IMRT Technique Research Articles

Radiotherapy Infrastructure Shielding Calculations: software development for shielding calculations in a linear accelerator radiotherapy room.

This work aimed to develop and validate software that calculates the shielding thickness required for a radiotherapy room with a linear accelerator utilising geometric and dosimetric data. The software "Radiotherapy Infrastructure Shielding Calculations" (RISC) was developed using MATLAB programming. It does not require the installation of the MATLAB platform, and the user only needs to download and install the application, which displays a graphical user interface (GUI). The GUI includes empty cells to insert numerical values for several parameters to calculate the proper shielding thickness. The GUI comprises two main interfaces, one for the primary and one for the secondary barrier calculation. The interface of the primary barrier is divided into four tabs: (a) primary radiation, (b) patient scattered and leakage radiation, (c) IMRT techniques and (d) the shielding cost calculations. The interface of the secondary barrier includes three tabs: (a) patient scattered and leakage radiation, (b) IMRT techniques and (c) the shielding cost calculations. Each tab consists of two sections: one for input and one for output of the necessary data. The RISC is based on the methods and formulae of the NCRP 151 and calculates the primary and secondary barrier thickness for ordinary concrete with a density of 2.35g/cm3 and the cost for a radiotherapy room with a linear accelerator that performs conventional or IMRT techniques. Calculations can be performed for photon energies of 4, 6, 10, 15, 18, 20, 25 and 30 MV of a dual-energy linear accelerator, while instantaneous dose rate (IDR) calculations are also performed. The RISC has been validated using all comparative examples of NCRP 151 and the calculations from shielding reports of the Varian IX linear accelerator at Methodist Hospital of Willowbrook and Elekta Infinity at the University Hospital of Patras. The RISC is accompanied by two text files: (a) "Terminology," extensively describing all parameters, and (b) "User's Manual," providing useful instructions to the user. The RISC is user-friendly, simple, fast and precise, providing accurate shielding calculations and quickly and easily reproducing different shielding scenarios for a radiotherapy room with a linear accelerator. Additionally, it could be used during the educational process of shielding calculations by graduate students or trainee medical physicists. As a future work, the RISC will be updated with new features such as skyshine radiation, door shielding, and other types of machines and shielding materials.

Re-irradiation in Head and Neck Squamous Cell Carcinoma – A Single Institute Experience

Background: In head and neck squamous cell carcinomas (HNSCC), residual disease, loco regional recurrence or development of second primary are causes of treatment failure. A combination of either surgery or chemotherapy or radiotherapy is used. The aim of this study was to evaluate recurrent/ relapsed HNSCC who were treated with re-irradiation, its toxicities and survival analysis.
 Materials and Methods: 72 patients were analysed retrospectively who had undergone re-irradiation at our institute. All patients were histologically proven cases of recurrent/relapsed HNSCC. Treatment was done using conformal radiotherapy techniques like IMRT or IGRT technique.
 Results: Patients who had recurrent disease and second primary were 38 (52.8%) and 34 (47.2%) respectively. The time interval between radiotherapy treatments ranged from 7 months to 25 years. Salvage surgery preceded radiotherapy in 16 (22.2%) patients and 56 patients (78.8%) underwent radical radiotherapy. The PTV volume ranged from 15.6 to 672.2 cc (median: 117 cc) and median dose was 54Gy. Mucositis and skin reactions were associated in patients with larger PTV volumes and lower time interval between the radiation treatments. The median DFS and OS was 13 months and 29 months respectively. OS at 1 year and 2 years was 58.3% and 36.1%. Patients who received radiation dose of >54Gy and who had >24 months interval between the radiation treatments fared better.
 Conclusions: Treatment approaches have to be personalized in cases of recurrent HNSCC. For re-irradiation in HNSCC we found better outcomes when there is adequate time period (> 24 months) between the radiation treatments and with dose > 54Gy.

Analysis of Radiation Dose Distribution and Organs at Risk in Breast Cancer Using Intensity Modulated Radiation Therapy Technique on A Linear Accelerator at RSUP Prof. Dr. I.G.N.G. Ngoerah

The aim of the study was to analyze the radiation dose distribution in breast cancer cases using IMRT techniques on a LINAC equipment, specifically examining the Conformity Index (CI), Homogeneity Index (HI), and radiation dose distribution to the OAR, including lungs and heart on a 6 MV photon beam energy LINAC equipment at the Radiotherapy Sub-Installation of Prof. Dr. I.G.N.G Ngoerah Hospital. Analysis of the Conformity Index (CI), Homogeneity Index (HI) and radiation dose distribution to the OAR, namely the lungs and heart in cases of right and left breast cancer using statistical data on the Dose Volume Histogram (DHV) graphic obtained from patient calculations using the Treatment Planning System (TPS) Monaco. The CI value for the right and left breast cancer cases is 0.9819 and 0.9942 respectively with a nonparametric statistical test result of 0.141 that greater than 0.05 which means it is not significant. Meanwhile, the HI values for the right and left breast cancer cases are 0.1211 and 0.1410 respectively with the multivariate statistical test result of 0.159 that greater than 0.05 which means it is not significant. For the dose distribution values in the lungs close and far from the cancer, the average values of 32.24% and 440.03 cGy for right breast cancer and 33.04% and 500.55 cGy for left breast cancer were obtained, respectively, with a multivariate statistical test value for both of them of 0.115 that greater than 0.05 in the lungs close to the cancer and 0.124≥0.05 in the lungs far from the cancer, which means insignificant. As for the heart, a value of 3.13% was obtained for right breast cancer and 8.02% for left breast cancer with a nonparametric statistical test result of 0.000 that less than 0.05 which means significant. This can be caused by the position of the heart in cases of left breast cancer closer to the target or cancer than cases of left breast cancer.

Analysis of Radiation Dose Distribution in Nasopharyngeal and Organ Cancer Cases at Risk with Linear Accelerator Radiotherapy 6 MV Photon Energy Using the IMRT Technique at Prof. Hospital. Dr. I. G. N. G. Ngoerah

This study aims to determine the distribution of radiation doses on PTV and OAR radioteraphy planning in RSUP. Prof. Dr. I.G.N.G Ngoerah, Bali, Indonesia does no exceed a predetermined limit. The research metode used is the value of Homogenity Index (H), Conformity Index (CI), and the maximum value of radiation ose to the Organ At Risk (OAR), amely the right eye lens, left eye lens, brainstem, optic chiasma, and spinal cord. These data are compared with the provisions of ICRU report 83 and the maximum dose reference value for OAR. Using data from 30 nasopharyngeal cancer patients with a total radiation dose of 7000 cGy. Obtained a value for HI of 0.1214 with a t-test result of 0.459> 0.05 which means it is not significant. While the value for CI is 0.9850 with nonparametric statistical test results of 0.285> 0.05 which means it is not significant. The maximum dose value for the right eye lens is 772.7 cGy with a t-test result of 0.779> 0.05 which means it is not significant. For the maximum value of the dose in the lens of the left eye of 771.0 cGy with a t test result of 0.791> 0.05 which means it is not significant. For the maximum value of the dose in the brain stem of 5178.1 cGy with nonparametric test results of 0.686> 0.05 which means not significant. The maximum dose value at the optic chiasma is 4,837.2 cGy with a nonparametric test result of 0.225>0.05 which means it is not significant. For the maximum value of the dose in the spinal cord of 4,663.3 cGy with a t test result of 0.958> 0.05 which means it is not significant.

Post-mastectomy radiotherapy: Impact of bolus thickness and irradiation technique on skin dose

PurposeTo determine 10 MV IMRT and VMAT based protocols with a daily bolus targeting a skin dose of 45 Gy in order to replace the 6 MV tangential fields with a 5 mm thick bolus on alternate days method for post-mastectomy radiotherapy. MethodWe measured the mean surface dose along the chest wall PTV as a function of different bolus thicknesses for sliding window IMRT and VMAT plans. We analyzed surface dose profiles and dose homogeneities and compared them to our standard 6 MV strategy. All measurements were performed on a thorax phantom with Gafchromic films while dosimetric plans were computed using the Acuros XB algorithm (Varian). ResultsWe obtained the best compromise between measured surface dose (mean dose and homogeneity) and skin toxicity threshold obtained from the literature using a daily 3 mm thick bolus. Mean surface doses were 91.4 ± 2.8% [85.7% – 95.4%] and 92.2 ± 2.3% [85.6% – 95.2%] of the prescribed dose with IMRT and VMAT techniques, respectively. Our standard 6 MV alternate days 5 mm thick bolus leads to 89.0 ± 3.7% [83.6% – 95.5%]. Mean dose differences between measured and TPS results were < 3.2% for depths as low as 2 mm depth. Conclusion10 MV IMRT-based protocols with a daily 3 mm thick bolus produce a surface dose comparable to the standard 6 MV 5 mm thick bolus on alternate days method but with an improved surface dose homogeneity. This allows for a better control of skin toxicity and target volume coverage.

The Effect of Volume Target on Quality of Radiotherapy using 3DCRT and IMRT: Dosimetry and Radiobiological Evaluation

&lt;span&gt;The main goal of radiotherapy is to deliver the maximum possible dose to the target volume and the minimum possible to the surrounding healthy tissue. In this study, planning was carried out on the TPS Eclipse Varian Medical System using 3DCRT and IMRT techniques for 14 cancer patients. 6 cases of lung cancer with PTV were in the range of 175.1 cc - 875.5 cc, and eight brain cancer patients with a PTV range of 148.5 cc - 841.2 cc. This study aims to determine the effect of target volume on the quality of radiation therapy planning using the 3DCRT and IMRT techniques. The evaluation was carried out using dosimetry and radiobiology analysis. Dosimetry assessment analyzes the average dose, D98, D50, D2, CI, and HI on PTV and the average dose on OAR. Radiobiological evaluation by calculating the value of TCP, NTCP, and UTCP. The results showed that based on dosimetry and radiobiology evaluation, the IMRT technique provides better planning quality for radiation therapy by increasing the probability of cancer cells dying at PTV and reducing the risk of OAR compared to planning using the 3DCRT technique. The effect of PTV on planning quality using statistical regression tests showed that PTV did not significantly impact the quality of radiation therapy planning results either using the 3DCRT technique or the IMRT technique.&lt;/span&gt;

Abstract P1-10-15: Concious sparing of contralateral thyroid lobe in Ca Breast patients receiving post mastectomy radiotherapy by IMRT technique – A single institution dosimetric study

Abstract Purpose/Objective(s): The purpose of this paper is to report the dosimetric effects of conscious sparing of contralateral lobe of thyroid gland in carcinoma breast patient receiving locoregional radiation by tangential beam Intensity Modulated radiotherapy technique. Materials/Methods: Treatment plans of 20 Ca Breast patients, who received post mastectomy adjuvant locoregional radiotherapy, were evaluated. Since October 2021 we adopted a department protocol of conscious sparing of contralateral thyroid in breast radiotherapy. 10 of these had conscious sparing of contralateral thyroid (group A) whereas 10 of old plans were evaluated when C/L thyroid were not given constraints &amp; are being passively spared due to location on contralateral/non treatment side of neck (group B). Treatment planning was done using tangential beam (6 MV) IMRT in Eclipse 13.7 TPS in all of these patients. All of these patients received treatment to chest wall &amp; SCF. RTOG contouring guidelines were followed in all the patients. Prescription Dose was 40Gy in 15# for both groups. The best treatment plans were selected ensuring 95% PTV dose coverage and acceptable dose to OARs. Uniform contouring, plan optimization &amp; evaluation protocols were followed for all of these patients. Results: The mean thyroid volume in group A is 4.30cc &amp; in group B is 3.99cc which is not statistically different (P value -0.639) The mean dose of thyroid in group A is 7.98Gy whereas in group B it is 17.00Gy which is spastically significant (P value – 0.000003). Comparison of mean dose to contralateral lobe (in Gy) between the two groups Groups No. Mean ± SD ‘t’ value P value Thyroid dose with constraint 10 7.98±1.46 -6.702, df=18 0.000003* Thyroid dose without constraint 10 17.00±3.99 Unpaired ‘t’ test applied. P value = 0.000003, Significant Conclusion: OARs present on contralateral side are passively spared due to the location. This often results in a tendency of not actively prescribing constraints to these. This study emphasizes that conscious sparing of contralateral Thyroid lobe can further reduce the dose to significant levels. This reduction can preserve thyroid function further. Further clinical trials are required to corroborate this dosimetric gain with clinical thyroid function preservation. Citation Format: Manish Chomal, Minaal Iyer, Ananth Kalimurthy, Joshua Sahay, Sushanta Banik. Concious sparing of contralateral thyroid lobe in Ca Breast patients receiving post mastectomy radiotherapy by IMRT technique – A single institution dosimetric study [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 P1-10-15.

Radiation technique and outcomes following moderately hypofractionated treatment of low risk prostate cancer: a secondary analysis of RTOG 0415.

While moderately hypofractionated radiotherapy (MHRT) for prostate cancer (PC) is commonly delivered by intensity modulated radiation therapy, IMRT has not been prospectively compared to three-dimensional conformal radiotherapy (3D-CRT) in this context. We conducted a secondary analysis of the phase III RTOG 0415 trial comparing survival and toxicity outcomes for low-risk PC following MHRT with IMRT versus 3D-CRT. RTOG 0415 was a phase III, non-inferiority trial randomizing low-risk PC patients to either MHRT or conventionally fractionated radiation with stratification by RT technique. A secondary analysis for differences in overall survival (OS), biochemical recurrence free survival (BRFS), or toxicity by EPIC scores and Common Terminology Criteria for Adverse Events (CTCAE) was performed. 1079 patients received the allocated intervention with a median follow up of 5.8 years. 79.1% of patients were treated with IMRT and radiation technique was balanced between arms. Across all patients, RT technique was not associated with significant differences in BRFS, OS, or rates of acute and late toxicities. For patients completing MHRT, there was a difference in the late GU toxicity distribution between 3D-CRT and IMRT but no difference in late grade 2 or greater GU or GI toxicity. Stratifying patients by RT technique and fractionation, no significant differences were observed in the minimal clinically important difference (MCID) in EPIC urinary and bowel scores following RT. RT technique did not impact clinical outcomes following MHRT for low-risk PC. Despite different late GU toxicity distributions in patients treated with MHRT by IMRT or 3D-CRT, there was no difference in late Grade 2 or greater GU or GI toxicity or patient reported toxicity. Increases in late GU and GI toxicity following MHRT compared to CFRT, as demonstrated in the initial publication of RTOG 0415, do not appear related to a 3D-CRT treatment technique.

Escalation of radiotherapy dose in large locally advanced drug-resistant gastrointestinal stromal tumors by multi-shell simultaneous integrated boost intensity-modulated technique: a feasibility study

BackgroundResistance to conventional dose schemes and radiotoxicity of healthy tissue is a clinical challenge in the radiation therapy of large locally advanced drug-resistant gastrointestinal stromal tumor (LADR-GIST). This study aimed to assess the feasibility of using multi-shell Simultaneous Integrated Boost Intensity-Modulated modality (SIB-IMRT) strategy to provide a safe and effective escalation dose regimen for LADR-GIST.Methods7 patients with LADR-GIST were selected in this study. The modified SIB-IMRT plans for all patients were generated by delivering different escalation-dose gradients to four ring shaped regions (shells) within the gross tumor volume (GTV). The doses of the central volume of the tumor (GTVcenter) were escalated up to 70–92.5 Gy (25 fractions), while the doses of planning target volume (PTV) and shell-1 were kept at 50.0 Gy. Based on different escalation-dose gradients, the modified SIB-IMRT plans were divided into four groups (SIB-IMRT groups). For comparison purposes, plans obtained by conventional IMRT technique (Con-IMRT) with 50 Gy (25 fractions) were also generated for all patients (Con-IMRT group). All plans were normalized to cover 95% of the PTV with the prescribed dose of 50.0 Gy. The equivalent uniform dose (EUD), relative equivalent uniform dose (rEUD), dose volume histogram (DVH), dose profile, conformity index (CI) and monitor unit (MU) were evaluated in five groups. The Friedman Test was performed to determine whether there were significant differences (P < 0.05).ResultsCompared with the Con-IMRT group, the EUD of GTV (EUDGTV) and rEUD of SIB-IMRT groups were improved when escalation-dose gradient was increased, and the improvement became significant when the escalation-dose gradient reached 20% of the prescription dose. The rEUD tended to be stable as the escalation-dose gradient went up to 25% of the prescription dose. There were no significant differences in CIs and DVH metrics for OARs between the Con-IMRT group and any SIB-IMRT group, but the significant differences were observed between the SIB10-IMRT group and the SIB25-IMRT group. For the SIB-IMRT groups, as the dose gradient became steeper in the dose profiles, the higher dose was mainly accumulated in the inner part of GTV accompanied with a higher MU.ConclusionsThe proposed multi-shell SIB-IMRT strategy is feasible in dosimetry for LADR-GIST and can acquire higher therapeutic gain without sacrifice of healthy tissues. It appears that the scheme of delivering 20% of the prescribed escalation-dose gradient to the target volume can provide satisfactory dose irradiation for LADR-GIST, and it should be evaluated in future clinical study.

Dosimetric comparison of fixed field dynamic IMRT and VMAT techniques in simultaneous integrated boost radiotherapy of prostate cancer

High-risk prostate cancer can take advantage of the combination of hypofractionated radiotherapy and pelvic conventional fraction radiotherapy. The comparison between fixed field dynamic IMRT and VMAT techniques can provide suggestions for clinical treatment. We selected 10 high-risk prostate cancer patients who received radiotherapy at the cancer center of Sun Yat-sen University from January 2016 to December 2019. The targets contained in prostate, seminal vesicles and pelvic lymph nodes. With the same prescription and optimized parameters, 9F, single-arc (1ARC) and double-arc (2ARC) treatment plans were developed. The dose distribution of the targets, OAR, MU, treatment time and gamma pass ratios of dose verification was compared. The D2% (69.37 ± 0.89) Gy, D50% (66.92 ± 0.63) Gy, HI (0.09 ± 0.02), and CI (0.83 ± 0.05) of PTV1 in 9F were slightly better than those of 1ARC which were (71.13 ± 1.21) Gy, (68.50 ± 0.76) Gy, (0.12 ± 0.02), (0.74 ± 0.07), except D98%, the difference was significant (P < .05). All dosimetry indices of PTV1 in 9F and 2ARC were close and have no significant differences (P > .05). The V95% (99.45 ± 0.78)% of PTV2 in 9F was slightly better than that in 1ARC (99.35 ± 1.28)%. The difference was significant (P < .05). All dosimetry indices of PTV2 in 9F and 2ARC were close and the difference was not significant (P > .05). The Dmean of the bladder and the V67.5 Gy of rectum between all three plans were similar. The Dmean of left and right femoral in 1ARC and 2ARC were lower than that in 9F, and the difference was significant (P < .05). Other dosimetry indices of OARs in 9F were lower than those in 1ARC and 2ARC, and much lower than 1ARC. The difference was significant (P < .05). Mean monitor units in 1ARC and 2ARC were fewer by 70.0% and 67.2% in comparison with 9F. The treatment mean time in 1ARC and 2ARC was shorter by 81.7% and 61% in comparison with 9F. Verification pass ratios of γ (3%/3 mm) were 97.8% (9F), 98.9% (1ARC) and 99.4% (2ARC) respectively. The difference was significant (P < .05). Compared with IMRT, VMAT improved delivery efficiency noticeably. Two arcs provided comparable tumor dosimetry coverage, but performed worse in dose sparing for bladder, rectum and small bowel. The IMRT plan was preferable to VMAT in prostate cancer simultaneous integrated boost radiotherapy.

RADT-08. DOSIMETRIC FEASIBILITY OF DIRECT POST-OPERATIVE MRI-LINAC-BASED STEREOTACTIC RADIOSURGERY FOR RESECTION CAVITIES OF BRAIN METASTASES

Abstract Background Post-operative stereotactic radiosurgery (SRS) of patients with brain metastases with single resection cavities is typically planned on a post-recovery MRI, 4-6 weeks after resection. However, meanwhile the intracranial metastasis may (re-)grow, and postponing adjuvant systemic treatment increases chance on extracranial progression as well. Anticipating direct post-operative SRS to minimize this interval would enable rapid start of systemic therapy. In this study, we considered treatment with MRI-Linac (MRL) SRS, because of the possibility to execute the post-operative MRI and SRS treatment combined on the MRL instead of on two separate systems, improving logistics and increasing patient comfort. However, it is unclear whether MRL-based SRS may be feasible from a dosimetric perspective. This study aims to shed light on the dosimetric feasibility of MRL-based SRS. METHODS We simulated MRL treatments including thirteen patients with resectable single brain metastases treated with single fraction CT-Linac (CTL) SRS. We therefore contoured direct post-operative gross tumor volumes (GTV) and compared them to post-recovery MRI GTV. Next, we compared a non-coplanar VMAT technique for CTL (ncVMAT) to a coplanar IMRT technique for MRL (cIMRT), creating three plans per patient: a ncVMAT plan and a cIMRT plan for the direct post-operative GTV, and a post-recovery ncVMAT plan as current clinical standard. RESULTSCompared to GTVs defined on direct post-operative MRI, on post-recovery MRI 15.5% of cavities shrunk by &amp;gt; 2cc, and 46% expanded by &amp;gt; 2cc. Although direct post-operative ncVMAT plans had lower median gradient index and higher median V3Gy of the skin, they were clinically acceptable according to clinical guidelines. CONCLUSION Although slightly inferior to non-coplanar CTL plans, direct post-operative MRL-based SRS for resection cavities of brain metastases is dosimetrically acceptable, at the trade-off between increased patient comfort and logistics. Additionally, MRL-based SRS enables substantially earlier start with adjuvant systemic therapies, thereby maximizing tumor control.

MR-Guided Online Adaptive Stereotactic Body Radiotherapy (SBRT) of Primary and Metastatic Lung Tumors

<h3>Purpose/Objective(s)</h3> Radiotherapy has an important role in management of lung tumors. Online adaptive radiotherapy is a method that provides dosimetric accuracy by considering anatomical and functional changes with real-time images taken during treatment, and MR-guided radiotherapy is the latest technological development in this field. In our study, we aimed to present preliminary results and toxicity in patients who underwent magnetic resonance (MR) guided online adaptive radiotherapy (MRgRT) for primary or metastatic lung tumors. <h3>Materials/Methods</h3> Fifty-one patients with a diagnosis of primary lung cancer or lung metastases treated with MRgRT and a minimum follow-up period of 3 months were included. The treatment was carried out with the "step-and-shoot" IMRT technique and daily online adaptive planning. All patients were treated with breath-hold with audio-visual coaching. Patients were evaluated for treatment response, acute and late toxicity. <h3>Results</h3> The median age was 64 (range, 22-83 years) and 68.6% of the patients were male. MRgRT was performed in 21.6% of the patients for primary lung cancer and 78.4% for lung metastases from different primaries. MRgRT was applied to a single lesion in 38 patients and more than one lesion in 13 patients (a total of 69 lesions). Tumors were peripherally located in 78.3% of the patients and 21.7% of lesions were in the "no-fly zone". Median GTV volume was 1.8 cc (range, 0.2-172.1 cc). Target volume and doses of organs at risk met the criteria in all initial plans. Online adaptive treatment approach was applied in all patients. The median total dose was 50 Gy (range, 24-70), the median fraction number was 5 (range, 1-15 fractions), and the median fraction dose was 10 Gy (range, 4-34). The patients were treated every other day, except for two patients treated with 10 and 15 fractions. Median follow-up was 18.7 months. One- and 3-year overall survival (OS) rates were 92.4% and 68.0%, respectively. During the follow-up period, complete response was obtained in the MRgRT applied lesions in 37 patients, partial response was observed in 8 patients and local recurrence or progression was detected in 6 patients. One- and 3- year local progression free survival (LPFS) and distant progression free survival (DPFS) rates were 97.3%, 67.1% and 36.4%, 13.0%, respectively. There were no statistically significant differences in OS, LPFS and DPFS between primary and metastatic tumors. No Grade 3+ acute or late toxicity was observed. <h3>Conclusion</h3> In conclusion, MRgRT is a new method for the application of SBRT with better soft tissue contrast, no need for invasive marker placement, online adaptive radiotherapy in every fraction, and continuous real-time cine-MR tumor tracking. Our study shows that MRgRT is an acceptable method for the treatment of lung tumors. Randomized prospective studies with longer follow-up are needed comparing this technique with other modalities.

Radiotherapy with Multimodality Therapy for Hepatocellular Carcinoma with Hepatic Vein and/or Inferior Vena Cava Tumor Thrombus

<h3>Purpose/Objective(s)</h3> Liver cancer is the seventh most common malignancy and second leading cause of cancer-related death worldwide. Hepatic vein and/or inferior vena cava (IVC) tumor thrombus are less common. Improvement in techniques allowed the increasing use of radiotherapy in treating tumor thrombus in hepatocellular carcinoma (HCC). Hence, the present study evaluated the treatment response and survival outcomes of HCC with hepatic vein tumor thrombus (HVTT) and/or IVC involvement receiving radiotherapy in modern RT technique combined with other multimodality therapies. <h3>Materials/Methods</h3> HCC patients with HVTT and/or IVC tumor thrombus receiving radiotherapy were identified at our institution. All patients were treated with VMAT or IMRT technique and 4D-CT was used in simulation. All thrombus and primary tumor in liver were included in the GTV unless they were far from gross primary tumor. The prescription dose to 95% of the PTV was planned at 50-65Gy in 22-28 fractions over 5-6 weeks. After the completion of RT, chest-abdominal CT and liver MRI were performed at 1, 3, 6, 12 months and then 3 to 6 months thereafter. Treatment response was defined as the best response evaluation in 3 months after RT. Overall survival (OS), progression free survival (PFS) and in-field PFS were recorded during follow-up. <h3>Results</h3> Between April 2010 and September 2021, 30 men and 4 women with a median age of 53.5 years (range 30-71 years) were retrospectively included in the cohort. 7 (20.6%) patients had lymph node metastasis and 10 (29.4%) patients had distant metastasis before radiotherapy (RT). In addition to hepatic vein/inferior vena cava (IVC) tumor thrombus, portal vein and right atrium involvement were present in 17 (50.0%) and 6 (17.6%) patients. Half of the patients received TACE and 14 (41.2%) patients received systemic treatment including target therapy and immune therapy before radiotherapy. Most patients received target therapy concurrent with (70.6%) and/or post RT (79.4%). During follow-up (median 13.0 months), the median PFS and median in-field PFS were 4.2 months and not reached, respectively. The PFS and in-field PFS rate were 24.6% and 79.2% at 1 year, 19.7% and 72.0% at 2 years. The OS rate was 77.6% at 1 year and 36.3% at 2 years with a median OS of 15.8 months. PFS and OS were not associated with portal vein involvement, IVC involvement and distant metastasis before RT. The most common first failure site was lung (13/34 patients, 38.2%), followed by liver (7/34 patients, 20.6%). Only 5 (14.7%) patients had progression in the RT field of liver during follow-up. No patients had radiation-induced liver disease or pulmonary embolism during follow-up. <h3>Conclusion</h3> Our study proved that HCC lesions and tumor thrombus were sensitive to RT even after other local therapies. Combination of RT and systemic therapy in treating HCC patients with HVTT and IVC tumor thrombus was safe and effective.

Locoregional Control Following Adjuvant Chemotherapy and Radiotherapy for Treatment of High-Risk Endometrial Cancer

<h3>Purpose/Objective(s)</h3> Patients with locally advanced stage and aggressive histology endometrial cancer are at high risk of relapse, and usually treatment includes surgery, chemotherapy and radiotherapy. The timing and coordination of chemotherapy and radiotherapy remain controversial, though historically we have delivered adjuvant radiotherapy after completion of chemotherapy. The premise being to avoid delaying chemotherapy, which confers an overall survival benefit. We decided to review oncologic outcomes and patterns of recurrence among our patients and compare them with the published literature. <h3>Materials/Methods</h3> A retrospective review was conducted to evaluate patients who underwent primary surgery for endometrial cancer between 2005 and 2017, had a final pathology demonstrating Stage I-II endometrial cancer of serous or clear cell histology, Stage III endometrial cancer of any histology or Stage IV endometrial cancer of endometrioid adenocarcinoma histology, and were considered appropriate for adjuvant chemotherapy and radiotherapy. Kaplan-Meier analysis was used to calculate progression-free survival (PFS) and overall survival (OS). <h3>Results</h3> A total of 140 patients met the eligibility criteria and were included, with a median age of 65. The distribution according to stage was as follows: 41 (29.3%) Stage I, 24 (17.1%) Stage II, 68 (48.6%) Stage III, and 7 (5.0%) Stage IV. Of these patients, 52 (37.1%) had endometrioid, 75 (53.6%) had serous, and 11 (7.9%) had clear cell histology. All patients received chemotherapy with the median start time being 49 days after initial surgery. In total, 120 (92%) completed 6 cycles of chemotherapy. The median start time for radiotherapy was 35 days after chemotherapy and 192 days after surgery, with 129 (92.1%) completing adjuvant radiotherapy. The median dose of external beam radiotherapy (EBRT) was 4500 cGy in 25 fractions and the median dose of vaginal brachytherapy, when used, was 1800 cGy in 3 fractions. In terms of EBRT technique, 54 were treated with traditional conformal fields and 74 with IMRT techniques. The median follow-up was 63.9 months and the 5-year PFS and OS rates were 69% and 66% respectively. A total of 42 patients (30.0%) developed a recurrence; of which 2 (1.4%) were local, 10 (7.1%) were locoregional (any with component of locoregional failure), 8 (5.7%) were isolated para-aortic and 27 (19.3%) were distant. Among the 129 patients receiving radiotherapy, 6 (4.6%) patients had locoregional failure. Only 7 (5.4%) of patients had an "in-field" recurrence after EBRT, with 4 (3.1%) among patients treated with conformal fields and 3 (2.3%) among those treated with IMRT. <h3>Conclusion</h3> Adjuvant radiotherapy given after completion of surgery and adjuvant chemotherapy leads to favorable outcomes with regards to PFS and OS (compared to published randomized studies), and still results in excellent locoregional control.

Cardiac Events in Breast Cancer Patients Treated with Modern Radiotherapy

<h3>Purpose/Objective(s)</h3> To characterize cardiac events in a large cohort of breast cancer patients treated with curative radiation therapy at our institution from 2006-2017. Recent reports of cardiac toxicity have primarily been limited to ischemic events. Our hypotheses were that (1) multiple classes of cardiac events would be observed, including ischemic, arrhythmia, cardiomyopathy, pericardial, and valvular events, and (2) toxicity would decrease as modern RT techniques evolved during the study period. <h3>Materials/Methods</h3> Baseline patient characteristics, comorbidities, tumor characteristics, surgical, RT, and systemic treatment were recorded. RT volumes included accelerated partial breast, whole breast, or breast/chest wall and nodal RT. Techniques included 3D-CRT, IMRT, brachytherapy, protons, with prone and deep inspiration breath hold techniques also introduced during the study period. Cardiac events were categorized by class (ischemic, arrhythmia, cardiomyopathy, pericardial, and valvular), as well as by grade (1-5) based on CTCAE and American College of Cardiology criteria. <h3>Results</h3> 3,435 breast cancer patients received adjuvant RT at our institution during this time period and were therefore included in the analysis. Median follow up for cardiac events was 96 months. Mean age at diagnosis was 57 years old and 70% of patients were postmenopausal. 71% were Caucasian, 26% African American, 2% Asian, 1% other. At baseline, 14% of patients had diabetes, 47% hypertension, 24% hyperlipidemia, and 11% had history of a cardiac event prior to treatment. Systemic therapy included endocrine therapy (66%), any chemotherapy (49%), anthracycline (25%) and Herceptin (11%). Incidence of cardiac events was 15% overall. Events by class were 4.5% cardiomyopathy, 3.6% ischemic, 7.0% arrhythmia, 1.8% pericardial, and 5.0% valvular. Patients with history of cardiac events prior to treatment had a greater risk of new events compared to those without pre-existing disease (p <0.01, RR 2.8). Incidence of Grade 1 events was 2.3%, Grade 2 was 7.2%, Grade 3 was 3.2%, and Grade 4 was 2.2%. Incidence of events by year of RT were 22% (2006-2007), 19% (2008-09), 17% (2010-11), 15% (2012-13), 12% (2014-15), and 12% (2016-17). Logistic regression found a significant decrease in cardiac events over time (p < 0.001). Median interval from RT to cardiac event was 45 months (all events), 41 mos (cardiomyopathy), 47 mos (ischemia), 53 mos (arrhythmia), and 45 mos (pericardial). <h3>Conclusion</h3> Incidence of cardiac events were overall fairly low, but not uncommon when all event classes were recorded. Incidence of events was lower in patients treated later in the study period, which may be due to introduction of further advances in RT for breast cancer patients over time. Although patients treated earlier have potential for longer follow up, the median interval to cardiac event was less than the median follow up for the cohort, so these findings will likely be observed with further follow up.

PSA Kinetics and Outcomes after Magnetic Resonance Image-Guided Stereotactic Body Radiotherapy for Prostate Cancer

<h3>Purpose/Objective(s)</h3> Using moderate or ultra-hypofractionation, which is also known as stereotactic body radiotherapy (SBRT) for treatment of localized prostate cancer patients has been increased. Assessment of the efficacy of treatment response after radiotherapy relies heavily on the monitoring of prostate specific antigen (PSA) levels and PSA kinetics. The aim of our study was to evaluate tumor control outcomes with PSA response and toxicity after magnetic resonance image-guided adaptive radiotherapy (MRgRT) for prostate cancer patients. <h3>Materials/Methods</h3> A total of 95 prostate cancer patients treated with MRgRT were included in the study. Treatment was performed with IMRT (step and shoot) technique and daily plan adaptation using MRgRT. Patients received 36.25 Gy in 5 fractions, per institutional standards. Outcome measurements included tumor control evaluation with PSA levels, acute and late toxicities. Nadir PSA was defined as the lowest serum PSA value from the time of SBRT completion to date of last follow-up. Biochemical failure (BCF) was defined using the Phoenix definition (nadir + 2 ng/mL). <h3>Results</h3> The median follow-up for our cohort was 23.7 months (range; 3-41.4 months). The median age was 74 years (range; 50-87 years). The median initial PSA (iPSA) was 7.6 ng/mL (range; 2.7-44 ng/mL) for all patients. According to the NCCN guidelines, 13 (13.7%), 53 (55.8%) and 29 (30.5%) patients were in low-, intermediate- and high-risk group, respectively. Twenty-nine patients (30.5%) received androgen deprivation therapy (ADT). The median nadir PSA (nPSA) for all patients was 0.72 ng/mL (range, 0.01-4.96 ng/mL). For the entire cohort, 52.6% patients had an nPSA <1 ng/mL, with 35.8% of patients reaching an nPSA 0.5 ng/mL and 20% reaching an nPSA 0.2 ng/mL. For the patients who didn't receive ADT, median nPSA was 1.26 ng/mL (range; 0.16-4.96 ng/mL); 45.0% patients had an nPSA <1 ng/mL, with 21.3% of patients reaching an nPSA 0.5 ng/mL and 3.3% reaching an nPSA 0.2 ng/mL. For the patients who received ADT, median nPSA was 0.06 ng/mL (range; 0.01-1.55 ng/mL); 95.8% patients had an nPSA <1 ng/mL, with 87.5% of patients reaching an nPSA 0.5 ng/mL and 70.8% reaching an nPSA 0.2 ng/mL. A patient who did not yet meet the Phoenix criteria for biochemical recurrence but a PSA rising was diagnosed with two bone metastases with imaging evaluation and one patient with a nPSA and positive PSMA-PET had radical prostatectomy. MRgRT was well tolerated by all patients. There was no Grade ≥3 GU or GI toxicity. <h3>Conclusion</h3> In conclusion, MRgRT represents a new method for delivering SBRT with markerless soft tissue visualization, online adaptive planning and real-time tracking. Our study suggests that ultra-hypofractionation with MRgRT has an acceptable toxicity profile with favorable efficacy and PSA response. Further studies with longer follow-up time and larger cohorts are warranted.

The MARRTA Project: Safety and Risk Analysis in Radiation Oncology

<h3>Purpose/Objective(s)</h3> To improve the patient safety and quality in the radiotherapy treatment, by applying the risk matrix methodology to the process. to obtain a theoretical risk model with the potential errors and failures of that process, and to develop a computer application to introduce the model and offer the possibility of applying this methodology in an exhaustive and as simple as possible way to different professionals involved in the treatment <h3>Materials/Methods</h3> 23 working group meetings at the headquarters of the Spanish Nuclear Safety Council in Madrid, in which the results of the different proposals previously discussed and agreed by the different professional societies involved in the process representatives (Radiation Oncologists, Medical Physicists/Dosimetrists and Radiologic Technologists), were integrated. We analyzed IMRT, IGRT and SBRT techniques performed with LINAC. Radiosurgery, brachytherapy, metabolic treatments with non-encapsulated sources. <h3>Results</h3> Development of a Process Map: The different professional's tasks were analyzed. The process was divided into 7 phases (Therapeutic decision, Volume localization, Volume delineation, Treatment planning, Post-planning verification, Initial treatment session and Daily treatment), and the process map was prepared. Possible errors and failures (Initiating Events) identification: Once the analysis was done, the possible Initiating Events (IE) with consequences for the patients were identified, analyzed and consensed in the working group meetings. A total of 138 initiating events identified, analyzed and consensed are presented, separated in the different stages of the process, in Table 1. Identification of possible Barriers and Reducers of Frequency and Consequences: 125 barriers, 60 frequency reducers and 35 consequence reducers were identified. Computer application development: The MARRTA computer application was developed presenting the risk model resulting that includes: list of stages and sub-stages, flow chart, list of IE with their associated barriers and frequency and consequence reducers, and the risk of each of these IE. One can create new risk models by modifying the existing ones (indicating in the model to modify what applies and what does not to his department) or he can create a new one from scratch. It allows: Calculation of the risk of each one of the IE, statistics of the number of IE of very high risk, high, medium and low risk at each stage/sub-stage and analysis of the importance of the barriers and frequency and consequence reducers. <h3>Conclusion</h3> the MARRTA computer application provides radiotherapy departments with a tool to easily apply the risk matrix methodology to perform risk analysis in an exhaustive and easy way, and to modify the model to adapt to its particular map of processes and risks.

The clinical outcome of postoperative radiotherapy using hybrid planning technique in left breast cancer after breast-conserving surgery.

The purpose of this study is to observe the preliminary clinical outcome and acute toxicity of hybrid intensity modulated radiotherapy and volumetric modulated arc therapy planning technique with simultaneous integrated boost (SIB). From November 2015 to December 2018, 149 female patients with left-side breast cancer who underwent adjuvant radiotherapy with hybrid IMRT and VMAT planning technique with SIB were reviewed retrospectively. The primary endpoint was acute toxicities and the secondary endpoints were local recurrence-free survival (LRFS), distant metastasis-freesurvival (DMFS), disease-free survival (DFS), and overall survival (OS). The median age was 52 years old and median follow-up was 43.4months. Eighty-six percent of patients had acute grade 0 to grade1 dermatitis and 14% had grade 2 dermatitis. No acute radiation pneumonitis, esophagitis, or cardiovascular events were recorded during follow-up. The 3-year LRFS, DMFS, DFS, and OS rates were 95.1%, 95.1%, 90.3%, and 97.9%, respectively. The subgroup analysis revealed that patients with lymphovascular invasion had more local recurrence rate and worse DFS rate. Patients with advanced N stage had the trend of worse DMFS. In conclusion, the hybrid IMRT and VMAT technique is feasible, safe and has less acute radiation related toxicities in SIB postoperative radiotherapy for left-sided breast cancer.

Safety of Inhomogeneous Dose Distribution IMRT for High-Grade Glioma Reirradiation: A Prospective Phase I/II Trial (GLIORAD TRIAL).

Simple SummaryGlioblastoma multiforme (GBM) is the most frequent primary malignant brain tumor, and despite advances in imaging techniques and treatment options, the outcome remains poor and recurrence is inevitable. Salvage therapy presents a challenge, and re-irradiation can be a therapeutic option in recurrent GBM. The decision-making process for re-irradiation is a challenge for radiation oncologists due to the expected toxicity of a second course of radiotherapy and the limited radiation tolerance of normal tissue; nevertheless, it is being increasingly used, as several studies have demonstrated its feasibility. The current study aimed to investigate the safety of moderate–high-voxel-based dose escalation radiotherapy in recurrent GBM patients after conventional concurrent chemoradiation. Twelve patients were enrolled in this prospective single-center study. Retreatment consisted of re-irradiation with a total dose range of 30–50 Gy over 5 days using the IMRT (arc VMAT) technique using dose painting planning. The treatment was well tolerated. No toxicities greater than 3 were recorded; only one patient had severe G3 acute toxicity, characterized by muscle weakness and fatigue. Median overall survival (OS2) and progression-free survival (PFS2) from the time of re-irradiation were 10.4 months and 5.7 months, respectively. Our phase I study demonstrated an acceptable tolerance profile of this approach, and the future prospective phase II study will analyze the efficacy in terms of PFS and OS.Glioblastoma multiforme (GBM) is the most aggressive astrocytic primary brain tumor, and concurrent temozolomide (TMZ) and radiotherapy (RT) followed by maintenance of adjuvant TMZ is the current standard of care. Despite advances in imaging techniques and multi-modal treatment options, the median overall survival (OS) remains poor. As an alternative to surgery, re-irradiation (re-RT) can be a therapeutic option in recurrent GBM. Re-irradiation for brain tumors is increasingly used today, and several studies have demonstrated its feasibility. Besides differing techniques, the published data include a wide range of doses, emphasizing that no standard approach exists. The current study aimed to investigate the safety of moderate–high-voxel-based dose escalation in recurrent GBM. From 2016 to 2019, 12 patients met the inclusion criteria and were enrolled in this prospective single-center study. Retreatment consisted of re-irradiation with a total dose of 30 Gy (up to 50 Gy) over 5 days using the IMRT (arc VMAT) technique. A dose painting by numbers (DPBN)/dose escalation plan were performed, and a continuous relation between the voxel intensity of the functional image set and the risk of recurrence in that voxel were used to define target and dose distribution. Re-irradiation was well tolerated in all treated patients. No toxicities greater than G3 were recorded; only one patient had severe G3 acute toxicity, characterized by muscle weakness and fatigue. Median overall survival (OS2) and progression-free survival (PFS2) from the time of re-irradiation were 10.4 months and 5.7 months, respectively; 3-, 6-, and 12-month OS2 were 92%, 75%, and 42%, respectively; and 3-, 6-, and 12-month PFS2 were 83%, 42%, and 8%, respectively. Our work demonstrated a tolerable tolerance profile of this approach, and the future prospective phase II study will analyze the efficacy in terms of PFS and OS.

Three-Dimensional Dosimetry by Optical-CT and Radiochromic Gel Dosimeter of a Multiple Isocenter Craniospinal Radiation Therapy Procedure.

Craniospinal irradiation (CSI) is a complex radiation technique employed to treat patients with primitive neuroectodermal tumors such as medulloblastoma or germinative brain tumors with the risk of leptomeningeal spread. In adults, this technique poses a technically challenging planning process because of the complex shape and length of the target volume. Thus, it requires multiple fields and different isocenters to guarantee the primary-tumor dose delivery. Recently, some authors have proposed the use IMRT technique for this planning with the possibility of overlapping adjacent fields. The high-dose delivery complexity demands three-dimensional dosimetry (3DD) to verify this irradiation procedure and motivated this study. We used an optical CT and a radiochromic Fricke-xylenol-orange gel with the addition of formaldehyde (FXO-f) to evaluate the doses delivered at the field junction region of this treatment. We found 96.91% as the mean passing rate using the gamma analysis with 3%/2 mm criteria at the junction region. However, the concentration of fail points in a determined region called attention to this evaluation, indicating the advantages of employing a 3DD technique in complex dose-distribution verifications.