On dosimetric characteristics of detectors for relative dosimetry in small fields: a multicenter experimental study.

Objective. In this multicentric collaborative study, we aimed to verify whether the selected radiation detectors satisfy the requirements of TRS-483 Code of Practice for relative small field dosimetry in megavoltage photon beams used in radiotherapy, by investigating four dosimetric characteristics. Furthermore, we intended to analyze and complement the recommendations given in TRS-483.Approach. Short-term stability, dose linearity, dose-rate dependence, and leakage were determined for 17 models of detectors considered suitable for small field dosimetry. Altogether, 47 detectors were used in this study across ten institutions. Photon beams with 6 and 10 MV, with and without flattening filters, generated by Elekta Versa HDTMor Varian TrueBeamTMlinear accelerators, were used.Main results. The tolerance level of 0.1% for stability was fulfilled by 70% of the data points. For the determination of dose linearity, two methods were considered. Results from the use of a stricter method show that the guideline of 0.1% for dose linearity is not attainable for most of the detectors used in the study. Following the second approach (squared Pearson's correlation coefficientr2), it was found that 100% of the data fulfill the criteriar2> 0.999 (0.1% guideline for tolerance). Less than 50% of all data points satisfied the published tolerance of 0.1% for dose-rate dependence. Almost all data points (98.2%) satisfied the 0.1% criterion for leakage.Significance. For short-term stability (repeatability), it was found that the 0.1% guideline could not be met. Therefore, a less rigorous criterion of 0.25% is proposed. For dose linearity, our recommendation is to adopt a simple and clear methodology and to define an achievable tolerance based on the experimental data. For dose-rate dependence, a realistic criterion of 1% is proposed instead of the present 0.1%. Agreement was found with published guidelines for background signal (leakage).

CyberKnife versus multicatheter interstitial brachytherapy for accelerated partial breast irradiation: a dosimetrical assessment with focus on organs at risk.

Background: The purpose of the study was to dosimetrically compare multicatheter interstitial brachytherapy (MIBT) and stereotactic radiotherapy with CyberKnife (CK) for accelerated partial breast irradiation with special focus on dose to organs at risk (OARs). Materials and methods: Treatment plans of thirty-one patients treated with MIBT were selected and additional CK plans were created on the same CT images. The OARs included ipsilateral non-target and contralateral breast, ipsilateral and contralateral lung, skin, ribs, and heart for left sided cases. The fractionation was identical (4 × 6.25 Gy). Dose-volume parameters were calculated for both techniques and compared. Results: The D90 of the PTV for MIBT and CK were similar (102.4% vs. 103.6%, p = 0.0654), but in COIN the MIBT achieved lower value (0.75 vs. 0.91, p < 0.001). Regarding the V100 parameter of non-target breast CK performed slightly better than MIBT (V100: 1.1% vs. 1.6%), but for V90, V50 and V25 MIBT resulted in less dose. Every examined parameter of ipsilateral lung, skin, ribs and contralateral lung was significantly smaller for MIBT than for CK. Protection of the heart was slightly better with MIBT, but only the difference of D2cm3 was statistically significant (17.3% vs. 20.4%, p = 0.0311). There were no significant differences among the dose-volume parameters of the contralateral breast. Conclusion: The target volume can be properly irradiated by both techniques with high conformity and similar dose to the OARs. MIBT provides more advantageous plans than CK, except for dose conformity and the dosimetry of the heart and contralateral breast. More studies are needed to analyze whether these dosimetrical findings have clinical significance.

Relationship between biodosimetric parameters and treatment volumes in three types of prostate radiotherapy.

Brachytherapy (BT) and external beam radiotherapy (EBRT) apply different dose rates, overall treatment times, energies and fractionation. However, the overall impact of these variables on the biological dose of blood is neglected. As the size of the irradiated volume influences the biological effect as well, we studied chromosome aberrations (CAs) as biodosimetric parameters, and explored the relationship of isodose surface volumes (ISVs: V1%, V1Gy, V10%, V10Gy, V100%, V150%) and CAs of both irradiation modalities. We performed extended dicentrics assay of lymphocytes from 102 prostate radiotherapy patients three-monthly for a year. Aberration frequency was the highest after EBRT treatment. It increased after the therapy and did not decrease significantly during the first follow-up year. We showed that various types of CAs 9 months after LDR BT, 3 months after HDR BT and in a long time-range (even up to 1 year) after EBRT positively correlated with ISVs. Regression analysis confirmed these relationships in the case of HDR BT and EBRT. The observed differences in the time points and aberration types are discussed. The ISVs irradiated by EBRT showed stronger correlation and regression relationships with CAs than the ISVs of brachytherapy.

Comparative dosimetrical analysis of intensity-modulated arc therapy, CyberKnife therapy and image-guided interstitial HDR and LDR brachytherapy of low risk prostate cancer.

BACKGROUND: The objective of the study was to dosimetrically compare the intensity-modulated-arc-therapy (IMAT), Cyber-Knife therapy (CK), single fraction interstitial high-dose-rate (HDR) and low-dose-rate (LDR) brachytherapy (BT) in low-risk prostate cancer. MATERIALS AND METHODS: Treatment plans of ten patients treated with CK were selected and additional plans using IMAT, HDR and LDR BT were created on the same CT images. The prescribed dose was 2.5/70 Gy in IMAT, 8/40 Gy in CK, 21 Gy in HDR and 145 Gy in LDR BT to the prostate gland. EQD2 dose-volume parameters were calculated for each technique and compared. RESULTS: EQD2 total dose of the prostate was significantly lower with IMAT and CK than with HDR and LDR BT, D90 was 79.5 Gy, 116.4 Gy, 169.2 Gy and 157.9 Gy (p < 0.001). However, teletherapy plans were more conformal than BT, COIN was 0.84, 0.82, 0.76 and 0.76 (p < 0.001), respectively. The D2 to the rectum and bladder were lower with HDR BT than with IMAT, CK and LDR BT, it was 66.7 Gy, 68.1 Gy, 36.0 Gy and 68.0 Gy (p = 0.0427), and 68.4 Gy, 78.9 Gy, 51.4 Gy and 70.3 Gy (p = 0.0091) in IMAT, CK, HDR and LDR BT plans, while D0.1 to the urethra was lower with both IMAT and CK than with BTs: 79.9 Gy, 88.0 Gy, 132.7 Gy and 170.6 Gy (p < 0.001). D2 to the hips was higher with IMAT and CK, than with BTs: 13.4 Gy, 20.7 Gy, 0.4 Gy and 1.5 Gy (p < 0.001), while D2 to the sigmoid, bowel bag, testicles and penile bulb was higher with CK than with the other techniques. CONCLUSIONS: HDR monotherapy yields the most advantageous dosimetrical plans, except for the dose to the urethra, where IMAT seems to be the optimal modality in the radiotherapy of low-risk prostate cancer.

Acute side effects after definitive stereotactic body radiation therapy (SBRT) for patients with clinically localized or locally advanced prostate cancer: a single institution prospective study.

BACKGROUND: The aim of the study was to evaluate acute side effects after extremely hypofractionated intensity-modulated radiotherapy (IMRT) with stereotactic body radiation therapy (SBRT) for definitive treatment of prostate cancer patients. PATIENTS AND METHODS: Between February 2018 and August 2019, 205 low-, intermediate- and high-risk prostate cancer patients were treated with SBRT using "CyberKnife M6" linear accelerator. In low-risk patients 7.5-8 Gy was delivered to the prostate gland by each fraction. For intermediate- and high-risk disease a dose of 7.5-8 Gy was delivered to the prostate and 6-6.5 Gy to the seminal vesicles by each fraction with a simultaneous integrated boost (SIB) technique. A total of 5 fractions (total dose 37.5-40 Gy) were given on every second working day. Acute radiotherapy-related genitourinary (GU) and gastrointestinal (GI) side effects were assessed using Radiation Therapy Oncology Group (RTOG) scoring system. RESULTS: Of the 205 patients (28 low-, 115 intermediate-, 62 high-risk) treated with SBRT, 203 (99%) completed the radiotherapy as planned. The duration of radiation therapy was 1 week and 3 days. The frequencies of acute radiotherapy-related side effects were as follows: GU grade 0 - 17.1%, grade I - 30.7%, grade II - 50.7%, grade III - 1.5%; and GI grade 0 - 62.4%, grade I-31.7%, grade II-5.9%, grade III-0%. None of the patients developed grade ≥ 4 acute toxicity. CONCLUSIONS: SBRT with a total dose of 37.5-40 Gy in 5 fractions appears to be a safe and well tolerated treatment option in patients with prostate cancer, associated with slight or moderate early side effects. Longer follow-up is needed to evaluate long-term toxicity and biochemical control.

Multicatheter interstitial brachytherapy versus stereotactic radiotherapy with CyberKnife for accelerated partial breast irradiation: a comparative treatment planning study with respect to dosimetry of organs at risk.

BACKGROUND: The aim of the study was to dosimetrically compare multicatheter interstitial brachytherapy (MIBT) and stereotactic radiotherapy with CyberKnife (CK) for accelerated partial breast irradiation (APBI) especially concerning the dose of organs at risk (OAR-s). PATIENTS AND METHODS: Treatment plans of thirty-two MIBT and CK patients were compared. The OAR-s included ipsilateral non-target and contralateral breast, ipsilateral and contralateral lung, skin, ribs, and heart for left-sided cases. The fractionation was identical (4 x 6.25 Gy) in both treatment groups. The relative volumes (e.g. V100, V90) receiving a given relative dose (100%, 90%), and the relative doses (e.g. D0.1cm3, D1cm3) delivered to the most exposed small volumes (0.1 cm3, 1 cm3) were calculated from dose-volume histograms. All dose values were related to the prescribed dose (25 Gy). RESULTS: Regarding non-target breast CK performed slightly better than MIBT (V100: 0.7% vs. 1.6%, V50: 10.5% vs. 12.9%). The mean dose of the ipsilateral lung was the same for both techniques (4.9%), but doses irradiated to volume of 1 cm3 were lower with MIBT (36.1% vs. 45.4%). Protection of skin and rib was better with MIBT. There were no significant differences between the dose-volume parameters of the heart, but with MIBT, slightly larger volumes were irradiated by 5% dose (V5: 29.9% vs. 21.2%). Contralateral breast and lung received a somewhat higher dose with MIBT (D1cm3: 2.6% vs. 1.8% and 3.6% vs. 2.5%). CONCLUSIONS: The target volume can be properly irradiated by both techniques with similar dose distributions and high dose conformity. Regarding the dose to the non-target breast, heart, and contralateral organs the CK was superior, but the nearby organs (skin, ribs, ipsilateral lung) received less dose with MIBT. The observed dosimetric differences were small but significant in a few parameters at the examined patient number. More studies are needed to explore whether these dosimetric findings have clinical significance.

Is stereotactic CyberKnife radiotherapy or multicatheter HDR brachytherapy the better option dosimetrically for accelerated partial breast irradiation?

OBJECTIVE: To compare dosimetrically the stereotactic CyberKnife (CK) therapy and multicatheter high-dose-rate (HDR) brachytherapy (BT) for accelerated partial breast irradiation (APBI). METHODS: Treatment plans of 25 patients treated with CK were selected, and additional plans using multicatheter HDR BT were created on the same CT images. The prescribed dose was 6.25/25 Gy in both plans to the target volume (PTV). The dose-volume parameters were calculated for both techniques and compared. RESULTS: The D90 total dose of the PTV was significantly lower with CK than with HDR BT, D90 was 25.7 Gy, and 27.0 Gy (p < 0.001). However, CK plans were more conformal than BT, COIN was 0.87, and 0.81 (p = 0.0030). The V50 of the non-target breast was higher with CK than with BT: 10.5% and 3.3% (p = 0.0010), while there was no difference in the dose of the contralateral breast and contralateral lung. Dose to skin, ipsilateral lung, and ribs were higher with CK than with BT: D1 was 20.6 Gy vs. 11.5 Gy (p = 0.0018) to skin, 11.4 Gy vs. 9.6 Gy (p = 0.0272) to ipsilateral lung and 18.5 Gy vs. 12.3 Gy (p = 0.0013) to ribs, while D0.1 to heart was lower, 3.0 Gy vs. 3.2 Gy (p = 0.0476), respectively. CONCLUSIONS: Multicatheter HDR BT yields more advantageous plans than stereotactic CyberKnife treatment in accelerated partial breast irradiation, except in terms of dose conformality and the dose to the heart. There was no difference in the dose of the contralateral breast and lung.

Accelerated partial breast irradiation with 3-dimensional conformal and image-guided intensity-modulated radiotherapy following breast conserving surgery - 7-Year results of a phase II trial.

PURPOSE: To present the 7-year results of accelerated partial breast irradiation (APBI) using three-dimensional conformal (3D-CRT) and image-guided intensity-modulated radiotherapy (IG-IMRT) following breast-conserving surgery (BCS). PATIENTS AND METHODS: Between 2006 and 2014, 104 patients were treated with APBI given by means of 3D-CRT using 3-5 non-coplanar, isocentric wedged fields, or IG-IMRT using kV-CBCT. The total dose of APBI was 36.9 Gy (9 × 4.1 Gy) using twice-a-day fractionation. Survival results, side effects and cosmetic results were assessed. RESULTS: At a median follow-up of 90 months three (2.9%) local recurrences, one (0.9%) regional recurrence and two (1.9%) distant metastases were observed. The 7-year local (LRFS), recurrence free survival was 98.9%. The 7-year disease-free (DFS), metastases free (MFS) and overall survival (OS) was 94.8%, 97.9% and 94.8%, respectively. Late side effects included G1 skin toxicity in 15 (14.4%), G1, G2, and G3 fibrosis in 26 (25%), 3 (2.9%) and 1 (0.9%) patients respectively. Asymptomatic (G1) fat necrosis occurred in 10 (9.6%) patients. No ≥ G2 or higher late side effects occurred with IMRT. The rate of excellent/good and fair/poor cosmetic results was 93.2% and 6.8%, respectively. CONCLUSION: 7-year results of APBI with 3D-CRT and IG-IMRT are encouraging. Toxicity profile and local tumor control are comparable to other series using multicatheter interstitial brachytherapy. Therefore, these external beam APBI techniques are valid alternatives to whole breast irradiation and brachytherapy based APBI.

Implementation of Stereotactic Accelerated Partial Breast Irradiation Using Cyber-Knife - Technical Considerations and Early Experiences of a Phase II Clinical Study.

To report the implementation, dosimetric results of and early experiences with stereotactic accelerated partial breast irradiation (SAPBI) following breast conserving surgery (BCS) for postmenopausal low-risk St I-II invasive breast cancer (IBC) patients. Between November 2018 and August 2019, 27 patients were registered in our phase II prospective study. SAPBI was performed with Cyber-Knife (CK) M6 machine, in 4 daily fractions of 6.25 Gy to a total dose of 25 Gy. Respiratory movements were followed with implanted gold markers and Synchrony system. Corrections for patient displacement and respiratory movement during treatment were performed with the robotic arm. Early side effects, cosmetic results, and dosimetric parameters were assessed. The average volume of the surgical cavity, clinical target volume (CTV), and planning target volume (PTV_EVAL) were 8.1 cm3 (range: 1.75-27.3 cm3), 55.3 cm3 (range: 26.2-103.5 cm3), and 75.7 cm3 (range: 40-135.4 cm3), respectively. The mean value of the PTV_eval/whole breast volume ratio was 0.09 (range: 0.04-0.19). No grade 2 or worst acute side-effect was detected. Grade 1 (G1) erythema occurred in 6 (22.2%) patients, while G1 oedema was reported by 3 (11.1%) cases. G1 pain was observed in 1 (3.4%) patient. Cosmetic result were excellent in 17 (62.9%) and good in 10 (37.1%) patients. SAPBI with CK is a suitable and practicable technique for the delivery of APBI after BCS for low-risk, St. I-II. IBC. Our early findings are encouraging, CK-SAPBI performed with four daily fractions is convenient and perfectly tolerated by the patients.

Acute and Late Toxicity after Moderate Hypofractionation with Simultaneous Integrated Boost (SIB) Radiation Therapy for Prostate Cancer. A Single Institution, Prospective Study.

ASBTRACT: To evaluate the acute and late toxicity using moderately hypofractionated, intensity-modulated radiotherapy (IMRT) with a simultaneous integrated boost (SIB) to prostate for patients with intermediate and high risk prostate cancer. From 2015 to 2017, 162 patients were treated with IMRT with SIB to the prostate. IMRT plans were designed to deliver 50.4Gy in 28 fractions (1.8 Gy/fraction) to the pelvic lymph nodes (whole pelvis radiotherapy, WPRT) while simultaneously delivering 57.4 Gy in 28 fractions (2.05 Gy/fraction) to the seminal vesicles and 70 Gy in 28 fractions (2.5 Gy/fraction) to the prostate for high risk patients. For intermediate risk patients the same technique was applied, without WPRT. Acute and cumulative late genitourinary (GU) and gastrointestinal (GI) toxicities were scored according to the Radiation Therapy Oncology Group (RTOG) scoring system. Of the 162 patients enrolled, 156 (96%) completed the treatment as planned. The median follow-up time was 30 months. Seventy-eight patients (48.2%) were treated with WPRT. The rate of acute grade ≥ 2 GI and GU toxicities in all patients were 22% and 58%, respectively. The rate of cumulative late grade ≥ 2 GI and GU toxicities were 11% and 17%, respectively. Acute grade 3 GI and GU toxicities occurred in 1% and 1%. Late grade 3 GI and GU side effects occurred in 5% and 4%, respectively. None of the patients developed grade ≥ 4 toxicity. IMRT with SIB technique using moderate hypofractionation to the prostate is feasible treatment option for intermediate and high risk patients, associated with low rate of severe GU and GI toxicities.

Measurement of dose exposure of image guidance in external beam accelerated partial breast irradiation: Evaluation of different techniques and linear accelerators.

INTRODUCTION: Verifying the patient position is always an essential part of the treatment process, especially in hypofractionated treatments such as accelerated partial breast irradiation (APBI). The purpose of the study was to compare five image guidance techniques with respect to imaging dose and image quality. METHODS AND MATERIALS: We chose five types of imaging methods applicable for APBI and measured their dose exposure on four different accelerators (Synergy, TrueBeam, Artiste and CyberKnife). Absorbed dose was measured with ionization chamber in thorax phantom. Besides dose exposure image quality was also compared. RESULTS: The lowest dose exposure was measured with kV-kV planar imaging followed by kV-CBCT, MV-MV pair and MV-CBCT in ascending order. Average phantom dose with kV-kV image pair on CyberKnife was 0.01 cGy as the lowest and with MV-CBCT on Artiste was 7.11 cGy as the highest. Average dose exposures of MV-MV images with TrueBeam, Synergy and Artiste were 1.18 cGy, 2.13 cGy and 1.61 cGy, respectively, with similar image quality. For the same machines the doses of kV-CT imaging were comparable: 0.65 cGy, 0.65 cGy and 0.52 cGy, with some differences in image quality. MV-CBCT technique resulted in the highest dose and poorest image quality. CONCLUSIONS: In APBI the position of the patient and tumour bed can be verified with many tools. When fiducials are available, often 2D imaging is enough to achieve appropriate positioning and the kV-kV method is recommended. Imaging with 2.5MV can also be a good solution instead of 6MV. Without fiducials 3D images should be acquired and the recommended method is the kV-CBCT.

Second breast-conserving surgery and interstitial brachytherapy vs. salvage mastectomy for the treatment of local recurrences: 5-year results.

PURPOSE: The purpose of this study was to report the clinical outcomes of a second breast-conserving therapy (2nd BCT) with perioperative interstitial brachytherapy (iBT) vs. those of salvage mastectomy (sMT) in the treatment of ipsilateral breast tumor recurrences (IBTRs). METHODS AND MATERIALS: Between 1999 and 2015, 195 patients with IBTR after a previous breast-conserving treatment were salvaged either with reexcision and perioperative high-dose-rate iBT (n = 39), or with sMT (n = 156). In the 2nd BCT group, a total dose of 22 Gy in five fractions of 4.4 Gy was delivered to the tumor bed with intraoperatively implanted catheters for 3 consecutive days. RESULTS: The median followup time was 59 months (1-189) in the 2nd BCT, and 56 months (3-189) in the sMT group. The mean size of IBTR was 16 mm (2-70) vs. 24 mm (2-90), respectively (p = 0.0005), but there were no other significant differences in patient- or IBTR-related parameters between the two groups. During the followup period, 4 of 39 (10.2%) and 28 of 156 (17.9%) second local recurrences (2nd LR) occurred in the 2nd BCT and the sMT group, respectively. The 5-year actuarial rate of 2nd LR was 6% vs. 18% (p = 0.22), the 5-year probability of disease-free, cancer-specific and overall survival was 69% vs. 65% (p = 0.13), 85% vs. 78% (p = 0.32), and 81% vs. 66% (p = 0.15), respectively. In the 2nd BCT group, the rate of good to excellent cosmesis was 70%. CONCLUSIONS: 2nd BCT with perioperative high-dose-rate iBT is a safe and feasible option for the management of IBTR, resulting in similar 5-year oncological outcomes and better cosmetic results compared with sMT.

[Stereotactic body radiation therapy with CyberKnife accelerator for low- and intermediate risk prostate cancer]. / Kis és közepes kockázatú prosztatarákos betegek sztereotaxiás sugárkezelése CyberKnife gyorsítóval: korai radiogén mellékhatások.

We report implementation of stereotactic body radiotherapy (SBRT) for the treatment of early, localized prostate cancer patients, and acute side effects caused by radiation therapy. Between February 2018 and July 2018, 36 prostate cancer patients were treated with SBRT. Treatments were performed with "CyberKnife M6" linear accelerator. In low-risk patients 8 Gy was delivered to the prostate in each fraction. For intermediate risk, 8 Gy to the prostate and 6.5 Gy to the seminal vesicles were delivered by each fraction with a simultaneous integrated boost technique. A total of 5 fractions (total dose 40 Gy) were given every second working days. Acute radiogenic genitourinary (GU) and gastrointestinal (GI) side effects were assessed using the Radiation Therapy Oncology Group (RTOG) score. The duration of radiotherapy was 1 week and 3 days. The frequency of acute radiogenic side effects was as follows: GU grade 0: 13.9%, grade I: 30.6%, grade II: 52.8%, grade III: 2.7%. GI grade 0: 55.5%, grade I: 30.6%, grade II: 13.9%, grade III: 0%. Grade IV-V side effects were not observed. SBRT appears to be a safe and well tolerated treatment in patients with early stage, localized prostate cancer.

External beam accelerated partial breast irradiation: dosimetric assessment of conformal and three different intensity modulated techniques.

Background The aim of the study was to evaluate and compare four different external beam radiotherapy techniques of accelerated partial breast irradiation (APBI) considering target coverage, dose to organs at risk and overall plan quality. The investigated techniques were three dimensional conformal radiotherapy (3D-CRT), "step and shoot" (SS) and "sliding window" (SW) intensity-modulated radiotherapy (IMRT), intensity-modulated arc therapy (RA). Patients and methods CT scans of 40 APBI patients were selected for the study. The planning objectives were set up according to the international recommendations. Homogeneity, conformity and plan quality indices were calculated from volumetric and dosimetric parameters of target volumes and organs at risk. The total monitor units and feasibility were also investigated. Results There were no significant differences in the coverage of the target volume between the techniques. The homogeneity indices of 3D-CRT, SS, SW and RA plans were 0.068, 0.074, 0.058 and 0.081, respectively. The conformation numbers were 0.60, 0.80, 0.82 and 0.89, respectively. The V50% values of the ipsilateral breast for 3D-CRT, SS, SW and RA were 47.5%, 40.2%, 39.9% and 31.6%, respectively. The average V10% and V40% values of ipsilateral lung were 13.1%, 28.1%, 28%, 36% and 2.6%, 1.9%, 1.9%, 3%, respectively. The 3D-CRT technique provided the best heart protection, especially in the low dose region. All contralateral organs received low doses. The SW technique achieved the best plan quality index (PQI). Conclusions Good target volume coverage and tolerable dose to the organs at risk are achievable with all four techniques. Taking into account all aspects, we recommend the SW IMRT technique for APBI.

[Second breast conserving surgery and interstitial radiotherapy for the treatment of breast tumor local recurrences. Five-year results]. / Második emlomegtartó mutét és szövetközi sugárkezelés az emlodaganat lokális kiújulásának kezelésére. Ötéves eredmények.

INTRODUCTION AND AIM: To report the clinical outcomes of second breast-conserving therapy with perioperative interstitial radiotherapy for the treatment of ipsilateral breast tumor recurrences. METHOD: Between 1999 and 2015, 33 patients, presenting with an ipsilateral breast tumor recurrence after previous breast conserving therapy, were salvaged by re-excision and perioperative high-dose-rate interstitial brachytherapy. A median of 8 (range: 4-24) catheters were implanted into the tumor bed intraoperatively. A total dose of 22 Gy in 5 fractions of 4.4 Gy was delivered to the tumor bed with a margin of 1-2 cm, on 3 consecutive days. The adjuvant systemic treatments consisted of hormonal therapy for 24 patients (73%) and chemotherapy for 6 patients (18%). The survival results were estimated by the Kaplan-Meier method. Late side effects and cosmetic results were also registered. RESULTS: The median follow-up time following the second breast conserving therapy was 61 months (range: 26-189 months). During the follow-up, 4 patients (12.1%) developed second local recurrence. The five-year actuarial rates of the second local, regional and distant recurrence were 6.3%, 6.1%, and 14.9%, respectively. The five-year probabilities of disease-free, cancer-specific and overall survival were 76.2%, 92.4%, and 89.2%, respectively. Four (12%), 19 (58%), 4 (12%) and 6 (18%) patients had excellent, good, fair and poor cosmetic results, respectively. Grade 2 and 3 fibrosis developed in 9 (27%) and 1 (3%) patients. Asymptomatic fat necrosis was detected in 7 (21%) women. CONCLUSION: Second breast conserving therapy with perioperative high-dose-rate interstitial brachytherapy is a safe and feasible option for the management of ipsilateral breast tumor recurrences. Interstitial brachytherapy may decrease the risk of second local relapse with acceptable cosmetic results and low rate of late side effects. Hence, in selected cases it can provide a feasible alternative to salvage mastectomy. Orv Hetil. 2018; 159(11): 430-438.

[Stereotactic body radiotherapy of liver metastasis: early experience]. / Májáttétes betegek sztereotaxiás ablatív sugárkezelésével (SABRT) elért elsõ eredményeink.

Recently the prevalence of oligometastatic patients is increasing. A common site of distant spread is the liver. The standard of care is curative surgical resection, however, the resecability rate is only 10-20%. Alternatively, radiofrequency ablation (RFA) or transarterial chemoembolization (TACE) may be used. Stereotactic ablative body radiotherapy (SABRT) makes it possible to deliver curative radiation dose without radiation injury to the healthy liver tissue. We delivered SABRT to three patients with inoperable hepatic metastases. The primary tumors were rectal (2) and lung (1). The dose was 3x20 Gy every other day. We observed one grade 1 side effect. All the metastases showed complete remission and no local recurrence or late side effect occurred during the one year of follow-up. One patient is tumor-free, one has stable disease, in one patient two new hepatic metastases appeared and receives chemo-biological therapy. SABRT of liver metastases is safe and highly effective. It can be expected that in the near future it will become one of the standard treatments of hepatic tumors.

[Stereotactic ablative body radiotherapy (SABRT) for locally advanced pancreatic cancer. Case report and review of literature]. / Lokálisan kiterjedt hasnyálmirigy-daganatos beteg sztereotaxiás ablatív sugárkezelése (SABRT): esetismertetés és irodalmi áttekintés.

Pancreatic cancer has one of the worst outcomes among malignant tumors. At the time of diagnosis only 20% of the cases are resectable and 30-50% are locally advanced, when curative intervention cannot be performed. After resection local relapse occurs in 20-60%, and in 30% it is the reason of death. This latter highlights the importance of local control. However, there have been no convincing results with conformal radiation therapy and radiochemotherapy yet. Adjuvant radiochemotherapy has been settled into the routine in the US, but not in Europe and Asia and only sporadic data are available about neoadjuvant radiotherapy. Based on the result of recent studies, conformal radiation therapy does not seem to become part of the standard treatment of locally advanced disease. Radiation resistance, long treatment time and incompatibility with the most advanced chemotherapy regimens may make conformal radiotherapy ineffective. Stereotactic ablative body radiotherapy (SABRT) when a limited target volume is irradiated in few fractions, with high precision and high biological effective dose, is ablative for the tumor and could be a possible solution for this issue. In our report, we describe to our knowledge the first SABRT for locally advanced pancreatic cancer in Hungary and give a short literature review.

[Image-guided radiotherapy for muscle invasive bladder cancer with intravesical lipiodol injection. A new option for bladder sparing treatment]. / Izominvazív hólyagrák képvezérelt sugárkezelése intravesicalisan befecskendezett lipiodolos jelöléssel. A hólyagmegtartó kezelés új lehetosége.

INTRODUCTION AND AIM: To implement lipiodol as a fiducial marker of the tumor bed for image-guided radiotherapy with simultaneous integrated boost technique as part of radiochemotherapy for muscle invasive bladder tumors. METHOD: Since April 2016, radiochemotherapy was performed in 3 male patients with muscle invasive, transitional cell bladder carcinoma. Prior to radiochemotherapy, tumor bed resection was performed for each patient, at the same time 10 ml of lipiodol solution was injected submucosally into the resection site, thus marking the tumor bed for escalated dose irradiation. During radiochemotherapy 51 Gy (1.7 Gy/die) to the pelvis, 57 Gy (1.9 Gy/die) to the whole bladder, and 63 Gy (2.1 Gy/die) to the lipiodol-labeled tumor bed was delivered with simultaneous integrated boost technique. The accuracy of the irradiation was controlled by daily kilovoltage CT. Early radiogenic urogenital and gastrointestinal side effects were recorded according to Radiation Therapy Oncology Group side-effects grading recommendation. RESULTS: Substantial perioperative side effect or toxicity were not observed during and after the injection of lipiodol. The prescribed dose was successfully delivered in all patients. Radiotherapy duration was 6 weeks. The lipiodol-labeled tumor bed was clearly visible on daily kilovoltage cone beam CT. In one patient grade II cystitis and proctitis was observed, another patient experienced only grade I cystitis. These complaints improved with symptomatic medication. In the third patient no significant side effect occurred. CONCLUSIONS: The injection of lipiodol into the bladder wall is a safe technique, without any perioperative toxicity or complication. The tumor bed demarcated by lipiodol was visible both on treatment planning and kilovoltage CTs. The total treatment time was shortened by 4 days. The treatment was well tolerated, early side effects were moderate, or slight. Orv Hetil. 2017; 158(51): 2041-2047.

Atypical teratoid/rhabdoid tumor arising in a malignant glioma.

Atypical teratoid/rhabdoid tumor (AT/RT), a highly malignant brain tumor in young children, usually arises de novo and has only rarely been described as a secondary malignancy. Here, we present a case of a child with glioblastoma, who was treated postoperatively by a combination of temozolomide, irradiation, and bevacizumab. AT/RT was diagnosed as a secondary tumor, 2.5 years following primary diagnosis. The child died 13 months after the diagnosis of AT/RT. This case demonstrates that malignant gliomas may give rise to AT/RT. It also emphasizes the diagnostic value of a repeated tumor biopsy in the recurrence setting.

Multicatheter interstitial brachytherapy versus intensity modulated external beam therapy for accelerated partial breast irradiation: A comparative treatment planning study with respect to dosimetry of organs at risk.

OBJECTIVE: To dosimetrically compare multicatheter interstitial brachytherapy (MIBT) and intensity modulated radiotherapy (IMRT) for accelerated partial breast irradiation (APBI) with special focus on dose to normal tissues and organs at risk (OAR-s). MATERIAL AND METHODS: Thirty-four patients with early stage breast cancer treated with MIBT were selected for the study. For each patient an additional IMRT treatment plan was created using the same CT data and contours as used in MIBT plans. OAR-s included ipsilateral non-target and contralateral breast, lung of both sides, skin, ribs and heart for left sided lesions. The CTV was created from the outlined lumpectomy cavity with a total margin (surgical+radiation) of 20mm in six main directions. The PTV in IMRT plans was generated from CTV with an addition of isotropic 5mm margin. The prescribed dose was 30.1Gy with 7×4.3Gy fractionation for both techniques. From dose-volume histograms quality parameters including volumes receiving a given dose (e.g. V100, V90, V50) and doses to specified volumes (e.g. D0.01cm3, D0.1cm3, D1cm3) were calculated and compared. RESULTS: Except for high dose, non-target breast received less dose with MIBT. V90 was 3.6% vs. 4.8% and V50 was 13.7% vs. 25.5% for MIBT and IMRT, respectively. Ipsilateral lung was spared better with MIBT. Mean lung dose was 5.1% vs. 7.1%, [Formula: see text] was 39.0% vs. 54.3% and V5 was 32.9% vs. 41.7% in favour of MIBT. For left sided lesions the heart was generally irradiated by larger doses with MIBT. Mean heart dose was 4.5% vs. 2.0% and [Formula: see text] was 18.3% vs. 19.7%, correspondingly. Volumetric maximal skin doses were similar, but regarding dose to 0.1cm3 and 1cm3 of most exposed volume MIBT provided significantly less doses (76.6% vs. 94.4% and 60.2% vs. 87.8%, respectively). Ribs received less dose with MIBT with values of 45.6% vs. 69.3% for [Formula: see text] and 1.4% vs. 4.2cm3 for V50. Dose to contralateral breast and lung was low with both techniques. No significant differences were observed in maximal doses, but dose to volumes of 0.1cm3 and 1cm3 were less with MIBT for both organs. [Formula: see text] was 3.2% vs. 6.7% for breast and 3.7% vs. 5.6% for lung with MIBT and IMRT, respectively. CONCLUSIONS: The target volume can be appropriately irradiated by both techniques, but MIBT generally spares normal tissues and organs at risk better than IMRT. Except for the heart, other critical structures receive less doses with brachytherapy. To observe whether these dosimetric findings translate into clinical outcome more studies are needed with assessment of toxicity profiles.