V100 Values Research Articles

Improper lung volume-dose parameters are risk factors for acute fatal radiation pneumonitis among esophageal cancer patients receiving chemoradiotherapy: a case-control study

BackgroundDefinitive concurrent chemoradiotherapy (DCRT) is the standard treatment for locally advanced unresectable esophageal cancer (EC). However, acute fatal radiation pneumonitis (AFRP) is one of the most harmful complications and it is still controversial which factors pose a greater risk.AimThis case-control study aims to investigate the relationship between AFRP and lung volume-dose parameters in patients with esophageal cancer undergoing DCRT.MethodsCases are patients who died of AFRP after DCRT, whereas controls are patients who did not develop RP. Participants were enrolled using the International Classification of Diseases Codes Searching and then verified by medical record review. One-to-three propensity score matching was performed between EC patients undergoing DCRT who died from AFRP and those who did not develop radiation pneumonitis(RP). Prognostic factors were determined using univariate and multivariate analyses. The exposure factors were lung volume-dose parameters, including V5, V20, V30, and mean lung dose (MLD). Overall survival was compared between the two groups of patients before and after propensity score matching.Results17 cases were confirmed with AFRP among 568 EC patients were treated with DCRT between June 2008 and June 2013, and 51 cases with no RP matched by PSM method in the control group. The median V5 and MLD values in the case group were significantly higher than the control group: 88.39% versus 65.045% and 17.325 gray (Gy) versus 14.38 Gy, respectively. V5 > 60%, V20 > 25%, and MLD > 15 Gy were identified as independent risk factors for AFRP. V5 > 80% significantly increased the susceptibility to AFRP and predicted worse overall survival.ConclusionV5 > 60%, V20 > 25% and MLD > 15 Gy are key risk factors for AFRP in EC patients undergoing DCRT. Furthermore, V5 > 80% is a strong indicator of mortality risk.

Sequential or simultaneous-integrated boost in early-stage breast cancer patients: trade-offs between skin toxicity and risk of compromised coverage

PurposeTo determine the dosimetric effects of set-up errors on boost coverage, and compares skin toxicity of sequential and simultaneous boost techniques for left-sided breast cancer.Materials and methodsThis retrospective study included 23 early-stage breast cancer cases. Single isocenter HFWBI-SIB(s-SIB), single isocenter HFWBI-SB(s-SB) and dual isocenter HFWBI-SB(d-SB) were planing. Rotations of 0.5°, 1°, and 2° coupled with translationals of 0.5 mm, 1.0 mm, and 2.0 mm were applied along three orthogonal axes. The dose to 95% of the PTV (D95) and the volume covered by 95% of the prescribed dose (V95) were evaluated using GEE univariate analysis to determine how PTV coverage was related to 1/CIRTOG, PTVboost volume, PTVboost separation to isocenter. The relationship between the high-dose regions within the PTVbreast and Ratio_V was evaluated using univariate analysis.ResultsThe s-SIB had optimal target coverage and lower high-dose volume, but it increased the risk of compromised coverage to tumor bed. For the s-SB technique, V95 exceeded 95% under all setup errors. At 2.0° coupled with 2.0 mm, s-SIB and d-SB exhibited V95 values below 95% in 34.8% and 8.7% of cases, respectively. At other setup errors, both s-SIB and d-SB demonstrated V95 values greater than 95%. Notably, high-dose regions such as V105%, V107%, and V110% within the PTVbreast across the three techniques displayed a significant correlation with Ratio_V.ConclusionSimultaneous-integrated boost for early-stage breast cancer can reduce skin toxicity compared to sequential techniques but with the risk of compromising tumor bed coverage.

Exploration of an adaptive proton therapy strategy using CBCT with the concept of digital twins

Objective.This study aims to develop a digital twin (DT) framework to achieve adaptive proton prostate stereotactic body radiation therapy (SBRT) with fast treatment plan selection and patient-specific clinical target volume (CTV) setup uncertainty. Prostate SBRT has emerged as a leading option for external beam radiotherapy due to its effectiveness and reduced treatment duration. However, interfractional anatomy variations can impact treatment outcomes. This study seeks to address these uncertainties using DT concept to improve treatment quality.Approach. A retrospective study on two-fraction prostate proton SBRT was conducted, involving a cohort of 10 randomly selected patient cases from an institutional database (n= 43). DT-based treatment plans were developed using patient-specific CTV setup uncertainty, determined through machine learning predictions. Plans were optimized using pre-treatment CT and corrected cone-beam CT (cCBCT). The cCBCT was corrected for CT numbers and artifacts, and plan evaluation was performed using cCBCT to account for actual patient anatomy. The ProKnow scoring system was adapted to determine the optimal treatment plans.Main Results.Average CTV D98 values for original clinical and DT-based plans across 10 patients were 99.0% and 98.8%, with hot spots measuring 106.0% and 105.1%. Regarding bladder, clinical plans yielded average bladder neck V100 values of 29.6% and bladder V20.8 Gy values of 12.0cc, whereas DT-based plans showed better sparing of bladder neck with values of 14.0% and 9.5cc. Clinical and DT-based plans resulted in comparable rectum dose statistics due to SpaceOAR. Compared to clinical plans, the proposed DT-based plans improved dosimetry quality, improving plan scores ranging from 2.0 to 15.5.Significance.Our study presented a pioneering approach that leverages DT technology to enhance adaptive proton SBRT, potentially revolutionizing prostate radiotherapy to offer personalized treatment solutions using fast adaptive treatment plan selections and patient-specific setup uncertainty. This research contributes to the ongoing efforts to achieve personalized prostate radiotherapy.

Is clinical target volume necessary for locally advanced non-small cell lung cancer treated with 4D-CT intensity-modulated radiation therapy

BackgroundA dosimetric evaluation is still lacking in terms of clinical target volume (CTV) omission in stage III patients treated with 4D-CT Intensity-Modulated Radiation Therapy (IMRT).Methods49 stage III NSCLC patients received 4D-CT IMRT were reviewed. Target volumes and organs at risk (OARs) were re-delineated. Four IMRT plans were conducted retrospectively to deliver different prescribed dose (74 Gy–60 Gy), and with or without CTV implementation. Dose and volume histogram (DVH) parameters were collected and compared.ResultsIn the PTV-g 60 Gy plan (PTV-g refers to the PTV generated from the internal gross tumor volume), only 5 of 49 patients had the isodose ≥ 50 Gy line covering at least 95% of the PTV-c (PTV-c refers to the PTV generated from the internal CTV) volume. When the prescribed dose was elevated to 74 Gy to the PTV-g, 33 of 49 patients could have the isodose ≥ 50 Gy line covering at least 95% of the PTV-c volume. In terms of OARs protection, the SIB-IMRT plan showed the lowest value of V5, V20, and mean dose of lung, had the lowest V55 of esophagus, and the lowest estimated radiation doses to immune cells (EDIC). The V20, V30, and mean dose of heart was lower in the simultaneous integrated boost (SIB) IMRT (SIB-IMRT) plan than that of the PTV-c 60 Gy plan.ConclusionsCTV omission was not suitable for stage III patients when the prescribed dose to PTV-g was 60 Gy in the era of 4D-CT IMRT. CTV omission plus high dose to PTV-g (74 Gy for example) warranted further exploration. The SIB-IMRT plan had the best protection to normal tissue including lymphocytes, and might be the optimal choice.

An investigation of the advantages of the adjustable angle stitch template compared with CT-guided 125I seeds free-hand implantation in the treatment of non-small cell lung carcinoma

Objective: To investigate the advantages of adjustable angle needle path template compared with CT-guided 125I seeds free-hand implantation in the treatment of non-small cell lung carcinoma. Methods: This randomized controlled trial involved the retrospective analysis of the clinical data of 45 patients with non-small cell lung carcinoma who underwent 125I seeds implantation at the Shandong Cancer Hospital, Shaanxi Provincial Tumor Hospital and The Third Affiliated Hospital of Shandong First Medical University from May 2018 to January 2023. Patients were divided into the template (n=21) and free-hand (n=24) groups, according to the modality used. The template group comprised 16 males and 5 females, aged (66±12) years, while the free-hand group comprised 16 males and 8 females, aged (62±8) years. The dose distribution, implant quality, intraoperative computed tomography (CT) scan times, and 125I seed reseeding numbers after implantation were compared between the two groups to evaluate the potential advantages of adjustable angle needle path template-assisted implantation over free-hand 125I implantation. Results: Statistical comparison revealed no significant differences in age (t=1.16, P=0.253), tumor volume [(71±26) vs. (71±22) cm3, t=0.21, P=0.837), or any other baseline characteristics between the template and free-hand groups. Overall, 45 patients successfully completed the operation. In the template group, the mean values of the D90 (dose that was delivered to 90% of the target volume), V100 (the target volume receiving 100% of the prescription dose), coverage index (CI), relative dose homogeneity index (HI), and external volume index (EI) pre-and post-implantation were (131.0±2.1) vs. (131.1±5.5) Gy, 90.0%±0.4% vs. 91.0%±2.8%, 0.83±0.07 vs. 0.82±0.05, 41%±11% vs. 37%± 13%, and 4.3%(2.9%, 14.0%) vs.8.8%(5.2%,14.6%), respectively. None of these parameters showed any significant difference (all P>0.05). In the free-hand group, the mean value of D90 pre- and post-implantation was (131.4±2.9) vs.(128.6±8.6) Gy, showing no significant difference (P>0.05), the mean values of V100, CI, HI, and EI pre-and post-implantation were 90.0%±0.5% vs. 89.0%± 3.0%, 0.84±0.04 vs. 0.71±0.09, 41%±9% vs. 34%±10%, and 7.7% (4.9%,11.0%) vs.24.2% (14.3%, 35.3%), respectively, showing significant differences (all P<0.05). The number of reseeding seeds in the template group was lower than that in the free-hand group [2.0 (0,2.5) vs. 4.0 (2.0, 7.0), Z=-3.36, P=0.001], showing a statistically significant difference. Further, the number of CT scans in the template group was significantly less than that in the free-hand group (3.9±0.5 vs. 4.6±1.2, t=-2.54, P=0.016). The incidences of adverse reactions were 23.8% (5/21) and 33.3% (8/24) (χ2=12.86, P=0.002) in the template and free-hand groups, respectively, indicating a significant difference. Conclusion: Compared with free-hand implantation, use of the adjustable angle needle path template technique can shorten the operation time, reduce the number of scans, reduce the incidence of complications, and improve treatment efficacy to a certain extent.

Real world clinical experience using daily intelligence-assisted online adaptive radiotherapy for head and neck cancer

BackgroundAdaptive radiation therapy (ART) offers a dynamic approach to address structural and spatial changes that occur during radiotherapy (RT) for locally advanced head and neck cancers. The integration of daily ART with Cone-Beam CT (CBCT) imaging presents a solution to enhance the therapeutic ratio by addressing inter-fractional changes.MethodsWe evaluated the initial clinical experience of daily ART for patients with head and neck cancer using an online adaptive platform with intelligence-assisted workflows on daily CBCT. Treatment included auto-contour and structure deformation of Organs at Risk (OARs) and target structures, with adjustments by the treating physician. Two plans were generated: one based on the initial CT simulation with the edited structures (scheduled) and a re-optimized plan (adaptive). Both plans were evaluated and the superior one approved and delivered. Clinical and dosimetric outcomes were reviewed.ResultsTwenty two patients with head and neck cancers (7 Nasopharynx, 6 Oropharynx, 1 oral cavity, 8 larynx) stages I-IVA were treated with daily ART. 770 adaptive and scheduled radiotherapy plans were generated. 703 (91.3%) adaptive plans were chosen. Median time to deliver ART was 20 minutes (range: 18-23). Adaptive compared to scheduled plans demonstrated improved mean V95 values for the PTV70, PTV59.5, and PTV56 by 1.2%, 7.2%, and 6.0% respectively and a mean 1.4% lower maximum dose in PTV70. Fourteen of 17 OARs demonstrated improved dosimetry with adaptation, with select OARs reaching statistical significance. At a median follow up of 14.1 months, local control was 95.5%, two patients developed metastatic disease and four patients died. 9.1% of patients had acute grade 3 dysphagia and 13.6% had grade 2 chronic xerostomia.DiscussionThese findings provide real world evidence of the feasibility and dosimetric benefit of incorporating daily ART on CBCT in the treatment of head and neck cancer. Prospective study is needed to determine if these dosimetric improvements translate into improved outcomes.

Cardiac segments dosimetric benefit from deep inspiration breath hold technique for left-sided breast cancer radiotherapy.

The objective was to compare dosimetry in left-sided breast cancer (LSBC) patients receiving deep inspiration breath hold (DIBH) radiotherapy (RT) with free-breathing (FB) treatment plans. Voluntary DIBH with a spirometer-based video-assisted system and CT-simulation were performed under FB and DIBH conditions on 40 LSBC patients, segmented according Duane's atlas. IMRT plans kept the same dosimetric goals on FB and DIBH conditions. Target, lungs and heart volumes were measured. Planning target volume (PTV) dose distribution, organs at risk (OARs) dose/volume parameters, including cardiac substructures, were calculated. Lungs and left-lung volumes increased in DIBH conditions (ΔV = 1637.8 ml ± 555.3 and 783.5 ml ± 286.4, respectively). Heart volume slightly decreased in apnea (p = 0.04), but target volumes, CTV and PTV were similar in FB or DIBH plans. PTV dose coverage was similar irrespective of respiratory conditions (median D50% = 41.1 Gy vs 41.0 Gy, p = 0.665; V95% = 96.9% vs. 97%). Mean dose for the whole heart (MHD), left ventricle (LV), and LV segments were significantly reduced in DIBH plans. V20 values for heart subvolumes were significantly different only for those that received considerable doses (apical and anterior). DIBH plans provided significantly smaller doses (Dmax, D2%, and V20) to the LAD artery. Important dosimetric improvements can be achieved with DIBH technique for LSBC patients, reducing the dose to the LAD artery and heart, particularly to the segments closer to the chest wall. Apical/anterior LV segments, should be considered as separate organ at risk in breast RT.

Dosimetric Effect of Target Position Accuracy on Single-Isocenter Multiple Liver Metastases SBRT.

Purpose: To evaluate the dosimetric effects of intrafraction baseline shifts combined with rotational errors on Four-dimensional computed tomography-guided stereotactic body radiotherapy for multiple liver metastases (MLMs). Methods: A total of 10 patients with MLM (2 or 3 lesions) were selected for this retrospective study. Baseline shift errors of 0.5, 1.0, and 2.0 mm; and rotational errors of 0.5°, 1°, and 1.5°, were simulated about all axes. All of the baseline shifts and rotation errors were simulated around the planned isocenter using a matrix transformation of 6° of freedom. The coverage degradation of baseline shifts and rotational errors were analyzed according to the dose to 95% of the planning target volume (D95) and the volume covered by 95% of the prescribed dose (V95), and related changes in gross tumor volume were also analyzed. Results: At the rotation error of 0.5° and the baseline offset of less than 0.5 mm, the D95 and V95 values of all targets were >95%. For rotational errors of 1.0° (combined with all baseline shift errors), 36.3% of targets had D95 and V95 values of <95%. Coverage worsened substantially when the baseline shift errors were increased to 1.0 mm. D95 and V95 values were >95% for about 77.3% of the targets. Only 11.4% of the D95 and V95 values were >95% when the baseline shift errors were increased to 2.0 mm. When the rotational error was increased to 1.5° and baseline shift errors increased to 1.0 mm, the D95 and V95 values were >95% in only 3 cases. Conclusions: The multivariate regression model analysis in this study showed that the coverage of the target decreased further with reduced target volume, increasing the baseline drift, the rotation error, and the distance to the target.

Dosimetric analysis of half-field-based VMAT with the deep inspiration breath-hold technique for left breast cancer patients following breast-conserving surgery.

Compared the dosimetric characteristics of half-field-based VMAT and half-field-based IMRT for left breast cancer patients combined with deep inspiration breath-hold (DIBH) and free breathing (FB) techniques. Twenty-one left breast cancer patients were included. Each patient underwent DIBH and FB CT scans, IMRT and VMAT plans in half-field beam mode for both breathing techniques, resulting in four plans: FB-IMRT (F-IMRT), FB-VMAT (F-VMAT), DIBH-IMRT (D-IMRT) and DIBH-VMAT (D-VMAT). The conformity index (CI), homogeneity index (HI), and the doses received at the heart, left anterior descending (LAD), left lung, right breast, and right lung, were compared among plans.The correlation between the difference in the volume of lung_L (ΔLVL) and the difference in the mean dose (ΔDmean) of lung_L under the DIBH and FB plans, the correlation between the difference in the heart-chest distance (ΔHCD) and the ΔDmean of the heart,LAD under the DIBH and FB plans. The D-VMAT plan lower lung_L V5 than both the F-IMRT and F-VMAT plans (p<0.05), The D-VMAT plan lower values for V10, V20, V30, and Dmean than did the other plans (p < 0.05). For the heart, the D-VMAT plan lower V5, V10, V20, and Dmean values than did the other plans (p < 0.05). The D1% and Dmax of the heart and the Dmax and Dmean of the LAD obtained with the D-VMAT plan were lower than those obtained with the F-IMRT and F-VMAT plans (p < 0.05). ΔHCD exhibited correlation with the ΔDmean of the LAD between the D-VMAT and F-IMRT plans and between the D-VMAT and F-VMAT plans (R = -0.765 and -0.774, respectively, p = 0.000). the D-VMAT plan offered enhanced protection for OARs. The integration of the DIBH technique with half-field and VMAT technology in the D-VMAT plan offers a superior dose distribution.

A data-driven model for personalised risk prediction of radiation-induced oral mucositis in oral cavity cancer patients

Abstract Aim: Radiation-induced oral mucositis (OM) is the most common complication presenting with chemo radiation therapy of oral cavity cancer. Tobacco use, oral hygiene and nutritional status are important entities that impact the incidence of OM. These entities must also be studied along with treatment planning strategies, to alleviate its incidence. Our study aims to present a novel method to model the OM incidence using a mucosal surface contour (MSC). Methods: Computed tomography (CT) images of 60 oral cavity patients who have started their intensity-modulated radiation therapy (IMRT)/volumetric-modulated arc therapy (VMAT) with concomitant chemotherapy (Cisplatin) were delineated with MSC as one of the organs at risk by three expert radiation oncologists. V30, V50 and Dmean doses of MSC and the PTV 60 (planning target volume for 60 Gy), along with Dmax of PTV60, were extracted from the dose volume histograms. OM toxicity was assessed once weekly, and the outcome was scored using CTCAE v5·0 grading. Tobacco use (Tb), oral hygiene (OHy) and nutritional status (Ns) were also numerically scored. A multiple linear regression analysis was done using the patient parameters and the outcome scores as predictor variables and response variables, respectively. Optimal dose volume constraints (Dmean, V30, V50) for a 20% reduction of OM were derived from the mathematical equations. Another 20 patients were planned prospectively using IMRT/VMAT with the above resulted in dose constraints. Clinical outcome was scored for these patients using CTCAE v5·0. Outcome results of the two phases (60 patients and 20 patients) were statistically compared with two-sample t-test. Results: For MSC, three mathematical equations were formulated using multiple linear regression analysis. Derived values of V30, V50 and Dmean constraints were used for dose optimisation in the second phase of treatment planning. It has showed a statistically significant deviation from the first phase of the study, with a confidence interval of 95% (p value: 0·0348) by introducing calculated dose constraints for MSC in dose optimisation. Conclusion: In this study, the feasibility of using multiple linear regression analysis to model OM incidence in radiation therapy clinics was explored. Derived dose–volume constraints for MSC could be used in IMRT/VMAT optimization to reduce its incidence. Patient treatment could be individualised by incorporating dose–volume parameters, nutritional status, tobacco use and oral hygiene status in the treatment planning procedure.

Effect of model-based dose-calculation algorithms in high dose rate brachytherapy of cervical carcinoma.

Task Group 43 (TG-43) formalism does not consider the tissue and applicator heterogeneities. This study is to compare the effect of model-based dose calculation algorithms, like Advanced Collapsed Cone Engine (ACE), on dose calculation with the TG-43 dose calculation formalism in patients with cervical carcinoma. 20 patients of cervical carcinoma treated with a high dose rate of intracavitary brachytherapy were prospectively studied. The target volume and organs at risk (OARs) were contoured in the Oncentra treatment planning system (Elekta, Veenendaal, The Netherlands). All patients were planned with cobalt-60 (Co-60) and iridium-192 (Ir-192) sources with doses of 21 Gy in 3 fractions. These plans were calculated with TG-43 formalism and a model-based dose calculation algorithm ACE. The dosimetric parameters of TG-43 and ACE-based plans were compared in terms of target coverage and OAR doses. For Co-60-based plans, the percentage differences in the D90 and V100 values for high-risk clinical target volume (HR-CTV) were 0.36 ± 0.43% and 0.17 ± 0.31%, respectively. For the bladder, rectum and sigmoid, the percentage differences for D2cc volumes were -0.50 ± 0.51%, -0.16 ± 0.53% and -0.37 ± 1.21%, respectively. For Ir-192-based plans, the percentage difference in the D90 for HR-CTV was 0.54 ± 0.79%, while V100 was 0.24 ± 0.29%. For the bladder, rectum and sigmoid, the doses to 2cc volume were 0.35 ± 1.06%, 0.99 ± 0.74% and 0.74 ± 1.92%, respectively. No significant differences were found in the dosimetric parameters calculated with ACE and TG-43. The ACE algorithm reduced doses to OARs and targets. However, ACE and TG-43 did not show significant differences in the dosimetric parameters of the target and OARs with both sources.

Dosimetric comparison of intra-cavitary brachytherapy technique with free-hand (intra-cavitary + interstitial) technique in cervical cancer.

The aim of the study was to dosimetrically compare intra-cavitary brachytherapy technique (ICBT) with free-hand (intra-cavitary + interstitial, IC + IS) technique. Twenty seven locally advanced carcinoma cervix patients were included in the study. Patients with more than medial 1/3rd parametrial residual disease without extending upto lateral pelvic wall were included, following external beam radiotherapy (EBRT), in which cobalt-60 high-dose-rate (60Co HDR) brachytherapy source was used. Dose for both plans were 6.5 Gy × 4 fractions, 2 fractions per day, 6 hours apart, over 2 days. Free-hand brachytherapy technique, consisted of placement of central tandem and 2 ovoids along with needles without using template, was applied. Two plans were generated by activating and deactivating the needles, and compared by normalizing to V100. A total of 79 needles were applied. Using paired-t test, dosimetric comparison of both the plans was done. Free-hand plan had a significant higher mean V90 (volume receiving 90% of the dose) of 94.2% compared with 87.22% in ICBT plan (p ≤ 0.0001). Free-hand and ICBT plans presented a mean V100 values of 89.06% and 81.51% (p ≤ 0.0001), respectively, favoring free-hand plan. The mean D90 (dose to 90% volume), D98, and D100 of free-hand plan were 6.28 Gray (Gy), 4.91 Gy, and 3.62 Gy, respectively, but equivalent parameters in ICBT plan were 5.26 Gy, 3.72 Gy, and 2.61 Gy, with p value ≤ 0.0001. In both the plans, D2cc of the bladder, rectum, and sigmoid were 4.59 Gy, 3.98 Gy, 2.77 Gy, and 4.46 Gy, 3.90 Gy, 2.67 Gy, respectively, with no statistical significance. Free-hand brachytherapy (IC + IS) achieves a statistically significant better dose distribution to high-risk clinical target volume (HR-CTV) comparing with ICBT technique with similar dose to organs at risk.

Deep Learning-based Lung dose Prediction Using Chest X-ray Images in Non-small Cell Lung Cancer Radiotherapy.

This study aimed to develop a deep learning model for the prediction of V20 (the volume of the lung parenchyma that received ≥20 Gy) during intensity-modulated radiation therapy using chest X-ray images. The study utilized 91 chest X-ray images of patients with lung cancer acquired routinely during the admission workup. The prescription dose for the planning target volume was 60 Gy in 30 fractions. A convolutional neural network-based regression model was developed to predict V20. To evaluate model performance, the coefficient of determination (R2), root mean square error (RMSE), and mean absolute error (MAE) were calculated with conducting a four-fold cross-validation method. The patient characteristics of the eligible data were treatment period (2018-2022) and V20 (19.3%; 4.9%-30.7%). The predictive results of the developed model for V20 were 0.16, 5.4%, and 4.5% for the R2, RMSE, and MAE, respectively. The median error was -1.8% (range, -13.0% to 9.2%). The Pearson correlation coefficient between the calculated and predicted V20 values was 0.40. As a binary classifier with V20 <20%, the model showed a sensitivity of 75.0%, specificity of 82.6%, diagnostic accuracy of 80.6%, and area under the receiver operator characteristic curve of 0.79. The proposed deep learning chest X-ray model can predict V20 and play an important role in the early determination of patient treatment strategies.

Application research on reducing radiation-induced lung injury with a trigger operator based on overlap volume histogram (OVH) in breast cancer postoperative radiotherapy

This study aims to develop a trigger operator based on the Overlap Volume Histogram (OVH) and examined its effectiveness in enhancing plan quality to minimize radiation-induced lung injury in postoperative radiotherapy for breast cancer. This trigger operator was applied for plan re-optimization to the previous Volumetric Modulated Arc Therapy (VMAT) plans of 16 left breast conserving surgery cases. These cases were categorized into a Contiguous Group (CG) and a Separated Group (SG) based on the relative position between the target and the Left-Lung (L-Lung). We investigated the changes in Vx, mean dose, and Normal Tissue Complication Probability (NTCP) values of organs-at-risk (OARs) before and after using the trigger operator. The Pairwise Sample T test was employed to evaluate the differences in indices between the two groups before and after optimizations. The trigger operator effectively initiated plan re-optimization. The values of V5, V10, V20, V30, and V40 of the L-Lung, as well as the mean dose of the heart, all decreased after re-optimization. The Pairwise Sample T test results showed statistically significant differences in the V20, V30, and V40 of the L-Lung in the CG (P < 0.01), and in the V5, V10, V20, V30, and V40 of the L-Lung in the SG (P < 0.01). Our findings suggest that the proposed trigger operator can improve plan quality, thereby reducing radiation-induced lung injury in postoperative radiotherapy for breast cancer.

Meme kanseri nedeniyle radyoterapi uygulanan hastalarda Tp-e aralığı ve Tp-e/QT oranının prospektif olarak incelenmesi

Aims: The aim of this prospective study was to investigate ventricular repolarization using the Tp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio in breast cancer patients treated with adjuvant radiotherapy(RT) following systemic chemotherapy.&#x0D; Methods: The study was designed as a national, single-center prospective study. According to the treatment protocol, electrocardiograms (ECGs) were taken from all patients on their first and last days of RT. Tp-e intervals, Tp-e/QT ratios, and Tp-e/QTc ratios were calculated based on the ECG recordings. The heart doses due to radiation exposure were examined with mean heart dose, V5, V10,V20, and V30 values. &#x0D; Results: 51 postsurgical patients, who were all treated with AC followed by weekly paclitaxel and had an indication for adjuvant RT, were included in the study. The mean heart dose was observed as median 205 cGy, and the V30 value was 0.01%. When ECG measurements were analyzed, statistically significant increases were observed in Tp-e interval (p

Pneumonitis Rates Before and After Adoption of Immunotherapy Consolidation in Patients With Locally Advanced Non-Small Cell Lung Cancer Treated With Concurrent Chemoradiation

We hypothesized that after adoption of immune checkpoint inhibitor (ICI) consolidation for patients with locally advanced non-small cell lung cancer (LA-NSCLC) receiving concurrent chemoradiation therapy (cCRT), rates of symptomatic pneumonitis would increase, thereby supporting efforts to reduce lung radiation dose. This single institution, multisite retrospective study included 783 patients with LA-NSCLC treated with definitive cCRT either before introduction of ICI consolidation (pre-ICI era cohort [January 2011-September 2017]; N=448) or afterward (ICI era cohort [October 2017-December 2021]; N=335). Primary endpoint was grade ≥2 pneumonitis (G2P) and secondary endpoint was grade ≥3 pneumonitis (G3P), per Common Terminology Criteria for Adverse Events v5.0. Pneumonitis was compared between pre-ICI era and ICI era cohorts using the cumulative incidence function and Gray's test. Inverse probability of treatment weighting (IPTW)-adjusted Fine-Gray models were generated. Logistic models were developed to predict the 1-year probability of G2P as a function of lung dosimetry. G2P was higher in the ICI era than in the pre-ICI era (1-year cumulative incidence 31.4% vs 20.1%; P < .001; IPTW-adjusted multivariable subdistribution hazard ratio, 2.03; 95% confidence interval, 1.53-2.70; P < .001). There was no significant interaction between ICI era treatment and either lung volume receiving≥20 Gy (V20) or mean lung dose in Fine-Gray regression for G2P; however, the predicted probability of G2P was higher in the ICI era at clinically relevant values of lung V20 (≥24%) and mean lung dose (≥14 Gy). Cut-point analysis revealed a lung V20 threshold of 28% in the ICI era (1-year G2P rate 46.0% above vs 19.8% below; P < .001). Among patients receiving ICI consolidation, lung V5 was not associated with G2P. G3P was not higher in the ICI era (1-year cumulative incidence 7.5% vs 6.0%; P=.39; IPTW-adjusted multivariable subdistribution hazard ratio, 1.12; 95% confidence interval, 0.63-2.01; P=.70). In patients with LA-NSCLC treated with cCRT, the adoption of ICI consolidation was associated with an increase in G2P but not G3P. With ICI consolidation, stricter lung dose constraints may be warranted.

Application of tangent-arc technology for deep inspiration breath-hold radiotherapy in left-sided breast cancer.

To explore the advantages of dosimetry and the treatment efficiency of tangent-arc technology in deep inspiration breath-hold radiotherapy for breast cancer. Forty patients with left-sided breast cancer who were treated in our hospital from May 2020 to June 2021 were randomly selected and divided into two groups. The first group's plan was a continuous semi-arc that started at 145° ( ± 5°) and stopped at 325° ( ± 5°). The other group's plan, defined as the tangent-arc plan, had two arcs: the first arc started at 145° ( ± 5°) and stopped at 85° ( ± 5°), and the second arc started at 25° ( ± 5°) and stopped at 325° ( ± 5°). We compared the target dose, dose in organs at risk (OARs), and treatment time between the two groups. The target dose was similar between the continuous semiarc and tangent-arc groups. The V5 of the right lung was significantly different between the two groups (Dif 5.52, 95% confidence interval 1.92-9.13, t=3.10, P=0.004), with the patients in the continuous semi-arc and tangent-arc groups having lung V5 values of (9.16 ± 1.62)%, and (3.64 ± 0.73)%, respectively. The maximum dose to the spinal cord was (1835.88 ± 222.17) cGy in the continuous semi-arc group and (599.42 ± 153.91) cGy in the tangent-arc group, yielding a significant difference between the two groups (Dif 1236.46, 95% confidence interval 689.32-1783.6, t=4.57, P<0.001). The treatment times was (311.70 ± 60.45) s for patients in the continuous semi-arc group and (254.66 ± 40.73) s for patients in the tangent-arc group, and there was a significant difference in the mean number of treatment times between the two groups (Dif 57.04, 95% confidence interval 24.05-90.03, t=3.5, P=0.001). Both the continuous semi-arc and tangent-arc plans met the clinical prescription dose requirements. The OARs received less radiation with the tangent-arc plan than the continuous semi-arc plan, especially for the lung (measured as V5) and the spinal cord (measured as the maximum dose). Tangent-arc plan took significantly less time than the continuous semi-arc, which can greatly improve treatment efficiency. Therefore, tangent-arc plans are superior continuous semi-arc plans for all cases.

Dosimetric Comparision of Coplanar versus Noncoplanar Volumetric Modulated Arc Therapy for Treatment of Bilateral Breast Cancers.

The purpose of this study was to compare the dosimetric parameters of volumetric modulated arc therapy (VMAT) treatment plans using coplanar and noncoplanar beams in patients with bilateral breast cancer/s (BBCs) in terms of organ at risk sparing and target volume coverage. The hypothesis was to test whether VMAT with noncoplanar beams can result in lesser dose delivery to critical organs such as heart and lung, which will result in lesser overall toxicity. Data of nine BBC cases treated at our hospital were retrieved. Computed tomography simulation data of these cases was used to generate noncoplanar VMAT plans and the parameters were compared with standard VMAT coplanar plans. Contouring was done using radiation therapy oncology group guidelines. Forty-five Gray in 25 fractions was planned followed by 10 Gy in five fractions boost in breast conservation cases. No significant difference in planning target volume (PTV) coverage was found for the right breast/chestwall (P = 0.940), left breast/chestwall (P = 0.872), and in the total PTV (P = 0.929). Noncoplanar beams resulted in better cardiac sparing in terms of Dmean heart. The difference in mean dose was >1 Gy (8.80 ± 0.28 - 7.28 ± 0.33, P < 0.001). The Dmean, V20 and V30 values for total lung slightly favor noncoplanar beams, although there was no statistically significant difference. The average monitor units (MUs) were similar for coplanar plans (1515 MU) and noncoplanar plans (1455 MU), but the overall treatment time was higher in noncoplanar plans due to more complex setup and beam arrangement. For noncoplanar VMAT plans, the mean conformity index was slightly better although the homogeneity indices were similar. VMAT plans with noncoplanar beam arrangements had significant dosimetric advantages in terms of sparing of critical organs, that is Dmean of heart doses with almost equivalent lung doses and equally good target coverage. Larger studies with clinical implications need to be considered to validate this data.

Dosimetric comparison of three-dimensional conformal radiation therapy, intensity-modulated radiation therapy, and volumetric-modulated arc therapy for free-breathing whole-breast irradiation: A planning study.

Currently, recommended heart dose constraints are difficult to meet in whole-breast irradiation (WBI) for left-sided breast cancer patients, who cannot be treated with the deep inspiration breath hold. We performed a radiotherapy planning study to establish if the use of intensity-modulated radiation therapy (IMRT) or volumetric-modulated arc therapy (VMAT) allows for better sparing of the heart and its subvolumes than the three-dimensional conformal radiation therapy (3D-CRT), and how these attempts affect the dose delivered to the other organs. A total of 17 left-sided and 10 right-sided consecutive patients treated with free-breathing WBI were retrospectively included. The 3D-CRT, IMRT, and VMAT plans were generated. Several dose-volume parameters and plan quality indices were compared, separately for the left- and right-sided plans. All the techniques fulfilled the planning objectives. In the left-sided plans, there was no heart or left ventricle dose reduction with IMRT, nor with VMAT; the maximum dose in the left anterior descending coronary artery was reduced with VMAT (P = 0.005); V5 for the contralateral breast, contralateral lung, and total-body increased markedly in VMAT, and for the ipsilateral lung (V5IL) also in IMRT, compared with 3D-CRT (P < 0.001). In the right-sided plans, the V5 values, except for V5IL, did not differ between the three techniques. IMRT and VMAT had a limited heart-sparing benefit in the left-sided free-breathing WBI, at the cost of increased low-dose volumes, measured by V5. The low-dose volumes are not increased by IMRT or VMAT in the right-sided WBI, where heart sparing is not a problem, but the attempts to reduce cardiac doses in the left-sided WBI increase them.

The effect of breath-hold technique on conformal and intensity modulated radiotherapy techniques at right breast cancer radiotherapy including internal mammarian field

Background/Aim: Significantly lower heart doses can be achieved by breath-hold technique at left-sided breast cancer radiotherapy (RT). We see high doses at organs at risk such as lung, heart, and contralateral breast during right-sided breast cancer RT planning especially in the presence of RT indication for mammaria interna (MI) lymph nodes. This study compared RT-planning methods that are conformal with intensity-modulated RT (IMRT) with breath holding and free breathing for right-sided breast cancer RT including full axillary and MI lymph node fields. Methods: Computed tomography (CT) simulations were performed using free-breath (FB) and breath-hold (BH) methods in 10 patients with right-sided breast cancer. A total of 40 RT treatment plans were calculated. Right-sided breast, level 1-2-3 axillary regions, and MI regions served for the target-planning volume. Left-sided breast, heart, as well as right-sided and left lungs were contoured as critical organs according to the atlas of the "Radiation Therapy Oncology Group." We used a Varian Eclipse v.13 for treatment planning. Conformal “FieldinField” RT (FinFRT) and dynamic IMRT (dIMRT) planning were performed separately for each patient over breath-hold and free-breath images. For PTV, 50 Gy was prescribed in 25 fractions and optimized such that the planned target volume (PTV) remained between 95% and 110% of the dose. The mean and maximum doses of the heart, V5 and V20 of the lungs, as well as V95 doses for MI were recorded. Statistical analyses were performed with SPSS version 22, and a paired t-test was used for comparison. Results: Four treatment plans (FB FinFRT, BH FinFRT, FB dIMRT, BH dIMRT) were made separately for 10 patients. For comparison, common FB FinFRT plans were accepted as the baseline plan. As expected, there were no significant differences in PTV coverage. The mean dose received by 95% of the MI volume was between 42.27 Gy and 42.4 Gy. For the maximum heart dose, the breath hold technique had no significant effect on plans. The lowest average maximum heart dose was seen in the BH FinFRT group. Mean heart doses are between 1.28 Gy – 4.85 Gy. There was no significance between BH FinFRT and FB FinFRT plan (P=0.504), and there was a significant difference for heart mean dose versus dIMRT plans (P=0.001). The mean V20 of the lungs ranged from 11.9 to 17.8. There was a significant decrease in V20 with BH or FB dIMRT plans (P=0.001). There was no difference between BH FinFRT (P=0.138). On the contrary, lung V5 values were significantly higher in dIMRT plans, and the lowest mean V5 value was seen in BH FinFRT plan. Conclusion: With the BH method, lower doses (but not significantly lower doses) were obtained in critical organ doses. There was a significant decrease with FinFRT plans in terms of heart mean and maximum dose and lung V5 percentages. The dIMRT plans were significant only in lung V20 percentages. When planning RT, we recommend evaluating all treatment techniques individually for right-sided breast cancer patients to obtain lower doses in critical organs.