Safety of Three-Dimensional Conformal Radiotherapy on the Sheep with Pulmonary Cystic Echinococcosis: A Preliminary Study.

PURPOSE: Radiotherapy showed the potential to effectively kill the cysts of pulmonary cystic echinococcosis (CE). However, little is known about its safety. This study was designed to investigate the safety of three-dimensional conformal radiotherapy (3D-CRT) on the normal lung tissue adjacent to the cyst and blood of sheep naturally infected with pulmonary CE. METHODS: Twenty pulmonary CE sheep were randomly divided into control group (n = 5) and radiation groups with a dose of 30 Gray (Gy) (n = 5), 45 Gy (n = 5), and 60 Gy (n = 5), respectively. Animals in control group received no radiation. Heat shock protein 70 (Hsp70), tumor growth factor-ß (TGF-ß), matrix metalloproteinase-2 (MMP-2) and MMP-9 in the lung tissues adjacent to the cysts, which were considered to be closely related to the pathogenesis of CE, were evaluated after 3D-CRT. A routine blood test was conducted. RESULTS: The results showed that there were multiple cysts of various sizes with protoscoleces in the lung tissues of sheep, and necrotic cysts were found after 3D-CRT. 3D-CRT significantly increased the mRNA level of Hsp70, enhanced the protein level of TGF-ß and slightly increased the expression of MMP-2 and MMP-9 in lung tissues adjacent to the cysts. 3D-CRT did not significantly alter the amount of WBC, HB and PLT in sheep blood. CONCLUSIONS: The results suggested that 3D-CRT may suppress the inflammation and induce less damage of the normal lung tissues and blood. We preliminarily showed that 3D-CRT under a safe dose may be used to treat pulmonary CE.

A comparison of the incidence of ≥ grade 2 radiation pneumonitis between intensity-modulated radiotherapy and three-dimensional conformal radiotherapy in patients with unresectable non-small cell lung cancer treated with durvalumab after concurrent chemoradiotherapy.

BACKGROUND: Intensity-modulated radiation therapy (IMRT) has been increasingly used as a new radiation modality for unresectable non-small cell lung cancer (NSCLC). The risk factors for radiation pneumonitis (RP) during consolidation durvalumab following concurrent chemoradiotherapy (CCRT) using IMRT have not been thoroughly investigated. METHODS: This retrospective study analyzed medical record data from consecutive patients diagnosed with NSCLC who underwent CCRT and consolidation durvalumab at our institution between April 2018 and September 2022. Since we adopted IMRT for the treatment of NSCLC in April 2020, these patients were categorized into two groups: those treated with IMRT after April 2020 and those treated with three-dimensional conformal radiotherapy (3D-CRT) before April 2020. RESULTS: A total of 31 patients underwent IMRT (the IMRT group), while 25 patients underwent 3D-CRT (the 3D-CRT group). In both groups, the total dose was 60 Gy in 30 fractions. The cumulative incidence of ≥ grade 2 RP at 12 months was significantly lower in the IMRT group than in the 3D-CRT group (27.0% vs. 64.0%, hazard ratio [HR]: 0.338, 95% confidence interval [CI]: 0.144-0.793, p = 0.013). In the multivariable analysis, V20 (≥ 25.6%, HR: 2.706, 95% CI: 1.168-6.269, p = 0.020) and radiotherapy technique (IMRT, HR: 0.414, 95% CI: 0.172-0.994, p = 0.048) were identified as significant risk factors for ≥ grade 2 RP. CONCLUSIONS: IMRT is associated with a lower rate of ≥ grade 2 RP in patients with NSCLC who received CCRT followed by durvalumab.

A Retrospective Comparison of Toxicity, Response and Survival of Intensity-Modulated Radiotherapy Versus Three-Dimensional Conformal Radiation Therapy in the Treatment of Rectal Carcinoma.

INTRODUCTION: The main target of neoadjuvant treatment in rectal cancer is to downstage and downsize large tumours to increase the chance of complete surgical resection, and therefore decrease the chances of local recurrence. With or without the addition of chemotherapy, until recently, three-dimensional conformal radiotherapy (3D-CRT) used to be the radiotherapy treatment modality of choice. However, intensity-modulated radiotherapy (IMRT) is being increasingly adopted by many radiotherapy centres as a more modern, conformal technique due to its ability to minimize radiation dose to nearby organs. The aim of our analysis was to assess the difference in toxicity, response to treatment, and survival between the patients treated with these two different treatment modalities in our institution. METHODS: We performed a retrospective analysis of data and compared two groups of patients with locally advanced rectal cancer who were treated with either 3D-CRT or IMRT. The main outcomes were radiation toxicity and response to treatment. Overall survival was a secondary outcome. RESULTS: One hundred and thirty-six patients were included in the study: 71 patients treated with 3D-CRT and 65 patients treated with IMRT. With regard to toxicity, there was no significant difference between the groups for bladder and skin toxicity, but there was a significant reduction in acute grade 2 bowel toxicity in patients treated with a long course of IMRT [3D-CRT 77% (48/62) vs IMRT 64% (30/47) p=0.042]. There was no statistically significant difference in the treatment response rates of these two radiotherapy treatment modalities, as well as in overall survival between the groups (p=0.604).  Conclusion: Our study showed that IMRT can significantly reduce acute bowel side effects for patients undergoing neoadjuvant radiotherapy for locally advanced rectal cancers. Further studies are needed to confirm the clinical advantage of IMRT in rectal carcinoma.

Curative Intent Radiation for Anal Cancer in Pelvic Kidney Transplant: A Case Report With an Eight-Year Follow-Up.

The incidence of malignancies seen after solid organ transplant is increasing, and oncologists are seeing more patients with transplanted organs. In this case report, we present how pelvic radiotherapy can be safely administered in a patient with a transplanted kidney by conducting a comprehensive chart review and analyzing the dosimetry in the radiotherapy planning software Eclipse. A 52-year-old female patient received a kidney transplant in 2002 and was diagnosed 11 years later with a cT3 N0 M0 squamous cell carcinoma of the anal canal. She was offered radical radiation therapy with 45 Gy in 25 fractions using a volumetric modulated arc therapy plan to the pelvic lymph nodes and tumor followed by a 9-Gy boost to the anal tumor alone using a three-dimensional conformal radiation therapy plan with concurrent 5-fluorouracil/mitomycin chemotherapy for a total dose of 54 Gy. The right external iliac and inguinal lymph nodes coverage was compromised to decrease the solitary pelvic kidney dose in addition to creating a 1-cm planning risk volume around the kidney and using half-beam blocks. Her pelvic kidney only received a mean dose of 6.68 Gy. Eight years later, the patient continues to be cancer-free, as evident with a recent sigmoidoscopy in 2021 and a physical examination in 2022. Her creatinine started to rise one year post-treatment, but age of the transplanted kidney is likely the cause of kidney failure.

Heart and Coronary Artery Dose Sparing in Left-sided Breast Cancer: 3D-Conformal Radiotherapy vs. Helical Tomotherapy.

BACKGROUND/AIM: To compare heart, left ventricle (LV) and coronary artery dose-sparing with three-dimensional conformal radiotherapy (3D-CRT) vs. helical tomotherapy (HT) in left-sided breast cancer (BC). PATIENTS AND METHODS: 3D-CRT and HT treatments were planned for 20 patients (pts). Computed tomography (CT) scans without and with intravenous contrast (ic) were performed and co-registered. Left breast and organs at risk (OARs) were contoured. Dose-volume histograms (DVHs) for 3D-CRT and HT treatment plans were evaluated in terms of planning target volume for evaluation (PTVeval) coverage and dose to the OARs. RESULTS: HT provided the best target coverage and significantly reduced D2% and mean dose to the left anterior descending artery (LADA) and to the LADA-planning organ at risk volume (PRV), D2%, V5 and mean dose to the LV and D2% and V25 to the heart. As expected, due to the rotational delivery, the dose to all other coronary arteries and their PRV, contralateral breast and lungs was higher with HT. CONCLUSION: In left-sided BC, HT provided the best target coverage and significantly reduced LV and LADA doses. Moreover D2% and V25 to the heart were significantly reduced. Further studies are needed to correlate dosimetric findings with in-depth cardiac monitoring.

Deep-learning Method for the Prediction of Three-Dimensional Dose Distribution for Left Breast Cancer Conformal Radiation Therapy.

AIMS: An increase in the demand of a new generation of radiotherapy planning systems based on learning approaches has been reported. At this stage, the new approach is able to improve the planning speed while saving a reasonable level of plan quality, compared with available planning systems. We believe that new achievements, such as deep-learning models, will be able to review the issue from a different point of view. MATERIALS AND METHODS: The data of 120 breast cancer patients were used to train and test the three-dimensional U-Res-Net model. The network input was computed tomography images and patients' contouring, while the patients' dose distribution was addressed as the output of the model proposed. The predicted dose distributions, created by the model for 10 test patients, were then compared with corresponding dose distributions calculated by a reliable treatment planning system. In particular, the dice similarity coefficients for different isodose volumes, dose difference and mean absolute errors (MAE) for all voxels inside the body, Dmean, D98%, D50%, D2%, V95% for planning target volume and organs at risk were calculated and were statistically analysed with the paired-samples t-test. RESULTS: The average dose difference for all patients and voxels in body was 0.60 ± 2.81%. The MAE varied from 3.85 ± 6.65% to 8.06 ± 10.00%. The average MAE for test cases was 5.71 ± 1.19%. The average dice similarity coefficients for isodose volumes was 0.91 ± 0.03. The three-dimensional gamma passing rates with 3 mm/3% criteria varied from 78.99% to 97.58% for planning target volume and organs at risk, respectively. CONCLUSIONS: The investigation showed that a deep-learning model can be applied to predict the three-dimensional dose distribution with optimal accuracy and precision for patients with left breast cancer. As further study, the model can be extended to predict dose distribution in other cancers.

Determination and comparison of dosimetric parameters of three-dimensional conformal radiotherapy, field in field, and intensity-modulated radiotherapy techniques in radiotherapy of breast conserving patients.

Purpose: Three radiation therapy techniques for breast are common, namely three-dimensional conformal radiotherapy (3D-CRT), Field-in-Field (FIF), and Intensity-Modulated Radiotherapy (IMRT). The purpose of this study was to determine and compare dosimetric parameters of three different treatment planning planning types; 3D-CRT, FIF, and IMRT in target and normal tissues after breast-conserving surgery. Methods: One hundred patients with left or right breast cancer cooperated in this study. They were divided into three categories (small, medium, and large size) based on breast volume. Three treatment planning techniques were carried out by planner for each patient in Prowess® 5.2 Treatment Planning System. The dosimetric parameters were obtained from dose-volume histograms using the CERR software (MATLAB Company, Washington, USA), which runs as an add-on in MATLAB software. Results: 3D-CRT technique with the highest value of Dmax creates more hot spots than the other techniques in the tumor region (P = 0.013). IMRT and FIF showed the best uniformity compared to 3D-CRT in all groups with respect to the values of the parameters D98 and D2. IMRT provided the best coverage in the tumor compared to other methods (P < 0.001). 3D-CRT technique yielded a high volume receiving ≥107% of the prescription dose (P < 0.001). Among the three methods, the FIF method results in a lower dose to the lung for treatment based on the V5 and V20 parameters (P < 0.001). Homogeneity index for IMRT was better than FIF, as well as, conformity index (CI) for IMRT and FIF was better than 3D-CRT. Conclusion: IMRT and FIF plans offered excellent target coverage and uniformity, whereas FIF had better protection of healthy tissues. Thus FIF method is an efficient method to improve the quality of treatment for breast cancer patients.

Target volume coverage in clinically designed radiotherapy plan of post-mastectomy adjuvant radiotherapy of breast cancer patients in comparison with radiation therapy oncology group-based contoured plan: A dosimetric study.

Objective: Conventional field radiotherapy based on anatomical landmarks has been the traditional treatment for breast cancer. Having proven efficacy, it is still the current standard of treatment. The Radiation Therapy Oncology Group (RTOG) has published guidelines for contouring target volumes in postmastectomy patients. The impact of this guideline in the current clinical practice is less known; hence, we have analyzed dose-volume histograms (DVHs) for these plans and compared them with the proposed treatment plans to treat RTOG-defined targets. Subjects and Methods: RTOG consensus definitions were used to contour the target volumes in 20 previously treated postmastectomy patients. The prescription was 42.4 Gy in 16 fractions. DVHs were generated from clinically designed plans that had actually been delivered to each patient. For comparing dose to target volumes, new plans were generated with the goal of covering 95% of volume to 90% of prescribed dose. Results: In RTOG contoured Group, coverage improved for the supraclavicular (V90 = 83 vs. 94.9%, P < 0.05) and chest wall (V90 = 89.8 vs. 95.2%, P < 0.05). Axillary nodal coverage improved for Level-1(V90 = 80.35 vs. 96.40%, P < 0.05), Level-II (V90 = 85.93 vs. 97.09%, P < 0.05) and Level III (V90 = 86.67 vs. 98.6%, P < 0.05). The dose to the ipsilateral lung is increased (V20 = 23.87 vs. 28.73%, P < 0.05). Low dose to heart is increased in left-sided cases (V5 = 14.52 vs. 16.72%, P < 0.05) while same in right-sided cases. Conclusions: The study shows that radiotherapy using the RTOG consensus guidelines improves coverage to target volumes with a nonsignificant increase in normal organ dose compared to that based on anatomical landmarks.

Angle of concavity in planning target volume can be adopted as selection criteria for intensity-modulated radiation therapy or three-dimensional conformal radiotherapy technique in brain tumors.

Introduction: With innovation of medical imaging, radiotherapy attempts to conform the high dose region to the planning target volume (PTV). The present work aimed to assess the angle of concavity in PTV can be adopted as selection criteria for intensity-modulated radiation therapy (IMRT) or three-dimensional conformal radiotherapy (3DCRT) technique in Brain tumors. Materials and Methods: Thirty previously irradiated patients with brain tumors were replanned with both 3DCRT and IMRT technique. Angle of concavity (dip) in the PTV near the organs at risk was measured in the contoured structure set images of each patient. These cases were divided into three groups where angles were 0°, >120° and <120°. Dose of 60 Gy/30# was fixed. Results: In Group 1, the IMRT plan had better TV95% as compared to 3DCRT respectively with significant P value (P = 0.002). Mean of conformity index (CI) and Homogeneity Index (HI) were comparable. For Group 2 (angle >120°), the IMRT plan had better TV95% as compared to 3DCRT respectively with a significant P value (P = 0.021). HI and CI were not significant. For Group 3 (<120°), IMRT plan had better TV95% as compared to 3DCRT respectively with a significant P value (P = 0.001). HI and CI were better in IMRT arm with significant P value. Conclusion: The results from this study showed that the angle of concavity can be considered as an additional objective tool for selection criteria whether tumor can be treated with IMRT or 3DCRT. Tumors where angle of concavity was <120°, HI and CI provided more uniformity and conformity of dose distribution inside PTV with significant P values.

Advances in radiotherapy and its impact on second primary cancer risk: A multi-center cohort study in prostate cancer patients.

BACKGROUND: Modelling studies suggest that advanced intensity-modulated radiotherapy may increase second primary cancer (SPC) risks, due to increased radiation exposure of tissues located outside the treatment fields. In the current study we investigated the association between SPC risks and characteristics of applied external beam radiotherapy (EBRT) protocols for localized prostate cancer (PCa). METHODS: We collected EBRT protocol characteristics (2000-2016) from five Dutch RT institutes for the 3D-CRT and advanced EBRT era (N = 7908). From the Netherlands Cancer Registry we obtained patient/tumour characteristics, SPC data, and survival information. Standardized incidence ratios (SIR) were calculated for pelvis and non-pelvis SPC. Nationwide SIRs were calculated as a reference, using calendar period as a proxy to label 3D-CRT/advanced EBRT. RESULTS: From 2000-2006, 3D-CRT with 68-78 Gy in 2 Gy fractions, delivered with 10-23 MV and weekly portal imaging was the most dominant protocol. By the year 2010 all institutes routinely used advanced EBRT (IMRT, VMAT, tomotherapy), mainly delivering 78 Gy in 2 Gy fractions, using various kV/MV imaging protocols. Sixteen percent (N = 1268) developed ≥ 1 SPC. SIRs for pelvis and non-pelvis SPC (all institutes, advanced EBRT vs 3D-CRT) were 1.17 (1.00-1.36) vs 1.39 (1.21-1.59), and 1.01 (0.89-1.07) vs 1.03 (0.94-1.13), respectively. Nationwide non-pelvis SIR was 1.07 (1.01-1.13) vs 1.02 (0.98-1.07). Other RT protocol characteristics did not correlate with SPC endpoints. CONCLUSION: None of the studied RT characteristics of advanced EBRT was associated with increased out-of-field SPC risks. With constantly evolving EBRT protocols, evaluation of associated SPC risks remains important.

TACE and conformal radiotherapy vs. TACE alone for hepatocellular carcinoma: A randomised controlled trial.

Background & Aims: Transcatheter arterial chemoembolisation (TACE) is recommended for patients with hepatocellular carcinoma devoid of macrovascular invasion or extrahepatic spread but not eligible for curative therapies. We compared the efficacy and safety of the combination of a single TACE and external conformal radiotherapy (CRT) vs. classical TACE. Methods: TACERTE was an open-labelled, randomised controlled trial with a 1:1 allocation rate to two or three TACE (arm A) or one TACE + CRT (arm B). Participants had a mean age of 70 years, and 86% were male. The aetiology was alcohol in 85%. The primary endpoint was liver progression-free survival (PFS) in the intention-to-treat population. The typical CRT schedule was 54 Gy in 18 sessions of 3 Gy. Results: Of the 120 participants randomised, 64 were in arm A and 56 in arm B; 100 participants underwent the planned schedule and defined the 'per-protocol' group. In intention-to-treat participants, the liver PFS at 12 and 18 months were 59% and 19% in arm A and 61% and 36% in arm B (hazard ratio [HR] 0.69; 95% CI 0.40-1.18; p = 0.17), respectively. In the per-protocol population, treated liver PFS tended to be better in arm B (HR 0.61; 95% CI 0.34-1.06; p = 0.081) than in arm A. Liver-related grade III-IV adverse events were more frequent in arm B than in arm A. Median overall survival reached 30 months (95% CI 23-35) in arm A and 22 months (95% CI 15.7-26.2) in arm B. Conclusions: Although TACE + CRT tended to improve local control, this first Western randomised controlled trial showed that the combined strategy failed to increase PFS or overall survival and led more frequently to liver-related adverse effects. Impact and implications: Hepatocellular carcinoma is frequently treated by arterial embolisation of the tumour and more recently by external radiotherapy. We tried to determine whether combination of the two treatments (irradiation after embolisation) might produce interesting results. Our results in this prospective randomised study were not able to demonstrate a beneficial effect of combining embolisation and irradiation in these patients. On the contrary, we observed more adverse effects with the combined treatment. Clinical Trials Registration: NCT01300143.

Impact of Advanced External Beam Radiotherapy on Second Haematological Cancer Risk in Prostate Cancer Survivors.

AIMS: External beam radiotherapy (EBRT) for prostate cancer (PCa) has rapidly advanced over the years. Advanced techniques with altered dose distributions may have an impact on second haematological cancer (SHC) risks. We assessed SHC risk after EBRT for PCa and explored whether this risk has changed over the years. MATERIALS AND METHODS: Patients diagnosed with a T1-T3 PCa between 1990 and 2015 were selected from the Netherlands Cancer Registry. Patients treated with EBRT were assigned to EBRT eras based on the date of diagnosis. These eras represented two-dimensional radiotherapy (2D-RT; 1991-1996), three-dimensional conformal radiotherapy (3D-CRT; 1998-2005) or advanced EBRT (2008-2015). Standardised incidence ratios (SIR) and absolute excess risks (AER) were calculated overall and by EBRT era. Sub-hazard ratios (sHRs) were calculated for the comparison of EBRT versus radical prostatectomy and active surveillance. RESULTS: PCa patients with EBRT as the primary treatment (n = 37 762) had an increased risk of developing a SHC (SIR = 1.20; 95% confidence interval 1.13-1.28) compared with the Dutch male general population. Estimated risks were highest for the 2D-RT era (SIR = 1.32; 95% confidence interval 1.14-1.67) compared with the 3D-CRT era (SIR = 1.16; 95% confidence interval 1.05-1.27) and the advanced EBRT era (SIR = 1.21; 95% confidence interval 1.07-1.36). AER were limited, with about five to six extra cases per 10 000 person-years. Relative risk analysis (EBRT versus radical prostatectomy/active surveillance) showed significant elevation with EBRT versus active surveillance (sHR = 1.17; 95% confidence interval 1.03-1.33; P = 0.017), but not for EBRT versus radical prostatectomy (sHR = 1.08; 95% confidence interval 0.94-1.23; P = 0.281). CONCLUSION: Increased SHC risks after EBRT for PCa cancer were observed for all EBRT eras compared with the general Dutch male population. Excess risks for EBRT versus other PCa treatment groups were found for only EBRT versus active surveillance.

Three-dimensional conformal radiotherapy (3D-CRT) vs. volumetric modulated arc therapy (VMAT) in deep inspiration breath-hold (DIBH) technique in left-sided breast cancer patients-comparative analysis of dose distribution and estimation of projected secondary cancer risk.

PURPOSE: The purpose of this study was to compare two techniques of irradiation of left-sided breast cancer patients who underwent breast-conserving surgery, three-dimensional conformal radiotherapy technique (3D-CRT) and volumetric modulated arc therapy (VMAT), in terms of dose distribution in the planning target volume (PTV) and organs at risk (OARs). The second aim of the study was estimation of the projected risk of radiation-induced secondary cancer for both radiotherapy techniques. MATERIALS AND METHODS: For 25 patients who underwent CT simulation in deep inspiration breath-hold (DIBH), three treatment plans were generated: one using a three-dimensional conformal radiotherapy technique and two using volumetric modulated arc therapy. First VMAT-DIBH geometry consisted of three partial arcs (ARC-DIBH 3A) and second consisted of four partial arcs (ARC-DIBH 4A). Cumulative dose-volume histograms (DVHs) were used to compare dose distributions within the PTV and OARs (heart, left anterior descending coronary artery [LAD], ipsilateral and contralateral lung [IL, CL], and contralateral breast [CB]). Normal tissue complication probabilities (NTCPs) and organ equivalent doses (OEDs) were calculated using the differential DVHs. Excess absolute risks (EARs) for second cancers were estimated using Schneider's full mechanistic dose-response model. RESULTS: All plans fulfilled the criterium for PTV V95% ≥ 95%. The PTV coverage, homogeneity, and conformity indices were significantly better for VMAT-DIBH. VMAT showed a significantly increased mean dose and V5Gy for all OARs, but reduced LAD Dmax by 15 Gy. For IL, CL, and CB, the 3D-CRT DIBH method achieved the lowest values of EAR: 28.38 per 10,000 PYs, 2.55 per 10,000 PYs, and 4.48 per 10,000 PYs (p < 0.001), compared to 40.29 per 10,000 PYs, 15.62 per 10,000 PYs, and 23.44 per 10,000 PYs for ARC-DIBH 3A plans and 41.12 per 10,000 PYs, 15.59 per 10,000 PYs, and 22.73 per 10,000 PYs for ARC-DIBH 4A plans. Both techniques provided negligibly low NTCPs for all OARs. CONCLUSION: The study shows that VMAT-DIBH provides better OAR sparing against high doses. However, the large low-dose-bath (≤ 5 Gy) is still a concern due to the fact that a larger volume of normal tissues exposed to lower doses may increase a radiation-induced risk of secondary cancer.

Efficacy and Safety of Three-dimensional Conformal Radiotherapy for Macroscopic Vascular Invasion of Hepatocellular Carcinoma.

Chemotherapy is insufficient to treat macroscopic vascular invasion (MVI) of hepatocellular carcinoma (HCC). We retrospectively investigated the treatment outcomes of patients who underwent three-dimensional conformal radiotherapy (3D-CRT) for HCC MVI and analyzed prognostic factors by multivariate analysis using a Cox proportional hazard model. Sixty-five patients were studied. MVI sites were the portal vein (n=48 patients), portal and hepatic veins (n=8), and hepatic vein (n=9). The median irradiation dose was 50 Gy. The median survival time (MST) was 7.5 months. Performance status 2 or 3, modified albumin-bilirubin grade 2b or 3, and massive/diffuse type were poor prognostic factors. Nineteen patients (29%) with a treatment effect of 3 or 4 (≥ 50% of tumor necrosis or regression) at the irradiation sites according to the Response Evaluation Criteria in Cancer of the Liver showed longer survival than those with an effect of 1 or 2 (MST 18.7 vs. 5.9 months, p<0.001). No treatment-related death occurred. The hepatic function reserve was preserved in more than 70% of patients. 3D-CRT controlled HCC MVI safely and was suggested to be a good treatment option.

Dosimetric evaluation of hybrid and volumetric-modulated arc therapy plan for left-sided chest wall irradiation in MONACO treatment planning system.

Background and Objective: Radiation induced toxicities in heart and lungs are diminishes the survival rate of cancer patients. The purpose of this study is to evaluate the dosimetric parameters of hybrid plans for chest wall irradiation of left breast carcinoma patients using Monaco treatment planning system and compare with the volumetric-modulated arc therapy (VMAT) treatment plans. Materials and Methods: Fifteen carcinoma left breast patients were randomly selected to evaluate the advantage of hybrid plan over VMAT. Hybrid plans were generated with 70% and 30% dose contribution from forward intensity-modulated radiotherapy and VMAT, respectively, whereas VMAT had been done with full prescription. Conformity and homogeneity indices were evaluated for target coverage between hybrid and VMAT plans. Results: Hybrid plan has proved its superiority over VMAT in terms of better organ at risk sparing and lesser low dose spillage and at the same time providing comparable target coverage. In low-dose spectrum, VMAT showed higher dose-volume than the hybrid plan. The maximum variation was found to be 44.75% at 7 Gy and the minimum dose difference was observed at 1 Gy (6.02%). Conclusion: This study suggests that the hybrid plan could be a better option for left-sided chest wall irradiation in regular clinical practice.

Examination of the dose distribution of volumetric modulated arc radiotherapy using a high-definition multi-leaf collimator for breast cancer patients with irradiated regional lymph nodes.

Background: A high-definition multi-leaf collimator (HD-MLC) with 5- and 10-mm fine MLCs is useful for radiotherapy. However, it is difficult to irradiate the mammary gland and supraclavicular region using a HD-MLC because of the narrow field of volumetric modulated arc radiotherapy (VMAT). Therefore, we aimed to evaluate the dose distribution of the VMAT dose using a HD-MLC in 15 patients with left breast cancer undergoing postoperative irradiation of breast and regional lymph nodes, including the internal mammary node. Materials and methods: The following four plans were generated: three-arc VMAT using HD-MLC (HD-VMAT), two tangential arcs and one-arc VMAT using HD-MLC (tHD-VMAT), three-dimensional conformal radiotherapy (3DCRT) using HD-MLC, and two-arc VMAT using the Millennium 120-leaf MLC (M-VMAT). We assessed the doses to the target volume and organs at risk. Results: The target dose distributions were higher for HD-VMAT than 3DCRT. There were no significant differences in the heart mean dose (Dmean) or lung volume receiving 20 Gy (V20 Gy) between HD-VMAT and 3DCRT. The heart Dmean and lung V20 Gy of tHD-VMAT were higher than those of HD-VMAT, and the heart Dmean of M-VMAT was higher than that of HD-VMAT. However, the target doses of tHD-VMAT, M-VMAT, and HD-VMAT were equivalent. Conclusions: In cases of the mammary gland and regional lymph node irradiation, including the internal mammary node in patients with left breast cancer, HD-VMAT was not inferior to M-VMAT and provided a better dose distribution to the target volume and organs at risk compared with 3DCRT and tHD-VMAT.

Inter-fractional entrance dose monitoring as quality assurance using Gafchromic EBT3 film.

Introduction: This study describes a simple method of inter-fractional photon beam monitoring to measure the entrance dose of radiation treatment using Gafchromic EBT3 film. Materials and Methods: The film was placed at the center of a 1-cm thick phantom shaped like a block tray and fixed on the accessory tray of the gantry. The entrance dose was measured following the placement of the film in the accessory tray. The dose distribution calculated with the treatment planning system was compared with the dose distribution on the irradiated EBT3 films. The effectiveness of this methodology, as determined by gamma passing rates, was evaluated for the 22 fields of eight three-dimensional conformal radiotherapy (3D-CRT) plans and the 41 fields of nine intensity-modulated radiotherapy (RT) plans. The plans for three-dimensional conformal RT included treatments of the rectum, liver, breast, and head and neck, whereas the plans for intensity-modulated RT included treatments of the liver, brain, and lung. Results: The gamma passing rates for 3D-CRT ranged from 96.4% to 99.5%, with the mean gamma passing rate for 22 fields being 98.0%. The gamma passing rate for intensity-modulated RT ranged from 96.1% to 98.9%, with the mean gamma passing rate for 41 fields being 97.7%. All gamma indices were over the 95% tolerance level. Conclusions: The methodology described in this study, based on Gafchromic EBT3 film, can be utilized for inter-fractional entrance dose monitoring as quality assurance during RT. Clinical application of this method to patients can verify the accuracy of beam delivery in the treatment room.

Trends in radiotherapy administration in the management of hepatocellular carcinoma: Analysis of a Korean tertiary hospital registry of hepatocellular carcinoma patients diagnosed between 2005 and 2017.

Purpose: To present the trends in radiotherapy for the management of hepatocellular carcinoma (HCC) at a single tertiary referral hospital in South Korea. Materials and Methods: We retrospectively reviewed prospectively collected registry data of patients newly diagnosed with HCC between January 2005 and December 2017 at the Samsung Medical Center. Trends in radiotherapy, delivery techniques, tumor stage, and age were evaluated. Results: During the study period, 9,132 patients were newly diagnosed with HCC at our institution. Of these, 2,445 patients (26.8%) received radiotherapy for all lesions, including extrahepatic metastases; 1,865 patients (20.4%) received radiotherapy for intrahepatic lesions alone, and 469 patients (5.1%) received radiotherapy as initial management. Although the proportion of patients receiving radiotherapy increased slightly over the study period (24.2% vs. 26.6%), the proportions of patients receiving radiotherapy for intrahepatic lesions (16.8% vs. 21.9%) and as initial management (0.1% vs. 12.5%) increased dramatically. The majority of patients treated between 2005 and 2008 received three-dimensional conformal radiotherapy (56.3%), whereas the majority of patients treated between 2018 and 2021 received proton beam therapy (43.6%). With the technical developments, the overall survival (OS) of patients who received radiotherapy as initial management increased significantly (5-year OS: from 5.4% to 30.1%), and the OS difference between patients who did and did not receive radiotherapy as initial management significantly decreased (ratio of restricted mean survival time: from 0.383 to 0.544). Conclusion: This registry-based, retrospective study indicated an increasing trend in the utilization of radiotherapy, adoption of advanced radiotherapy techniques, and OS improvements in patients with HCC.

Intensity-Modulated Radiotherapy and Three-Dimensional Conformal Radiotherapy Combined with Intracavitary Posterior Radiotherapy for the Treatment of Medium-Term and Advanced Cervical Cancer: Efficacy, Safety and Prognostic Factors.

Objective: To explore the efficacy, safety, and prognostic factors of intensity modulated radiation therapy (IMRT) and three dimensional conformal radiation therapy (3D-CRT) combined with intracavitary posterior radiotherapy for medium-term and advanced cervical cancer. Methods: Retrospectively analyze the clinical data of 104 patients with medium-term and advanced cervical cancer who were treated in the radiotherapy department of our hospital from September 2015 to March 2017. According to the different radiotherapy techniques, they were divided into the IMRT combined with intracavitary posterior radiotherapy group (n = 52) and the 3D-CRT combined with intracavitary posterior radiotherapy group (n = 52). Observe and compare the short-term efficacy, occurrence of adverse reactions and overall survival rate of the two groups. The clinicopathological characteristics of the survival group and the death group were compared, and univariate analysis and multiple logistic regression models were used to analyze the relationship between the clinicopathological characteristics and the patient's prognosis. Results: The total effective rate of IMRT combined with intracavitary posterior radiotherapy group was 96.15%, which was higher than that of 3D-CRT combined with intracavitary posterior radiotherapy group (88.46%), but the difference was not statistically significant (p > 0.05). The incidence of digestive system injury, thrombocytopenia, and radiation proctitis in the IMRT combined intracavitary posterior radiotherapy group was lower than that of the 3D-CRT combined intracavitary posterior radiotherapy group, and the differences were statistically significant (p < 0.05). The prognosis and survival of the two groups of patients were similar, and the difference was not statistically significant (p > 0.05). Pathological classification, clinical stage, and lymph node metastasis are independent influencing factors of 3-year prognosis in patients with medium-term and advanced cervical cancer (p < 0.05). Conclusion: IMRT combined with intracavitary posterior radiotherapy is equivalent to 3D-CRT combined with intracavitary posterior radiotherapy, but it can reduce the incidence of adverse reactions in patients with medium-term and advanced cervical cancer, and has higher safety. Pathological typing, clinical staging, Lymph node metastasis were independent factor affecting the prognosis of patients. In clinical treatment, IMRT combined with intracavitary posterior radiotherapy is more recommended as a treatment plan for patients with medium-term and advanced cervical cancer.

Impact of Advanced Radiotherapy on Second Primary Cancer Risk in Prostate Cancer Survivors: A Nationwide Cohort Study.

PURPOSE: External Beam Radiotherapy (EBRT) techniques dramatically changed over the years. This may have affected the risk of radiation-induced second primary cancers (SPC), due to increased irradiated low dose volumes and scatter radiation. We investigated whether patterns of SPC after EBRT have changed over the years in prostate cancer (PCa) survivors. MATERIALS AND METHODS: PCa survivors diagnosed between 1990-2014 were selected from the Netherlands Cancer Registry. Patients treated with EBRT were divided in three time periods, representing 2-dimensional Radiotherapy (RT), 3-dimensional conformal RT (3D-CRT), and the advanced RT (AdvRT) era. Standardized incidence ratios (SIR) and absolute excess risks (AER) were calculated to estimate relative and excess absolute SPC risks. Sub-hazard ratios (sHRs) were calculated to compare SPC rates between the EBRT and prostatectomy cohort. SPCs were categorized by subsite and anatomic region. RESULTS: PCa survivors who received EBRT had an increased risk of developing a solid SPC (SIR=1.08; 1.05-1.11), especially in patients aged <70 years (SIR=1.13; 1.09-1.16). Pelvic SPC risks were increased (SIR=1.28; 1.23-1.34), with no obvious differences between the three EBRT eras. Non-pelvic SPC were only significantly increased in the AdvRT era (SIR=1.08; 1.02-1.14), in particular for the 1-5 year follow-up period. Comparing the EBRT cohort to the prostatectomy cohort, again an increased pelvic SPC risk was found for all EBRT periods (sHRs= 1.61, 1.47-1.76). Increased non-pelvic SPC risks were present for all RT eras and highest for the AdvRT period (sHRs=1.17, 1.06-1.29). CONCLUSION: SPC risk in patients with EBRT is increased and remained throughout the different EBRT eras. The risk of developing a SPC outside the pelvic area changed unfavorably in the AdvRT era. Prolonged follow-up is needed to confirm this observation. Whether this is associated with increased irradiated low-dose volumes and scatter, or other changes in clinical EBRT practice, is the subject of further research.