Omer Sager's research while affiliated with Ankara University Faculty of Sport Sciences and other places

Aims and background: The aim of the study was to examine the feasibility of non-invasive image-guided radiosurgery to improve patient comfort and quality of life in stereotactic radiosurgery planning and treatment of patients with brain metastasis. Precise immobilization is a rule of thumb for stereotactic radiosurgery. Non-invasive immobilization techniques have the potential of improved quality of life compared with invasive procedures. Methods and study design: A total of 92 lesions from 42 patients with brain metastasis were included in the study. After immobilization with a thermoplastic mask and a bite-block unlike the invasive frame-based procedure, planning computed tomography images were acquired and fused with magnetic resonance images. After contouring, intensity-modulated stereotactic radiosurgery (IM-SRS) planning was done, and the patients were re-immobilized on the treatment couch for the therapy procedures. While patients were on the treatment couch, kilovoltage-cone beam computed tomography images were acquired to determine setup errors and achieve on-line correction and then repeated after on-line correction to confirm precise tumor localization. The patients then underwent single-fraction definitive treatment. Results: For the 92 lesions treated, mean ± SD values of translational setup corrections in X (lateral), Y (longitudinal), and Z (vertical) dimensions were 0.7 ± 0.7 mm, 0.8 ± 0.7 mm, and 0.6 ± 0.5 mm, and rotational set-up corrections were 0.5 ± 1.1°, 0.06 ± 1.1°, and -0.1 ± 1.1° in X (pitch), Y (roll), and Z (yaw), respectively. The mean three-dimensional correction vector was 1.2 ± 1.1 mm. Conclusions: Non-invasive image-guided radiosurgery for brain metastasis is feasible, and the non-invasive treatment approach can be routinely used in clinical practice to improve patients' quality of life.

Aims and background The aim of the study was to examine the feasibility of non-invasive image-guided radiosurgery to improve patient comfort and quality of life in stereotactic radiosurgery planning and treatment of patients with brain metastasis. Precise immobilization is a rule of thumb for stereotactic radiosurgery. Non-invasive immobilization techniques have the potential of improved quality of life compared with invasive procedures. Methods and study design A total of 92 lesions from 42 patients with brain metastasis were included in the study. After immobilization with a thermoplastic mask and a bite-block unlike the invasive frame-based procedure, planning computed tomography images were acquired and fused with magnetic resonance images. After contouring, intensity-modulated stereotactic radiosurgery (IM-SRS) planning was done, and the patients were re-immobilized on the treatment couch for the therapy procedures. While patients were on the treatment couch, kilovoltage-cone beam computed tomography images were acquired to determine setup errors and achieve on-line correction and then repeated after on-line correction to confirm precise tumor localization. The patients then underwent single-fraction definitive treatment. Results For the 92 lesions treated, mean ± SD values of translational setup corrections in X (lateral), Y (longitudinal), and Z (vertical) dimensions were 0.7 ± 0.7 mm, 0.8 ± 0.7 mm, and 0.6 ± 0.5 mm, and rotational set-up corrections were 0.5 ± 1.1°, 0.06 ± 1.1°, and -0.1 ± 1.1° in X (pitch), Y (roll), and Z (yaw), respectively. The mean three-dimensional correction vector was 1.2 ± 1.1 mm. Conclusions Non-invasive image-guided radiosurgery for brain metastasis is feasible, and the non-invasive treatment approach can be routinely used in clinical practice to improve patientís quality of life.

The purpose of this study is to evaluate the effect of Active Breathing Control-moderate deep inspiration breath-hold (ABC-mDIBH) on tumor motion and critical organ doses in non-small cell lung cancer (NSCLC) radiotherapy. 23 patients with locally advanced NSCLC were included in the study. All patients were scanned at free breathing and ABC-mDIBH for radiation treatment planning. 3 separate treatment plans were generated for each patient including one plan with ABC-mDIBH and uniform margins, one plan with free breathing and uniform margins, and one plan with free breathing and 3-dimensional non-uniform margins determined by Cone Beam Computed Tomography (CBCT) and XVI Motion View (X-ray Volume Imaging, Elekta, UK). Critical organ dose-volumes and physical lung parameters were comparatively evaluated on 3 separate dose-volume histograms of each patient acquired from planning software. Individual tumor motion of each patient with and without ABC-mDIBH was documented and compared. Use of ABC-mDIBH resulted in statistically significant improvement in physical lung parameters of V20 (lung volume receiving ≥ 20 Gy) and mean lung dose (MLD) which are predictors of radiation pneumonitis (p<0.001). Reduction in spinal cord dose and tumor motion with ABC-mDIBH was also statistically significant (p<0.001). ABC-mDIBH increases normal lung tissue sparing in definitive NSCLC radiotherapy by improving physical lung parameters along with spinal cord dose reduction through exact tumor immobilization. The incorporation of ABC-mDIBH into NSCLC radiotherapy may have implications for potential margin reduction and dose escalation to improve treatment outcomes.

The aim of this monoinstitutional study is to evaluate the efficiency of stereotactic radiosurgery (SRS) in the management of arteriovenous malformations (AVM). Between June 1998 and July 2011, 51 patients with AVM were treated with linear accelerator-based SRS at our department. All patients were preevaluated for AVM size, location, neurological status, previous history of hemorrhage and Spetzler-Martin grading. Treated patients then underwent follow-up to evaluate obliteration and clinical status. Median followup time was 32 months (range; 20-93 months). Spetzler-Martin grade I-II and AVM sizes below 3 cm were associated with increased obliteration rate (p=0.01). The annual hemorrhage risk was 1.9%. No patients experienced deterioration of neurological status at follow-up. LINAC-based SRS is a safe and effective treatment modality in the management of cerebral AVMs. SRS comprises an effective alternative to surgery for the treatment of particularly small AVMs inaccessible with surgery.

The aim of this study is to evaluate the dosimetric impact of utilizing Active Breathing Control-moderate deep inspiration breath-hold (ABC-mDIBH) technique in early-stage left-sided breast cancer radiotherapy (RT). Twenty-five patients with left-sided early-stage breast cancer undergoing breast-conserving surgery referred to our department for adjuvant radiotherapy between October 2010 and October 2011 were scanned with computed tomography (CT)-simulator at free breathing (FB) and ABC-mDIBH for radiation treatment planning. Two separate treatment plans were generated for each patient, with and without ABC-mDIBH to comparatively evaluate dose-volume parameters of both plans. Dose-volume parameters of lung, heart, left anterior descending artery (LAD), contralateral breast and spinal cord were significantly reduced with ABC-mDIBH compared to free breathing (p< 0.001). The use of ABC-mDIBH technique in the practice of early-stage left-sided breast cancer radiotherapy improves critical organ sparing with the dosimetrically-confirmed potential to decrease treatment-related morbidity and mortality. This respiratory management strategy is a promising tool that may be routinely used for the treatment of patients with early-stage left-sided breast cancer.

The aim of this study was to evaluate the efficiency of stereotactic radiosurgery (SRS) in the management of pituitary adenomas. Between June 1998 and July 2011, 57 patients with pituitary adenomas were treated using SRS at our department. All patients underwent high-precision single dose SRS using a linear accelerator with 6-MV photons. Median follow-up time was 31.5 (3-92) months. Median age was 40 years (range: 19-57 years). Radiological tumor growth control was achieved in 48 patients (84.2%) (a decrease in tumor size in 25 patients and no change in tumor size in 23 patients). 13 patients with functioning adenomas had available biochemical follow-up and biochemical complete response was achieved in 8 (61.5%) of these 13 patients. Treatment of pituitary adenomas using LINAC-based single dose SRS is safe and effective in improving local tumor and biochemical control.

Management of patients with recurrent glioblastoma (GB) comprises a therapeutic challenge in neurooncology owing to the aggressive nature of the disease with poor local control despite a combined modality treatment. The majority of cases recur within the high-dose radiotherapy field limiting the use of conventional techniques for re-irradiation due to potential toxicity. Stereotactic radiosurgery (SRS) offers a viable noninvasive therapeutic option in palliative treatment of recurrent GB as a sophisticated modality with improved setup accuracy allowing the administration of high-dose, precise radiotherapy. The aim of the study was to, we report our experience with single-dose linear accelerator (LINAC) based SRS in the management of patients with recurrent GB. Between 1998 and 2010 a total of 19 patients with recurrent GB were treated using single-dose LINAC-based SRS. The median age was 47 (23-65) years at primary diagnosis. Karnofsky Performance Score was > or = 70 for all the patients. The median planning target volume (PTV) was 13 (7-19) cc. The median marginal dose was 16 (10-19) Gy prescribed to the 80%-95% isodose line encompassing the planning target volume. The median follow-up time was 13 (2-59) months. The median survival was 21 months and 9.3 months from the initial GB diagnosis and from SRS, respectively. The median progression-free survival from SRS was 5.7 months. All the patients tolerated radiosurgical treatment well without any Common Toxicity Criteria (CTC) grade > 2 acute side effects. Single-dose LINAC-based SRS is a safe and well- tolerated palliative therapeutic option in the management of patients with recurrent GB.