Automated treatment planning systems are available for linear accelerator (LINAC) based single and more isocenter multitarget stereotactic radiosurgery (SRS) of brain metastases. HyperArc Volumetric Modulated Arc Therapy (HA-VMAT) is a relatively new isocentric Volumetric Modulated Arc Therapy (VMAT) technique developed specifically for non-coplanar, multileaf collimator (MLC)-based stereotactic radiotherapy with automatic treatment optimization and dose delivery. The HA-VMAT planning approach was developed to accom-modate dosing procedures for brain metastases stereotactic radiosurgery. In this study, it was aimed to compare the dosimetric parameters of treatment plans created with single and multi-isocenter retrospectively VMAT and HA-VMAT techniques in patients with lung cancer and multiple brain metastases (4-7) who received single and multi-fraction stereotactic radiosurgery (SRS). Using VMAT and HA-VMAT techniques, two separate treatment plans were created for each case, and tumor target coverage (homogeneity index (HI); conformity index (CI); gradient index (GI)) and organ at risk (OAR) were evaluated dosimetrically. Physical properties and Monitor unit (MU) values of both treatment approaches were compared. Treatment plans were created for study purposes and patients were not treated with these plans. In the study, HI (p = 0.000), CI (p = 0.000) and GI (p = 0.002) values calculated with the HA-VMAT technique are superior to the VMAT technique. Medium-low dose spreads (V4Gy-V16Gy) were significantly reduced in HA-VMAT plans compared to plans with VMAT. HA-VMAT plans result in lower MU than VMAT plans. HA-VMAT planning has significantly less radiation necrosis indicator (V8Gy-V16Gy) compared to VMAT plans. However, there are few studies investigating the ability of the HA-VMAT technique to create high-quality treatment plans for extracranial lesions. HA-VMAT may constitute one of the new options for SRS dose delivery for both single target and multiple targets.

Objective: This study aimed to evaluate the diagnostic accuracy of preoperative 18F-fluorodeoxy- glucose (FDG) positron emission tomography/computed tomography (PET/CT) metabolic parameters for the prediction of risk factors and detection of lymph node metastasis (LNM) in patients with endometrial cancer. Material and Methods: This study included 26 patients with endometrioid carcinoma who underwent preoperative PET/CT and treated with adjuvant local radiotherapy. The maximum standard uptake value of the tumor (SUVmax-T), SUVmax of the pelvic and/or para-aortic LNs, metabolic tumor volume (MTV), and tumor lesion glycolysis (TLG) with cut-off values of 30-40% were calculated. International Federation of Gynecology and Obstetrics stages 3 and 4, highgrade disease, lymphovascular invasion (LVI), cervical involvement (CI), and myometrial invasion (MI) ≥50% were established as high-risk features. Disease-free survival and overall survival were analyzed in comparison with 18F-FDG PET/CT parameters. Results: SUVmax-T was only associated with tumor diameter (p=0.01). It was not correlated with MI, high-grade disease, CI, or LNM. With SUVmax-P ≥2.81 as a cut-off value, the sensitivity, specificity, and accuracy in the detection of LNM were high (90%, 83.3%, 71.4%, respectively). For LNM, the mean MTV-30 (p=0.021), TLG-30 (p=0.030), and SUVmax-P (p=0.009) were significant predictors. According to the regression analysis, MTV-40 (p=0.043) was an independent predictor of LNM, and LVI (p=0.037) was the only significant predictor of MI. MTV-30 was a significant predictor of CI (p=0.04). Conclusion: SUVmax-P, MTV, and TLG cut-off values, to predict LN metastases, increase diagnostic accuracy for EC.

Objective: This study aimed to compare the effectiveness and to plan parameters of the Monte Carlo (MC)-based volumetric arc radiation therapy (VMAT) plan, which was devised using the equivalent uniform dose concept for endometrial cancers, to the dose volume (DV)-based helical tomotherapy (HT) plan. Additionally, both approaches were evaluated in terms of tumor control probability (TCP) and normal tissue complication probability (NTCP). Material and Methods: The study comprised ten patients diagnosed with endometrial cancer, and treated with radixact tomotherapy unit. The target volumes (PTV) and organs at risks (OARs) were contoured through an accuracy planning system. All plans were devised to receive a total of 50.4 Gy in 28 fractions with the fractional dose to be 1.8 Gy for patient treatment. Monaco 5.51 planning system hosted all planning computed tomography images to devise MC-based VMAT plans. Both plans were analyzed in terms of TCP and NTCP. Results: DV-HT plans (CI: 1.1) came with the more conformal plan while the difference between both approaches was <1% for HI. Based on the results of the analyses, no statistical difference between DV-HT plan of MC-VMAT for the dose values of 2%, 30%, and 40% of rectal volume (p>0.05) was observed. The same results were obtained for the dose values of 2% and 30% of the bladder volume (p>0.05). The D5% of the femoral heads were 7 Gy which is < MC-VMAT plan compared to DV-HT plan. The NTCP values of all OARs were <1% in both approaches. Conclusion: Statistically, similar results were obtained in MC-VMAT and DV-HT plans for OAR's doses when the treatment dose was given to PTV. Both approaches had no significant difference for NTCP statistically; however, the possibility of bone marrow complications to be investigated as well was concluded, so as to evaluate hematological toxicity.

Objectives Cervical cancer is one of the main causes of cancer death worldwide. Fluorine-18-fluorodeoxyglucose (18F-FDG) PET/computed tomography (PET/CT) has been playing an increasingly important role in staging and monitoring treatment response in the disease. In the current study, we investigated metabolic 18F-FDG PET/CT parameters among patients with locally advanced squamous cell cervical cancer treated with concurrent chemoradiotherapy for predicting disease-free survival (DFS). Patients and methods Forty-four patients with biopsy-proven locally advanced squamous cell cervical cancer were included in the study. Pretreatment and after treatment 18F-FDG PET/CT metabolic parameters [metabolic tumor volume, tumor lesion glycolysis, maximum standard uptake value (SUVmax)] for the primary tumor area and/or pelvic/para-aortic lymph nodes and also accompanying distant metastases were analyzed. Treatment response was divided into four groups according to a post-treatment 18F-FDG PET/CT scan. Results For all patients, the 3-year DFS was 79%. Pretreatment primary tumor SUVmax and tumor lesion glycolysis, pelvic lymph node SUVmax, and pretreatment para-aortic lymph node SUVmax were significant prognostic factors for DFS with different cut-off values. In contrast, for metabolic tumor volume-T1, there was no statistical significance for DFS. Conclusion 18F-FDG PET/CT cut-off values may help clinicians with their treatment planning and follow-up in locally advanced squamous cell cervical cancer patients.

INTRODUCTION:The current study aimed to investigate the diagnostic performance of metabolic parameters of pre-treatment F-18 fluorodeoxyglucose PET/computed tomography for predicting axillary lymph node metastases, distant metastases, and overall survival rates in breast cancer patients.MATERIALS AND METHODS:One hundred thirteen breast cancer patients who underwent pre-treatment F18 [FDG] PET-computed tomography with biopsy-proven axillary lymph node status were included in the current study. In pre-treatment F18 [FDG] PET-computed tomography for primary tumour area maximum standard uptake value, metabolic tumour volume, tumour lesion glycolysis, tumour diameter and for axillary lymph nodes maximum standard uptake value-LN were recorded. Also if distant metastatic sites were observed they were verified.RESULTS:The median follow-up period was 43.8 months. Five-year overall survival was 98% vs. 56% in patients with tumour diameter < vs. ≥22 mm, 93% vs. 50% in patients with maximum standard uptake value-T < vs. ≥6.7, 71% vs. 70% in patients with metabolic tumour volume < vs. ≥8.31cm, 94% vs. 49% in patients with maximum standard uptake value-LN < vs. ≥1.6, 98% vs. 48% in patients with tumour lesion glycolysis < vs. ≥19 084 g/ml × cm, 90% vs. 30% in patients with negative or positive distant metastases in initial PET/computed tomography, respectively. Maximum standard uptake value-LN with a cut-off level of <1.6 and <5.7 had high sensitivity and specificity for predicting axillary lymph node and systemic metastasis, respectively. Additionally, tumour lesion glycolysis was the strongest independent prognostic factor for overall survival.CONCLUSION:Our data shows that the combination of pre-treatment tumour lesion glycolysis and maximum standard uptake value-LN could improve risk stratification among breast cancer patients.