Intensity-modulated Radiotherapy For Cancer Research Articles

Prophylactic Effect of Clarithromycin on Radiation Pneumonitis in IMRT for Lung Cancer.

To evaluate the association between prophylactic administration of clarithromycin (CAM) and the development of radiation pneumonitis (RP) in patients treated with intensity modulated radiation therapy (IMRT) for lung cancer. A total of 89 patients who underwent definitive or salvage IMRT for lung cancer were retrospectively evaluated. The median total and daily doses were 60 Gy and 2 Gy, respectively. A total of 39 patients (44%) received CAM for a median of three months after the start of IMRT. The relationship between the development of RP and certain clinical factors was analyzed. RP of Grade ≥2 was recognized in 10 (11%) patients; Grade 2 in six patients and Grade 3 in four patients. The incidence of Grade ≥2 RP was 3% (1/39) in patients treated with CAM, which was significantly lower than that of 18% (9/50) in patients without CAM. The median lung V20 and V5 in the 10 patients with RP Grade ≥2 were 24% and 46%, respectively, compared with 18% and 37% in the 79 patients with RP Grade 0-1, and the differences were significant. Durvalumab administration after IMRT was also a significant factor for RP Grade ≥2. Prophylactic administration of CAM may reduce Grade ≥2 RP in patients treated with IMRT for lung cancer. Therefore, further clinical trials are warranted.

Comparison of plan quality and robustness using VMAT and IMRT for breast cancer

Abstract To evaluate the plan quality and robustness of volumetric modulated arc therapy (VMAT) and intensity modulated radiation therapy (IMRT) for breast cancer, 50 patients, including 25 patients who received radiotherapy after breast-conserving surgery (BCR) and 25 patients who received postmastectomy radiotherapy (PRT), were selected for this study. Nominal VMAT and IMRT plans were generated for each patient on Eclipse treatment planning system (version 15.6). The dosimetric metrics, dose distribution, gamma passing rate, and delivery time were compared. In addition, 12 uncertainty plans with plan isocenter uncertainty and CT density uncertainty were recalculated based on the nominal plans for each patient. The dose volume histogram (DVH) band width (DVHBW) was adopted to quantify the plan robustness of the nominal plans for the perturbed scenarios in this study. For BCR, the dosimetric metrics except planning target volume (PTV) conformal index (CI) and ipsilateral lung V 5 were not statistically different for IMRT and VMAT plans. PTV CI of VMAT plans was better than that of IMRT plans (VMAT: 0.923 ± 0.024, IMRT: 0.855 ± 0.032, p = 0.003). The ipsilateral lung V 5 of VMAT plan was higher than that of IMRT plan (VMAT: 42.4% ± 2.8%, IMRT: 40.5% ± 4.0%, p = 0.045). The VMAT plans save more than 1.20 min compared to the IMRT plans (VMAT: 0.87 min, IMRT: 2.08 min, p < 0.001). The gamma passing rates of VMAT plans were better than those of IMRT plans (3 mm/3%, VMAT: 99.7% ± 0.2%, IMRT: 99.4% ± 0.4%, p < 0.001; 2 mm/2%, VMAT: 97.2% ± 1.0%, IMRT: 96.9% ± 0.6%, p = 0.108). For PRT, the dosimetric metrics of VMAT plans, including PTV D mean, homogeneity index (HI), CI, and D max of spinal cord, were significantly better than those of IMRT plans. The VMAT plans save more than 45% time compared with IMRT plans (VMAT: 1.54 min, IMRT: 2.81 min, p < 0.001). The difference in gamma passing rates between VMAT plans and IMRT plans was not statistically significant. For the plan robustness, the DVHBW of VMAT plans and IMRT plans for BCR were 2.09% ± 0.23% and 2.98% ± 0.40%, respectively (p < 0.05). For PRT, the DVHBW of VMAT plans was significantly better than those of IMRT plans (VMAT: 3.05% ± 0.26%, IMRT: 3.57% ± 0.27%, p < 0.05). The results show that the dosimetric metrics of VMAT plans were comparable to those of IMRT plans. More importantly, the VMAT plans had excited dose distribution and fast execution efficiency. The plan robustness of VMAT plans were superior.

Less than whole uterus irradiation for patients with locally advanced cervical cancer

IntroductionCurrent consensus guidelines for definitive cervical cancer intensity modulated radiation therapy (IMRT) recommend inclusion of the entire uterus within the clinical target volume, however this is debated. We aimed to evaluate outcomes of patients with cervical cancer who were treated with less than whole uterus irradiation. MethodsWe identified 109 patients with FIGO Stage IB-IVA cervical cancer treated definitively with concurrent chemoradiation, including IMRT and brachytherapy, from 2010 to 2022 at a single institution where the practice was to include the gross cervix tumor with an internal target volume with differences in bladder filing accounted for, plus additional 5 mm planning target volume (PTV) margin. Local, regional, and distant recurrences were analyzed using competing risk methods, and a Wilcoxon rank sum test was performed to assess differences in dose to organs at risk based on the proportion of the uterus included in the PTV, with the median proportion of the uterus included (75 %) used as the cut-point. ResultsThe median follow-up time was 65 months (range 3–352 months). The 2-year cumulative incidence of LR for the entire cohort was 4.2 % (95 % confidence interval [CI] 1.3–9.7). Compared with patients who had ≥ 75 % of the uterus included in the PTV, patients who had < 75 % of the uterus included in the PTV had significantly lower bowel D200cc (p = 0.02). The cumulative incidence of local failure (LR) was not significantly different between the two groups. ConclusionsIncluding less than the whole uterus for definitive cervix cancer IMRT does not seem to compromise local control. Less than whole uterus irradiation could be considered for carefully selected cervix cancer patients to decrease bowel dose and possible treatment-related toxicity.

Does intensity-modulated radiation therapy by helical tomotherapy for prostate cancer increase the subsequent risk of bladder cancer? A propensity score-matched analysis.

This study aimed to evaluate the risk of bladder cancer after intensity-modulated radiation therapy (IMRT) using helical tomotherapy for prostate cancer in comparison to the risk post-radical prostatectomy (RP) using propensity score-matched analysis and to assess the risk factors for bladder cancer. This retrospective study included 2067 patients with non-metastatic prostate cancer treated at our institution between June 2007 and December 2016. Of these, 1547 patients were treated with IMRT and 520 underwent RP. The propensity scores were calculated using age, National Comprehensive Cancer Network risk classification, prostate volume, Brinkman index, and follow-up time as matched covariates. A propensity score-matched patient cohort (n = 718; IMRT: 359, RP: 359) was created, and the risk of bladder cancer after treatment was compared. In total, bladder cancer was detected in 33 patients. Five patients in the IMRT group and one in the RP group died of bladder cancer. In the propensity score-matched analysis, the 5-year bladder cancer-free survival rate was significantly lower in the IMRT group than in the RP group (91.7% and 96.2%, respectively; p < 0.001). Multivariate analysis revealed that IMRT and the Brinkman index were the risk factors for bladder cancer in this cohort (odds ratio = 5.085, 95% confidence interval = 1.436-18.008, p = 0.012 and odds ratio = 1.001, 95% confidence interval = 1.000-1.001, p = 0.010, respectively). IMRT for prostate cancer using helical tomotherapy increases the subsequent risk of bladder cancer compared with RP and is an independent risk factor for bladder cancer similar to smoking.

Impact of prostate position-based image-guidance in intensity-modulated radiation therapy for localized prostate cancer.

The long-term clinical impact of prostate position-based image-guided radiotherapy (IGRT) for localized prostate cancer remains unclear. We retrospectively compared clinical outcomes following intensity-modulated radiation therapy (IMRT) with cone-beam computed tomography-based prostate position-based IGRT (P-IGRT) or without P-IGRT (non-P-IGRT). From June 2011, we applied P-IGRT in IMRT for intermediate-risk (IR) prostate cancer (PCa) (D'Amico risk classification) (76Gy in 38 fractions, with smaller margins). Clinical outcomes of patients who received P-IGRT between June 2011 and June 2019 were retrospectively compared with those of patients with IR PCa who received IMRT without P-IGRT between October 2002 and May 2011 in our institution (74Gy in 37 fractions). A total of 222 consecutive patients were analyzed: 114 in the P-IGRT cohort and 108 in the non-P-IGRT cohort. The median follow-up period after IMRT was 7.1years for the P-IGRT cohort and 10.8years for the non-P-IGRT cohort. The biochemical failure-free rate was significantly better in the P-IGRT cohort (94.9% for the P-IGRT cohort vs 82.7% for the non-P-IGRT cohort at 10years, p = 0.041). The rate of rectal bleeding which needs intervention including the use of suppositories was significantly lower in the P-IGRT cohort (p < 0.001). The use of P-IGRT with higher doses and smaller margins was correlated with significantly better biochemical control, and a lower incidence of rectal bleeding in IMRT for intermediate-risk prostate cancer. The enhanced accuracy using P-IGRT has the potential to independently improve disease control and reduce late rectal bleeding.

Long-term findings of rectal endoscopy and rectal bleeding after moderately hypofractionated, intensity-modulated radiotherapy for prostate cancer

To present rectal endoscopic findings and toxicity after definitive moderately hypofractionated, intensity-modulated radiotherapy (IMRT) for prostate cancer. We retrospectively reviewed patients who underwent IMRT for prostate cancer and underwent post-radiotherapy endoscopies between 2008 and 2018. Endoscopic findings were reviewed and graded using Vienna Rectoscopy Score (VRS). We have analyzed the association between endoscopic findings and rectal bleeding, and investigated risk factors for rectal bleeding. Total 162 patients met the inclusion criteria of this study. There was a trend of VRS worsening during the initial 3 years after radiotherapy followed by recovery. Rectal bleeding was highest at 1 year after radiotherapy and improved thereafter. The 5-year cumulative incidence of grade ≥ 2 rectal bleeding was 14.8%. In the multivariable Cox regression analysis, cardiovascular disease (hazard ratio [HR] 2.732, P = 0.037), rectal wall V65 (HR 1.158, P = 0.027), and VRS ≥ 3 in first post-radiotherapy endoscopy (HR 2.573, P = 0.031) were significant risk factors for rectal bleeding. After IMRT for prostate cancer, VRS and rectal bleeding worsened over 1–3 years after radiotherapy and recovered. Cardiovascular disease, rectal wall V65, and VRS ≥ 3 in first post-radiotherapy endoscopy were significant risk factors for rectal bleeding.

A Prospective Phase II Dose Escalation Study Using IMRT for High Risk N0M0 Prostate Cancer.

Published data supports the use of very high dose intensity modulated radiotherapy (IMRT) in achieving high efficacy and low toxicity for high-risk prostate cancer (HRPCa). This phase II multi-institutional non-randomized prospective dose escalation study using intensity modulated radiotherapy (IMRT) for high risk N0M0 prostate cancer was designed to investigate dose escalation using 1.8 Gy increments from baseline 75.6 Gy up to maximum 81 Gy, once dose volume constraints were adhered to. Inclusion criteria were patients undergoing a radical course of RT for high and very high-risk disease, defined as one or more of the criteria ≥ T3*, ≥ Gleason 8, Prostate specific antigen (PSA) > 20ng/ml. All patients received Androgen Deprivation Therapy (ADT) and none had radiological evidence of distant metastatic disease. The primary objective was to determine if dose escalated IMRT for high risk localized prostate cancer could provide freedom from biochemical relapse (BR; PSA rising > nadir +2ng/mL or initiation of salvage hormone therapy) similar to that reported in the literature. The Kaplan-Meier method was used to estimate survival times. Secondary objectives included OS, Disease Free Survival (DFS), and the incidence and severity of Genito-urinary (GU), Gastro-intestinal (GI) and erectile dysfunction (ED) toxicities (CTCAE v.3). Toxicities and performance status were collected and graded weekly during RT, 2 months after completing RT, 8 months' post RT, and 6 monthly thereafter to year five and annually thereafter to year nine. A total of 230 evaluable patients were enrolled between April 2009 and June 2016. The median follow-up was 7.3 years. The cumulative proportion of patients surviving without BR at 5 years was 91% (95% Confidence Interval (CI): 86% to 94%). Overall survival at 5 and 7 years was 92% (88% to 95%) and 89% (83% to 92%) respectively, while the cumulative proportion of patients free from disease was 89% (84% to 93%) at 5 years and 81% (75% to 86%) at 7 years. The incidence of acute G2 and G3 toxicities were; GU; 57.8% G2, 12.6% G3, GI; 15.2% G2, 0.4% G3, ED; 30.0% G2 and 61.7% G3. The incidence of late G2, G3 and G4 toxicities were; GU; 40.9% G2, 8.7% G3, GI; 36.5% G2, 2.2% G3, 0.4% G4, ED; 11.7% G2 and 86.1% G3. The percentage of patients receiving each dose level was; 3.5% received 75.6Gy in 42 fractions, 2.2% received 77.4Gy in 43 fractions, 93% received 81Gy in 45 fractions. The findings indicate that high-dose IMRT is well tolerated and is associated with excellent long-term tumor-control outcomes in patients with localized high and very high-risk prostate cancer, with 91% of patients surviving at 5 years without biochemical relapse. The rates of long term G3 GU and GI toxicity were low at 8.7% and 0.4% respectively.

Prostate Advanced Radiation Technologies Investigating Quality of Life (PARTIQoL): A Phase III Randomized Clinical Trial of Proton Therapy vs. IMRT for Low or Intermediate Risk Prostate Cancer.

Prostate cancer is the most common non-cutaneous cancer diagnosed among men in the United States, and the majority of patients are diagnosed with localized disease. Men with localized prostate cancer have several treatment options including external beam radiotherapy with either photons or protons. Proton beam therapy (PBT) has certain dosimetric advantages and the potential to reduce treatment-associated morbidity and improve oncologic outcomes, but current PBT is significantly more costly than intensity-modulated radiotherapy (IMRT). The PARTIQoL trial (NCT01617161) is the first multicenter phase 3 randomized trial comparing protons to photons in the treatment of localized prostate cancer. Patients with low or intermediate risk prostate cancer (Stage T1c-T2c, PSA < 20, Gleason score ≤ 7) are randomized to receive either PBT or IMRT, with targeted recruitment efforts for minority populations. A companion registry study has concurrently enrolled patients who declined randomization or whose insurance denied coverage for PBT. Patients are stratified by clinical site, age, use of rectal spacer, and fractionation schedule (conventional fractionation: 79.2 Gy in 44 fractions vs moderate hypofractionation: 70.0 Gy in 28 fractions). Participants are followed longitudinally to assess patient-reported outcomes (PROs) of bowel, urinary, and erectile function for 60 months after completion of radiotherapy (with an option for additional follow up through 10 years). Participants may also participate in correlative studies, including serial CT imaging during treatment and analyses of biopsy tissue, blood and urine specimens. The primary objective is to compare PROs of bowel function using the EPIC score at 24 months following completion of radiation. Secondary objectives are to assess treatment-related differences in urinary and erectile functions, adverse events, efficacy endpoints (biochemical control, metastasis-free survival, disease-specific survival, and overall survival), health state utilities, perceptions of care, late effects, cost-effectiveness, association between radiotherapy dose distribution and PROs, and to identify biomarkers of radiation response and toxicity. The randomized trial has completed accrual, with 450 patients enrolled at 27 sites between June 2012 and November 2021. 20.3% of patients enrolled are non-white. Accrual on the companion registry is active, with 354 patients enrolled as of February 2023. Follow-up for the primary endpoint on the randomized trial will be reached in 2024. The PARTIQoL randomized clinical trial will rigorously assess the clinical benefits of PBT relative to IMRT and results will inform decision making by patients, providers, policymakers, and payers.

Long Term Patient Reported Quality of Life Outcomes and Patient Satisfaction of 1-Week Hypofractionated Whole Breast Radiation Therapy Using IMRT for Early-Stage Breast Cancer

Novel whole breast radiation therapy (WBRT) regimens have been recently reported with the aim of improving patient convenience while preserving local control and breast cosmesis. The UK FAST Forward trial showed that 26 Gy in 5 fx using 3D conformal WBRT was equivalent to the standard 3-week regimen. However, the use of inverse planned intensity modulated radiation therapy (IMRT) for this novel ultra-hypofractionated regimen has not been previously studied. We aim to study the patient reported quality of life (QOL) outcomes and patient satisfaction of WBRT using IMRT delivering 26 Gy in 5 fractions. Patients receiving WBRT with 26 Gy in 5 fractions using IMRT at our institution from 2020 to 2022 were included. Patients were treated with 26 Gy in 5 daily fx with or without a single fx boost of 4-5.2 Gy. IMRT plans were generated using inverse planning with 2 to 3 volumetric modulated arcs (VMAT). To assess patient-reported QOL outcomes, a questionnaire was prospectively administered at 1 month post treatment and yearly thereafter including the EORTC QLQ-BR23 breast cancer module and other patient satisfaction questions. Patient assessment involved a four-point scale (not at all, a little, quite a bit, and very much; very satisfied, moderately satisfied, moderately dissatisfied, and very dissatisfied). Here, we report the 1-year patient reported acute toxicity QOL outcomes and patient satisfaction for those undergoing IMRT based WBRT. Cross-sectional analyses were used to determine the prevalence of "quite a bit" or "very much" effects versus "not at all" or "a little" effects. A total of 96 patients were included. The median age at diagnosis was 65 years. The most common histology was invasive ductal carcinoma (53.1%). ER-positivity was found in 75.5% patients. Oncoplastic reconstruction was used in 51.0% patients. The median tumor size was 1.5 cm. There were 4/98 (4.3%) node positive patients and 22.5% received adjuvant chemotherapy. Endocrine therapy was used in 74.5% patients. A boost fraction was delivered in 95.9% patients. At the 1-year assessment, only 1/35 (2.9%), 2/35 (5.7%), and 4/35 (11.4%) patients reported "quite a bit" or "very much" breast pain, skin problems, and changes in breast appearance respectively. Additionally, 32/35 (91.4%) patients were either "very satisfied" or "moderately satisfied" with their treatment, while 32/35 (91.4%) patients reported "excellent" (n = 12) or "good" (n = 20) physical appearance of the breast. WBRT using inverse planned IMRT with 26 Gy in 5 fx shows excellent patient reported QOL and patient satisfaction at 1-year post RT. Longer follow up is needed to assess the long-term toxicity, normal tissue effects, and cosmetic outcomes of IMRT based delivery of this ultra-hypofractionated regimen.

Clinical Implementation of Optical Surface Imaging Systems in Vulvar Cancer to Reduce Setup Error

Optical surface monitoring system (OSMS) could achieve continuous monitoring of patient position through a nonradiographic and noninvasive technology, which has been widely applied to many sites of radiation therapy including breast, intracranial, head and neck, abdomen, and the extremities. However, no study has investigated the application of OSMS in radiation therapy of vulvar cancer. In this study, we hypothesized using OSMS would reduce setup error in the vulvar cancer compared to standard laser-based setup (SLS). A single-center prospective trial included 10 patients with vulvar cancer treated with intensity modulated radiation therapy (IMRT) for a total of 250 fractions. Every patient was immobilized with Styrofoam in a frog-leg position and used marks on the patient's skin to align to the room lasers for pre-setup. The treatment couch values of lateral (Lat), longitudinal (Lng), vertical (Vrt) in three translation directions and Rtn (the rotation along the z axis), Pitch (the rotation along the x axis), Roll (the rotation along the y axis) in three rotations directions were recorded. Then completed the setup of patient with information from a surface imaging system and obtained deviation values. Setup is followed by pretreatment cone-beam computed tomography (CBCT) to further verify patient and target position by registering to the planning CT with respect to bony anatomy. With CBCT as a gold standard for patient setup, the absolute values of setup error and error distribution of SLS method and OSMS method from the same patient in above six directions were compared. The mean of absolute values of setup errors in the SLS method were significantly higher than those of OSMS method in Lat (0.34cm vs 0.20cm), Lng (0.42cm vs 0.29cm), Vrt (0.43cm vs 0.28cm) and Rtn (0.90° vs 0.67°) directions (P<0.05). The mean errors in SLS and OSMS methods in Pitch and Roll directions were 0.93° and 1.02° (P = 0.16), 0.42° and 0.45° (P = 0.48), respectively, with no significant difference. In the OSMS method, the distribution rates of the setup errors within 0.5cm in three translation directions and within 1.5° in three rotations directions were significantly higher in Lat (90.8% vs 80.4%), Lng (82.0% vs 68.8%), Vrt (83.2% vs 65.6%), and Rtn (91.2% vs 80.4%) directions than those of SLS method (P<0.05). In the Pitch (79.2% vs 80.4%) and Roll (97.2% vs 98.0%) directions, the distribution rates of the OSMS method were slightly lower than those of the SLS method, with no significant difference (P = 0.738 and P = 0.559). The implementation of OSMS in IMRT for vulvar cancer could reduce setup error and increase precision of setup, especially for the directions of Lat, Lng, Vrt and Rtn.

Clinical Application of Individualized 3D-Printed Chest Wall Conformal Device in IMRT for Post-Mastectomy Breast Cancer.

Background Breast cancer is the most common malignant tumour in women. Radical mastectomy with postoperative radiotherapy is now the standard treatment for locally advanced breast cancer. Intensity-modulated radiotherapy (IMRT) has now been developed, which employs linear accelerators to deliver precise radiation to a tumour while minimizing the dose to surrounding normal tissue. It significantly improves the efficacy of breast cancer treatment. However, there are still some flaws that must be addressed. Objective To assess the clinical application of the three-dimensional (3D)-printed chest wall conformal device for breast cancer patients who need to be treated by chest wall intensity modulated radiotherapy (IMRT) after radical mastectomy. Methods The 24 patients were divided into three groups. During a computed tomography (CT) scan, patients in the study group were fixed by a 3D-printed chest wall conformal device, nothing in control group A, and a traditional 1-cm thick silica gel compensatory pad on the chest wall in control group B. The parameters of mean Dmax, Dmean, D2%, D50%, D98%, the conformity index (CI), and the homogeneity index (HI) of the planning target volume (PTV) are compared. Results The study group had the best dose uniformity (HI = 0.092) and the highest conformation (CI = 0.97), the worst in control group A (HI = 0.304, CI = 0.84). The mean Dmax, Dmean, and D2% of the study group were lower than control groups A and B (p<0.05). The mean D50% was higher than control group B (p<0.05), while the mean D98% was higher than control groups A and B (p<0.05). The mean Dmax, Dmean, D2%, and HI of control group A were higher than control group B (p<0.05), whereas the mean D98% and CI were lower than control group B (p<0.05). Conclusion By improving the efficacy of postoperative radiotherapy for breast cancer, using 3D-printed chest wall conformal devices may greatly improve the accuracy of repeating position fixation, increase the dose on the skin surface of the chest wall, optimise the dose distribution of the target area, and thus further reduce tumour recurrence and prolong patients' survival.

A predicted three-dimensional dose sequence based treatment planning optimization method for gynecologic IMRT.

In knowledge-based treatment planning (KBTP) for intensity-modulated radiation therapy (IMRT), the quality of the plan is dependent on the sophistication of the predicted dosimetric information and its application. In this paper, we propose a KBTP method that based on the effective and reasonable utilization of a three-dimensional (3D) dose prediction on planning optimization. We used an organs-at-risk (OARs) dose distribution prediction model to create a voxel-based dose sequence based optimization objective for OARs doses. This objective was used to reformulate a traditional fluence map optimization model, which involves a tolerable spatial re-assignment of the predicted dose distribution to the OAR voxels based on their current doses' positions at a sorted dose sequencing. The feasibility of this method was evaluated with ten gynecology (GYN) cancer IMRT cases by comparing its generated plan quality with the original clinical plan. Results showed feasible plan by proposed method, with comparable planning target volume (PTV) dose coverage and greater dose sparing of the OARs. Among ten GYN cases, the average V30 and V45 of rectum were decreased by 4%±4% (p=0.02) and 4%±3% (p<0.01), respectively. V30 and V45 of bladder were decreased by 8%±2% (p<0.01) and 3%±2% (p<0.01), respectively. Our predicted dose sequence-based planning optimization method for GYN IMRT offered a flexible use of predicted 3D doses while ensuring the output plan consistency.

A robust optimization method with successive linear programming for intensity-modulated radiation therapy

Intensity-modulated radiation therapy for cancer is considered to be effective when dealing with complicated tumour shapes because the dose distribution for each irradiation can be modulated. Fluence map optimization is often formulated as an optimization problem with dose volume constraints (DVCs). A linear programming (LP) method that approximated DVCs was proposed, and it was modified to the successive LP method (SLPM) to find a feasible treatment plan in a wider region. In the present paper, we propose a numerical method called SLPM-R (the SLPM with robustness) that enhances the SLPM using a robust optimization approach. We mathematically prove that the proposed method with extended LP problems has the favourable properties of the SLPM, even taking uncertainty in the influence matrix into consideration. In particular, when the optimal value of the LP problem is non-positive, the proposed SLPM-R guarantees that the output solution can satisfy all DVCs. Through numerical experiments, we observed that the proposed method found a feasible plan that the SLPM could not find. In addition, for a test case that even the SLPM-R failed, the largest deviations of 5.65 Gray in the SLPM was reduced to 3.15 Gray by the SLPM-R.

Late hepatic toxicity after breast cancer intensity-modulated radiotherapy using helicoidal tomotherapy

PurposeHelical tomotherapy (HT) is a rotational intensity-modulated radiation therapy (IMRT) technique that allows target conformal irradiation and efficient organs at risk (OAR) sparing in the case of complex target volumes and specific anatomic considerations, but increases the “low-dose bath” to non-target volumes. The aim of this study was to analyze the delayed hepatotoxicity after rotational IMRT (HT) radiation therapy for non-metastatic breast cancer. Patients and methodsThis single-center retrospective study included all non-metastatic breast cancer patients with a normal pre-radiotherapy biological hepatic function who were treated with tomotherapy between January 2010 and January 2021 and for whom the dosimetric parameters for the whole liver were assessable. A logistic regression analysis was employed. The selected covariates for the multivariate analysis were those with a P-value that was less or equal to 0.20 in the univariate analysis. ResultsForty-nine patients were included in this study: 11 patients (22%) received Trastuzumab for 1 year in tumors with an HER2-expression; 27 patients (55%) received radiation therapy for cancer of the right or bilateral breasts; 43 patients (88%) received lymph node irradiation and 41 patients (84%) received a tumor bed boost. Mean and maximum doses to the liver were 2.8Gy [0.3–16.6] and 26.9Gy [0.7–51.7], respectively. With a median follow-up after irradiation was 5.4 years (range, 6 to 115 months), 11 patients (22%) had developed delayed low grade biological hepatic abnormalities: all patients had grade 1 delayed hepatotoxicity; 3 patients (6%) had additional grade 2 delayed hepatotoxicity. There was no hepatotoxicity at grade 3 or higher. According to the univariate and multivariate analysis, Trastuzumab was a significant predictive variable of late biological hepatotoxicity (OR=4.4 [1.01–20.18], P=0.04). No other variable was statistically associated with delayed biological hepatotoxicity. ConclusionDelayed hepatotoxicity after multimodal non-metastatic breast cancer management including rotational IMRT was negligible. Consequently, the liver doesn’t have to be considered like an organ-at-risk in the analysis of breast cancer radiotherapy but future prospectives studies are needed to confirm these findings.

Intensity-Modulated Radiation Therapy for Early-Stage Squamous Cell Carcinoma of the Glottic Larynx: A Systematic Review and Meta-Analysis

Early-stage squamous cell carcinoma of the glottic larynx is commonly treated with 2-dimensional or 3-dimensional conventional radiation therapy (CRT). Despite its use in other head and neck cancers, intensity-modulated radiation therapy (IMRT) remains controversial in this patient population. A systematic review was performed by querying 3 databases (Pubmed, Embase, Web of Science) for articles published between December 1, 2000 and September 2, 2022. Included studies reported outcomes in at least 10 patients treated with IMRT for early-stage glottic cancer. Data were extracted and reported following PRISMA standards. Pooled outcomes were estimated using random-effects models. Primary outcome was the rate of local failure (LF) following IMRT. Secondary outcomes included rates of regional failure (RF) following IMRT and rates of LF and RF following CRT. A total of 15 studies (14 retrospective, 1 prospective) consisting of 2083 patients were identified. IMRT was used in 873 patients (64% T1, 28% T2). Multiple treatment (partial larynx, single vocal cord carotid sparing) and image-guided radiation therapy techniques were used. The pooled crude rate of LF was 7.6% (95% confidence inverval [CI], 3.6%-11.5%) and actuarial LF rates at 3 and 5 years were 6.3% (95% CI, 2.2%-10.3%) and 9.0% (95% CI, 4.4%-13.5%), respectively. The pooled crude rate of RF after IMRT was 1.5% (95% CI, 0.5%-2.5%). On metaregression analysis, increased rate of LF was significantly associated with T2 disease (P < .001) and grade 2 to 3 histology (P < .001). Treatment with CRT was reported in 738 patients (76% T1, 22% T2). Among the studies reporting outcomes of both modalities, there was no significant difference in LF (log odds ratio; P=.12) or RF (log odds ratio; P=.58) between IMRT or CRT. In patients with early-stage glottic cancer, retrospective data suggests local and regional control are similar for patients treated with IMRT and CRT. Additional prospective studies with uniform methods of volume delineation and image guidance are needed to confirm the efficacy of IMRT.

Case study: Dosimetric comparison of VMAT, IMRT and 3DCRT techniques for left-sided breast cancer treated in deep inspiration breath-hold

The aim of this case study was to compare 3D conformal radiotherapy (3DCRT) plans for patients treated for left-sided breast cancer (whole breast without positive lymph nodes in deep inspiration breath-hold (DIBH)) to volumetric modulated arc therapy (VMAT) and intensity modulated radiation therapy (IMRT) plans. The original clinical plans used tangential field-in-field 3DCRT technique with a combination of 6 MV and 18 MV photon beams. VMAT and IMRT plans were based on several previously published techniques and used 6 MV beams. Two patients were included in this case study and 4 plans were created and compared for each one. All plans were compared in terms of tumour coverage, gradient measure and conformity index, doses to organs at risk (OARs), the volume of body receiving 5 Gy and also the number of Monitor Units (MUs). While better tumour coverage and conformity was achieved with IMRT and VMAT plans, OARs were better spared with the 3DCRT technique, which also resulted in the lowest dose bath and number of MUs.

Evaluation of Heterogeneity and Conformity Index Using IMRT and VMAT Techniques in Breast Cancer

One of the most prevalent cancers in both men and women is breast cancer. A number of choice therapy covers surgery, radiotherapy, chemotherapy, and hormonal therapy. Radiotherapy is typically used as a cancer treatment because it can eliminate cancer cells and aid in preventing cancer recurrence following surgery. Dose planning must be completed before irradiating the patient. Planning is carried out in a treatment planning system (TPS) with several available technique options. In this study, we chose intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) techniques. To determine the quality of the dose planning of these two techniques, a comparison of the heterogeneity index (HI) and conformity index (CI) parameters was carried out. The results of the comparison between IMRT and VMAT show that VMAT is superior to IMRT in terms of homogeneity and conformity. This is consistent with the HI results on VMAT showing a mean of 1.060 while IMRT shows a mean of 1.081. In addition, the CI results at VMAT showed a mean of 0.641 while IMRT showed a CI value of 0.519.

Long-Term Efficacy and Toxicity of Intensity-Modulated Radiotherapy in Bulky Cervical Cancer.

Treatment of bulky cervical cancer is associated with both high adverse effects and local recurrence rates with traditional box method radiotherapy. Intensity-modulated radiotherapy (IMRT) has been adopted for the treatment of cervical cancer in order to deliver more precise radiation doses to the target region. We retrospectively enrolled a total of 98 patients with cervical cancer ≥4 cm who completed IMRT and point A-based brachytherapy treatment. The median follow-up time of the cohort was 6.84 years, with the 5-year OS and DFS being 66.33% and 75.12%, respectively. In addition, 7.14% of patients experienced local recurrence, 12.24% had distant recurrence, 6.12% had both local and distant recurrence, and 3.06% had persistent disease. In the univariate analysis, lymph node metastasis, higher creatinine levels, higher initial CA-125 and receiving chemotherapy other than cisplatin were all associated with a worse PFS. A tumor size ≥6 cm was associated with an increased incidence of higher grade of acute diarrhea. Grade 3 late radiation proctitis and cystitis developed in 11.22% and 13.27% of patients, respectively. The local recurrence rates and overall efficiencies were not inferior to other studies involving traditional pelvic external beam radiation therapy with concurrent chemotherapy. The safety and efficacy of IMRT for bulky cervical cancer were acceptable.

Dosimetric comparison of sequential intensity-modulated radiation therapy (IMRT) and simultaneous integrated boost IMRT for lymph node-positive cervical cancer

Abstract Introduction: Nodal boost is being increasingly employed to escalate the dose to involved nodes in node-positive cervical cancer. The study aimed to compare the dosimetric differences between sequential boost intensity-modulated radiation therapy (SeB-IMRT) and simultaneous integrated boost IMRT (SIB-IMRT) in terms of target coverage and organs-at-risk (OARs) with special emphasis on the effect of nodal shrinkage and anatomical change of normal tissues during radiotherapy. Methods: Two computed tomography (CT) datasets (of phase I and phase II) of 40 patients of node-positive cervical cancer treated with SeB-IMRT [planning target volume (PTV) 45/25] followed by SeB to residual nodes (PTV 12·6/7) were utilised. SIB-IMRT1 plan consisted of PTV pelvis and para-aortic nodal region (PTV 45/25) and SIB to gross nodes (PTV 55/25). In order to account for the change in nodal and normal tissue topography during treatment, a third plan (SIB-IMRT2) was generated by utilising the SIB-IMRT1 plan for 44 Gy in 20 fractions and reproducing the plan on the second CT dataset for 11 Gy in 5 fractions. Dosimetric parameters of the three plans were compared using the Friedman test with Bonferroni correction. Results: We observed that the doses to OARs (bowel, rectum and bladder) were significantly higher in SeB-IMRT plan as compared to the SIB-IMRT plans. V40 Gy of bowel for SeB-IMRT, SIB-IMRT1 and SIB-IMRT2 plans were 354·8 cc, 271 cc and 321·8 cc, respectively (p = 0·001), whereas V30 Gy were 687·8 cc, 635·5 cc and 680 cc, respectively (p = 0·001). The target coverage was marginally better in SeB-IMRT plan as compared to SIB-IMRT1 and SIB-IMRT2 plans (V95% = 99·2 versus 97·7 versus 97·9, respectively, p = 0·000) Conclusion: SIB-IMRT led to better sparing of OARs, especially bowel. However, the magnitude of benefit decreases if the change in nodal and normal tissue topography during radiotherapy is not considered implying the need for frequent image guidance when SIB-IMRT is planned for node-positive cervical cancer.

A dosimetric comparison of intensity-modulated radiotherapy versus rapid arc in gynecological malignancies: Dose beyond planning target volume, precisely 5Gy volume.

Aim of radiotherapy is precise dose delivery with objective of achieving maximum local control and minimal toxicity by decreasing dose to organ at risk (OAR).This aim can be achieved by technologies like intensity-modulated radiotherapy (IMRT) and volumetric arc therapy. However, later offers comparable or even better plan quality with shorter treatment time. It is important to note that low dose regions are also a concern due long-term risk of developing a second cancer after radiotherapy. The objective of our study is to do dosimetric comparison of IMRT vs. Rapid arc (RA) plan in gynecology cancer and specifically to assess dose beyond planning target volume (PTV), precisely 5 Gy volume. Each 20 eligible patients underwent radiotherapy planning on eclipse by both IMRT and RA plans as per institution protocols. Comparative dosimetric analysis of both plans was done by paired sample t-test. PTV metrics compared were D95%, homogenecity index (HI), and conformity index (CI). OAR dose compared were bowel V40 Gy <30%, Rectum V30 Gy <60%, Bladder V45 Gy <35%, and bilateral femur head and neck V30 Gy < 50%. Futhermore, calculated monitor units (MUs) were also compared. Finally, volume of normal tissue beyond the PTV, specifically 5 Gy volume, was compared between plans. Dosimetric plan comparison showed statistically significant difference in RA and IMRT plans with improved PTV coverage and better OAR tolerance with RA plan. In addition, MU used were significantly less in RA plan, coupled with reduced V5 Gy volume. In sum, RA plans are dosimetrically significantly better compared to IMRT plans in gynecological malignancies in terms of PTV coverage and OAR sparing. Importantly, not only less MU used but also significantly less normal tissue V5 Gy volume is less in RA compared to IMRT plans.