Frameless linac-based stereotactic radiosurgery (SRS) for brain metastases: analysis of patient repositioning using a mask fixation system and clinical outcomes

<p>Abstract</p> <p>Purpose</p> <p>To assess the accuracy of patient repositioning and clinical outcomes of frameless stereotactic radiosurgery (SRS) for brain metastases using a stereotactic mask fixation system.</p> <p>Patients and Methods</p> <p>One hundred two patients treated consecutively with frameless SRS as primary treatment at University of Rome Sapienza Sant'Andrea Hospital between October 2008 and April 2010 and followed prospectively were involved in the study. A commercial stereotactic mask fixation system (BrainLab) was used for patient immobilization. A computerized tomography (CT) scan obtained immediately before SRS was used to evaluate the accuracy of patient repositioning in the mask by comparing the isocenter position to the isocenter position established in the planning CT. Deviations of isocenter coordinates in each direction and 3D displacement were calculated. Overall survival, brain control, and local control were estimated using the Kaplan-Meier method calculated from the time of SRS.</p> <p>Results</p> <p>The mean measured isocenter displacements were 0.12 mm (SD 0.35 mm) in the lateral direction, 0.2 mm (SD 0.4 mm) in the anteroposterior, and 0.4 mm (SD 0.6 mm) in craniocaudal direction. The maximum displacement of 2.1 mm was seen in craniocaudal direction. The mean 3D displacement was 0.5 mm (SD 0.7 mm), being maximum 2.9 mm. The median survival was 15.5 months, and 1-year and 2-year survival rates were 58% and 24%, respectively. Nine patients recurred locally after SRS, with 1-year and 2-year local control rates of 91% and 82%, respectively. Stable extracranial disease (P = 0.001) and KPS > 70 (P = 0.01) were independent predictors of survival.</p> <p>Conclusions</p> <p>Frameless SRS is an effective treatment in the management of patients with brain metastases. The presented non-invasive mask-based fixation stereotactic system is associated with a high degree of patient repositioning accuracy; however, a careful evaluation is essential since occasional errors up to 3 mm may occur.</p

Conformal radiotherapy in head and neck tumors: increased tumor control and decreased morbidity?

Conformal radiotherapy in head and neck tumors is only at its premise. Its offers attractive prospect to decrease late morbidity and increase loco-regional control probability not only in patients with primary treatment but also in patients with recurrent disease previously fully irradiated. Such modality however, requires complex infrastructure and qualified staff. Comprehensive evaluation are thus needed to determine the patient population that will benefit the most from this new promising technique before its use can be generalized

[Acneiform eruptions induced by cetuximab.]

introduction. Many drugs may induce acneiform eruptions: vitamine B12, corticosteroids, androgens, lithium, tuberculostatics, halogens, some antidepressants, anticonvulsives and immunosuppressors. Many cases of acneiform eruptions can be observed following treatment with cetuximab, a drug used for solid cancers at advanced stages in experimental protocols. Case reports. Case 1. A 56 year-old woman, suffering from a colorectal cancer, developed a sudden acneiform eruption after 6 cures of cetuximab, at a one-week interval. She was treated with bisoprolol hemifumarate, sodium levothyroxin, cyproterone acetate and estradiol valerate. Clinical examination revealed inflammatory and follicular papulopustules localized on the face and upper chest. Comedos were absent. Itching sensations were discrete. Histopathological examination of a papulopustule revealed a folliculitis with polymorphonuclear neutrophils. PAS staining did not reveal the presence of bacteria or yeasts. Bacterial and fungal cultures were negative. Lesions faded in approximately 2 weeks following minocycline treatment (100 mg/day). Case 2. A 65 year-old man, treated by cetuximab for a colorectal adenocarcinoma, suddenly developped follicular inflammatory papulopustules on the face, trunk and extensor surfaces of both arms, after 3 weeks of treatment. Itching was discrete. Comedos were absent. Histopathology revealed the presence of a folliculitis with polymorphonuclear neutrophils. Bacteriology and mycology were negative. Lesions were partly controlled by administration of minocycline (100 mg/day) but worsened again in the days following each cure of cetuximab. Discussion. Cetuximab is a monoclonal antibody binding to the epidermal-growth-factor-receptor. It is used in the treatment of solid cancers at advanced stages. Both case reports share some similarities: the development of follicular inflammatory papulopustules distributed on the face and trunk typical, of acneiform drug eruptions. Itching is discrete. Comedos are absent. Quick onset of lesions is the rule. Cetuximab can be added to the list of drugs responsible for acneiform eruption

Frameless fractionated stereotactic radiation therapy of intracranial lesions: impact of cone beam CT based setup correction on dose distribution

Background The purpose of this study was to evaluate the impact of Cone Beam CT (CBCT) based setup correction on total dose distributions in fractionated frameless stereotactic radiation therapy of intracranial lesions. Methods Ten patients with intracranial lesions treated with 30 Gy in 6 fractions were included in this study. Treatment planning was performed with Oncentra® for a SynergyS® (Elekta Ltd, Crawley, UK) linear accelerator with XVI® Cone Beam CT, and HexaPOD™ couch top. Patients were immobilized by thermoplastic masks (BrainLab, Reuther). After initial patient setup with respect to lasers, a CBCT study was acquired and registered to the planning CT (PL-CT) study. Patient positioning was corrected according to the correction values (translational, rotational) calculated by the XVI® system. Afterwards a second CBCT study was acquired and registered to the PL-CT to confirm the accuracy of the corrections. An in-house developed software was used for rigid transformation of the PL-CT to the CBCT geometry, and dose calculations for each fraction were performed on the transformed CT. The total dose distribution was achieved by back-transformation and summation of the dose distributions of each fraction. Dose distributions based on PL-CT, CBCT (laser set-up), and final CBCT were compared to assess the influence of setup inaccuracies. Results The mean displacement vector, calculated over all treatments, was reduced from (4.3 ± 1.3) mm for laser based setup to (0.5 ± 0.2) mm if CBCT corrections were applied. The mean rotational errors around the medial-lateral, superior-inferior, anterior-posterior axis were reduced from (−0.1 ± 1.4)°, (0.1 ± 1.2)° and (−0.2 ± 1.0)°, to (0.04 ± 0.4)°, (0.01 ± 0.4)° and (0.02 ± 0.3)°. As a consequence the mean deviation between planned and delivered dose in the planning target volume (PTV) could be reduced from 12.3% to 0.4% for D95 and from 5.9% to 0.1% for Dav. Maximum deviation was reduced from 31.8% to 0.8% for D95, and from 20.4% to 0.1% for Dav. Conclusion Real dose distributions differ substantially from planned dose distributions, if setup is performed according to lasers only. Thermoplasic masks combined with a daily CBCT enabled a sufficient accuracy in dose distribution