Current practices of craniospinal irradiation techniques in Turkey: a comprehensive dosimetric analysis.

OBJECTIVE: This study evaluates various craniospinal irradiation (CSI) techniques used in Turkish centers to understand their advantages, disadvantages and overall effectiveness, with a focus on enhancing dose distribution. METHODS: Anonymized CT scans of adult and pediatric patients, alongside target volumes and organ-at-risk (OAR) structures, were shared with 25 local radiotherapy centers. They were tasked to develop optimal treatment plans delivering 36 Gy in 20 fractions with 95% PTV coverage, while minimizing OAR exposure. The same CT data was sent to a US proton therapy center for comparison. Various planning systems and treatment techniques (3D conformal RT, IMRT, VMAT, tomotherapy) were utilized. Elekta Proknow software was used to analyze parameters, assess dose distributions, mean doses, conformity index (CI), and homogeneity index (HI) for both target volumes and OARs. Comparisons were made against proton therapy. RESULTS: All techniques consistently achieved excellent PTV coverage (V95 > 98%) for both adult and pediatric patients. Tomotherapy closely approached ideal Dmean doses for all PTVs, while 3D-CRT had higher Dmean for PTV_brain. Tomotherapy excelled in CI and HI for PTVs. IMRT resulted in lower pediatric heart, kidney, parotid, and eye doses, while 3D-CRT achieved the lowest adult lung doses. Tomotherapy approached proton therapy doses for adult kidneys and thyroid, while IMRT excelled for adult heart, kidney, parotid, esophagus, and eyes. CONCLUSION: Modern radiotherapy techniques offer improved target coverage and OAR protection. However, 3D techniques are continued to be used for CSI. Notably, proton therapy stands out as the most efficient approach, closely followed by Tomotherapy in terms of achieving superior target coverage and OAR protection.

Preliminary findings of German-sourced ONC201 treatment in H3K27 altered pediatric pontine diffuse midline gliomas.

PURPOSE: H3K27 altered pediatric pontine diffuse midline gliomas (pDMG) have a poor prognosis, and conventional treatments offer limited benefits. However, recent advancements in molecular evaluations and targeted therapies have shown promise. The aim of this retrospective analysis was to evaluate the effectiveness of German-sourced ONC201, a selective antagonist of dopamine receptor DRD2, for the treatment of pediatric H3K27 altered pDMGs. METHODS: Pediatric patients with H3K27 altered pDMG treated between January 2016 and July 2022 were included in this retrospective analysis. Tissue samples were acquired from all patients via stereotactic biopsy for immunohistochemistry and molecular profiling. All patients received radiation treatment with concurrent temozolomide, and those who could acquire GsONC201 received it as a single agent until progression. Patients who could not obtain GsONC201 received other chemotherapy protocols. RESULTS: Among 27 patients with a median age of 5.6 years old (range 3.4-17.9), 18 received GsONC201. During the follow-up period, 16 patients (59.3%) had progression, although not statistically significant, the incidence of progression tended to be lower in the GsONC201 group. The median overall survival (OS) of the GsONC201 group was considerably longer than of the non-GsONC201 group (19.9 vs. 10.9 months). Only two patients receiving GsONC201 experienced fatigue as a side effect. 4 out of 18 patients in the GsONC201 group underwent reirradiation after progression. CONCLUSION: In conclusion, this study suggests that GsONC201 may improve OS in pediatric H3K27-altered pDMG patients without significant side effects. However, caution is warranted due to retrospective design and biases, highlighting the need for further randomized clinical studies to validate these findings.

An analysis of phase angle and standard phase angle cut-off values and their association with survival in head and neck cancer patients undergoing radiotherapy.

OBJECTIVE: The objective of this study is to identify the cutoff values for phase angle (PA) and standard phase angle (SPA) parameters, as determined by bioelectrical impedance analysis (BIA), for predicting malnutrition and investigating their association with overall survival in head and neck cancer (HNC) patients undergoing radiotherapy. METHODS: In this study, nutritional assessment and follow-up of HNC patients undergoing radiotherapy (RT) between November 2017 and September 2022 were assessed. Nutritional assessment, body composition (BC), and PA results obtained from BIA (Tanita MC-980) were retrospectively evaluated. Statistical Package for Social Sciences (SPSS) version 25.0 (IBM Corp., Armonk, NY, USA) was used for statistical analysis. The results were evaluated at a confidence interval of 95% and a significance level of p ≤ 0.05. RESULTS: A total of 53 patients, including 37 (70%) men and 16 (30%) women, with a median age of 60 (23-87 years) were included. The median follow-up time was 51 (range 24-59) months. The mean PA of the patients was calculated as 4.99° (±0.92, 95% CI: 4.74-5.25). The PA of patients with malnutrition (4.66° ± 0.87) was lower than that of well-nourished patients (5.71° ± 0.56) (p < 0.001). As a result of the ROC analysis based on this finding, the ideal PA cut-off point for determining the presence of malnutrition was found to be 5.65, with a sensitivity of 85%, specificity of 79%, accuracy of 83%, and a model discrimination power of excellent level (AUC: 85%, p < 0.001). The median overall survival time of the patients was calculated as 51 months (24-59 months). The mortality rate during the follow-up period was 13%, while the 1-, 3-, and 5-year overall survival rates of the patients were 96.1%, 89.3%, and 86.8%, respectively. Patients with SPA values less than -1.65 had a 5-year overall survival rate of 77.4%, while those with SPA values greater than or equal to -1.65 had a 5-year overall survival rate of 100% (p = 0.030) CONCLUSION: Our study recommends using PA and SPA as standard criteria for detecting malnutrition in HNC patients undergoing RT, with cut-off points of 5.65 and -1.65 respectively, to prevent treatment interruptions and improve outcomes. Further research is needed to validate the SPA cut-off value and its relationship with clinical outcomes, as SPA may be a more effective predictor of malnutrition and overall survival than PA alone.

Magnetic Resonance Imaging-Guided Stereotactic Body Radiation Therapy for Medically Inoperable Endometrial Cancer.

Endometrial carcinoma is the most frequently diagnosed gynecological cancer among women aged 50 and older in developed countries. In patients who are not amenable to surgery, radiotherapy results in improved survival with acceptable adverse effect profiles. Definitive stereotactic body radiotherapy (SBRT) as a monotherapy remains an unaddressed concept in the literature. Here, we present the case of an 86-year-old woman who was diagnosed with early-stage endometrial carcinoma and was medically inoperable due to cardiac comorbidities. She was treated with magnetic resonance imaging-guided online adaptive radiotherapy-based SBRT. She tolerated the treatment well, with mild increased vaginal discharge. Complete metabolic and radiological responses were obtained. She continues to be disease free in the first year of treatment with no long-term side effects. Our protocol presents promising results with a safe toxicity profile for inoperable early-stage endometrial cancer. Future studies are warranted in light of the current knowledge.

Dosimetric evaluation of VMAT and helical tomotherapy techniques comparing conventional volumes with clinical target volumes based on new ESTRO ACROP post-mastectomy with immediate implant reconstruction contouring guidelines.

BACKGROUND: The ESTRO-ACROP Consensus Guideline (EACG) recommends implant excluded clinical target volume (CTVp) definitions for post-mastectomy radiation therapy after implant-based immediate breast reconstruction (IBR). The purpose of this study is to investigate the effectiveness of Helical Tomotherapy (HTp) and Volumetric Modulated Arc Therapy (VMATp) treatment techniques in terms of CTVp coverage and reduced organ at risk (OAR), normal tissue and implant doses when CTVp was used for treatment planning as the target structure instead of conventional CTV. METHODS: Eight left-sided and eight right-sided breast cancer patients who underwent IBR after mastectomy were included in this study. Planning CT data sets were acquired during free breathing and patients were treated with HT technique targeted to conventional CTV. Retrospectively, CTVp was delineated based on EACG by the same radiation oncologist, and treatment plans with HTp and VMATp techniques were generated based on CTVp. For each patient, relevant dosimetric parameters were obtained from three different treatment plans. RESULTS: There was no statistically significant difference on target coverage in terms of, PTVp-D95, PTVp-Vpres, homogeneity index (p > 0.05) between HTp and VMATp plans. But, the conformity numbers were significantly higher (HTp vs VMATp, 0.69 ± 0.15 vs 0.79 ± 0.12) for VMATp (Z = - 2.17, p = 0.030). While HTp significantly lowered Dmax and Dmean for LAD (LAD-Dmax: χ2 = 12.25, p = 0.002 and LAD-Dmean: χ2 = 12.30, p = 0.002), neither HTp nor VMATp could reduce maximum and mean dose to heart (p > 0.05). Furthermore, heart volume receiving 5 Gy was significantly higher for VMATp when compared to HTp (21.2 ± 9.8 vs 42.7 ± 24.8, p: 0.004). Both techniques succeeded in reducing the mean dose to implant (HTp vs HT, p < 0.001; VMATp vs HT, p < 0.001; VMATp vs HTp, p = 0.005). CONCLUSION: Both HTp and VMATp techniques succeeded to obtain conformal and homogeneous dose distributions within CTVp while reducing the mean implant dose. HTp was found to be superior to VMATp with regards to lowering all OAR doses except for CB.

Limited field adaptive radiotherapy for glioblastoma: changes in target volume and organ at risk doses.

OBJECTIVE: This study aimed to investigate the tumor volume changes occurring during limited-field radiotherapy (RT) for glioblastoma patients and whether a volume-adapted boost planning approach provided any benefit on tumor coverage and normal tissue sparing. MATERIALS AND METHODS: Twenty-four patients underwent simulation with magnetic resonance (MR) and computed tomography (CT) scans prior to RT (MR_initial, CT_initial) and boost treatment (MR_adapt, CT_adapt). For the boost phase, MR_initial and MR_adapt images were used to delineate GTV2 and GTV2_adapt, respectively. An initial boost plan (Plan_initial) created on CT_initial for PTV2 was then reoptimized on CT_adapt by keeping the same optimization and normalization values. Plan_adapt was generated on CT_adapt for PTV2_adapt volume. Dose volume histogram parameters for target volumes and organs-at-risk were compared using these boost plans generated on CT_adapt. Plan_initial and Plan_adaptive boost plans were summed with the first phase plan and the effect on the total dose was investigated. RESULTS: Target volume expansion was noted in 21% of patients while 79% had shrinkage. The average difference for the initial and adaptive gross tumor volume (GTV), clinical target volume (CTV), and planning target volume (PTV) volumes were statistically significant. Maximum dose differences for brainstem and optic chiasm were significant. Healthy brain tissue V10 and ipsilateral optic nerve maximum doses were found to decrease significantly in Plan_adaptive. CONCLUSION: Results of this study confirm occurrence of target volume changes during RT for glioblastoma patients. An adaptive plan can provide better normal tissue sparing for patients with lesion shrinkage and avoid undercoverage of treatment volumes in case of target volume expansion especially when limited-fields are used.

Coronaphobia: A barrier to ongoing cancer treatment?

INTRODUCTION: Increased stress levels caused by the pandemic might cause delays in cancer treatment. We conducted a survey among cancer patients undergoing treatment to evaluate their psychological wellbeing and treatment adherence during Coronavirus disease 19 (COVID-19) pandemic. MATERIAL AND METHODS: Patients receiving active chemotherapy at a private oncology center between January and May 2021 were included. Healthy volunteers were employees of a district health directorate with no history of cancer or chronic disease. Treatment adherence was described as compliant if the prescribed treatment was received within a week and the information was gained from patient charts. Hospital anxiety and depression scale (HADS) and COVID-19 phobia scale (CP19-S) were administered to participants. RESULTS: 402 participants were included; 193 (48%) were cancer patients. The mean age of the participants was 44 years old and 68% of the participants were female. All participants' CP19-S mean score was 47.9. Patient group had significantly lower CP19-S (p = 0.006). Chronic disease and history of a shocking event were the factors associated with CP19-S. All participants reporting hospital anxiety were found to have significantly higher COVID-19 phobia levels (p < 0.05). Patients' mean HADS-anxiety score was significantly higher (7.3 vs. 6.5, p = 0.027). COVID-19 phobia was an independent factor increasing the level of anxiety and depression in both groups. Adherence to treatment was 100%. CONCLUSION: The pandemic increased levels of anxiety, however, cancer treatment continued to be a priority in patients' lives. Strategies should be developed to support oncology patients cope with the pandemic and increase their courage to avoid treatment delays.

Identifying Knowledge and Practices regarding Cancer Patient Malnutrition: A Survey Study among Oncologists.

Malnutrition is one of the most common complications of cancer and its treatments with a prevalence of up to 80% among cancer patients. Thus, standardized and target-oriented attitudes of oncologists toward nutritional management are particularly important. This study aims to report the questionnaire-based evaluation of different views toward medical nutrition among medical and radiation oncologists with the purpose to underline the problems and requirements of cancer nutrition. A national web-based survey composed of 26 multiple choice questions about participant demographics, level of knowledge about cancer nutrition, and approaches to malnutrition were completed by 247 oncologists. The survey was answered by a total of 247 (34%) radiation and medical oncologists. The majority of the oncologists (77%) were working at the University Hospitals and Education & Research Hospitals. Most of them were specialists with 5-10 years of experience. Nutritional status was routinely assessed in oncology units of 84% of (206) oncologists. However, only 50% reported nutritional evaluation follow-ups without waiting for a patient's declaration and 5 (2%) oncologists reported the absence of nutritional evaluation in their unit. Additionally, more than 79% of participants reported that their knowledge was not enough about enteral and parenteral nutrition while 8% were skeptical about the benefits of medical nutrition. Although the role of nutrition as an essential part of cancer care is widely recognized, the availability of limited high-quality evidence, problems of accessibility, lack of routine nutritional evaluation, and varying indicators for malnutrition are some of the problems preventing standardized nutritional management. Therefore, there are a variety of approaches and barriers to the implementation of guidelines. Further studies are needed to identify areas of improvement, as well as strategies to implement nutritional therapy in cancer care.

Does Integrative Medicine Reduce Prescribed Opioid Use for Chronic Pain? A Systematic Literature Review.

BACKGROUND: Chronic pain (CP) is a major public health problem. Many patients with CP are increasingly prescribed opioids, which has led to an opioid crisis. Integrative medicine (IM), which combines pharmacological and complementary and alternative medicine (CAM), has been proposed as an opioid alternative for CP treatment. Nevertheless, the role of CAM therapies in reducing opioid use remains unclear. OBJECTIVES: To explore the effectiveness of the IM approach or any of the CAM therapies to reduce or cease opioid use in CP patients. METHODS: An online search of MEDLINE and Embase, CINAHL, PubMed supp., and Allied and Complementary Medicine Database (AMED) for studies published in English from inception until February 15, 2018, was conducted. The Mixed Methods Appraisal Tool (MMAT) was used to critically appraise selected studies. RESULTS: The electronic search yielded 5,200 citations. Twenty-three studies were selected. Eight studies were randomized controlled trials, seven were retrospective studies, four studies were prospective observational, three were cross-sectional, and one was quasi-experimental. The majority of the studies showed that opioid use was reduced significantly after using IM. Cannabinoids were among the most commonly investigated approaches in reducing opioid use, followed by multidisciplinary approaches, cognitive-behavioral therapy, and acupuncture. The majority of the studies had limitations related to sample size, duration, and study design. CONCLUSIONS: There is a small but defined body of literature demonstrating positive preliminary evidence that the IM approach including CAM therapies can help in reducing opioid use. As the opioid crisis continues to grow, it is vital that clinicians and patients be adequately informed regarding the evidence and opportunities for IM/CAM therapies for CP.

Gamma Knife Radiosurgery for Arteriovenous Malformations: Clinical Series of 199 Patients.

AIM: Cerebral arteriovenous malformations (AVM) are pathological connections between arteries and veins without capillaries. Stereotactic radiosurgery (RS) is a proven and accepted treatment method for cerebral AVMs. Our objective was to analyze the factors influencing the clinical outcome in patients suffering from AVMs. MATERIAL AND METHODS: We retrospectively reviewed 199 patients who were treated with Gamma-Knife RS for intracranial AVMs between 13 October 2005 and 31 October 2010. There were 89 male, 110 female patients with a median age of 32 years (range, 3-74 years). Obliteration was assessed with MRI angiography and DSA imaging. RESULTS: Complete obliteration rate after RS was 71 % (141 out of 199), including second RS treatments. In terms of obliteration rates, there was no significant difference between patients younger and older than 21 years old (p=0.669). After RS, 3 patients died due to intracranial hemorrhage and 1 died of heart disease. Death from AVM was determined as 1.5 %. Intracranial hemorrhage was observed in 7 (3.5 %) patients post-RS. CONCLUSION: Obliteration was found to be associated with Spetzler-Martin Grade, Pollock-Flickinger Grade, AVM volume, RS dose, bleeding history before RS and no previous embolization before RS. Gamma knife RS is an effective treatment method for the treatment of AVMs both for pediatric and adult patients. It provides high obliteration and low mortality rates.

Tumor-stage mycosis fungoides of the vulva successfully treated with local low-dose radiotherapy.

Mycosis fungoides (MF) is the most common type of primary cutaneous T-cell lymphoma. According to the proposed guidelines for MF, skin-directed therapies are the treatment of choice for patients with limited stage disease. We present a case of early-stage MF, who progressed to tumor-stage MF during the postpartum period, showing a solitary ulcerated tumor on the vulva, which was successfully treated with local response-based, low-dose radiotherapy.

Comparison of 3D dose distributions for HDR 192Ir brachytherapy sources with normoxic polymer gel dosimetry and treatment planning system.

Radiation fluence changes caused by the dosimeter itself and poor spatial resolution may lead to lack of 3-dimensional (3D) information depending on the features of the dosimeter and quality assurance of dose distributions for high-dose rate (HDR) iridium-192 ((192)Ir) brachytherapy sources is challenging and experimental dosimetry methods used for brachytherapy sources are limited. In this study, we investigated 3D dose distributions of (192)Ir brachytherapy sources for irradiation with single and multiple dwell positions using a normoxic gel dosimeter and compared them with treatment planning system (TPS) calculations. For dose calibration purposes, 100-mL gel-containing vials were irradiated at predefined doses and then scanned in an magnetic resonance (MR) imaging unit. Gel phantoms prepared in 2 spherical glasses were irradiated with (192)Ir for the calculated dwell positions, and MR scans of the phantoms were obtained. The images were analyzed with MATLAB software. Dose distributions and profiles derived with 1-mm resolution were compared with TPS calculations. Linearity was observed between the delivered dose and the reciprocal of the T2 relaxation time constant of the gel. The x-, y-, and z-axes were defined as the sagittal, coronal, and axial planes, respectively, the sagittal and axial planes were defined parallel to the long axis of the source while the coronal plane was defined horizontally to the long axis of the source. The differences between measured and calculated profile widths of 3-cm source length and point source for 70%, 50%, and 30% isodose lines were evaluated at 3 dose levels using 18 profiles of comparison. The calculations for 3-cm source length revealed a difference of > 3mm in 1 coordinate at 50% profile width on the sagittal plane and 3 coordinates at 70% profile width and 2 coordinates at 50% and 30% profile widths on the axial plane. Calculations on the coronal plane for 3-cm source length showed > 3-mm difference in 1 coordinate at 50% and 70% and 2 coordinates at 30% profile widths. The point source measurements and calculations for 50% profile widths revealed a difference > 3mm in 1 coordinate on the sagittal plane and 2 coordinates on the axial plane. The doses of 3 coordinates on the sagittal plane and 4 coordinates on the axial plane could not be evaluated in 30% profile width because of low doses. There was good agreement between the gel dosimetry and TPS results. Gel dosimetry provides dose distributions in all 3 planes at the same time, which enables us to define the dose distributions in any plane with high resolution. It can be used to obtain 3D dose distributions for HDR (192)Ir brachytherapy sources and 3D dose verification of TPS.

Treatment of brainstem metastases with gamma-knife radiosurgery.

The aim was to investigate the efficacy and safety of gamma-knife stereotactic radiosurgery (SRS) for treating brainstem metastases. The cases of 44 patients who underwent SRS as treatment for 46 brainstem metastases were retrospectively evaluated. The median age was 57 years (range 42-82 years) and the median Karnofsky performance score (KPS) was 80 (range 60-90). The primary tumor was lung carcinoma in 28 cases, breast carcinoma in 7 cases, colon carcinoma in 3 cases, renal cell carcinoma in 3 cases, malignant melanoma in 1 case, and unknown origin in 2 cases. Of the 46 metastases, 30 were in the pons, 14 were in the mesencephalon, and 2 were in the medulla oblongata. The median volume of the 46 metastases was 0.6 cc (range 0.34-7.3 cc). The median marginal dose of radiation was 16 Gy (range 10-20 Gy). Twenty-three patients (52 %) received whole brain radiotherapy prior to SRS, and 6 (14 %) received this therapy after SRS. In the remaining 15 cases (34 %), SRS was applied as the only treatment. Recursive partitioning analysis, graded prognostic assessment, and basic score for brain metastases were used to predict survival time. Local control was achieved for all but two of the 46 metastases (96 %). The overall survival time after SRS was 8 months. Female gender, KPS >70, mesencephalon tumor location, and response to treatment were associated with longer survival. Basic score for brain metastases class I and recursive partitioning analysis classification were associated with better prognosis. Peri-tumoral changes were detected radiologically at 2 (4 %) of the metastatic lesion sites but neither of these patients exhibited symptoms. Gamma-knife radiosurgery is effective for treating brainstem metastases without a higher risk for radiation necrosis.

The great mimicker: zona zoster at the mastectomy site causing contralateral intramammary lymph node enlargement.

Zona zoster is rarely observed in patients with malignancy; when present, it follows a dermatomal fashion. Involvement of widely separated regions is very rare. Hereby, zona zoster causing enlarged intramammary lymph nodes (IMLN) in the opposite breast is reported for the first time in literature. The masses were hypoechoic on US with no hilum and hypervascular on color Doppler US. MRI showed hypointense masses with type 3 time-intensity curve and adjacent vessel sign. The complete regression of the nodes after the antiviral therapy confirmed the diagnosis. In breast cancer patients, IMLN enlargements may mimic breast cancer metastasis, and zona zoster infection of the mastectomy site may present with contralateral IMLN enlargement due to altered lymphatic drainage. When breast US is not sufficient for the differential diagnosis, breast MRI may warrant proper diagnosis, and prevent unnecessary biopsies. Antiviral treatment with followup would be sufficient for management.

Does radiotherapy planning without breath control compensate intra-fraction heart and its compartments' movement?

This prospective study investigated radiation dose and volume changes during breathing cycle. Ten patients with left breast carcinoma receiving radiotherapy were included. Treatment planning images were obtained as three different sets of series taken: without breath control (F), deep inspiration (I), and end of expiration (E), with 3-mm intervals. As such, whole breath cycle was simulated. CT images taken during I and E were registered to F, according to DICOM coordinates. Each patient's target and organ at risk volumes were contoured by the primary radiation oncologist except heart components which were contoured by radiologist on F, I and E series. Radiotherapy planning was done on F series, then planning and beam data were transferred from F to I and E image series. Target and organs at risk (OAR) dose distributions for E and I image series were obtained. Dose changes between F, E, and I phases for whole heart and components, namely, left ventricle (LV), right ventricle (RV), left auricle (LA), right auricle (RA), and left anterior descendent artery (LAD) were examined. Furthermore, the issue of any compartment representing the maximum heart dose was investigated. Volume and dose variations for heart, LV, RV, LA, RA, and LAD were observed during breath cycle. Exposured dose was more than defined tolerance level for LV, RV, and LAD in some patients. However, dose differences between F-I and F-E were not statistically significant. Radiotherapy planning without breath control is not capable of compensating for whole intra-fraction heart and its components' volumes and dose changes.

A clinical comparison of patient setup and intra-fraction motion using frame-based radiosurgery versus a frameless image-guided radiosurgery system for intracranial lesions.

BACKGROUND AND PURPOSE: A comparison of patient positioning and intra-fraction motion using invasive frame-based radiosurgery with a frameless X-ray image-guided system utilizing a thermoplastic mask for immobilization. MATERIALS AND METHODS: Overall system accuracy was determined using 57 hidden-target tests. Positioning agreement between invasive frame-based setup and image-guided (IG) setup, and intra-fraction displacement, was evaluated for 102 frame-based SRS treatments. Pre and post-treatment imaging was also acquired for 7 patients (110 treatments) immobilized with an aquaplast mask receiving fractionated IG treatment. RESULTS: The hidden-target tests demonstrated a mean error magnitude of 0.7mm (SD=0.3mm). For SRS treatments, mean deviation between frame-based and image-guided initial positioning was 1.0mm (SD=0.5mm). Fusion failures were observed among 3 patients resulting in aberrant predicted shifts. The image-guidance system detected frame slippage in one case. The mean intra-fraction shift magnitude observed for the BRW frame was 0.4mm (SD=0.3mm) compared to 0.7mm (SD=0.5mm) for the fractionated patients with the mask system. CONCLUSIONS: The overall system accuracy is similar to that reported for invasive frame-based SRS. The intra-fraction motion was larger with mask-immobilization, but remains within a range appropriate for stereotactic treatment. These results support clinical implementation of frameless radiosurgery using the Novalis Body Exac-Trac system.