: Prospective pilot study., Setting: Gynaecological oncology cancer centre., Population: From January 2006 to February 2008, 22 consecutive women presented with cervical cancer and bulky metastatic lymph nodes (>2 cm)., Methods: All women underwent resection of bulky lymph nodes by laparoscopy. A prospective record of the main surgical outcomes was performed., Main Outcome Measures: Safety and efficacy of laparoscopic resection of bulky lymph nodes, conversion to laparotomy, intra- and perioperative morbidity., Results: All the operations were completed by laparoscopy. Median operative time was 197 minutes (range 180-320). Median blood loss was 60 cc (range 10-100), two women experienced complications: one thermal injury of the sciatic root provoking postoperative leg palsy and one chylous ascites. The woman with the thermal injury has recovered most leg function with physiotherapy and the woman with chylous ascites recovered within 2 weeks, slightly delaying the adjuvant treatment. All women were discharged within 4 days from the operation (range 2-4). Pathology reports confirmed the presence of tumour metastases and the lymph nodes size. The adjuvant treatment started at a median time of 12 days (range 3-22)., Conclusion: Debulking of large pelvic and para-aortic lymph nodes was effectively accomplished by laparoscopy in all 22 women with 9% complication rate. The surgical outcome is similar to historical series on women operated on by laparotomy, with the advantage of a faster recovery and an early start of adjuvant treatment.

Historically, Radiation Therapy (RT) has played a minor role in the treatment of hepatocellular carcinoma, especially because of toxicity related to conventional techniques. However, high radiation doses can now be given safely by means of 3D-conformal techniques and other more specialized techniques. 3D-conformal RT, in which both target definition and treatment planning are based on three-dimensional image data sets, provided good local control in several series. As an evolution of cranial radiosurgery, stereotactic body radiation therapy (SBRT) is currently being employed as a new tool for the treatment of HCC, as it offers the opportunity of achieving radioablation for tumors up to 6 cm in diameter with a minimal risk of radiation induced liver disease. SBRT is distinguished by the fact that both planning and treatment are guided by reference to a system of external stereotactic coordinates. As a consequence, SBRT may succeed in minimizing geometric treatment uncertainties, thus allowing the delivery of high doses to the target, given in a small number of fractions. In several published series of SBRT for HCC, actuarial 5-year local control rates higher than 80% have been achieved In short, radiation therapy should be considered as a useful addition to the treatment spectrum of HCC.

Granular cell astrocytomas are uncommon tumors of the central nervous system (CNS) of which no cases have been documented in the spinal cord. This variant of glioma should not be confused with benign granular cell tumor which, although rare, has been well characterized in the spinal cord. We describe here the clinical, pathological, and radiological features of such an astrocytoma arising within the spinal cord at the dorsal level. A 48-year-old female was seen after about 1 year of dorsal pain and gradual spastic paraparesis. Magnetic resonance imaging (MRI) studies showed a 2-cm contrast-enhanced mass in the spinal cord at T6-T7, which had the appearance of an astrocytoma. At surgery, the tumor was found to be infiltrating a posterior column with no dural attachment. It was debulked and dissected. The histological diagnosis was astrocytoma with granular cell differentiation. In addition to documenting a unique example of intramedullary granular cell astrocytoma, we review the literature to investigate differences from other tumors with granular changes described in the spinal cord.

Background: Non-small cell lung cancer (NSCLC) is the leading cause of cancer death worldwide. Stereotactic body irradiation offers a non-invasive treatment modality for patients with early stage NSCLC who are not amenable to surgery or other invasive approaches because of their poor medical condition., Patients and Methods: Forty-three inoperable patients with NSCLC were treated with SBRT at our institution. A mean total dose of 30.5 Gy in 1-4 fractions was applied. The median follow-up duration was 14 months (range 6-36 months)., Results: The actuarial survival at two years was 53%: two patients died from cancer progression whereas a further 8 patients died from comorbidities. Acute toxicity was practically absent, with 7 (16.3%) patients suffering from grade 1 symptoms and two from (4.6%) grade II effects. At the time of this report, only 1 patient had grade II and 6 patients (13.9%) grade I chronic symptoms., Conclusion: Our results compare favourably with recently published studies and confirm that stereotactic radiotherapy has the potential to produce high local control rates with a low risk of lung toxicity in patients not amenable to curative resection. The low grade of side-effects is encouraging for shortening the treatment using a greater dose per fraction.

Primary brain high-grade gliomas, excluding glioblastoma are rare and heterogeneous tumors, showing different characteristic mutations and a better prognosis than glioblastomas. The addition of chemotherapy to the radiotherapy in the newly diagnosed disease has not been established yet. We treated 9 patients with newly diagnosed tumors with temozolomide at 75 mg/m2 for 7 days a week during standard radiotherapy, followed by six cycles at 200 mg/m2 on days 1-5 every 28 days. Fluorescence in situ hybridization for the 1 p/19 q loss was performed in seven out of the 9 patients. With a median follow-up of 15 months (range, 8-50), eight patients are alive and one died from disease progression. Four patients had disease progression at 7, 15, 14 and 13 months from the diagnosis. The 1 p/19 q loss was found in 5 patients; three have no evidence of disease, one had partial disease remission and one disease progression. Toxicities included one discitis requiring treatment withdrawal and specific antibiotic therapy, and one transient grade 3 psoriasiform reaction. Based on this small series of patients, the addition of temozolomide to radiotherapy may be recommended.

Gliomatosis cerebri of oligodendroglial origin is very unusual. In the present article we illustrate a case of this pathology, outlining his severity and suggesting it seems to be more aggressive than the astroglial type. We give a short focus about the diagnosis and the therapy of this neoplastic disease.

The authors' experience with a point matching algorithm for image registration belonging to a commercially available software package for conformal radiotherapy, is reported. The algorithm IFS (Image Fusion System) permits the registration of two image data-sets in two different manners: by use of a stereotactic localization frame, dedicated to brain studies, and by means of point markers that may be internal anatomical landmarks or external fiducials fixed on the patient skin. Position errors were obtained by evaluating the stereotactic coordinates of seven sources detectable by Magnetic Resonance Imaging (MRI) and Computed Tomography (CT), for the first method. The comparison of the geometric centers of cylindrical rods enclosed in a second phantom was employed to evaluate the registration accuracy of the second algorithm. The mean differences in source identification between CT and MRI images are inferior to 1 mm with both techniques, if MRI distortion phenomenon and patient movements are excluded. The software utility of the IFS algorithm to draw, after fusion, a target ROI that is the synthesis of the two information modalities undergoing registration may be a useful tool for the optimization of a radiotherapy treatment planning.

Radiographically occult lung carcinoma has a very good prognosis after complete surgical resection. In medically inoperable patients three-dimensional conformal radiation therapy cannot be performed, as computed tomography scan images fail to localize the disease. Presented here is an original technique of marking radiographically occult tumors by fiberoptic bronchoscopy, applied on four patients. No short-term complications were recorded. All the patients are alive, with no evidence of disease, after a mean follow-up of 15 months.

Purpose: A problem for clinicians is to mentally integrate information from multiple diagnostic sources, such as computed tomography (CT), magnetic resonance (MR), and single photon emission computed tomography (SPECT), whose images give anatomic and metabolic information., Methods and Materials: To combine this different imaging procedure information, and to overlay correspondent slices, we used commercially available software packages (SRS PLATO and IFS). The algorithms utilize a fiducial-based coordinate system (or frame) with 3 N-shaped markers, which allows coordinate transformation of a clinical examination data set (9 spots for each transaxial section) to a stereotactic coordinate system. The N-shaped markers were filled with fluids visible in each modality (gadolinium for MR, calcium chloride for CT, and 99mTc for SPECT). The frame is relocatable, in the different acquisition modalities, by means of a head holder to which a face mask is fixed so as to immobilize the patient. Position errors due to the algorithms were obtained by evaluating the stereotactic coordinates of five sources detectable in each modality., Results: SPECT and MR position errors due to the algorithms were evaluated with respect to CT: deltax was < or = 0.9 mm for MR and < or = 1.4 mm for SPECT, deltay was < or = 1 mm and < or = 3 mm for MR and SPECT, respectively. Maximal differences in distance between estimated and actual fiducial centers (geometric mismatch) were in the order of the pixel size (0.8 mm for CT, 1.4 mm for MR, and 1.8 mm for SPECT). In an attempt to distinguish necrosis from residual disease, the image fusion protocol was studied in 35 primary or metastatic brain tumor patients., Conclusions: The image fusion technique has a good degree of accuracy as well as the potential to improve the specificity of tissue identification and the precision of the subsequent treatment planning.

The characteristics of a prototype computer-assisted dynamic multileaf collimator (DMLC), specifically designed for small-field conformal radiotherapy, were evaluated at the Istituto Nazionale Tumori of Milan. The collimating device consists of two opposing banks of 16 pairs of 8 cm thick, 3.6 mm wide tungsten leaves and allows shaping of a radiation field up to a size of 10 x 10 cm2 at the isocentre. The screening thickness of each leaf is 6.25 mm at the accelerator gantry isocentre. The leaves have a trapezoidal cross section and move along an arched path, thus providing a 'double focused' collimation system. The DMLC was installed on the head of a Varian Clinac 2100C linear accelerator. Mechanical and dosimetric evaluations were performed to test the stability of the mechanical isocentre and to determine leaf leakage, penumbra width, accuracy of leaf positions and uniformity of leaf speed. Displacement of the mechanical isocentre was less than 1 mm at all gantry angles. Standard radiographic films exposed to 6 MV x-ray radiation were used for dosimetric evaluations. Leakage between leaves was less than 2.5%, and leakage through abutted leaves was less than 5.5%. The penumbra width between 20% and 80% isodose at different positions of leaf banks was 2.7 mm in the direction of the leaf motion and 3.1 mm along the side of the leaf with a standard deviation of 0.2 mm in both directions. Accuracy in the positioning of the leaf was 0.3 mm, whereas the maximum repositioning error was less than 0.2 mm. Finally, during movement of the leaves at the maximum speed of 0.5 mm s(-1), the standard deviation of the leaf positioning error was 0.2 mm, proving an accurate uniformity of leaf speed.

The small X-ray beam profiles produced by linear accelerators and used in stereotactic radiosurgery were studied. Circular focusing and not-focusing beams outlined by additional collimators (diameter ranging 10 to 30 mm) and square field outlined by the jaws (field size 10 to 30 mm) were measured. 6 and 18-MV X-ray beams from a dual energy accelerator and 6 and 15-MV X-ray beams produced by 2 single-energy accelerators were used. Measurements were carried out with Kodak X Omat V films in a perspex phantom in the same conditions for all the fields. To study the profile characteristics we introduced the V80/V20 = (R80/R20)3 ratio where R80 and R20 are respectively the mean distance of the 80% and 20% isodose lines from the beams axis. Measurement results show that 6-MV X-ray beams have a higher V80/V20 ratio than the ones obtained with the other energies. There is no significant difference between the beams produced with focused collimators and those produced with not-focused collimators. Square fields outlined by the jaws have a V80/V20 ratio greatly dependent on the accelerator used. This ratio is generally worse than the ones obtained with beams outlined by additional collimators.

In this work we first analyzed the reliability of materials supplied by the main firms, which must be considered when defining the lesion and planning target volume. The coordinates of specific target landmarks, i.e., bone, calcium deposition or catheters, on baseline CT scans were compared with those measured on control scans. Since the PLATO-SRS system yields 3 coordinates for each target, the final error is calculated by the evaluation of the shift of the different coordinates. The mean error reported for the first material (ORFIT) was 5 mm (13/23 patients). This margin of error is too high and was considered unacceptable; a second material was then tested. The latter, which is not recyclable and softens at higher temperatures, exhibited a mean error of 2.5 mm (10/23 patients), which allows daily repositioning of greater reliability. Treatment was repeated in 4/20 arcs in all, which number depended mainly on fraction size. Correct lesion location and patient positioning were allowed by laser landmarks on the mask made directly on the treatment couch. The laser too was checked before each treatment session, i.e., preferentially at the end of an ordinary working day.