Intensity-modulated Radiotherapy Research Articles

Planned Dental Extractions After Radiation Therapy.

Nonrestorable teeth are recommended to be extracted prior to radiation therapy (RT). Occasionally, preradiation extractions introduce unacceptable delays in treatment initiation. Planned dental extractions immediately postradiation presents an alternative strategy, though outcomes are uncertain. To evaluate the feasibility and safety of dental extractions immediately postradiation. A prospective cohort study including patients planned for curative-intent RT but unable or unwilling to proceed with 1 or more extractions recommended pretreatment was carried out. From January 2020 to September 2022, 58 patients were screened and 50 enrolled. The dental care was performed at a single academic department and the cancer care at regional centers. Analysis took place between September 22, 2023, and June 10, 2024. On completion of RT, patients were recommended to complete extractions as soon as feasible, and ideally within 4 months. The primary end point was the actuarial cumulative incidence of exposed alveolar bone noted by any practitioner at any time after extraction, calculated using Gray method with death as a competing risk. As a pilot study, no formal power calculation was performed; resources allowed for 50 evaluable patients. Among the 50 participants enrolled, RT was nonoperative for 32 patients (64%) and postoperative for 18 patients (36%). Intensity-modulated RT (IMRT) was delivered in all patients. Of the 50 patients, 20 (40%) declined dental extractions immediately postradiation and the remaining 30 (60%) underwent a median (range) of 8.5 (1-28) extractions at a median (range) of 64.5 (13-152) days after RT. The median (IQR) follow-up for survivors without exposed bone was 26 (17-35) months from the end of RT. The 2-year cumulative incidence of any exposed bone was 27% (95% CI, 14%-40%). The 2-year incidence of exposed bone for those who underwent dental extractions immediately postradiation was 40% (95% CI, 22%-58%) and 7% (95% CI, 0%-22%) for those who did not. Of the 13 who developed exposed bone: 4 resolved, 1 was lost to follow-up, and 8 were confirmed as osteoradionecrosis. This cohort study found that postradiation dental extractions incur considerable risk, even if performed within a 4-month window.

Reduced-dose radiotherapy for stage IE gastric mucosa-associated lymphoid tissue lymphoma: a multi-institutional prospective study (KROG 16–18)

PurposeDefinitive radiotherapy (RT) of 30 Gy or higher is commonly recommended to treat Helicobacter pylori-independent gastric mucosa-associated lymphoid tissue (MALT) lymphoma with an excellent disease control rate. However, the efficacy of reduced-dose RT has not yet been evaluated in a prospective cohort study. This multi-institutional study aimed to determine the role of reduced-dose RT in the treatment of stage IE gastric MALT lymphoma. MethodsBetween March 2017 and June 2022, 62 patients with histologically confirmed stage IE gastric MALT lymphoma without evidence of H. pylori infection were enrolled. The patients were treated with reduced-dose RT at a total dose of 24–25.5 Gy to the entire stomach. The response to therapy was evaluated by endoscopy with a biopsy of suspicious lesions if necessary. The primary endpoints were 6-month complete remission (CR) and local failure-free survival (LFFS). ResultsAmong 62 patients, 32 (51.6%) were previously treated for H. pylori eradication. Radiotherapy was delivered using 3D-conformal (n=20, 32.3%) or intensity-modulated radiotherapy (n=42, 67.7%). The median follow-up duration was 34.5 months (range, 9.6–68.8 months). The 6-month CR rate was 96.7%. The 5-year LFFS and progression-free survival rates were 92.0% and 90.4%, respectively. None of the patients experienced grade 3 or worse acute toxicities, and grade 2 acute toxicities were reported in 17 patients (27.4%). ConclusionReduced-dose RT exhibited excellent response rates in stage IE gastric MALT lymphoma, comparable to historical controls of standard dose (≥ 30 Gy) radiotherapy, with a minimal toxicity profile. Current prospective evidence strongly supports the use of definitive radiotherapy (24–25.5 Gy) for the treatment of H. pylori-independent stage IE gastric MALT lymphoma.

A hybrid meta-heuristic framework with ensemble deep learning for multi-functional simultaneous optimized automatic intensity-modulated radiotherapy planning

Intensity-modulated radiotherapy (IMRT) is one of the main treatments for patients with cancer, and its treatment planning holds significant importance. Compared to manual treatment planning, automatic treatment planning (ATP) is expected to improve plan quality and efficiency, which is of great clinical importance. However, treatment planning is an intractable “black art” that calls for intuition and heuristics from medical dosimetrists. There are two main issues with the current ATP methods: (i) they rely strongly on prior clinical experience and are not sufficiently scalable, and (ii) they use a single-functional optimization concept that ignores delivery accuracy information, which lowers the delivery accuracy of the generated ATP plans. To address these issues, this paper presents a novel multi-functional simultaneous optimized automatic treatment planning (MFSO-ATP) method. First, to address the issues of high reliance and insufficient scalability, an evolutionary strategy (ES) and simulated annealing (SA)-based hybrid meta-heuristic trial-and-error (ESSA-HMTE) framework is designed to automatically adjust optimization parameters without human intervention. Second, to address the issue of delivery accuracy deterioration, an ensemble deep learning-based gamma passing rate (GPR) prediction (EnDL-GPR) framework was constructed and trained to predict the plan delivery accuracy a priori. The ESSA-HMTE framework effectively fuses dosimetric quality information and delivery accuracy a priori information to simultaneously optimize the two, ensuring delivery accuracy while achieving automatic planning. We tested the MFSO-ATP method using multiple diseases with high inter-tumor heterogeneity. The results showed that the proposed method can improve the quality and delivery accuracy of IMRT plans, reduce the percentage of quality assurance failures, is highly scalable, and has good clinical application prospects.

Effects of minimum monitor unit per dynamic control point on intensity‐modulated radiotherapy planning for nasopharyngeal carcinoma: A retrospective study

The present study aimed to improve the dose distribution of radiotherapy planning for nasopharyngeal carcinoma (NPC) by comparing the effects of various minimum monitor units (MUs) per dynamic control point (MMCP) values on the quality and execution efficiency of dynamic intensity-modulated radiotherapy (IMRT) planning. Thirty-four clinically implemented dynamic IMRT plans for patients with NPC were retrospectively selected. In total, 170 plans were obtained by modifying only the MMCP values (set as 1, 3, 5, 7, and 9) in the treatment planning system's (TPS) optimization parameters. These plans were divided into 5 groups. Analyzing the effects of MMCP on the target and organ dose at risk (OAR), also the execution efficiency of the treatment plan in each group and using a quality score system, we conducted an objective quantitative study of the dose distribution and execution efficiency. The target dose evaluation indicators (target coverage (TC), homogeneity index (HI), and conformity index (CI)) of all IMRT plans showed a trend of variation with an increase in MMCP values, and the difference was statistically significant when MMCP values were 5, 7, 9, and 1 (p < 0.05). With an increase in MMCP, the dose to OAR slightly increased, but the difference was not statistically significant (p > 0.05). With an increase in MMCP, the average number of MUs per segment significantly increased (p < 0.01). The groups based on MMCP values of 1, 3, 5, 7, and 9 received quality score system of 1.188, 1.180, 1.171, 0.987, and 1.184, respectively, with the MMCP7 group achieving the lowest score, indicating that this plan had the highest overall quality. The MMCP value for dynamic IMRT planning in the Monaco TPS for patients with NPC should be set to 7 to achieve fewer segments, the best execution efficiency without significantly deteriorating the target and OAR dose.

Intensity-modulated proton radiotherapy spares musculoskeletal structures in regional nodal irradiation for breast cancer: a dosimetric comparison.

Regional nodal irradiation (RNI) for breast cancer delivers radiation in proximity to the shoulder and torso, and radiation exposure may contribute to long-term upper extremity and postural morbidity. To date, no studies have assessed the differential dosimetric impact of proton versus photon radiation on shoulder and torso anatomy. This study examined clinically relevant musculoskeletal (MSK) structures and assessed the dose delivered with each modality. Ten MSK structures were contoured on IMPT (intensity-modulated proton therapy) and VMAT (volumetric modulated arc therapy) plans for 30 patients receiving RNI. Relevant dose metrics were compared for each of the structures. Intensity-modulated proton therapy dose was calculated using the relative biological effective value of 1.1. Hypo-fractionated plans were scaled to the equivalent dose in 2 Gy fractions (EQD2) using an alpha/beta ratio of four. Wilcoxon signed rank sum tests compared doses. Select three-dimensional and optimised VMAT plans were also informally compared. Each of the 10 structures received a statistically significantly lower dose with the use of IMPT compared with VMAT. Differences were greatest for posterior structures, including the trapezius, latissimus dorsi and glenohumeral joint. Mean absolute differences were as great as 23 Gy (supraspinatus D5cc) and up to 30-fold dose reductions were observed (deltoid D50cc). An average 3.7-fold relative dose reduction existed across all structures. Measures of low/intermediate dose (V15Gy and D50cc) showed the largest differences. Intensity-modulated proton therapy results in statistically lower radiation exposure to relevant shoulder and torso anatomy compared to photon radiation for patients requiring RNI. Prospective study is needed to correlate functional outcomes with radiation dose.

466 - Dosimetric comparison between three-dimensional conformal radiation therapy, hybrid intensity-modulated radiation therapy and volumetric modulated arc therapy for left-breast cancer with lymph node involvement using breath-hold technique

466 - Dosimetric comparison between three-dimensional conformal radiation therapy, hybrid intensity-modulated radiation therapy and volumetric modulated arc therapy for left-breast cancer with lymph node involvement using breath-hold technique

Clinical Application of Equivalent Uniform Dose in Intensity-Modulated Rotational Radiotherapy Based on Eclipse TPS

To investigate the application of equivalent uniform dose (EUD) in intensity-modulated rotational radiotherapy and to explore optimization methods for improving the quality of modulated treatment plans. The impact of the parameter a in the EUD formula on the characteristics of the EUD curve was analyzed using Python. Thirty cases of head and neck tumors, thoracic tumors, and pelvic tumors were randomly selected for treatment planning. Dose optimization for the target area and organs at risk were performed using a physics-based optimization approach or an optimization approach that combines physical constraints with the EUD function. The dose distribution and compliance with constraints of the two groups of plans were compared, while also observing the effect of different values of a on the planning outcomes. The impact of the value of a on the changes in EUD curve characteristics was consistent with its impact on the results of EUD plan optimization. When -15≤ a≤-5, the dose distribution in the target area was more uniform; when 1≤ a≤7, the effect on the uniform dose and low-dose regions in organs at risk was more noticeable; when 10≤ a≤30, the effect of constraining the high-dose regions in organs at risk was more pronounced, with the EUD for the target area and organs at risk exhibiting different expressions under different a values. The study also found that the target dose distribution and the protection of organs at risk in the EUD optimization group were better than those in the physical optimization group only. The a-value has a significant impact on the, the dose distribution in the target area and the organ at risk, providing a reference for the setting of a-value while using EUD to optimize the intensity modulation plan. The using of EUD optimization method can not only achieve excellent dose distribution in the target area, but also significantly reduce the normal tissue dose and the probability of complications, which has certain clinical application value.

Intensity-modulated radiotherapy (IMRT) versus three-dimensional conformal radiotherapy (3DCRT) as treatment plans for head and neck tumours.

To compare intensity-modulated radiation therapy with three-dimensional conformal radiation therapy 3DCRTwith respect to dose coverage for target volume. The cross-sectional study was conducted at Al-Amal National Hospital, Baghdad, Iraq, from November 2020 to March 2021 and comprised patients with head and neck cancerous tumours. The patients underwent computed tomography scans, and were subsequently subjected to three-dimensional conformal radiotherapy and intensity-modulated radiotherapy treatment planning techniques on the basis of Monaco 5.1. The oncologist selected the better plan depending on evaluation parameters for each patient who was then irradiated with X-ray treatment. Data was analysed using SPSS 24. There were 30 patients, 17 (57%) females and 13 (43%) males with the age range of 19-45 years. Of the total, 28 received chemotherapy and 6 patients underwent brain surgery. The intensity-modulated radiation therapy resulted in significant coverage of the tumour than the three-dimensional conformal radiation therapy in phase 1 (p<0.00001) and phase II (p=0.0023). The intensity-modulated radiation therapy technique achieved a lower homogeneity value (p=0.0004) and higher conformity value (p<0.00001) than three-dimensional conformal radiation therapy. In phase II, no significant homogeneity index was found between the two therapies (p=0.072). The intensity-modulated radiation therapy showed significantly better conformity compared to three-dimensional conformal radiation therapy (p<0.00001). The intensity-modulated radiation therapy significantly improved coverage, plan conformity, and humongous dose distribution for head and neck tumours compared to the three-dimensional conformal radiation therapy 3DCRT.

An efficacy of protection the organs at risks comparison between the intensitymodulated radiotherapy therapy (IMRT) and the three-dimensional conformal radiotherapy (3DCRT).

To compare the efficiency of three-dimensional conformal radiotherapy and intensity-modulated radiation therapy techniques. The cross-sectional study was conducted from February to August 2021 at Al-Amal National Hospital, Baghdad, Iraq, and comprised patients aged 19-45 years with cancerous head and neck tumours of size 2-7cm. All the patients underwent magnetic resonance imaging or computed tomography simulation scans. Treatment planning techniques used for each patient were three-dimensional conformal radiotherapy and intensitymodulated radiotherapy. After evaluating patterns, a better plan and treatment with an X-ray beam was chosen. Data was analysed using SPSS 24. The study involved thirty participants, with 17(57%) females and 13(43%) males, aged 19-45, and 28 patients having chemotherapy. Six out of thirty had craniotomy surgery. The intensity-modulated radiation therapy had a safer radiation dose than the three-dimensional conformal radiotherapy for spinal cord (p=0.3203), brain stem (p= 0.17924), right parotid gland (p=0.8556) and left parotid gland (p=0.2193). The three-dimensional conformal radiotherapy protected the organs better than intensity-modulated radiation therapy for left optic nerve (p=0.1227), right optic nerve (p=0.0032), left eye (p=0.3859), right eye (p=0.1189), left lens (p=0.0004), right lens (p=0.0001), optic chiasm (p=0.0320) and pituitary gland (p=0.9162). The intensity-modulated radiation therapy technique protected the spinal cord, brain stem, and right and left parotid glands. The three-dimensional conformal radiotherapy was safe for left and right optic nerves, left and right eyes, left and right lenses, optic chiasm and pituitary glands.

The correlation of the modulation complexity score (MCS) with the number of segments and local gamma passing rate for the Intensity Modulated Radiation Therapy (IMRT) treatment planning delivery.

To compare the modulation complexity scores across treatment sites, and to examine their connection with monitor unit, segment number and global and local gamma passing percentage. The cross-sectional study was conducted at the Baghdad Centre for Radiation Therapy and Nuclear Medicine, Baghdad Medical City, Baghdad, Iraq, from May 2021 to February 2022. Included were 34 patients, with the age range between 20 - 50 years, subjected to intensity-modulated radiation therapy for head and neck tumours in group A or pelvic tumours in group B. Treatment planning was done using Monaco 5.1, and radiotherapy was done using Synergy linear accelerator. Modulation complexity scores were calculated using MATLAB 2019a. Data was analysed using SPSS 24. Of the 34 patients, 22(64.7%) were in group A; 12(54.5%) males and 10(45.5%) females. There were 12(35.3%) patients in group B; 8(66.7%) females and 4(33.3%) males. The number of segments was greater in group B than group A. A modest positive linear association was seen in group A, demonstrating that an increase in segment numbers resulted in a rise in modulation complexity score (R2=0.0244). Group B tumours had inverse negative linear correlation (R2=0.0189). As the complexity of plans increased in group A, local gamma passing percentage decreased (R2=0.0452). Group B showed a slight negative connection with modulation complexity score (R2=0.0622). The modulation complexity score may be used to provide a simple prediction for pre-treatment verification, and it may also serve as a simple quality assurance tool for intensity-modulated radiation therapy plans.

The evaluation of the two-dimensional gamma passing rate efficiency for the unilateral breast cancer dosimetry using the Intensity-Modulated Radiation Therapy.

To evaluate the efficacy of the commonly used two-dimensional gamma passing rate of 3%/3mm for females with unilateral breast cancer. The cross-sectional study was conducted at Al-Andalus Private Hospital, Baghdad, Iraq, from November 2021 to April 2022 after approval from the Medical Physics and Physiology Department of Mustansiriyah University, Baghdad, and comprised female patients with unilateral breast carcinomas. All the patients were subjected to a computed tomography simulation, and data was transferred to treatment planning system Monaco 5.1 for contouring and planning. An intensity-modulated radiation therapy method was selected. The planning comprised phantom detector and linear agility accelerator for pre-treatment verification. All patients were evaluated using two alternative dosimetry methods: 3%/3mm and 3%/2mm at the threshold of 10% and 5%. The Two-dimensional gamma analysis took each transversal slice in the simulation image for comparison. Data was analysed using SPSS 24. There were 15 female patients aged 26-65 years. There was a better impact of 3%/3mm compared to 3%/2mm criterion for 5% and 10% thresholds. The proportion was 10% higher than the cutoff point of 5%. The 3%/2mm criterion should be used for plans that give a high dosage to organs at risk, while the 3 %/3 mm criterion should be used for uncomplicated situations with moderate dosages to at-risk organs.

Sequential therapy for extramedullary plasmacytoma of the palate: a rare case report with seven years of follow-up and literature review

BackgroundExtramedullary plasmacytoma (EMP) is a rare solitary malignancy that accounts for 3% of plasma cell neoplasms, and EMP with a primary occurrence in the palate is extremely uncommon. Owing to the long course of EMP and the limited available data on treatment outcomes, there are no definitive guidelines for its management, especially for high-risk patients who are more susceptible to early progression to multiple myeloma.Case presentationIn this study, we review nine relevant studies and describe a 54-year-old woman who presented with an asymptomatic nonulcerative mass localized in the palate. After initial radical surgical resection of the lesion, the patient was definitively diagnosed with EMP with minimal plasmacytosis in the bone marrow, and adjuvant intensity-modulated radiation therapy with a minimum dose of 39.6 Gy was administrated in the surgical area. There was no evidence of local recurrence, nodal metastasis or progression to multiple myeloma (MM) during the seven-year follow-up period.ConclusionGiven the atypical clinical features of palate EMP reported in the literature and the encouraging results of our patient, sequential therapy involving surgery and adjuvant radiotherapy for primary palatal lesions in high-risk EMP patients without nodal involvement could be an effective treatment modality.

Fractionated Stereotactic Intensity-Modulated Radiotherapy for Large Brain Metastases: Comprehensive Analyses of Dose–Volume Predictors of Radiation-Induced Brain Necrosis

Background: The objective was to explore dosimetric predictors of brain necrosis (BN) in fractionated stereotactic radiotherapy (SRT). Methods: After excluding collinearities carefully, multivariate logistic models were developed for comprehensive analyses of dosimetric predictors in patients who received first-line fractionated SRT for brain metastases (BMs). The normal brain volume receiving an xx Gy biological dose in 2 Gy fractions (VxxEQD2) was calculated from the retrieved dose–volume parameters. Results: Thirty Gy/3 fractions (fr) SRT was delivered to 34 patients with 75 BMs (median target volume, 3.2 cc), 35 Gy/5 fr to 30 patients with 57 BMs (6.4 cc), 37.5 Gy/5 fr to 28 patients with 47 BMs (20.2 cc), and 40 Gy/10 fr to 20 patients with 37 BMs (24.3 cc), according to protocols, depending on the total target volume (p &lt; 0.001). After excluding the three-fraction groups, the incidence of symptomatic BN was significantly higher in patients with a larger V50EQD2 (adjusted odds ratio: 1.07, p &lt; 0.02), V55EQD2 (1.08, p &lt; 0.01), or V60EQD2 (1.09, p &lt; 0.01) in the remaining five- and ten-fraction groups. The incidence of BN was also significantly higher in cases with V55EQD2 &gt; 30 cc or V60EQD2 &gt; 20 cc (p &lt; 0.05). These doses correspond to 28 or 30 Gy/5 fr and 37 or 40 Gy/10 fr, respectively. Conclusions: In five- or ten-fraction SRT, larger V55EQD2 or V60EQD2 are BN risk predictors. These biologically high doses may affect BN incidence. Thus, the planning target volume margin should be minimized as much as possible.

Early recurrence as a pivotal event in nasopharyngeal carcinoma: identifying predictors and key molecular signals for survivors

PurposeThe duration of response to treatment is a significant prognostic indicator, with early recurrence (ER) often predicting poorer survival outcomes in nasopharyngeal carcinoma (NPC) survivors. This study seeks to elucidate the factors contributing to the onset of ER following radiotherapy in NPC survivors.MethodsThis investigation encompassed 2,789 newly diagnosed NPC patients who underwent radical intensity-modulated radiotherapy. Ordinal logistic regression analysis was employed to evaluate the independent predictors of earlier recurrence. A machine learning-based prediction model of NPC recurrence patterns was developed. Tumorous RNA-sequencing (in-house cohort: N = 192) and biological tipping point analysis were utilized to infer potential molecular mechanisms associated with ER.ResultsOur results demonstrated that ER within 24 months post-initial treatment was the optimal time frame for identifying early malignant progression in NPC survivors. The ER cohort (150 of 2,789, 5.38%) exhibited a notably short median overall survival of 48.6 months. Multivariate analyses revealed that male gender, T4 stage, local or regional residual disease, detectable pre- and post-radiotherapy EBV DNA, and the absence of induction chemotherapy were significant predictors of earlier recurrence. The machine learning-based predictive model further underscored the importance of tumor-related factors in NPC recurrence. Moreover, ER emerged as a pivotal stage in NPC progression, with 15 critical transition signals identified potentially associated with the negative modulation of the immune response.ConclusionsOur comprehensive analysis of NPC recurrence patterns has unveiled insights into the key factors driving ER and provided novel insights into potential early warning biomarkers and the mechanisms underlying NPC progression.

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.

High buttocks supine position to reduce small bowel exposure in gynecological radiotherapy

PurposeTo minimize radiation exposure to the small bowel (SB) in patients undergoing treatment for gynecological tumors by adopting a comfortable positioning method.Methods and patientsAll 76 women undergoing Intensity-Modulated Radiation Therapy (IMRT) were included in this study. Patients were immobilized in a supine position using a vacuum bag and thermoplastic cast formation. In the trial group (n = 36), patients raised their buttocks and a solid foam pad was placed under the sacral tail before immobilization. The control group (n = 40) received treatment in the standard supine position. The SB was delineated from the pubic symphysis to the total iliac bifurcation in computed tomography (CT) scans.ResultIn the trial group, a significant reduction in SB volume within the pelvic cavity was observed (mean 399.17 ± 158.7 cc) compared to the control group (mean 547.48 ± 166.9 cc), with a p-value less than 0.001. The trial group showed a statistically significant reduction in the absolute volume of irradiated SB at each dose, ranging from the low dose (10 Gy) to the high dose (45 Gy). In the control group, a negative correlation was found between SB and bladder volumes (R = -0.411, P = 0.008), whereas in the trial group, this correlation was weaker (R = -0.286, P = 0.091), with no significant relationship observed between bladder volume and SB.ConclusionThe high buttocks supine position effectively reduces SB radiation exposure without the need for bladder distension. This positioning method holds promise for reducing SB irradiation in various pelvic tumors.

Radiation Therapy in the Management of Head and Neck Mucosal Melanoma.

Mucosal melanoma of the head and neck (HNMM) is a rare but highly aggressive malignancy, often diagnosed at an advanced stage with poor prognosis. This review discusses current treatment strategies, emphasizing the role of radiotherapy in managing this challenging disease. A comprehensive analysis of 33 studies provides updated information on techniques and outcomes, highlighting the consistent benefit of adjuvant radiation in improving local control. Advances in conformal techniques, such as intensity-modulated radiotherapy (IMRT), have significantly reduced toxicity rates. Preliminary data on proton and carbon ion therapies suggest the potential for further enhancement of the therapeutic ratio, despite limited availability. Although recent studies report 3-year local control rates as high as 90%, overall survival within the same time frame remains well below 50-60%, underscoring the need for continued improvement in systemic therapies to address the persistent issue of distant metastases.

Dosimetric Evaluation of Hippocampus Sparing Intensity Modulated Radiation Therapy in Patients With Stage T1-T2 and Stage T3-T4 Nasopharyngeal Carcinoma

PurposeTo compare the hippocampus (HPC) dose reduced by HPC-sparing IMRT plans between nasopharyngeal carcinoma (NPC) patients of stages T1-T2 and T3-T4, and to investigate the correlation between the dose of the hippocampus and the volume of PTVnx70 (the planning target volume of the primary tumor in the nasopharynx received 70 Gy). Methods and MaterialsFifty-eight NPC patients were retrospectively evaluated. HPC non-sparing IMRT or sparing IMRT for each patient was designed according to the protocol for NPC. Dose-volume histogram (DVH) was used to evaluate the IMRT plans for each patient. The difference values of HPC parameters (e.g., Dmin[NS] - Dmin[S]) between HPC sparing and non-sparing plans in stage T1-T2 Group and stage T3-T4 Group were compared. The correlations between the dose of the hippocampus and the volume of PTVnx70 were analyzed. ResultsThere was no significance between HPC-sparing and non-sparing IMRT plans. Compared with the HPC non-sparing plans, the HPC sparing plans significantly decreased both dosimetric and volumetric parameters for the HPC (P < 0.05), except for Dmin, D98%, and V5. The medians of Dmedian[NS] - Dmedian[S], Dmean[NS] - Dmean[S], D40%[NS] - D40%[S], V30[NS] - V30[S], V40[NS] - V40[S] and V50[NS] - V50[S] in the T1-T2 Group were significantly lower than in the T3-T4 Group (P < 0.05), respectively. Both dosimetric and volumetric parameters for the HPC were positively correlated with the volume of PTVnx70 in HPC-sparing and non-sparing plans (P < 0.05). The volume of PTVnx70 was positively correlated with Dmedian[NS] - Dmedian[S], Dmean[NS] - Dmean[S], D40%[NS] - D40%[S], V40[NS] - V40[S] and V50[NS] - V50[S] (P < 0.05). ConclusionsHPC-sparing IMRT plans may play a more significant role in decreasing Dmedian, Dmean, D40%, and V30 ∼ V50 of HPC in NPC patients with stages T3-T4 than those in stages T1-T2. PTVnx70 volume of NPC patients are positively correlated with all dosimetric and volumetric parameters of HPC and the reduction of specific dosage parameters by HPC-sparing IMRT plans.

Recurrence pattern of glioblastoma treated with intensity-modulated radiation therapy versus three-dimensional conformal radiation therapy.

To evaluate recurrence patterns of and survival outcomes in glioblastoma treated with intensity-modulated radiation therapy (IMRT) versus three-dimensional conformal radiation therapy (3D-CRT). We retrospectively examined 91 patients with glioblastoma treated with either IMRT (n = 60) or 3D-CRT (n = 31) between January 2013 and December 2019. Magnetic resonance imaging showing tumor recurrence and planning computed tomography scans were fused for analyzing recurrence patterns categorized as in-field, marginal, and out-of-field based on their relation to the initial radiation field. The median overall survival (OS) was 18.9 months, with no significant difference between the groups. The median progression-free survival (PFS) was 9.4 months, with no significant difference between the groups. Patients who underwent gross total resection (GTR) had higher OS and PFS than those who underwent less extensive surgery. Among 78 relapse cases, 67 were of in-field; 5, marginal; and 19, out-of-field recurrence. Among 3D-CRT-treated cases, 24 were of in-field; 1, marginal; and 9, out-of-field recurrence. Among IMRT-treated cases, 43 were of in-field; 4, marginal; and 10, out-of-field recurrence. In partial tumor removal or biopsy cases, out-of-field recurrence was less frequent in the IMRT (16.2%) than in the 3D-CRT (36.3%) group, with marginal significance (p = 0.079). IMRT and 3D-CRT effectively managed glioblastoma with no significant differences in OS and PFS. The survival benefit with GTR underscored the importance of maximal surgical resection. The reduced rate of out-of-field recurrence in IMRT-treated patients with partial resection highlights its potential utility in cases with unfeasible complete tumor removal.

Research landscape of radiotherapy for nasopharyngeal carcinoma from 1959 to 2022: A bibliometric analysis

BackgroundRadiotherapy, as the main treatment method for nasopharyngeal carcinoma (NPC), has evolved over time, but there has been no bibliometric study on NPC radiotherapy to date. In our study, the scientific achievements of NPC radiotherapy around the world were evaluated by bibliometric analyses, and the previous research hotspots and future trends are described. MethodsOriginal articles related to NPC radiotherapy were obtained from the Web of Science Core Collection. To identify research hotspots and future trends, countries/regions, institutions, journals, references, authors, and keywords were evaluated and visualized by Excel, VOSviewer, and CiteSpace. ResultsFrom 1959 to 2022, 7139 original articles were collected. The annual publications showed an increasing trend, especially after 2011. China had the most publications (n = 3719, 52.09 %). Sun Yat-sen University has the most publications and citations among institutions. Jun Ma is most productive and SR Baker has the highest co-cited centrality. International Journal of Radiation Oncology-Biology-Physics is the core journal, with most publications, citations and co-citations. Analysis of keywords showed intensity-modulated radiotherapy and chemoradiotherapy were the main keywords, and multicenter showed the strongest burst. ConclusionNPC radiotherapy has attracted increasing attention, and precision and artificial intelligence may be the future trends in this field.