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Abstract Background/Purpose Radiotherapy (RT) volumes for anal cancer are large and of moderate complexity when organs at risk (OAR) such as testis, small bowel and bladder are at least partially to be shielded. Volumetric intensity modulated arc therapy (VMAT) might provide OAR-shielding comparable to step-and-shoot intensity modulated radiotherapy (IMRT) for this tumor entity with better treatment efficiency. Materials and methods Based on treatment planning CTs of 8 patients, we compared dose distributions, comformality index (CI), homogeneity index (HI), number of monitor units (MU) and treatment time (TTT) for plans generated for VMAT, 3D-CRT and step-and-shoot-IMRT (optimized based on Pencil Beam (PB) or Monte Carlo (MC) dose calculation) for typical anal cancer planning target volumes (PTV) including inguinal lymph nodes as usually treated during the first phase (0-36 Gy) of a shrinking field regimen. Results With values of 1.33 ± 0.21/1.26 ± 0.05/1.3 ± 0.02 and 1.39 ± 0.09, the CI's for IMRT (PB-Corvus/PB-Hyperion/MC-Hyperion) and VMAT are better than for 3D-CRT with 2.00 ± 0.16. The HI's for the prescribed dose (HI36) for 3D-CRT were 1.06 ± 0.01 and 1.11 ± 0.02 for VMAT, respectively and 1.15 ± 0.02/1.10 ± 0.02/1.11 ± 0.08 for IMRT (PB-Corvus/PB-Hyperion/MC-Hyperion). Mean TTT and MU's for 3D-CRT is 220s/225 ± 11MU and for IMRT (PB-Corvus/PB-Hyperion/MC-Hyperion) is 575s/1260 ± 172MU, 570s/477 ± 84MU and 610s748 ± 193MU while TTT and MU for two-arc-VMAT is 290s/268 ± 19MU. Conclusion VMAT provides treatment plans with high conformity and homogeneity equivalent to step-and-shoot-IMRT for this mono-concave treatment volume. Short treatment delivery time and low primary MU are the most important advantages.

Simple Summary: This multicenter study (n = 1133, inclusion criteria: 3.5 cm maximum tumor size and preoperative indication for a boost) provides detailed data on acute and long-term toxicities in breast cancer patients undergoing breast-conserving surgery combined with an anticipated intraoperative boost with low-energy X-rays followed by whole breast irradiation. Toxicity assessments, based on LENT SOMA criteria, were performed annually up to 10 years of follow-up. IORT boost was completed in 90% and EBRT in 97% of cases. No grade 3 or 4 acute toxicities were observed, with mild acute side effects reported in a small proportion of patients. Chronic toxicities were seen in 16.2% of patients with teleangiectasia, 14.3% with grade ≥ 2 fibrosis, 3.4% with grade ≥ 2 pain, and 1.1% with hyperpigmentation. The results show that the therapy is safe and feasible in terms of toxicity and confirms intraoperative boost as a standard method of boost application in a large prospective cohort. In the context of breast cancer treatment optimization, this study prospectively examines the feasibility and outcomes of utilizing intraoperative radiotherapy (IORT) as a boost in combination with standard external beam radiotherapy (EBRT) for high-risk patients. Different guidelines recommend such a tumor bed boost in addition to whole breast irradiation with EBRT for patients with risk factors for local breast cancer recurrence. The TARGIT BQR (NCT01440010) is a prospective, multicenter registry study aimed at ensuring the quality of clinical outcomes. It provides, for the first time, data from a large cohort with a detailed assessment of acute and long-term toxicity following an IORT boost using low-energy X-rays. Inclusion criteria encompassed tumors up to 3.5 cm in size and preoperative indications for a boost. The IORT boost, administered immediately after tumor resection, delivered a single dose of 20 Gy. EBRT and systemic therapy adhered to local tumor board recommendations. Follow-up for toxicity assessment (LENT SOMA criteria: fibrosis, teleangiectasia, retraction, pain, breast edema, lymphedema, hyperpigmentation, ulceration) took place before surgery, 6 weeks to 90 days after EBRT, 6 months after IORT, and then annually using standardized case report forms (CRFs). Between 2011 and 2020, 1133 patients from 10 centers were preoperatively enrolled. The planned IORT boost was conducted in 90%, and EBRT in 97% of cases. Median follow-up was 32 months (range 1–120, 20.4% dropped out), with a median age of 61 years (range 30–90). No acute grade 3 or 4 toxicities were observed. Acute side effects included erythema grade 1 or 2 in 4.4%, palpable seroma in 9.1%, punctured seroma in 0.3%, and wound healing disorders in 2.1%. Overall, chronic teleangiectasia of any grade occurred in 16.2%, fibrosis grade ≥ 2 in 14.3%, pain grade ≥ 2 in 3.4%, and hyperpigmentation in 1.1%. In conclusion, a tumor bed boost through IORT using low-energy X-rays is a swift and feasible method that demonstrates low rates in terms of acute or long-term toxicity profiles in combination with whole breast irradiation. [ABSTRACT FROM AUTHOR]

Purpose: To compare the late toxicity profile of hypofractionation and normofractionation for whole-breast radiotherapy in breast cancer (BC) patients after conserving surgery. Methods: Sixty-year-old or older patients with pTis-pT3, pN0-pN1a, M0 BC were recruited and stratified to hypofractionated (arm R-HF) or normofractionated (arm L-NF) intensity-modulated radiotherapy (IMRT), for right- and left-sided BC, respectively, in this single-center, non-randomized, non-inferiority trial. A boost was allowed if indicated. The primary outcome was the cumulative percentage of patients developing grade III fibrosis, grade I telangiectasia, and/or grade II hyperpigmentation after 2 years, with a pre-specified non-inferiority margin of 15% increase from an expected 2-year toxicity rate of 20%. Results: The Median follow-up was 4.93 (0.57–8.65) years for R-HF and 5.02 (0.65–8.72) years for L-NF (p=0.236). The median age was 68 (60–83 and 60–80) years, respectively. In total, 226 patients were recruited (107 for R-HF and 119 for L-NF), with 100 and 117 patients suitable for assessment, respectively. A boost was delivered in 51% and 53% of each arm, respectively. Median PTV volumes were 1013.6 (273–2805) cm3 (R-HF) and 1058.28 (315–2709) cm3 (L-NF, p=0.591). The 2-year primary endpoint rate was 6.1% (95% CI 1.3-11.7, n=5 of 82) and 13.3% (95% CI 7-20.2, n=14 of 105), respectively (absolute difference -7.2%, one-sided 95% CI ∞ to -0.26, favoring R-HF). No local recurrence-free- or overall-survival differences were found. Conclusion: In this prospective non-randomized study, hypofractionation did not have higher toxicity than normofractionated whole-breast IMRT. [ABSTRACT FROM AUTHOR]

Purpose: To characterize treatment plan (TP) quality, a quantitative quality control (QC) tool is proposed. The tool is validated using volumetric modulated arc therapy (VMAT) plans for treatment of prostate cancer by estimating the achievable organ at risk (OAR) sparing, based on the knowledge learned from prior plans. Methods: Prostate TP quality was investigated by evaluating the achieved OAR sparing in the rectum and bladder, based on their proximity to target surface. The knowledge base used in this work comprises 450 plans, consisting of 181 homogenous prostate plans and 269 simultaneous integrated boost (SIB) prostate plans. A knowledge‐based algorithm was used to relate the absorbed doses of the OARs (rectum and bladder) and their proximity to the planning target volume (PTV). A metric (Mq,r value) was calculated to characterize the OAR sparing based on the weighted differences of the mean doses at binned distances to the PTV surface. The 90% probability ellipse of the normally distributed OARs Mq,r values was considered to define a threshold above which the treatment plan was re‐optimized. Results: Following re‐optimization, 8/11 of the homogenous plans and 6/13 of the SIB plans outside the 90% probability ellipse could be re‐optimized to gain better OAR sparing while achieving the same or better target coverage. However, 3/4 of the homogenous TPs and 1/9 of the SIB TPs between 80% and 90% were improved. Mq,r values of bladder and rectum after re‐optimizing the plans in both groups of homogenous and SIB showed lower values compared to the corresponding values before re‐optimization, which implies that better OARs sparing was achieved. Conclusions: This work demonstrates an effective anatomy‐specific QC tool for identifying suboptimal plans and determining the achievable OAR sparing for each individual patient anatomy. [ABSTRACT FROM AUTHOR]

Purpose: Radiotherapy is the mainstay in the treatment of locally inoperable tumors. Interstitial electronic needlebased kilovoltage brachytherapy (EBT) could be an economic alternative to high-dose-rate (HDR) brachytherapy or permanent seed implantation (PSI). In this work, we evaluated if locally inoperable tumors treated with PSI at our institution may be suitable for EBT. Material and methods: A total of 10 post-interventional computed tomography (CT) scans of patients, who received PSI and simulated stepping-source EBT applied with Intrabeam system and needle applicator were used. EBT treatment planning software with 3-dimensional image and projection of applicator were applied for designing trajectories and establishing dwell positions. Dwell position doses were summarized, and doses covering 90% of the target volume (D90) achieved with stepping-source EBT were compared to those of PSI. Additionally, conformality of dose distributions and total irradiation time were assessed using conformation number (CN) or conformal index (COIN). Results: In all patients, D90 of EBT exceeded the prescribed dose or D90 of PSI on average by 4.7% or 21.3% relative to the prescribed dose, respectively. Mean number of trajectories was 5.0 for EBT and 6.9 for PSI. Average CN/COIN for EBT was 0.69, with a mean irradiation time of 27.8 minutes for standardized dose of 13 Gy. Conclusions: Stepping-source EBT allowed for a conformal treatment of inoperable interstitial tumors with similar D90. Fewer trajectories were required for EBT in majority of cases. [ABSTRACT FROM AUTHOR]

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Copyright of Strahlentherapie und Onkologie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: To dosimetrically evaluate different breast SIB techniques with respect to target coverage and organs at risk (OARs) doses. Methods: Four IMRT techniques were compared in 12 patients. Three techniques employ tangential whole breast irradiation with either two coplanar fields (T-2F), or four non-coplanar fields (T-NC), or one Volumetric Modulated Arc Therapy (T-VMAT) for the boost volume. The fourth technique is a fully-modulated VMAT technique (f-VMAT). Dosimetric parameters were compared for the boost and breast target volumes as well as OARs. Delivery efficiency was analysed based on number of monitor units (MUs) and estimated delivery time. Results: T-VMAT and f-VMAT ranked highest with respect to integral assessment of boost and breast treatment quality measures. T-VMAT significantly outperformed f-VMAT with respect to ipsi-lateral lung and left-sided patients' heart volumes ≥ 5 Gy (35 % ± 5 % vs. 52 % ± 6 % and 11 %±5 % vs. 22 %±6 %, respectively). f-VMAT significantly outperformed T-VMAT with respect to ipsi-lateral lung volume ≥ 20 Gy (13 % ± 2 % vs. 15 % ± 3 %) and heart volume ≥ 30 Gy in left breast cancer (0 % ± 0 % vs. 1 % ± 1 %). T-VMAT and f-VMAT needed 442 ± 58 and 1016 ± 152 MUs, respectively. Conclusions: The hybrid T-VMAT is considered the technique of choice due to its balance of quality, efficiency and dose to OARs. [ABSTRACT FROM AUTHOR]

Background Glioblastoma multiforme (GBM) is the most frequent primary malignant brain tumor in adults. Despite multimodal therapies, almost all GBM recur within a narrow margin around the initial resected lesion. Thus, novel therapeutic intensification strategies must target both, the population of dispersed tumor cells around the cavity and the postoperative microenvironment. Intraoperative radiotherapy (IORT) is a pragmatic and effective approach to sterilize the margins from persistent tumor cells, abrogate post-injury proliferative stimuli and to bridge the therapeutic gap between surgery and radiochemotherapy. Therefore, we have set up INTRAGO, a phase I/II dose-escalation study to evaluate the safety and tolerability of IORT added to standard therapy in newly diagnosed GBM. In contrast to previous approaches, the study involves the application of isotropic low-energy (kV) x-rays delivered by spherical applicators, providing optimal irradiation properties to the resection cavity. Methods and design INTRAGO includes patients aged 50 years or older with a Karnofsky performance status of at least 50% and a histologically confirmed (frozen sections) supratentorial GBM. Safety and tolerability (i.e., the maximum tolerated dose, MTD) will be assessed using a classical 3 + 3 dose-escalation design. Dose-limiting toxicities (DLT) are wound healing deficits or infections requiring surgical intervention, IORT-related cerebral bleeding or ischemia, symptomatic brain necrosis requiring surgical intervention and early termination of external beam radiotherapy (before the envisaged dose of 60 Gy) due to radiotoxicity. Secondary end points are progression-free and overall survival. Trial registration The study is registered with clinicaltrials.gov, number: NCT02104882 (Registration Date: 03/26/2014). [ABSTRACT FROM AUTHOR]

Purpose: Evaluation of dose escalated salvage radiotherapy (SRT) in patients after radical prostatectomy (RP) who had never received antihormonal therapy. To investigate prognostic factors of the outcome of SRT and to analyze which patient subsets benefit most from dose escalation.Materials and Methods: Between 2002 and 2008, 76 patients were treated in three different dose-groups: an earlier cohort treated with 66 Gy irrespective of pre-RT-characteristics and two later cohorts treated with 70 Gy or 75 Gy depending on pre-RT-characteristics. Biochemical-relapse-free-survival (bRFS), clinical-relapse-free-survival (cRFS) and late toxicity were evaluated.Results: Four-year bRFS and cRFS were 62.5% and 85%. Gleason score <8, positive surgical resection margin (PSRM) and low PSA (≤0.5 ng/ml) before SRT resulted in higher bRFS. Analysis of the whole group showed no clear dose-outcome relationship. Patients with PSRM, however, had improved bRFS when escalating >66 Gy. While > 70 Gy did not improve the overall results, 4-year bRFS for patients with manifest local recurrence in the high-dose group was still comparable to those without manifest local recurrences. No grade 4 and minimal grade 3 gastrointestinal and urinary toxicity were observed.Conclusions: Dose-escalated SRT achieves high biochemical control. The data strongly support the application of at least 70 Gy rather than 66 Gy. They do not prove positive effects of doses >70 Gy but do not disprove them as these doses were only applied to an unfavorable patients selection. [ABSTRACT FROM AUTHOR]

Purpose: Stereotactic radiosurgery represents one of the main treatment options for acoustic neuromas. At our institution, patients suffering from these tumors are either treated with linear accelerators (linacs) or Leksell Gamma Knife® (LGK, Elekta AB, Sweden). Although a single LGK fraction is preferred, in cases where the tumor is involving or abutting the brainstem, cranial nerves or cochlea, homogeneous normofractionated treatments are usually adopted. In this study, we investigated the range of homogeneity and organ at risk (OAR) sparing that can be achieved using a non-clinical alpha version of LGK Lightning enabling higher homogeneity. Methods: The data sets of six patients treated for acoustic neuromas at our institution were retrospectively analyzed. All tumors were either abutting and/or compressing the brainstem and/or the cochlea. For each patient, four treatment plans were generated (54Gy,1.8Gy/fx): one linac plan using Monaco (Elekta AB, Sweden) treatment planning system, one LGK Lightning plan (LGK) using the clinical version 11.3 and two LGK Lightning plans using the alpha version. Each plan was normalized to D95% of the target volume and the metrics Dmean and D2% for OAR were determined. Gradient Index (GI), Paddick Conformity Index (PCI) and Homogeneity Index (HI) were calculated, beam-on-times (BOT) reported and a mean dose-volume-histogram was generated (figure 1). Results: The linac and LGK clinical plans show the highest and lowest possible homogeneity and OAR doses, respectively. The two alpha plans represent the possible homogeneity range in-between: one plan gives the highest achievable homogeneity (LGK Hom) while the other promotes OAR sparing (LGK OAR). The median values were: GI 7.25 (linac), 3.5 (LGK Hom), 3.46 (LGK OAR) and 2.81 (LGK); PCI 0.74 (linac), 0.71 (LGK Hom), 0.7 (LGK OAR) and 0.79 (LGK); HI 1.1 (linac), 1.23 (LGK Hom), 1.33 (LGK OAR) and 1.6 (LGK). D2%,median brainstem was reduced from 30.3 Gy (linac) to 23.9 Gy (LGK Hom), 21.6 Gy (LGK OAR) and 16.3 Gy (LGK). Median Dmean cochlea decreased from 33.6 Gy (linac) to 26.3 Gy (LGK Hom), 22.7 Gy (LGK OAR) and 21.2 Gy (LGK). The median BOT per fraction was 73s (linac), 300s (LGK Hom), 330s (LGK OAR) and 600s (LGK). Conclusion: In this study we showed that the homogeneity of the LGK plans can be enhanced towards linac homogeneity while maintaining low OAR doses. Besides the reduction of BOT by up to half, higher dose gradients were observed. [ABSTRACT FROM AUTHOR]

Abstract: Purpose/objective(s): IMRT allows dose escalation for large lung tumors, but respiratory motion may compromise delivery. A treatment plan that modulates fluence predominantly in the transversal direction and leaves the fluence identical in the direction of the breathing motion may reduce this problem. Materials/methods: Planning-CT-datasets of 20 patients with Stage I–IV non small cell lung cancer (NSCLC) formed the basis of this study. A total of two IMRT plans and one 3D plan were created for each patient. Prescription dose was 60Gy to the CTV and 70Gy to the GTV. For the 3D plans an energy of 18MV photons was used. IMRT plans were calculated for 6MV photons with 13 coplanar and with 17 noncoplanar beams. Robustness of the used method of anisotropic modulation toward breathing motion was tested in a 13-field IMRT plan. Results: As a consequence of identical prescription doses, mean target doses were similar for 3D and IMRT. Differences between 3D and 13- and 17-field IMRT were significant for CTV Dmin (43Gy vs. 49.1Gy vs. 48.6Gy; p <0.001) and CTV D 95 (53.2Gy vs. 55.0Gy vs. 55.4Gy; p =0.001). The D mean of the contralateral lung was significantly lower in the 17-field plans (17-field IMRT vs. 13- vs. 3D: 12.5Gy vs. 14.8Gy vs. 15.8Gy: p <0.05). The spinal cord dose limit of 50Gy was always respected in IMRT plans and only in 17 of 20 3D-plans. Heart D max was only marginally reduced with IMRT (3D vs. 13- vs. 17-field IMRT: 38.2Gy vs. 36.8Gy vs. 37.8Gy). Simulated breathing motion caused only minor changes in the IMRT dose distribution (∼0.5–1Gy). Conclusions: Anisotropic modulation of IMRT improves dose delivery over 3D-RT and renders IMRT plans robust toward breathing induced organ motion, effectively preventing interplay effects. [Copyright &y& Elsevier]

Background/purpose: Radiotherapy (RT) volumes for anal cancer are large and of moderate complexity when organs at risk (OAR) such as testis, small bowel and bladder are at least partially to be shielded. Volumetric intensity modulated arc therapy (VMAT) might provide OAR-shielding comparable to step-and-shoot intensity modulated radiotherapy (IMRT) for this tumor entity with better treatment efficiency.Materials and Methods: Based on treatment planning CTs of 8 patients, we compared dose distributions, comformality index (CI), homogeneity index (HI), number of monitor units (MU) and treatment time (TTT) for plans generated for VMAT, 3D-CRT and step-and-shoot-IMRT (optimized based on Pencil Beam (PB) or Monte Carlo (MC) dose calculation) for typical anal cancer planning target volumes (PTV) including inguinal lymph nodes as usually treated during the first phase (0-36 Gy) of a shrinking field regimen.Results: With values of 1.33 +/- 0.21/1.26 +/- 0.05/1.3 +/- 0.02 and 1.39 +/- 0.09, the CI's for IMRT (PB-Corvus/PB-Hyperion/MC-Hyperion) and VMAT are better than for 3D-CRT with 2.00 +/- 0.16. The HI's for the prescribed dose (HI36) for 3D-CRT were 1.06 +/- 0.01 and 1.11 +/- 0.02 for VMAT, respectively and 1.15 +/- 0.02/1.10 +/- 0.02/1.11 +/- 0.08 for IMRT (PB-Corvus/PB-Hyperion/MC-Hyperion). Mean TTT and MU's for 3D-CRT is 220s/225 +/- 11MU and for IMRT (PB-Corvus/PB-Hyperion/MC-Hyperion) is 575s/1260 +/- 172MU, 570s/477 +/- 84MU and 610s748 +/- 193MU while TTT and MU for two-arc-VMAT is 290s/268 +/- 19MU.Conclusion: VMAT provides treatment plans with high conformity and homogeneity equivalent to step-and-shoot-IMRT for this mono-concave treatment volume. Short treatment delivery time and low primary MU are the most important advantages. [ABSTRACT FROM AUTHOR]

• Intraoperative radiotherapy as a boost added to the standard of care treatment is safe and feasible. • Apparently, intraoperative radiotherapy for glioblastoma increases the overall survival rate (~25% at 3 years). • Local failure was first progression in 35.3% of cases. • No additional severe toxicity was related to this modality in comparison to conventional treatment. To report the results of the first international pooled analysis of patients with glioblastoma treated with intraoperative radiotherapy (IORT) in addition to standard of care therapy. Data from 51 patients treated at five centers in Germany, China and Peru were analyzed. All patients underwent tumor resection followed by a single application of IORT (10–40 Gy, prescribed to the applicator surface) with low-energy X-rays. Thereafter, standard adjuvant radiochemotherapy and maintenance chemotherapy were applied. Factors of interest were overall survival (OS), progression-free survival (PFS), local PFS (L-PFS; defined as appearance of new lesions ≤1 cm to the cavity border) and distant PFS (D-PFS; lesions >1 cm). The same endpoints were estimated at 1-, 2- and 3-years using the Kaplan-Meier method. Additionally, rates and severity (as per Common Terminology Criteria for Adverse Events Version 5.0) of radionecrosis (RN) were analyzed. The median age was 55 years (range: 16–75) and the median Karnofsky Performance Status was 80 (20–100). At a median follow-up of 18.0 months (2–42.4), the median OS, PFS, L-PFS and D-PFS were 18.0 months (95% CI: 14.7–21.3), 11.4 months (95%CI: 7.58–15.22), 16 months (95%CI: 10.21–21.8) and 30.0 months (95%CI: 18.59 – 41.41), respectively. The estimated 1-, 2- and 3-year OS, PFS, L-PFS and D-PFS were 79.5%, 38.7% and 25.6%; 46.2%, 29.4%, and 5.9%; 60.9, 37.9%, and 12.6%; and 76.7%, 65.0%, and 39.0% respectively. First progression occurred locally in only 35.3% of cases. Grade 1 RN was detected in 7.8% and grade 3 in 17.6% of the patients. No grade 4 toxicity was reported and no treatment-related deaths occurred. Compared to historical data, this pooled analysis suggests improved efficacy and safety of IORT with low-energy X-rays for newly diagnosed glioblastoma. Prospective data is warranted to confirm these findings. [ABSTRACT FROM AUTHOR]

Background: Intraoperative radiotherapy can serve as an anticipated boost (IORT boost) in combination with a subsequent external whole breast irradiation in high-risk breast cancer patients and is part of many guidelines. Nevertheless, there are only few prospective data available regarding cosmetic outcome after IORT boost using kV X-rays. The aim of this study was to evaluate the cosmetic outcome of patients treated within the prospective phase IV TARGeted Intraoperative radioTherapy (TARGIT) Boost Quality Registry (BQR) study (NCT01440010) in one center., Methods: In the context of the TARGIT BQR study standardized photos in three positions (arms down, arms up, from the side) were available for different time points. For this analysis a layperson, a radiation oncologist and a gynecologist evaluated available photos at different time points during follow-up with up to 4 years using the Harvard scale (comparison of treated and the untreated breast; rating: excellent, good, fair, poor). Longitudinal results were compared to preoperative results (baseline)., Results: Seventy-three patients were available for the analysis. Baseline cosmetic assessment was excellent/good in 98.8% (mean value for all three positions). Postoperative cosmetic outcome (median) was good for all positions and remained constant for 4 years. Around 30% of the patients showed a constant or even improved cosmetic outcome compared to baseline. Only few patients showed a poor result at 4 years. The majority of patients showed an excellent or good cosmetic outcome at all time points., Conclusions: Patients from the prospective TARGIT BQR study treated with IORT boost and additional whole breast irradiation showed good or excellent cosmetic outcomes in most cases during 4 years of follow-up. These results add important information for shared decision making in breast cancer patients., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tcr.amegroups.com/article/view/10.21037/tcr-23-88/coif). ES received personal honoraria and travel costs for scientific talks at meetings and educational events from Carl Zeiss Meditec AG. ES was also an unpaid board member of ISIORT (International Society for Intraoperative Radiotherapy). The other authors have no conflicts of interest to declare., (2023 Translational Cancer Research. All rights reserved.)

Purpose: Radiotherapy is the mainstay in the treatment of locally inoperable tumors. Interstitial electronic needle-based kilovoltage brachytherapy (EBT) could be an economic alternative to high-dose-rate (HDR) brachytherapy or permanent seed implantation (PSI). In this work, we evaluated if locally inoperable tumors treated with PSI at our institution may be suitable for EBT., Material and Methods: A total of 10 post-interventional computed tomography (CT) scans of patients, who received PSI and simulated stepping-source EBT applied with Intrabeam system and needle applicator were used. EBT treatment planning software with 3-dimensional image and projection of applicator were applied for designing trajectories and establishing dwell positions. Dwell position doses were summarized, and doses covering 90% of the target volume (D 90 ) achieved with stepping-source EBT were compared to those of PSI. Additionally, conformality of dose distributions and total irradiation time were assessed using conformation number (CN) or conformal index (COIN)., Results: In all patients, D 90 of EBT exceeded the prescribed dose or D 90 of PSI on average by 4.7% or 21.3% relative to the prescribed dose, respectively. Mean number of trajectories was 5.0 for EBT and 6.9 for PSI. Average CN/COIN for EBT was 0.69, with a mean irradiation time of 27.8 minutes for standardized dose of 13 Gy., Conclusions: Stepping-source EBT allowed for a conformal treatment of inoperable interstitial tumors with similar D 90 . Fewer trajectories were required for EBT in majority of cases., Competing Interests: AMR, LI, JH, UO, and FW have nothing to disclose. FS, YAM, and FB report personal fees from CARL ZEISS MEDITEC AG, outside the submitted work. GRS reports grants and personal fees from CARL ZEISS MEDITEC AG, outside the submitted work. FG reports personal fees from Siemens Healthcare Diagnostics GmbH, grants, and personal fees from NOXXON Pharma AG, grants and personal fees from CARL ZEISS MEDITEC AG, personal fees from Merck Serono GmbH, personal fees from Roche Pharma AG, outside the submitted work; in addition, FG has a patent (US 62/435405) pending., (Copyright © 2020 Termedia.)

Purpose: Concurrent chemo-radiotherapy (CCRT) is the primary treatment modality for locally advanced head and neck squamous cell cancer patients (LAHNSCC). Intensity modulated radiotherapy (IMRT) with simultaneous integrated boost (SIB) and concurrent chemotherapy is not broadly implicated in our region mainly because of the lack of experience. This study aims at evaluating the response and compliance of this approach in our patients., Methods: Forty patients with LAHNSCC were included and 50% received induction chemotherapy. All the patients were treated with IMRT-SIB radiotherapy for 70Gy over 33 daily fractions. Weekly cisplatin (40mg/m2) was administered during the radiation course., Results: With median follow-up of 1.5 years, LC was achieved in 82.5% of cases and distant control rate was 90%. More than 5 interrupted radiation sessions and GTV volume > 50 cc significantly affected LRC (P= 0.02 and 0.001 respectively). Eighty percent of cases experienced grade 3 or 4 toxicities. Induction chemotherapy and PTV-70 volume >150 cc significantly affected the degree of toxicities (P=0.018 and 0.0001 respectively).The 2 years disease free survival (DFS) was 77%. ECOG PS, large GTV volume (> 50 cc) and RT interruption (>5 sessions) had negative impact on DFS (P= 0.041, 0.002 and 0.001 respectively). The 2 years overall survival (OS) was 87%. Radiation interruption (> 5 sessions) was the only factor which had significant detrimental effect on OS (P= 0.001)., Conclusion: Induction chemotherapy seems to have a negative impact on patient's compliance to CCRT. Bulky tumors and prolonged radiation interruptions were associated with significantly lower LRC, DFS and OS.

Purpose: A method is presented to radiobiologically compare sequential (SEQ) and simultaneously integrated boost (SIB) breast radiotherapy., Methods: The method is based on identically prescribed biologically effective dose (iso-BED) which was achieved by different prescribed doses due to different fractionation schemes. It is performed by converting the calculated three-dimensional dose distribution to the corresponding BED distribution taking into consideration the different number of fractions for generic α/β ratios. A cumulative BED volume histogram (BEDVH) is then derived from the BED distribution and is compared for the two delivery schemes. Ten breast cancer patients (4 right-sided and 6 left-sided) were investigated. Two tangential intensity modulated whole breast beams with two other oblique (with different gantry angles) beams for the boost volume were used. The boost and the breast target volumes with either α/β = 10 or 3 Gy, and ipsi-lateral and contra-lateral lungs, heart, and contra-lateral breast as organs at risk (OARs) with α/β = 3 Gy were compared., Results: Based on the BEDVH comparisons, the use of SIB reduced the biological breast mean dose by about 3 %, the ipsi-lateral lung and heart by about 10 %, and contra-lateral breast and lung by about 7 %., Conclusion: BED based comparisons should always be used in comparing plans that have different fraction sizes. SIB schemes are dosimetrically more advantageous than SEQ in breast target volume and OARs for equal prescribed BEDs for breast and boost.

The use of IORT as a treatment modality for patients with close or positive margins has increased over the past decade. For situations where a flat area (up to 6 cm in diameter) has to be treated intraoperatively, new applicators for superficial treatment with a miniature X-ray source (INTRABEAM system) were developed. Here we report our evaluation of the dosimetric characteristics of these new applicators and their first clinical use. Each of these flat and surface applicators consists of a radiation protective metal tube and a flattening filter, which converts the spherical dose distribution of the X-ray source into a flat one. The homogeneity of each dose distribution and depth-dose measurements were evaluated using film dosimetry in a solid water phantom and a soft X-ray ionization chamber in a water tank. The first patient was treated with 5 Gy delivered in 5 mm using a 4 cm FLAT applicator over 21 minutes. The flat applicators show the maximum homogeneity, with a uniformity ratio of 1.02-1.08 in certain depths. In 1 mm depth surface applicators show a uniformity ratio of 1.15-1.28. They also show a higher dose rate and a steeper dose gradient compared to the flat applicators. The results of this investigation demonstrated that the flat and surface applicators have unique dosimetric characteristics that need to be considered during the treatment planning stages. This work also showed that it is possible to perform a superficial localized IORT which provides new application possibilities for use of the INTRABEAM system.

Prophylactic cranial irradiation (PCI) with total doses of 20-30 Gy reduces the incidence of brain metastasis (BM) and increases survival of patients with limited and extensive-disease small-cell lung cancer (SCLC) that showed any response to chemotherapy. PCI is currently not applied in non-small-cell lung cancer (NSCLC) since it has not proven to significantly improve OS rates in stage IIIA/B, although novel data suggest that subgroups that could benefit may exist. Here we briefly review potential toxicities of PCI which have to be considered before prescribing PCI. They are mostly difficult to delineate from pre-existing risk factors which include preceding chemotherapy, patient age, paraneoplasia, as well as smoking or atherosclerosis. On the long run, this will force radiation oncologists to evaluate each patient separately and to estimate the individual risk. Where PCI is then considered to be of benefit, novel concepts, such as intensity-modulated radiotherapy and/or neuroprotective drugs with potential to lower the rates of side effects will eventually be superior to conventional therapy. This in turn will lead to a re-evaluation whether benefits might then outweigh the (lowered) risks.