Course Of Intensity-modulated Radiotherapy Research Articles

Survival outcomes and toxicity profiles among patients with nonmetastatic nasopharyngeal carcinoma treated with intensity-modulated radiotherapy (IMRT) versus IMRT + carbon-ion radiotherapy: A propensity score-matched analysis.

To compare survival outcomes and toxic effects among patients with newly diagnosed nonmetastatic nasopharyngeal carcinoma (NPC) when treated with intensity-modulated radiotherapy (IMRT) versus IMRT + carbon-ion radiotherapy (CIRT). We performed a retrospective propensity score matching analysis (1:1) of patients treated with IMRT and IMRT + CIRT. Descriptive statistics were used to examine the baseline characteristics of the patients. Survival was estimated using the Kaplan-Meier method. Univariate and multivariable logistic regression analysis were used to identify the independent predictors of survival. We examined the association between risk factors and adverse events (AEs) using chi-square tests. Cox model and logistic regression were used to analyze AEs. Hundred and nine patients who received IMRT + CIRT were included and the median follow-up time was 20.6 months (range: 4.6-82 months). There were no statistically significant differences in locoregional failure-free survival, distant metastasis-free survival, disease-free survival, or overall survival between the two groups, but potentially better in IMRT + CIRT group (p > 0.05, respectively). Nodal boost was the only significant factor associated with LRFS and DFS on multivariable analysis. Thirty-seven patients (34.0%) developed grade 3 acute OMs and no grade 4 acute OMs were observed in IMRT + CIRT group. All patients in IMRT + CIRT group developed grade 1 dermatitis; while in the match group, 76 patients developed grade 1 dermatitis, 27 patients developed grade 2 dermatitis, 5 patients developed grade 3 dermatitis, 1 patient developed grade 4 dermatitis. IMRT + CIRT treatment was associated with a significant trend of lower grades of OM and dermatitis (p < 0.05, respectively). Any severe (i.e., grade 3) chronic AEs, such as xerostomia, skin fibrosis, temporal lobe necrosis, osteoradionecrosis, or radiation-induced optic neuropathy, was not observed. In this study, IMRT + CIRT was associated with significantly reduced acute toxicity burden compared with full course of IMRT, with excellent survival outcomes. Patients with persistent disease after treatment and treated with nodal boost had a worse outcome. More accurate assessments of IMRT + CIRT to primary nonmetastatic NPC patients will be imperative.

The Failure Patterns of Nasopharygeal Carcinoma After Intensity-Modulated Radiotherapy and Implications for Surveillance.

ObjectiveTo investigate the treatment outcomes, failure patterns and surveillance strategy in patients with nasopharyngeal carcinoma (NPC) after intensity-modulated radiotherapy (IMRT).MethodsA cohort of patients with NPC who had received the full course of IMRT between 2008 and 2012 were retrospectively analyzed. The failure patterns, time to recurrence, and detection methods were recorded. The survival was calculated using the Kaplan–Meier method. Multivariate proportional hazard regression models were used to test the prognostic factors.ResultsIn total, 2607 patients with NPC treated with IMRT were recruited. After the median follow-up of 112 months, 402 (15.4%) patients experienced distant metastasis, 225 (8.6%) patients had local recurrence, and 77 (3.0%) patients had regional recurrences. The 10-year overall survival (OS), local recurrence-free survival (LRFS), and distant metastasis-free survival (DMFS) rates were 74.5%, 90.1%, and 79.3%, respectively. The factors of male sex, age >50 years, lactate dehydrogenase >245 IU/L, advanced T classification, and advanced N classification were associated with poor OS. The N disease classification was the most important factor in predicting distant metastasis, and advanced T disease classification for high risk of local recurrence. For patients with T1 disease, the incidence of local recurrence was less than 2%, and the incidence of distant metastasis was less than 5% for patients with N0 disease. About 83% of the recurrence occurred in the first 5 years, and 20% of the recurrences showed no symptoms.ConclusionHigh rate of local-regional control can be achieved for patients with NPC after IMRT, while distant metastasis remains as the major cause of failures. Patients with advanced N classification has high risk to develop distant metastasis, and most occurred within 5 years. Developing rational and individualized surveillance strategies based on the high risk factors of recurrence is helpful to balance the survival benefit and medical cost.

The Prognosis and Feasibility of Extensive Clinical Target Volume in Postoperative Radiotherapy for Esophageal Squamous Cell Carcinoma: A Phase II Clinical Trial

BackgroundThis trial aims to explore the feasibility and safety of postoperative radiotherapy covering all regional lymph node areas for locally advanced thoracic esophageal squamous cell carcinoma patients treated with intensity-modulated radiation therapy (IMRT).MethodsThis was a single-center single-arm, phase II clinical trial initiated in 2014. Patients who were treated with radical transthoracic resection and had negative margins within 3 months and histologically confirmed esophageal squamous cell carcinoma (pT3-4 or N+, M0 determined by the 7th edition of the AJCC guidelines) were recruited in this trial. Postoperative radiotherapy was performed with a total dose of 40 Gy in 20 fractions using IMRT. Clinical target volumes (CTVs) included the tumor bed, anastomosis, bilateral supraclavicular region, mediastinal lymph nodes, left gastric lymph nodes and celiac trunk lymph nodes. The primary endpoint was the 2-year local control rate, and the secondary endpoints were overall survival (OS) and adverse events (AEs).ResultsA total of 70 eligible patients were recruited from 2014 to 2016. The 2-year local control rate, as the primary endpoint, was 67.3%. In addition, the median OS was 57.0 months, with 1-year and 3-year OS rates of 92.8% and 60.9%, respectively. Among the patients, 28/40 (40%) developed locoregional recurrence, with 25.7% involving hematogenous recurrences. All reported AEs occurred during the course of IMRT or within 6 months thereafter. None of them suffered grade 4 hematological or nonhematological AEs. Nearly all patients completed the entire course of postoperative radiotherapy, with a completion rate of 97.1%.ConclusionFor an extensive target volume, 40 Gy is feasible and shows acceptable toxicity in patients with locally advanced thoracic esophageal squamous cell carcinoma, although the local recurrence rate is relatively high. Our findings provide a basis for further exploration of high-dose radiation with extensive CTV combined with chemotherapy.Clinical Trial Registration[http://www.clinicaltrials.gov/ct2/results?cond=&term=NCT02384811&cntry=&state=&city=&dist=], identifier [NCT02384811].

Lower urinary tract symptoms in patients with prostate cancer under and after intensity-modulated radiation therapy.

The aim of the present study was to collect data on the characteristics, degree, and natural course of urinary complications, as well as self-care for such complications, in patients during and after prostate intensity-modulated radiation therapy (IMRT). Quality of life data were collected retrospectively for all eligible patients who underwent IMRT. In all eligible patients, urinary symptoms were evaluated using questionnaires and face-to-face interview. Participants were asked to respond to a self-administered questionnaire concerning the core lower urinary tract symptom score during the course of IMRT and up to 12 months after the completion of IMRT. In all, 29 eligible patients were included in the study. The frequency of urinary symptoms increased over of the course of IMRT, decreased at ≥3 months after completion of IMRT, and disappeared 6 months after IMRT. Responses to the questionnaire revealed a variety of approaches to self-care and adaptations by patients to manage urinary symptoms. During and after IMRT for localized prostate cancer, patients often developed more frequent urination and urgency than at the start of IMRT, and recovered 3-6 months after the completion of IMRT. Based on the present study, clinicians and nurses could help convey this information to patients and thus offer better support.

Correlation of Salivary Gland Dose to Volume Changes Noted During Adaptive Replanning of Head and Neck Radiation Therapy

Salivary gland shrinkage is known to occur with radiation therapy (RT) for head and neck cancer. Adaptive Radiation Therapy (ART) is commonly performed during the course of Intensity-Modulated Radiation Therapy (IMRT) due to weight loss and/or tumor shrinkage. Our goal was to investigate changes in parotid (PG) and submandibular gland (SMG) volumes measured on initial and replanning CT. We hypothesize that dose received by gland at the time of replan predicts for quantitative gland volume reduction. Replanning thus has the potential to reduce this effect which ultimately may reduce severity of xerostomia. We analyzed 100 patients who underwent adaptive re-planning (200 plans) between December 2014 to August 2017. Volumetric Modified Arc Therapy (VMAT) based IMRT was used in all. All patients had an initial CT simulation scan (Plan 1) used for radiation planning and a subsequent new CT simulation for adaptive replan (Plan 2). Dose-volume histograms were used to measure mean and maximum doses to right and left PG and SMG. We then correlated these doses to PG and SMG volume changes noted at the time of replan (PG1-PG2; SMG1-SMG2). Univariate and multivariate analyses were performed to identify factors contributing to gland volume changes. Tumor site included 9 oral cavity, 50 oropharynx, 14 Larynx, 7 Nasopharynx, and 20 others. Treatments were definitive chemo-RT in 67%, adjuvant chemo-RT in 20%, or adjuvant RT alone in 10%. Chemo used was Cisplatin-based 36%, Carboplatin-based 22%, or Cetuximab-based in 28%. Median total RT dose was 70 Gy (60-70 Gy in 30-35 daily fractions). Median time to performing replan was at fraction #21 (42 Gy) and around day 37 of therapy (13-66 days). Mean weight loss at time of replan was -4.3% (-21.3 to +17.5%). Analysis included 181 PG and 116 SMG. Mean dose received at time of replan with corresponding volume change: RPG = 1548 cGy, -13.6%; LPG = 1647 cGy, -14.6%; RSMG = 3359 cGy, -12.7%; LSMG = 3366 cGy, -14.4%. The correlation values of dose received and volume change: RPG r = 0.17, LPG r = -0.21, RSMG r = -0.33, and LSMG r = -0.27 (all with P<.05 except RPG, P=.13). Anatomic changes during radiation can result in increased doses to normal tissues and increased risk of toxicity. Our results show a significant change in gland volume in 3 of 4 salivary glands at the time of replanning with a direct correlation to dose received to the gland. Adaptive replan has the potential to reduce salivary gland doses.

Research progress in replanning during intensity-modulated radiotherapy for nasopharyngeal carcinoma

Intensity-modulated radiotherapy (IMRT) is the first-line treatment for nasopharyngeal carcinoma currently. Previous studies have shown that regression of primary tumor and metastatic lymph nodes or a decrease in body weight causes the contour of normal organs and head-and-neck to shrink during the course of radiotherapy, which may lead to underdose in primary tumor and overdose in organs at risk (OARs) and then adversely affect treatment outcomes. Replanning during the course of radiotherapy can maintain the dose to target volume and reduce the exposure of OARs, which improves outcomes in some patients. For replanning during the course of IMRT, however, the advantages have not been widely recognized and there is still a long way to go before widely accepted timing and frequency of replanning are set up. Further studies are needed to figure out how to identify patients appropriate for plan modification. Key words: Nasopharyngeal neoplasm/intensity-modulated radiotherapy; Replanning

Radiation-induced changes in volume and CT number of gross tumour volume and parotid glands during the course of IMRT for head and neck cancers

Introduction. The CT number (CTN) for tumours and organs at risk can change with radiation therapy, which can be an early indicator for radiation response. This study investigates the correlation of radiation-induced changes in volume and CTN in gross tumour volume (GTV) and parotid glands (PG) during the course of intensity-modulated radiation therapy (IMRT) in head and neck cancers (HNC). Materials and methods. Re-CT scans were acquired at four weeks for 71 patients with stage II IVb HNC treated with chemoradiation. The changes in volumes and CTN of the GTV primary, GTV node, and PG at four weeks of radiation were analysed. Pearson’s correlation was used to assess any association between CTN change and volume reduction of the GTVs and PGs. Results. The volumes of the GTVs and the ipsilateral PG and contralateral PG were reduced during the course of the radiation therapy after four weeks with mean volume shrinkage of 26.30 ± 7.66 (p < 0.0001), 32.09 ± 37.2 (p < 0.04), 8.38 ± 1.61 (p < 0.0001), and 9.10 ± 1.81 cm3 (p < 0.0001), respectively, and the mean CTN reduced by 2.50 ± 5.4, 1.79 ± 4.12, 1.90 ± 3.57, and 1.99 ± 3.54 HUs, respectively. For GTVs, the CTN and GTV volume decreases were found to be positively correlated, but the relationship was weak. However, no noticeable correlation was observed between the CTN change and the volume change in both PGs. Conclusions. The CTN changes in GTVs and PGs during delivery of radiation for HNC are measurable and patient specific. The CTN can be reduced in GTVs and PGs with a reasonable correlation between the mean CTN and volume reductions in GTVs, but with no correlation with PGs.

Anatomic and dosimetric changes in patients with head and neck cancer treated with an integrated MRI-tri-60Co teletherapy device.

Prior studies have relied on CT to assess alterations in anatomy among patients undergoing radiation for head and neck cancer. We sought to determine the feasibility of using MRI-based image-guided radiotherapy to quantify these changes and to ascertain their potential dosimetric implications. 6 patients with head and neck cancer were treated with intensity-modulated radiotherapy (IMRT) on a novel tri-60Co teletherapy system equipped with a 0.35-T MRI (VR, ViewRay Incorporated, Oakwood Village, OH) to 66-70 Gy in 33 fractions (fx). Pre-treatment MRIs on Fx 1, 5, 10, 15, 20, 25, 30 and 33 were imported into a contouring interface, where the primary gross tumour volume (GTV) and parotid glands were delineated. The centre of mass (COM) shifts for these structures were assessed relative to Day 1. Dosimetric data were co-registered with the MRIs, and doses to the GTV and parotid glands were assessed. Primary GTVs decreased significantly over the course of IMRT (median % volume loss, 38.7%; range, 29.5-72.0%; p < 0.05) at a median rate of 1.2%/fx (range, 0.92-2.2%/fx). Both the ipsilateral and contralateral parotid glands experienced significant volume loss (p < 0.05, for all) and shifted medially during IMRT. Weight loss correlated significantly with parotid gland volume loss and medial COM shift (p < 0.05). Integrated on-board MRI can be used to accurately contour and analyze primary GTVs and parotid glands over the course of IMRT. COM shifts and significant volume reductions were observed, confirming the results of prior CT-based exercises. Advances in knowledge: The superior resolution of on-board MRI may facilitate online adaptive replanning in the future.

Salvage Intensity-Modulated Radiation Therapy (IMRT) for Locally Recurrent Nasopharyngeal Cancer after Definitive IMRT: A Novel Scenario of the Modern Era.

Locally recurrent nasopharyngeal carcinoma (rNPC) after definitive IMRT occurs in 10% of all cases and represents a distinct clinical entity that has been selectively enriched by radio-resistant cancer cells. Therefore, we report of the outcomes of 77 patients who had repeat salvage-IMRT for rNPC after only a definitive course of IMRT. Various clinical outcomes were measured. Log-rank tests were used to detect differences in the survival outcomes between factor-defined subgroups. Multivariable analysis was performed using the Cox proportional hazard model. The median follow-up time was 25.7 months (range 3.0–75.7 months), measured from the time of recurrence. The median OS time and PFS time of the entire cohort was 37.0 and 20.5 months, respectively. Thirty-four patients (44.2%) died. Approximately 35% of these patients died from disease progression, but 53% were from treatment-induced severe adverse effects (SAEs) without evidence of disease progression. Higher T-classification of the recurrent tumor and the development of SAEs were found to be the only independent and significant adverse prognostic factors on multivariable analysis. These outcomes underscore the particularly virulent characteristics of rNPC after definitive IMRT. Concerning is the impact of re-irradiation toxicity on patient mortality.

SU-F-P-25: Dosimetric Changes of Brainstem Caused by Weight Loss During Intensity-Modulated Radiation Therapy for Nasopharyngeal Carcinoma

Purpose: To explore dosimetric effects of brainstem (BS) caused by weight loss during the course of intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC). Methods: Seventy-seven patients who were diagnosed with NPC by pathology biopsy have been enrolled. Every patients should receive weight measurement weekly and three times of computed tomography (CT) scans and replanning, at the 15th and 25th fraction during the treatment, respectively. The vertical diameter at the level of odontoid process (d1) and cervical vertebra 3 (d2) be measured from CT images (Supporting document Figure 1). All IMRT plans were designed by inverse planning with commercial treatment planning systems (Corvus 6.2 version, NOMOS Corporation). The dose differences between plan and actual delivery were generated to compare. Results: The weight loss was more in week 4–5 (3.21±2.19kg) than in week 1–3 (1.79±1.83kg) (Supporting document Figure 2). The d1 and d2 decreased was more significantly in week 4–5 than week 1–3, 2.83±1.75mm vs. 0.55±0.75mm and 2.98±2.96mm vs. 1.23±2.09mm, respectively. The maximum dose to the brainstem (BS Dmax) and the percentage of brainstem volume receiving ≥50Gy (BS V50) increased more significantly in week 4–5 than week 1–3, −3.02±5.49Gy vs. −1.85 ±4.88Gy and −1.85±4.88% vs. −0.77±3.32%, respectively. The changes of d1 and d2 and the BS-V50 and BS-Dmax were closely related to weight loss (p≤0.001)(Supporting document Table 1). Conclusion: The study results indicate that weight loss leads to the vertical diameter reduction, which results has a close relationship with dose of the brainstem during IMRT of NPC. This study was supported by Zhejiang Provincial Medicine and Health Foundation (2013KYB290) and Research Foundation of Science and Technology Department of Zhejiang Province 2015C33257

Long-term efficacy and adverse effects of intensity-modulated radiotherapy for nasopharyngeal carcinoma

Objective To investigate the long-term efficacy and adverse effects of intensity-modulated radiotherapy (IMRT) for nasopharyngeal carcinoma (NPC). Methods A total of 869 patients with biopsy-proven NPC without distant metastasis who underwent the whole course of IMRT from 2009 to 2010 were enrolled. Of all the patients, 84.8% received cisplatin-based chemotherapy. The prescribed dose to the primary lesion in the nasopharynx was 66-70 Gy in 30-32 fractions, and the dose to the positive lymph nodes in the neck was 66 Gy in 30-32 fractions. The Kaplan-Meier method was used to calculate survival rates, the log-rank test was used for difference analysis and univariate prognostic analysis, and the Cox proportional hazards model was used for multivariate prognostic analysis. Results The 5-year overall survival (OS), local recurrence-free survival, regional recurrence-free survival, distant metastasis-free survival, and disease-free survival (DFS) were 84.0%, 89.7%, 94.5%, 85.6%, and 76.3%, respectively. In the patients with locally advanced NPC, concurrent chemotherapy tended to reduce distant metastasis (83.6% vs. 75.7%, P=0.050) and improve OS (82.6% vs. 77.0%, P=0.082). Induction chemotherapy tended to improve OS (80.7% vs. 71.4%, P=0.057), and the induction chemotherapy containing docetaxel or gemcitabine tended to improve OS (83.3% vs. 72.2%, P=0.058). The patients who received a boost after the initial radiotherapy had a significantly lower DFS rate than those who did not (52.2% vs. 71.1%, P=0.004). The concurrent chemotherapy increased the incidence rates of long-term xerostomia and trismus, while a high dose of cisplatin increased the incidence rates of xerostomia and hearing impairment. Conclusions IMRT for NPC provides satisfactory long-term efficacy. Concurrent chemotherapy combined with IMRT tends to reduce the incidence of distant metastasis, and other values need further investigation. The boost therapy after radiotherapy may be associated with poor prognosis. Chemotherapy increases the incidence of long-term toxicities. Key words: Nasopharyngeal neoplasms/intensity-modulated radiation therapy; Concurrent chemotherapy; Radiation boost; Late toxicity

Volumetric modulated arc radiotherapy of the whole larynx, followed by a single affected vocal cord, for T1a glottic cancer: Dosimetric analysis of a case.

Radiation therapy (RT) and endolaryngeal surgery are standard treatments for early-stage glottic cancer. They have closely matched oncological outcomes; however, it is debatable which method is superior in terms of functional outcomes. Several dosimetric studies have demonstrated that, compared with conventional RT, intensity-modulated RT (IMRT) reduces unnecessary radiation of the adjacent normal tissues, including the carotid artery and thyroid gland. However, RT targets the whole larynx, whereas endolaryngeal surgery is a highly focused treatment involving the en bloc resection of a tumor with safety margins. For T1a glottic cancer, in which the tumor is limited to one vocal cord, the technical feasibility of targeting IMRT on the single vocal cord affected has been investigated; however, the clinical feasibility and the possibility of inferior local control remain to be elucidated. In the present case study, IMRT was used to treat the whole larynx first, and then to treat a single vocal cord. The patient in the present study had T1a glottic cancer, and received volumetric modulated arc therapy with a total dose of 63 Gy/28 fractions. The first treatment phase (40.5 Gy/18 fractions) targeted the whole larynx to eliminate subclinical disease. The second treatment phase (22.5 Gy/10 fractions) targeted only the involved vocal cord. During this treatment phase, the exposure of the non-involved right vocal cord, the right carotid artery and the thyroid gland to the radiation was lower compared with the continuation of the initial treatment approach. These findings suggested that changing the target volume from the whole larynx to the affected vocal cord during the course of IMRT is feasible for T1a glottic cancer, and that it may reduce functional side effects while maintaining oncological outcomes.

Impact of head and neck cancer adaptive radiotherapy to spare the parotid glands and decrease the risk of xerostomia.

BackgroundLarge anatomical variations occur during the course of intensity-modulated radiation therapy (IMRT) for locally advanced head and neck cancer (LAHNC). The risks are therefore a parotid glands (PG) overdose and a xerostomia increase.The purposes of the study were to estimate:- the PG overdose and the xerostomia risk increase during a “standard” IMRT (IMRTstd);- the benefits of an adaptive IMRT (ART) with weekly replanning to spare the PGs and limit the risk of xerostomia.Material and methodsFifteen patients received radical IMRT (70 Gy) for LAHNC. Weekly CTs were used to estimate the dose distributions delivered during the treatment, corresponding either to the initial planning (IMRTstd) or to weekly replanning (ART). PGs dose were recalculated at the fraction, from the weekly CTs. PG cumulated doses were then estimated using deformable image registration. The following PG doses were compared: pre-treatment planned dose, per-treatment IMRTstd and ART. The corresponding estimated risks of xerostomia were also compared. Correlations between anatomical markers and dose differences were searched.ResultsCompared to the initial planning, a PG overdose was observed during IMRTstd for 59% of the PGs, with an average increase of 3.7 Gy (10.0 Gy maximum) for the mean dose, and of 8.2% (23.9% maximum) for the risk of xerostomia. Compared to the initial planning, weekly replanning reduced the PG mean dose for all the patients (p < 0.05). In the overirradiated PG group, weekly replanning reduced the mean dose by 5.1 Gy (12.2 Gy maximum) and the absolute risk of xerostomia by 11% (p < 0.01) (30% maximum). The PG overdose and the dosimetric benefit of replanning increased with the tumor shrinkage and the neck thickness reduction (p < 0.001).ConclusionDuring the course of LAHNC IMRT, around 60% of the PGs are overdosed of 4 Gy. Weekly replanning decreased the PG mean dose by 5 Gy, and therefore by 11% the xerostomia risk.

Comparison of Image-guided Radiotherapy Technologies for Prostate Cancer

Radiation oncology has seen a rapid increase in the use of image-guided radiotherapy technology (IGRT) for prostate cancer patients over the past decade. The increase in the use of IGRT is largely driven by the fact that these technologies have been approved by the Food and Drug Administration and are now readily reimbursed by many insurance companies. Prostate cancer patients undergoing intensity modulated radiotherapy (IMRT) now have access to a wide variety of IGRTs that can cost anywhere from $500,000 or more in upfront costs, and can add anywhere from 10 to 15 thousand dollars to a course of IMRT. Some of the IGRT options include daily cone beam computed tomography, ultrasound, orthogonal x-ray units using implanted fiducial markers, implanted radiofrequency markers with the ability to localize and track prostate motion during radiotherapy (Calypso 4D), and cine magnetic resonance imaging. Although these technologies add to the cost of IMRT, there is little direct comparative effectiveness data to help patients, physicians, and policy makers decide if one technology is better than another. In our critical review, the first of its kind, we summarize the advantages, disadvantages, and the limitations of each technology. We also provide an overview of existing literature as it pertains to the comparison of existing IGRTs. Lastly, we provide insights about the need for future outcomes research that may have a significant impact on health policies as it comes to reimbursement in the modern era.

Position shifts and volume changes of pelvic and para-aortic nodes during IMRT for patients with cervical cancer

Background and purposeTo evaluate volume changes and position shifts and their contribution to treatment margins of pelvic and para-aortic lymph nodes during Intensity Modulated Radiation Therapy (IMRT) for advanced cervical cancer. Materials and methodsSeventeen patients with visible nodes on MR images underwent T2-weighted MR scans before and weekly during the course of IMRT. Thirty-nine pelvic and para-aortic nodes were delineated on all scans. Margins accommodating for volume and position changes were taken from the boundaries of the nodal volumes in the six main directions. ResultsNodal volume regression from the pre-treatment situation to week 4 was 58% on average (range: 11.7% increase to 100% decrease). Nodal volumes partly increased between the pre-treatment scans and the scans in weeks 1–3, but in week 4 all nodes except one had regressed. Around the nodal volumes manually derived ITV margins accounting for volume changes and position shifts of 7.0, 4.0, 7.0, 8.0, 7.0 and 9.0mm to the medial, lateral, anterior, posterior, superior and inferior directions were needed to cover 95% of all nodes. ConclusionsWe used weekly MR scans to derive inhomogeneous margins that accommodate for nodal volume and position changes during treatment. These margins should be taken into consideration when planning external beam radiotherapy (EBRT) boosts, especially for highly conformal boosting techniques.

Will weight loss cause significant dosimetric changes of target volumes and organs at risk in nasopharyngeal carcinoma treated with intensity-modulated radiation therapy?

This study aimed to quantify dosimetric effects of weight loss for nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiation therapy (IMRT). Overall, 25 patients with NPC treated with IMRT were enrolled. We simulated weight loss during IMRT on the computer. Weight loss model was based on the planning computed tomography (CT) images. The original external contour of head and neck was labeled plan 0, and its volume was regarded as pretreatment normal weight. We shrank the external contour with different margins (2, 3, and 5mm) and generated new external contours of head and neck. The volumes of reconstructed external contours were regarded as weight during radiotherapy. After recontouring outlines, the initial treatment plan was mapped to the redefined CT scans with the same beam configurations, yielding new plans. The computer model represented a theoretical proportional weight loss of 3.4% to 13.7% during the course of IMRT. The dose delivered to the planning target volume (PTV) of primary gross tumor volume and clinical target volume significantly increased by 1.9% to 2.9% and 1.8% to 2.9% because of weight loss, respectively. The dose to the PTV of gross tumor volume of lymph nodes fluctuated from −2.0% to 1.0%. The dose to the brain stem and the spinal cord was increased (p < 0.001), whereas the dose to the parotid gland was decreased (p < 0.001). Weight loss may lead to significant dosimetric change during IMRT. Repeated scanning and replanning for patients with NPC with an obvious weight loss may be necessary.

Using neoadjuvant chemotherapy and replanning intensity-modulated radiotherapy for nasopharyngeal carcinoma with intracranial invasion to protect critical normal tissue

PurposeTo investigate the feasibility of neoadjuvant chemotherapy and replanning intensity-modulated radiotherapy (IMRT) for intracranial invasion nasopharyngeal carcinoma (NPC).Methods and materialsFrom June 2007 to January 2012, 32 patients with intracranial invasion NPC treated with TPF (docetaxel 75 mg/m2, cisplatin 75 mg/m2, 5-FU 2500 mg/m2 every 3 weeks for 3 cycles) neoadjuvant chemotherapy, and replanning IMRT with concurrent chemotherapy were retrospectively studied. The first IMRT plan for each patient was generated based on the original planning CT scan acquired before the start of treatment. Because of tumor shrinkage during radiotherapy, modified gross tumor volume of primary tumor (GTV-P) and high risk clinical target volume (CTV-H), and a new plan was generated and used to complete the course of IMRT. The DVHs of IMRT plan with or without replanning were compared.ResultsThere weren’t statistically significant differences in the V95, D-mean, D-95, and D-99 to the modified PTVGTV-P and PTVCTV-H with and without replanning IMRT. Replanning reduced the doses to the brain stem, optic nerve, optic chiasm and temporal lobe. Objective responses were 100.0% 3 months after completion of radiotherapy. Acute toxicities were well tolerated, except for the relatively high incidence of neutropenia. The 2-year local control rates and distant-metastasis free survival were 88.2% (95% CI, 72.9% to 100.0%) and 89.6% (95% CI, 75.9% to 100.0%).ConclusionNeoadjuvant chemotherapy and replanning IMRT according to tumor shrinkage during the treatment is essential to ensure safe doses to normal tissues, and produces encouraging outcome for intracranial invasion NPC.

A Comparative Dosimetric Analysis by Delivery of Adaptive Radiation Therapy in Locally-Advanced Head-and-Neck Cancer

Most patients receiving fractionated radiation therapy (RT) for head and neck cancer (HNC) have marked anatomical changes during their course of treatment, including shrinkage of the primary tumor or nodal masses, resolving edema, and changes in overall body habitus / weight loss. This study is aimed to investigate the dosimetric impact of these changes occurring during the intensity modulated radiation therapy (IMRT) for locally advanced head and neck cancer (LAHNC), to compare the planned and delivered dose to target volume (TV) and organ at risk (OAR) during IMRT and to compare the dose distribution with and without replanning. Twenty patients with LAHNC treated with concurrent chemoradiation therapy were enrolled prospectively in this study. Planning CT scans were acquired both pretreatment and after 40 Gy/20 number of RT. Original plan (OPLAN30) and hybrid plan (HPLAN30) for phase 2 was generated. Assessment of dosimetric changes was performed by comparing the HPLAN30 with the OPLAN30. Adaptive replanning (REPLAN30) based on the second CT scan was done and dose distribution for TV and OAR was compared with and without replanning. Planned doses (D98%, D95%, D50% and D2%) to GTV, CTV and PTV for second phase of RT were not significantly different from the actually delivered doses. However an increase in V110% was observed in the hybrid plan in comparison to the original treatment plan. With replanning, dose distribution to TV was made more homogenous as compared to hybrid plan (p = 0.00). Replanning significantly reduced V>110% and V<93% as compared to hybrid plan (p = 0.003 and p = 0.002, respectively). There was a significant increase in delivered doses (Dmax, D2% and D1%) to spinal cord as compared to planned dose (p = 0.00, 0.001 and 0.001, respectively). Adaptive replanning resulted in decrease in Dmax, D2% and D1% of spinal cord (p = Significant). The mean dose, D33%, D50% and D66% to ipsilateral (I/L) parotid was significantly higher in the HPLAN30 in comparison to the OPLAN30 (p < 0.05). On comparison between the HPLAN30 and REPLAN30, dose to I/L parotid was significantly reduced with replanning. Replanning with repeat CT simulation during the course of IMRT after 40 Gy significantly improves the target volume coverage and reduces the dose to OARs.

Is it necessary to repeat CT imaging and replanning during the course of intensity-modulated radiation therapy for locoregionally advanced nasopharyngeal carcinoma?

Our aim was to evaluate the volumetric and dosimetric changes of target volumes and organs at risk (OARs) during intensity-modulated radiation therapy (IMRT) for locoregionally advanced nasopharyngeal carcinoma (NPC) and the necessity of replanning. Twenty locoregionally advanced NPC patients treated by concurrent chemotherapy and IMRT were included. CT and MR images were acquired before treatment and at weeks 2, 3, 4, 5 and 6 during treatment. The target volumes and OARs were contoured based on the fused CT-MRI images and hybrid plans were generated. The changes of volume and dosimetry were measured by comparing original plan and hybrid plans. Significant volumetric changes of target volumes and parotid gland were observed. The primary nasopharyngeal tumor (GTVnx), CTV1, involved lymph nodes (GTVnd) and left and right parotid glands, shrank at a mean rate of 14.7, 11.56, 11.40, 6.54 and 6.78 % per treatment week, respectively. There were no significant dosimetric changes in GTVnx, GTVnd, CTV1, spinal cord and brain stem while the differences of dose to left and right parotid glands were significant (F = 6.73, P = 0.007; F = 7.43, P = 0.007). Remarkable volumetric changes were observed. However, the dosimetric changes were inconspicuous except for the parotid. Replanning might contribute to protect the parotid gland.

Assessment of anatomical and dosimetric changes by a deformable registration method during the course of intensity-modulated radiotherapy for nasopharyngeal carcinoma

The aim of this study was to quantify the anatomic variations and the dosimetric effects accessed by a deformable registration method throughout the entire course of radiotherapy, and to evaluate the necessity of replanning for patients with nasopharyngeal carcinoma (NPC). Plan1(CT1) was based on the original CT, and Plan2(CT2) was generated from the midtreatment CT scan acquired after 25 fractions of IMRT of Plan1. Both sets of CTs, RT structures and RT doses for the two group plans were transferred to a workstation, and then a hybrid IMRT plan, Plan1(CT2), was generated by deforming doses of Plan1 to CT2. Subsequently, the accumulated plan, Plan1 + 2(CT2), was generated to quantify the actual dosimetric effects during the course. The transverse diameter of the neck at the center of the odontoid process was (15.4 ± 1.0) cm and (14.4 ± 1.1) cm in CT1 and CT2, respectively (P < 0.05). Compared with CT1, the mean volumes of the right and left parotid glands were significantly decreased by (24.6 ± 11.9)% and (35.1 ± 20.1)%, respectively. Comparison of Plan1 (CT1) with Plan1 (CT2) indicated that the doses to targets decreased without replanning. With repeated CT and replanning after 25 fractions, the doses to targets would be improved. The doses to normal tissue were increased without replanning. For eight patients out of 12, the doses to the spinal cord and brainstem exceeded the constraints without replanning, while the corresponding values decreased with replanning. During the entire course of IMRT, the volumes of the targets and the parotid glands would be reduced significantly. Midtreatment CT scanning and replanning are recommended to ensure adaptive doses to the targets and critical normal tissues.