Abstract P2-14-01: MOLECULAR FLUORESCENCE-GUIDED SURGERY USING BEVA800 FOR THE ASSESSMENT OF TUMOR MARGINS DURING BREAST CONSERVING SURGERY OF PATIENTS WITH PRIMARY BREAST CANCER (MARGIN-II)

Introduction: The goal of breast conserving surgery (BCS) for early breast cancer (EBC) is to remove the tumor in toto and preserving as much of the normal breast tissue as possible. In 20-50% of cases a re-excision is necessary because of involved margins. Repeat surgeries are not only a burden to patients physically but also psychologically and can delay recommended adjuvant therapies. Accurate determination of tumor margins during surgery is therefore a critical need. Breast cancer tissue produces significantly higher amounts of VEGF-A than healthy tissue. VEGF-A stimulates tumor angiogenesis and is therefore a target for molecular imaging techniques. The fluorescence imaging agent bevacizumab-IRDye800CW (Beva800) is a conjugate of bevacizumab and IRDye800CW and binds specifically to VEGF-A. Beva800 provides a potentially efficacious approach to imaging specimen and cavity margins during BCS. We are presenting a phase II study that combined Beva800 with the SurgVision Explorer Air camera for intraoperative margin assessment during BCS for EBC. Methods: MARGIN II is a multicenter open-label single arm prospective clinical trial aimed at evaluating Beva800 for assessment of tumor margins in women with EBC scheduled for BCS. The study was a within-patient comparison of positive tumor margin rates using BCS standard of care margin assessment compared to intraoperative assessment with 4.5 mg Beva800 and fluorescence imaging with the SurgVision Explorer Air camera. All patients received an i.-v. bolus injection of 4.5 mg of Beva800 three days before surgery. The fluorescent signal was visualized during surgery using NIR fluorescence imaging (700–1000 nm). Standard of care margin assessment was defined as visual inspection, palpation and, in cases of pre-operative wire marking, specimen sonography or mammography. Beva800 efficacy was determined as the number of patients in which a pathology-confirmed positive margin was identified by fluorescence-guided surgery using Beva800 but not by standard of care BCS. Results: 49 patients were included in 5 centers. 4 training cases were only included in the safety analysis, 45 patients were evaluable for the efficacy analysis. 8 patients (17.8%) had involved margins after standard of care BCS, 4 of which were detected by molecular fluorescence intraoperatively resulting in the reduction of patients with positive margins by 50% (95% CI: 15.7%, 84.3%). 4 patients (8.9%; 95% CI: 2.5%, 21.1%) needed a re-excision because of involved margins. In 27 patients (60.0%) the additional molecular fluorescence guided cavity shaving did not change the resection status from positive to negative (false positive). Adverse events were reported by 16 of 49 patients (32.7%), but only 3 (6.1%) were related to Beva800 (syncope, hot flush, hypertensive crisis). One patient experienced a treatment related SAE (hypertensive crisis). No anti-Beva800 antibodies were detected. Conclusion: In our analysis the rate of necessary second operations was reduced by 50% using Beva800 and the SurgVision Explorer Air camera. The safety analysis confirmed the positive safety profile of Beva800 found in previous studies. Molecular fluorescence-guided surgery may have the potential to change the practice of breast conserving surgery by reducing unnecessary re-excisions. Future studies will have to address the high false positive rates.

Citation Format: Hans-Christian Kolberg, Carmen Röhm, Angrit Stachs, Florian Schütz, Jens-Uwe Blohmer, Sarah Wetzig, Steffi Hartmann, Jörg Heil, Markus Hahn. MOLECULAR FLUORESCENCE-GUIDED SURGERY USING BEVA800 FOR THE ASSESSMENT OF TUMOR MARGINS DURING BREAST CONSERVING SURGERY OF PATIENTS WITH PRIMARY BREAST CANCER (MARGIN-II) [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-14-01.

The Role of C-Reactive Protein as a Prognostic Biomarker in Patients with Early Breast Cancer Treated with Neoadjuvant Chemotherapy

Background

C-reactive protein (CRP) is an acute phase reactant influenced by inflammation and tissue damage. Elevated CRP levels have been associated with poor outcome of various cancers including breast cancer. However, evidence regarding a potential impact of CRP levels on outcome of neoadjuvant chemotherapy (NACT) in patients with early breast cancer (EBC) is insufficient.

Methods

Patients who had received NACT for EBC and had available data regarding CRP levels before therapy, pathologic complete remission (pCR), and follow-up were included. The association between CRP at baseline and outcome parameters was analyzed.

Results

152 women were included in this analysis; median follow-up was 5.8 years. No association between CRP at baseline and pCR rates could be detected. 6.6% of the patients developed a local recurrence, 10.5% developed a distant recurrence, and 5.2% died from breast cancer. A negative correlation (Spearman-Rho) between CRP at baseline and overall survival (OS) (correlation coefficient (CC) -0.255; p = 0.45), disease-free survival (DFS) (CC -0.348; p = 0.075), local recurrence-free survival (LRFS) (CC -0.245; p = 0.327), and distant DFS (DDFS) (CC -0.422; p = 0.057) was not statistically significant, although especially in DFS and DDFS a strong trend was detected. The probability of death from breast cancer was 2% if the CRP was <0.08 mg/dL and 40% if the CRP was >2.08 mg/dL; this association was highly statistically significant (χ²; p < 0.001). These results were independent from age, estrogen and progesterone receptor status, HER2 status, nodal status, and grading. The hazard ratio for OS was 5.75 (p = 0.004) for CRP <0.08 mg/dL versus CRP >2.08 mg/dL.

Discussion/Conclusion

CRP at baseline is not predictive for pCR in EBC after NACT in our patient dataset. However, an association of parameters of long-term prognosis with CRP could be demonstrated. Although the correlations of higher CRP levels at baseline and shorter OS, DFS, LRFS, and DDFS were not significant, a strong trend could be detected that was reproduced in the analysis of different groups of CRP levels and the probability of breast cancer mortality. Higher CRP levels are indicating a worse prognosis in EBC after NACT in this retrospective analysis. These results justify further investigation of CRP not as a predictive parameter for pCR but as a biomarker of long-term prognosis in EBC in prospective trials and may lead to therapeutic approaches with the aim of lowering CRP levels.

The role of C-reactive protein (CRP) as a prognostic biomarker in patients with early breast cancer (EBC) treated with neoadjuvant chemotherapy (NACT)

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Background: C-reactive protein (CRP) is an acute phase reactant influenced by inflammation and tissue damage. It has been demonstrated that elevated CRP levels are associated with poor outcome of cancer including metastatic breast cancer. However, evidence regarding an impact of CRP levels on outcome in early breast cancer (EBC) are missing. Methods: Patients after neoadjuvant chemotherapy (NACT) for EBC and with available data regarding CRP levels before therapy, pathologic complete remission (pCR) and follow-up were included. The association between CRP at baseline and outcome parameters was analyzed. Results: 156 women were included in this analysis, median follow up was 5.8 years. No association between CRP at baseline and pCR rates could be detected. 6.4% of the patients developed a local recurrence, 10.3% developed a distant recurrence and 5.1% died from breast cancer. A negative correlation (Spearman-Rho) between CRP at baseline and overall survival (OS) (Correlation coefficient (CC) -0.255; p = 0.45), disease free survival (DFS)(CC -0.348; p = 0.075), local recurrence free survival (LRFS)(CC -0.245; p = 0.327) and distant disease free survival (DDFS)(CC -0.422; p = 0.057) was not statistically significant, although especially in DFS and DDFS a strong trend was detected. The probability of death from breast cancer was 2% if the CRP was < 0.08 mg/dl and 40% if the CRP was > 2.08 m/dl, this association was highly statistically significant (Chi Square; p < 0.001). These results were independent from age, estrogen and progesterone receptor status, HER2 status and grading. Conclusions: CRP at baseline is not predictive for pCR in EBC after NACT in our patient dataset. However, an association of parameters of long-term prognosis with CRP could be demonstrated. Although the correlations of higher CRP at baseline and shorter OS, DFS, LRFS and DDFS were not significant, a strong trend could be detected that was reproduced in the analysis of different cut-offs for CRP and the probability of breast cancer mortality. Higher CRP-levels are indicating a worse prognosis in early breast cancer after NACT in this retrospective analysis. These results justify further investigation of CRP as a biomarker of long-term prognosis in early breast cancer in prospective trials.

Association between mammographic breast density and achievement of a pathologic complete remission (pCR) after neoadjuvant chemotherapy (NACT) for early breast cancer (EBC)

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Background: Neoadjuvant chemotherapy (NACT) is indicated in early breast cancer (EBC) with an unfavorable tumor biology. Achievement of pathologic complete remission (pCR) after NACT is indicating an improved prognosis. An association between pCR and mammographic breast density as defined by BIRADS (Breast Imaging Reporting and Data System) could be demonstrated. However, the definition of mammographic breast density by the American College of Radiology (ACR) is widely used worldwide and data regarding an association of breast density by this definition and pCR after NACT are missing. Methods: We conducted a retrospective analysis among patients who had received neoadjuvant chemotherapy (NACT) for EBC and had available data regarding mammographic breast density as defined by ACR before therapy, pCR, age, estrogen and progesterone receptor (ER, PR) status, HER2neu status and grading were included. An association between mammographic breast density (ACR) and pCR was analyzed. Results: 185 patients were included in this analysis, 35.7% of whom achieved a pCR. Mammographic breast density was ACR 1 in 15.1%, ACR 2 in 41.6%, ACR3 in 38.4% and ACR 4 in 4.9% of the patients. A negative correlation (Spearman-Rho) between mammographic breast density and pCR (correlation coefficient (CC) -0.240) was highly statistically significant (p = 0.001). The association of decreasing pCR rates with increasing mammographic breast density (pCR rates by ACR 1: 53.6%, ACR 2: 41.6, ACR 3: 25.4% and 11.1 %) was statistically significant (Chi-Square, p = 0.013). These results were independent of age, ER status, PR status, HER2neu status and grading. Conclusions: In our analysis higher mammographic breast density as defined by ACR was significantly correlated with a lower chance of achieving a pCR after NACT. Although this result has to be interpreted with caution due to the small sample size and the retrospective character of our investigation, it is completely in line with other investigations using other definitions of mammographic breast density. The pathophysiological cause of this association should be further elucidated to reveal potential mechanisms of treatment resistance.

The role of Ki67 in involved lymph nodes as a predictive biomarker for response to neoadjuvant chemotherapy in patients with early breast cancer

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Background: Neoadjuvant chemotherapy (NACT) is a standard in early breast cancer (EBC) with an unfavorable tumor biology and pathologic complete remission (pCR) after NACT is indicating an improved prognosis. Ki67 is well established as a prognostic and predictive biomarker in early breast cancer and the association of high Ki67-results in breast tumors at the time of initial diagnosis and pCR after NACT is used for decision making for versus against NACT in daily routine in many countries. Data about associations of Ki67 in involved lymph nodes and response to NACT are missing. Methods: We conducted a retrospective analysis among patients in our database who had received NACT for EBC, had lymph node involvement verified by core cut biopsy and available data for pCR, age, estrogen and progesterone receptor (ER, PR) status, HER2neu status, Ki67 in the breast tumor and grading. Patients treated in clinical studies were excluded. Ki67 was measured in the archived material of biopsies from involved lymph nodes and the association between Ki67 in involved lymph nodes and response to neoadjuvant chemotherapy was analyzed. Results: 52 patients were included with regard to the criteria mentioned above, 21 had to be excluded because there was not enough lymph node biopsy material for Ki67 analysis. 7 (22.6) of the remaining 31 patients achieved a pCR and 11 (35.5%) achieved a nodal conversion to ypN0. Median Ki67 was 35% [3%, 85%] in involved lymph nodes and 40% [10%, 90%] in the breast. There was no significant correlation (Spearman Rho) between Ki67 in involved lymph nodes and pCR whereas there was for Ki67 in the breast (p = 0.046). The ROC-analysis resulted in a cut-off of 47% with the highest sensitivity for Ki67 in lymph nodes regarding prediction of nodal conversion. An analysis with a cut-off of Ki67 in involved lymph nodes of 47% predicted a nodal conversion in 60% of the cases (Chi-Square and Fisher’s Exact test; p = 0.0049). Conclusions: Our analysis supports Ki67 as a strong predictive biomarker regarding pCR after neoadjuvant chemotherapy. Although high Ki67 expression in involved lymph nodes is significantly associated with nodal conversion, it does not add clinically meaningful information to Ki67 in the breast.

Abstract PS1-21: Molecular fluorescence-guided surgery using Beva800 for the assessment of tumor margins during breast conserving surgery of patients with primary breast cancer (MARGIN-II)

Introduction:The goal of breast conserving surgery (BCS) for early breast cancer (EBC) is to remove the tumor and a surrounding rim of normal tissue, while preserving as much of the normal breast tissue as possible. Incomplete resections are associated with higher rates of surgical re-excision. Repeat surgeries are not only a burden to patients physically but also psychologically and can delay recommended adjuvant therapies. Accurate determination of tumor margins during surgery is therefore critical for successful outcome. Breast cancer tissue produces significantly higher amounts of VEGF-A than healthy tissue. VEGF-A stimulates tumor angiogenesis and is therefore an excellent target for molecular imaging techniques. The fluorescence imaging agent bevacizumab-IRDye800CW (Beva800) is a conjugate of bevacizumab (a humanized antibody targeting human VEGF) and IRDye800CW (a near-infrared fluorescence dye) which binds specifically to VEGF-A. Beva800 provides a potentially highly efficacious approach to imaging specimen and cavity margins during BCS. Herein we present a phase II study that combined Beva800 with the SurgVision Explorer Air camera for intraoperative margin assessment during BCS for EBC.Methods:MARGIN II is a multicenter open-label single arm prospective clinical trial aimed at evaluating Beva800 for assessment of tumor margins in women with EBC scheduled for BCS. The study was a within-patient comparison of positive tumor margin rates using BCS standard of care compared to intraoperative assessment with 4.5 mg Beva800 and fluorescence imaging with the SurgVision Explorer Air camera. Patients undergoing neoadjuvant chemotherapy were excluded. All patients received a single intra-venous bolus injection of 4.5 mg of Beva800 three days before surgery. The fluorescent signal was visualized during surgery using NIR fluorescence imaging (700-1000 nm). This wavelength window typically has very low tissue auto-fluorescence (filtering out background noise) and greater tissue penetration depth due to reduced haemoglobin absorption. Standard of care assessment was defined as visual inspection, palpation and, in cases of pre-operative wire marking, specimen sonography or mammography. Beva800 efficacy was determined as the number of patients in which a pathology-confirmed positive margin was identified by fluorescence guided surgery using Beva800 but not by standard of care BCS. The results per patient were divided into two clusters: results after standard of care BCS and results after fluorescence guided surgery, according to their margin status at pathology. The need for re-operation because of involved margins within 30 days after the first BCS and the safety of 4.5 mg Beva800 was assessed.Results:The recruitment goal of 40 patients in 5 centers has almost been reached and results of the final analysis will be presented at the meeting.Conclusion:Molecular fluorescence-guided surgery using Beva800 has the potential to change the practice of breast conserving surgery by avoiding unnecessary re-operations. This would lead to fewer interventions, a reduced burden on patients through repeat surgery and reduced delay of adjuvant therapies.

Citation Format: Hans-Christian Kolberg, Carmen Röhm, Angrit Stachs, Florian Schütz, Jens-Uwe Blohmer, Sarah Wetzig, Steffi Hartmann, Jörg Heil, Markus Hahn. Molecular fluorescence-guided surgery using Beva800 for the assessment of tumor margins during breast conserving surgery of patients with primary breast cancer (MARGIN-II) [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS1-21.

A phase II single-arm, multicenter, open-label neoadjuvant study of pembrolizumab in combination with nab-paclitaxel followed by pembrolizumab in combination with epirubicin and cyclophosphamide in patients with triple-negative breast cancer: Neoimmunoboost

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Background: The NeoImmunoboost study (NCT03289819) was designed to evaluate the pathological complete response (pCR) rate and safety of a neoadjuvant combination of the PD-1 antibody pembrolizumab and nab-paclitaxel followed by pembrolizumab with epirubicin and cyclophosphamide in patients with early triple negative breast cancer (TNBC). Methods: This is a prospective, single-arm, multi-center, open-label phase II clinical trial. Female patients with early TNBC were eligible for trial participation. Patients received 12 cycles of weekly nab-paclitaxel intravenous (i.v.) 125 mg/m² body surface area (BSA) in combination with 4 cycles of pembrolizumab i.v. 200 mg q3w; followed by 4 cycles of epirubicin i.v. 90 mg/m² BSA and cyclophosphamide i.v. 600 mg/m² BSA q3w in combination with 4 cycles of pembrolizumab i.v. 200 mg q3w. After 25 patients the protocol was amended, with an initiation boost of 1 cycle of pembrolizumab i.v. 200 mg q3w monotherapy prior to the chemotherapy. Primary trial endpoint was pCR. Secondary endpoints included safety and clinical response rate. Results: Between March 2018 and October 2019, 53 patients were included into the trial. Until now, 47 patients have completed trial treatment and 6 patients are still receiving therapy. 28 patients have received the initiation boost with pembrolizumab, 25 patients did not receive the initiation boost. Up to now, 4 patients terminated the therapy prematurely. Conclusions: pCR data of all patients will be available at the meeting and results of the pCR rates and selected secondary endpoints will be presented at the meeting. Clinical trial information: NCT03289819.

Re-Excision Rates in Breast-Conserving Surgery for Invasive Breast Cancer after Neoadjuvant Chemotherapy with and without the Use of a Radiopaque Tissue Transfer and X-ray System

Background

Significant re-excision rates in breast-conserving surgery (BCS) after neoadjuvant systemic chemotherapy may result from difficulties in defining the surgical target particularly in cases with excellent treatment response. Devices allowing an exact topographic localisation of the lesion in the resected tissue could reduce re-excision rates by optimising the intraoperative detection of involved margins.

Methods

80 patients with invasive breast cancer receiving BCS after neoadjuvant chemotherapy were included in this non-randomized case-control study. 40 patients with specimen radiography performed in a standard approach (control group) were compared to 40 patients with use of a radiopaque tissue transfer system (study group).

Results

19/80 (23.75%) patients required re-excision because of involved margins; among those, 14/40 (35%) were in the control group and 5/40 (12.5%) in the study group. The association between the use of the radiopaque tissue transfer system and the lower re-excision rate was statistically significant (p = 0.023).

Conclusion

Our analysis provides a rationale for the routine use of a radiopaque tissue transfer system for specimen radiography in BCS after neoadjuvant chemotherapy for invasive breast cancer in order to reduce re-excision rates.

Efficacy of neoadjuvant pertuzumab in addition to chemotherapy and trastuzumab in routine clinical treatment of patients with primary breast cancer: a multicentric analysis

PURPOSE

Neoadjuvant combination treatment with chemotherapy (CTX), trastuzumab (TZM), and pertuzumab (PTZ) has been shown to result in higher pathological complete response rates (pCR) in comparison with treatment with chemotherapy and trastuzumab (CTX/TZM). This analysis was aimed at real-world validation of these results from prospective randomized trials.

METHODS

In a retrospective analysis conducted in the PRAEGNANT network, patients were eligible for inclusion if they had either received neoadjuvant therapy with CTX/TZM or chemotherapy, trastuzumab, and pertuzumab (CTX/TZM/PTZ) and subsequently underwent surgery for their primary breast cancer. The effect of the two neoadjuvant regimens on pCR in addition to commonly applicable predictors of pCR was analyzed in 300 patients from three study sites, using logistic regression analyses with treatment arm, age, clinical tumor stage, grading, and hormone receptor status as predictors.

RESULTS

pCR with complete disappearance of all tumor cells was seen in 30.2% (n = 58) of patients treated with CTX/TZM and in 52.8% (n = 57) of those treated with CTX/TZM/PTZ. CTX/TZM/PTZ was positively associated with pCR (adjusted odds ratio 2.44; 95% CI 1.49-4.02). Mastectomy rates were not influenced by the therapy.

CONCLUSIONS

The results of clinical trials were confirmed in this dataset of patients who were treated outside of clinical trials in everyday routine work. pCR rates can be improved by 20% with pertuzumab in routine clinical use.

Abstract P2-12-06: Re-excision rates in breast conserving surgery for invasive breast cancer after neoadjuvant chemotherapy with and without the use of a radiopaque tissue transfer and X-ray system

Background: Published re-excision rates after breast conserving surgery for invasive breast cancer vary between 20 and 50%. In patients after neoadjuvant chemotherapy even higher re-excision rates may result from difficulties in defining the surgical target particularly in cases with excellent treatment response. Specimen radiography is reducing re-excision rates, however, defining involved margins is often difficult using standard approaches. Devices allowing horizontal and vertical examination and an exact topographic localization of the lesion in the resected tissue could reduce re-excision rates by an intraoperative detection of involved margins.

Methods: 80 patients with invasive breast cancer receiving breast conserving surgery after neoadjuvant chemotherapy and an indication for wire marking by mammography were included in this analysis. All tumors were marked with titanium clips prior to chemotherapy. In 40 patients specimen radiography was performed in a standard approach (control group), in 40 patients a tissue transfer and X-ray system based on a non-radiopaque board with radiopaque topographic markers and a stand for cranio-caudal X-rays was used (study group). A univariate analysis was carried out to evaluate the association between the use of the radiopaque tissue transfer system and the re-excision rate using a logistic regression model. Calculations were performed using the XLSTAT Biomed Software (Version 19.03, Addinsoft, NY, USA.).

Results: 19/80 patients (23.75%) required re-excision because of involved margins; among those patients, 14/40 (35%) were in the control group and 5/40 (12.5%) in the study group. The association between the use of the radiopaque tissue transfer system and the lower re-excision rate was statistically significant (p=0.023).

Conclusion: Our analysis provides a rationale for the use of a radiopaque tissue transfer system for specimen radiography in breast conserving surgery after neoadjuvant chemotherapy for invasive breast cancer in order to reduce re-excision rates. Based on these results we are planning a study including also patients receiving primary surgery.

Citation Format: Kolberg H-C, Akpolat-Basci L, Stephanou M, Wetzig S, Cubuk Y, Gerharz J, Liedtke C. Re-excision rates in breast conserving surgery for invasive breast cancer after neoadjuvant chemotherapy with and without the use of a radiopaque tissue transfer and X-ray system [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-12-06.

An Ultralow-Dose 1-Day Protocol With Activities Lower Than 20 MBq for the Detection of Sentinel Lymph Nodes in Breast Cancer-Experiences After 150 Cases

Introduction:

Common protocols for the detection of sentinel lymph nodes in early breast cancer often include the injection of the tracer 1 day before surgery. In order to detect enough activity on the day of surgery, the applied activity in many protocols is as high as several hundred MBq. So far, very few protocols with an activity below 20 MBq have been reported. We developed an ultralow-dose 1-day protocol with a mean activity lower than 20 MBq in order to reduce radiation exposure for patients and staff. Here, we are presenting our experiences in 150 consecutive cases.

Materials and Methods:

A total of 150 patients with clinically and sonographically negative axilla and no multicentricity underwent a sentinel lymph node biopsy using an ultralow-dose protocol performed on the day of surgery. No patient received systemic therapy prior to sentinel node biopsy. After peritumoral injection of the tracer Technetium-99m, a lymphoscintigraphy was performed in all cases. Seven minutes before the first cut, we injected 5 mL of blue dye in the region of the areola.

Results:

In 148 (98.7%) of 150 patients, at least 1 sentinel lymph node could be identified by lymphoscintigraphy; the detection rate during surgery with combined tracers Technetium-99m and blue dye was 100%. The mean applied activity was 17.8 MBq (9-20). A mean number of 1.3 (0-5) sentinel lymph nodes were identified by lymphoscintigraphy and a mean number of 1.8 (1-5) sentinel lymph nodes were removed during sentinel lymph node biopsy.

Conclusion:

Ultralow-dose 1-day protocols with an activity lower than 20 MBq are a safe alternative to 1-day or 2-day protocols with significantly higher radiation doses in primary surgery for early breast cancer. Using Technetium-99m and blue dye in a dual tracer approach, detection rates of 100% are possible in clinical routine in order to reduce radiation exposure for patients and staff.