Modulated Arc Radiotherapy Research Articles

446 - Converting Varian LINAC plans to Elekta LINAC plans using Raystation fallback planning system in prostate cancers with Volumetric Modulated Arc Radiotherapy

446 - Converting Varian LINAC plans to Elekta LINAC plans using Raystation fallback planning system in prostate cancers with Volumetric Modulated Arc Radiotherapy

Impact of Smaller Gantry Arc Increments on Volumetric Modulated Arc Radiation Therapy in the Monaco Treatment Planning System

Impact of Smaller Gantry Arc Increments on Volumetric Modulated Arc Radiation Therapy in the Monaco Treatment Planning System

Impact Assessment of Systemic Geometric Distortion in 1.5T Magnetic Resonance Imaging Simulation through Three-dimensional Geometric Distortion Phantom on Dosimetric Accuracy for Magnetic Resonance Imaging-only Prostate Treatment Planning

Aims: Magnetic resonance imaging (MRI)-only radiotherapy has emerged as a solution to address registration errors that can lead to missed dose delivery. However, the presence of systemic geometric distortion (SGD) stemming from gradient nonlinearity (GNL) and inhomogeneity of the main magnetic field (B0) necessitates consideration. This study aimed to quantitatively assess residual SGD in 1.5T MRI simulation using a three-dimensional (3D) geometric distortion phantom and evaluate its impact on dosimetric accuracy for retrospective prostate cancer patients. Materials and Methods: Ten retrospective cases of prostate cancer patients treated with volumetric modulated arc radiotherapy (VMAT) were randomly selected. A geometric distortion phantom was scanned on a 1.5T MRI simulation using a 3D T1 volumetric interpolated breath-hold examination sequence, varying bandwidth (BW), and two-phase-encoding directions. Distortion maps were generated and applied to the original computed tomography (oriCT) plan to create a distorted computed tomography plan (dCT), and a dice similarity coefficient (DSC) was observed. Dosimetric accuracy was evaluated by recalculating radiation dose for dCT plans using identical beam parameters as oriCT. Results: The SGD increased with distance from the isocenter in all series. DSC exceeded 0.95 for all plans except the rectum. Regarding GNL’s impact on dosimetric accuracy, most mean percentage errors for clinical target volume, planning target volume, and both femurs were under 2% in all plans, except for the bladder and rectum. Conclusion: SGD pre-evaluation is crucial and should be incorporated into a quality assurance program to ensure effective MRI-simulation performance before MRI-only treatment planning for prostate cancer.

Stereotactic Radiosurgery with Volumetric Modulated Arc Radiotherapy: Final Results of a Multi-arm Phase I Trial (DESTROY-2)

AimsTo present the final results of a phase I trial on stereotactic radiosurgery (SRS) delivered using volumetric modulated arc therapy (VMAT) in patients with primary or metastatic tumors in different extracranial sites. Materials and methodsThe DESTROY-2 trial, planned as a prospective dose escalation study in oligometastatic (one to five lesions) cancer patients relied on the delivery of a single high dose of radiation utilizing high-precision technology. The primary study endpoint was the definition of the maximum tolerated dose (MTD) of SRS-VMAT. The secondary objectives of the study were the evaluation of safety, efficacy, and long-term outcomes. All patients consecutively observed at our radiotherapy unit matching the inclusion criteria were enrolled. Each enrolled subject was included in a different phase I study arm, depending on the tumor site and the disease stage (lung, liver, bone, other), and sequentially assigned to a particular dose level. ResultsTwo hundred twenty seven lesions in 164 consecutive patients (male/female: 97/67, median age: 68 years; range: 29–92) were treated. The main primary tumors were: prostate cancer (60 patients), colorectal cancer (47 patients), and breast cancer (39 patients). The maximum planned dose level was achieved in all study arms, and the MTD was not exceeded. 34 Gy, 32 Gy, 24 Gy, and 24 Gy were established as the single-fraction doses for treating lung, liver, bone, and other extracranial lesions, respectively. The prescribed BED 2Gyα/β:10 to the planning target volume ranged from 26.4 Gy to 149.6 Gy. Twenty-seven patients (16.5%) experienced grade 1–2 and only one grade 3 acute toxicity, which was a pulmonary one. In terms of late toxicity, we registered only 5 toxicity>G2: a G3 gastro-intestinal one, three G3 bone toxicity, and a G3 laryngeal toxicity. The overall response was available for 199 lesions: 107 complete response (53.8%), 50 partial response (25.1%), and 31 stable disease (15.6%), leading to an overall response rate of 94.5%. Progression was registered only in 11 cases (5.5%). The overall response rate in each arm ranged from 88.6% to 96.4%. The overall two-year local control, distant metastasis free survival, disease free survival, and overall survival were 81.7%, 33.0%, 25.4%, and 78.7% respectively. ConclusionIn conclusion, the planned doses of 34 Gy, 32 Gy, 24 Gy, and 24 Gy were successfully administered as single-fractions for the treatment of lung, liver, bone, and other extracranial lesions, respectively, in a prospective SRS dose-escalation trial. No dose-limiting toxicities were registered, and minimal acute and late toxicity were reported. New indications for SRS are currently being studied in oligoprogressive patients receiving targeted drugs or in combination with immunotherapy. The DESTROY-2 trial represents, in our opinion, a credible starting point for future modern radiosurgery trials.

HyperArc performance in radiotherapy and its correlations with number and volume of multiple brain metastases

ObjectiveTo assess the performance and advantages of HyperArc for radiotherapy of multiple brain metastases with dosimetric parameters with respect to coplanar volumetric modulated arc radiotherapy (c-VMAT), and characterize implicit correlations between tumor features and dosimetric parameters. MethodsThis retrospective study involved 40 patients with multiple brain metastases (4–16 tumors, 12.8–240.8 cm3) who received simultaneous radiotherapy at the Department of Radiation Oncology, Shenzhen People's Hospital from January 2019 to December 2022. Both HyperArc and c-VMAT plans were designed by the same and qualified physicist using the Eclipse system with Truebeam. A single isocenter and a 6 ​MV flattening filter-free (6FFF) photon beam were used for radiotherapy of multiple brain metastases in each plan. Dosimetric parameters of tumors and organs at risk (OARs) were compared between HyperArc and c-VMAT plans. Correlations between tumor features (number and volume) and dosimetric parameters were revealed and analyzed. Furthermore, monitor units (MUs) of both plan types were recorded to assess rays utilization and delivery efficiency. ResultsCompared to c-VMAT plans, HyperArc plans achieved higher maximum dose (Dmax) (5.23%, t ​= ​7.87, P ​< ​0.01), but lower minimum dose (Dmin) (3.94%, t ​= ​−2.12, P ​= ​0.04) and mean dose (Dmean) (1.05%, t ​= ​−3.29, P < ​0.01) for planning gross tumor volumes (PGTVs). The conformity index (CI), homogeneity index (HI), gradient index (GI) and R50% of PGTVs with HyperArc were better than those with c-VMAT, with the improvements of 20.78%, 1.68%, 19.83% and 36.20%, respectively (P ​< ​0.01). The dosimetric parameters of OARs were significantly improved in HyperArc plans compared to c-VMAT plans. Specifically, the Dmax and the Dmean to the brainstem decreased by 16.14% and 11.37%, respectively. The Dmax for eye_L decreased by 16.88%, for eye_R decreased by 11.67%, for optical nerve_L decreased by 12.56 ​%, and for chiasm decreased by 18.12%. Few correlations were observed between the differences of CI/HI/GI/R50% and the number of PGTVs between the two plan types. Whereas, regression analysis indicated that the differences of CI/ GI/ R50% were negatively correlated with the volume of PGTVs, respectively. Moreover, although HyperArc plans reduced the MUs by 4.74 ​% compared to c-VMAT, no significant difference was observed (P ​> ​0.05). ConclusionsThis study demonstrates the promising performance of HyperArc for radiotherapy of multiple brain metastases, including better dose conformity for the tumors, more rapid dose drop and less dose spillage outside the tumors area, effective reduction of dose bridges among close tumors, and sparing OARs. It also reveals the correlations between the number or volume of tumors and dose parameters, which can help optimize the use of HyperArc and predict clinical benefits.

PET/CT-Based Radiogenomics Supports KEAP1/NFE2L2 Pathway Targeting for Non-Small Cell Lung Cancer Treated with Curative Radiotherapy.

In lung cancer patients, radiotherapy is associated with a increased risk of local relapse (LR) when compared with surgery but with a preferable toxicity profile. The KEAP1/NFE2L2 mutational status (MutKEAP1/NFE2L2) is significantly correlated with LR in patients treated with radiotherapy but is rarely available. Prediction of MutKEAP1/NFE2L2 with noninvasive modalities could help to further personalize each therapeutic strategy. Methods: Based on a public cohort of 770 patients, model RNA (M-RNA) was first developed using continuous gene expression levels to predict MutKEAP1/NFE2L2, resulting in a binary output. The model PET/CT (M-PET/CT) was then built to predict M-RNA binary output using PET/CT-extracted radiomics features. M-PET/CT was validated on an external cohort of 151 patients treated with curative volumetric modulated arc radiotherapy. Each model was built, internally validated, and evaluated on a separate cohort using a multilayer perceptron network approach. Results: The M-RNA resulted in a C statistic of 0.82 in the testing cohort. With a training cohort of 101 patients, the retained M-PET/CT resulted in an area under the curve of 0.90 (P < 0.001). With a probability threshold of 20% applied to the testing cohort, M-PET/CT achieved a C statistic of 0.7. The same radiomics model was validated on the volumetric modulated arc radiotherapy cohort as patients were significantly stratified on the basis of their risk of LR with a hazard ratio of 2.61 (P = 0.02). Conclusion: Our approach enables the prediction of MutKEAP1/NFE2L2 using PET/CT-extracted radiomics features and efficiently classifies patients at risk of LR in an external cohort treated with radiotherapy.

DOSIMETRIC AND EARLY CLINICAL OUTCOMES OF THYROID-SPARING VOLUMETRIC MODULATED ARC RADIOTHERAPY IN LOCALLY ADVANCED HEAD AND NECK CANCERS.

Radiation-induced hypothyroidism is a well-recognized entity that occurs after an interval of 15-21 months. However, in the treatment of locally advanced Head and neck Squamous cell carcinoma (HNSCC), thyroid-sparing techniques are infrequently employed. To evaluate the dosimetric and early clinical outcomes of thyroid-sparing SIB-VMAT technique (Simultaneous Integrated Boost - Volumetric Modulated Arc Radiotherapy) in patients of locally advanced HNSCC. In this two-arm prospective pilot study, patients in the study group received radiotherapy by SIB-VMAT technique with a thyroid constraint to a dose of 70 Gy to the gross disease and 59.4 Gy to nodal and subclinical disease in 33 fractions over 6 ½ weeks with concurrent cisplatin. V50Gy<75% was the thyroid constraint used. The control group was treated with the same dose and technique but without using a thyroid gland constraint. The dose-volume parameters of the thyroid gland, PTV (Planning Target Volume) along with thyroid profile were analyzed. Twenty-six patients were recruited. Thyroid V50Gy of the study group (65.33 ±6.63 %) was significantly lower than that of control group (80.35 ±13.40 %) (p=0.003). Tumor dose parameters of both groups were compared and revealed no significant difference. At 18 months follow-up, the incidence of any degree of hypothyroidism was 46.15% in the study group and 23.07% in the control group (p=0.216). In locally advanced HNSCC, it is feasible to spare the thyroid gland without compromising the tumour coverage. This has the potential to reduce the frequency of radiation-induced hypothyroidism.

TransQA: deep hybrid transformer network for measurement-guided volumetric dose prediction of pre-treatment patient-specific quality assurance

Objective. Performing pre-treatment patient-specific quality assurance (prePSQA) is considered an essential, time-consuming, and resource-intensive task for volumetric modulated arc radiotherapy (VMAT) which confirms the dose accuracy and ensure patient safety. Most current machine learning and deep learning approaches stack excessive convolutional/pooling operations (CPs) to predict prePSQA with two-dimensional or one-dimensional information input. However, these models generally present limitations in explicitly modeling long-range dependency for volumetric dose prediction due to the loss of spatial dose features and the inherent locality of CPs. The purpose of this work is to construct a deep hybrid network by combining the self-attention mechanism-based Transformer with modified U-Net for predicting measurement-guided volumetric dose (MDose) of prePSQA. Approach. The enrolled 307 cancer patients underwent VMAT were randomly divided into 246 and 61 cases for training and testing the model. The input data included computed tomography images, radiotherapy dose images exported from the treatment planning system, as well as the MDose distribution from the verification system. The output was the predicted high-quality voxel-wise prePSQA dose distribution. Main results: qualitative and quantitative experimental results show that the proposed prediction method could achieve comparable or better performance on MDose prediction over other approaches in terms of spatial dose distribution, dose–volume histogram metrics, gamma passing rates, mean absolute error, root mean square error, and structural similarity. Significance. The preliminary results on multiple cancer sites show that our approach can be taken as a clinical guidance tool and help medical physicists to reduce the measurement work of prePSQA.

A pilot study of stereotactic body radiotherapy combined with pelvic radiotherapy and GTVp boost based on multiparameter magnetic resonance image in patients with high-risk prostate cancer.

This pilot study aimed to explore the preliminary effects and safety of stereotactic body radiotherapy (SBRT) combined with preventive pelvic radiotherapy and primary gross tumor volumes (GTVp) boost in patients with high-risk prostate cancer based on multiparameter magnetic resonance image (mpMRI). Tumors were contoured as GTVp based on mpMRI. The prostate and proximal seminal vesicles were considered as the clinical target volume1. The pelvic lymphatic drainage area constituted clinical target volume 2. Radiation doses were 40Gy or 45Gy/5fractions to planning target volume of primary tumor, 37.5Gy/5f to prostate, seminal vesicle, and positive pelvic lymph nodes, and 25Gy/5f to pelvic synchronously. The treatment was delivered 3 times per week. Volumetric modulated arc radiotherapy and intensity-modulated radiotherapy were used to complete SBRT. The genitourinary (GU) and gastrointestinal (GI) toxicities were evaluated. Quality of life data was also captured. A total of 15 patients were enrolled in this study with a median age of 78 (56-87) from 2017 to 2020. All patients received SBRT. At 3 months after radiotherapy, the proportion of PSA < 0.006 ng/mL was 66.7% (10/15). The 2-year biochemical relapse-free survival was 93.3%. The incidence of grade 1 acute GU side effects was 80% (12/15); the incidence of acute grade 1 GI toxicity was 66.7% (10/15); and no grade 2 or higher acute GU and GI side effects was observed. Two patients presented with temporary late grade 2 GI toxicity. International Prostatic System Score increased rapidly after a transient increase at 1 week (P = .001). There were no significant differences in EORTC quality of life scores in all domains except global health status. In this pilot study, it was revealed that SBRT combined with preventive pelvic radiotherapy and GTVp boost based on mpMRI image was effective and well tolerated for patients with high-risk prostate cancer.

Left Anterior Descending Coronary Artery-Optimized Knowledge-Based Radiotherapy Planning in Patients with Locally Advanced Non-Small Cell Lung Cancer

The left anterior descending (LAD) coronary artery volume receiving 15 Gy (V15 Gy) has been associated with major adverse cardiac events and mortality in patients with locally advanced non-small cell lung cancer (LA-NSCLC) treated with radiotherapy (RT). However, coronary arteries are not routinely contoured as standard-of-care and there is limited data describing coronary-sparing planning techniques. Our objective was to evaluate whether LAD-sparing could be improved compared to real-world plans using a commercial knowledge-based planning (KBP) software without clinically unacceptable tradeoffs to other critical organs at risk (OAR). Retrospective replanning analysis was conducted on 31 RT plans developed for patients with LA-NSCLC. Each case was manually replanned with volumetric modulated arc radiotherapy (VMAT) optimized for LAD V15 Gy sparing with a prescription dose of 60 Gy. The resulting plans were used to create an LAD-optimized KBP model. The model included both KBP-generated objectives and additional point objectives to meet LAD (V15 Gy < 10%), lung (V5 Gy < 60%, V20 < 30%, mean < 17 Gy), heart (mean < 20 Gy), spinal cord (D0.03cc < 45 Gy), esophagus (V60 Gy < 17%, mean < 34 Gy), and planning target volume (PTV; D95% = 100%). The LAD-optimized model was deployed to replan 33 additional VMAT plans for LA-NSCLC with prescription dose 60 Gy, delivered between 2018 and 2022. Dose constraints or objectives were only unmet with KBP when not met in the original plan. Descriptive statistics were used to compare dosimetric parameters between original and LAD-optimized KBP plans. For the 33 plans identified for LAD-optimized KBP replanning, the original plans had a mean LAD V15 Gy of 17.9% (standard error [SE], 3.9%), while the LAD-optimized KBP plans had a significantly lower mean LAD V15 Gy of 5.9% (SE, 1.9%; p = 0.031). There was no significant difference in mean heart dose between the original and LAD-optimized KBP plans (8.4 Gy [SE 6.6 Gy] vs. 7.3 Gy [SE 5.8 Gy]; p = 0.48). Of these 33 KBP plans, 42% (n = 14) had mean reductions in LAD V15 Gy from 40.5% (SE 4.3%) to 10.5% (SE 3.5%; p = 0.0002), with 9/14 now able to meet < 10%, without affecting other critical OAR objectives (p > 0.5 for lungs, esophagus, spinal cord). 45% (n = 15) originally had an LAD V15 Gy < 1%, which were unchanged using KBP (p > 0.3). Four plans (12%) had higher LAD V15 Gy in the KBP vs. original plan (2/4 still meeting < 10%), due to the model prioritizing other OARs to a greater degree. Improvements in LAD-sparing was achievable in more than 40% of plans without apparent clinically significant tradeoffs in other critical OARs and without corresponding change in MHD. This result underscores the importance of standard implementation of LAD contouring and dose constraints, particularly given the discordance between whole heart and LAD dose exposure.

23 A Retrospective Study Comparing Outcomes in Matched Patients with Poor Prognosis Treated with Targeted Conventional Volumetric Modulated ARC Radiotherapy Versus Whole Brain Radiotherapy for Brain Metastases

23 A Retrospective Study Comparing Outcomes in Matched Patients with Poor Prognosis Treated with Targeted Conventional Volumetric Modulated ARC Radiotherapy Versus Whole Brain Radiotherapy for Brain Metastases

Comparative study of setup errors between new and reused thermoplastic masks in irradiated head and neck cancer patients

Background: The accuracy and precision of patient setup are important in radiotherapy. The thermoplastic mask is used to immobilize head and neck cancer patient. However, the mask is reused for low-income patients. Therefore, the setup error should be evaluated to approve that these patients remain in the exact position during treatment. Objective: To investigate setup errors with the use of thermoplastic masks in head and neck cancer patients and to compare setup errors of new and reused thermoplastic masks. Materials and Methods: Eighty patients who underwent volumetric modulated arc radiotherapy (VMAT) for head and neck cancer lesions were retrospectively evaluated. The setup error, population systematic error, and population random error were calculated. Subsequently, setup errors in patients using the new and reused thermoplastic masks were compared. Results: The population systematic error in the vertical, longitudinal, and lateral directions for new masks was 2.02, 2.27, and 2.13 mm, respectively, and that for reused masks was 2.37, 1.96, and 2.33 mm, respectively. The population random error in the vertical, longitudinal, and lateral direction for new masks was 1.46, 1.54, and 1.57 mm, respectively, and that for reused masks was 1.65, 1.63, and 1.87 mm, respectively. The results showed no statistically significant difference supported by p value &gt; 0.05 in the setup error between using the new and reused thermoplastic masks in all directions. Conclusion: For head and neck radiotherapy, the population setup errors were &lt; 3 mm in all directions. Moreover, thermoplastic masks can be reused in patients with head and neck cancer.

Indian data on response of positive pelvic lymph nodes in carcinoma cervix patients treated with simultaneous integrated boost using volumetric modulated arc radiation therapy

Objectives The percentage of pelvic lymph node positivity in cervical cancer patients varies from 19% in early stages to 68% in advanced cases. Thirty three percent of patients will develop recurrence within 2 years following therapy and 5-year relative survival for patients with affected regional lymph nodes is 57%. Hence, pelvic lymph nodes need to be included in the definitive plan of radiation treatment for better disease control and longer survival. With conventional radiation therapy, dose escalation was not possible because of small bowel constraints. With higher conformity of intensity modulated radiotherapy technique (IMRT), doses to pelvic and abdominal organs can be minimized. The added advantage of simultaneous integrated boost (SIB) is that high dose per fraction is delivered to the gross disease and low dose to the microscopic disease, thereby reducing the total treatment time and improving the therapeutic ratio. Material and Methods Forty one patients presenting to the Department of Radiation Oncology, between January 2016 and June 2017, with newly biopsy proven carcinoma cervix Stage IB to IVA were enrolled in the study and all the investigations were performed. The radiation dose was delivered using volumetric modulated arc therapy plan to a dose of 5000 cGy in 25 fractions to the whole pelvis and 5500 cGy in 25 fractions at 220 cGy per fraction to the involved nodes using SIB along with weekly cisplatin at 40 mg/m2. After completion of external beam radiation, all the patients received three fractions of brachytherapy to a total dose of 21 Gy. Acute toxicities were assessed using RTOG criteria. At 3 months after completion of treatment, all the patients had been followed up with DW MRI of abdomen and pelvis to assess the response. Results Of the 41 carcinoma cervix patients with significantly positive lymph nodes treated with SIB VMAT, 9.8% of the patients (4 patients) had residual nodal disease, 87.8% of the patients (36 patients) had complete response, 19.5% (8 patients) had residual disease of primary disease, and 78% (32 patients) had complete response at 3 months after completion of treatment with only Grade – I and Grade – II toxicities. Conclusion Treatment with SIB VMAT in carcinoma cervix patients with significant pelvic lymph nodes shows very good response with acceptable acute toxicities. But longer follow-up period is required to see if this response translates into better DFS and OS.

Successful management of Australian patients with locally advanced keratinocyte cancer (KC) and/or extensive skin field cancerization (ESFC), using widefield volumetric arc radiation therapy (VMAT): Report with 24-month follow-up.

9586 Background: Keratinocyte cancer (KC) diagnoses are associated with an elevated risk of developing new skin lesions. Patients with extensive skin field cancerization (ESFC) have large areas (generally ≥50cm2) of actinic keratoses and often, frequent keratinocyte cancers, necessitating repeated interventions. Volumetric modulated arc radiation therapy (VMAT) can precisely target large, complex surfaces with modulated doses, as required, leading to its increasing application to ESFC +/- KC. This is a follow-up 24-month report on the efficacy, safety, cosmetic, and quality of life outcomes of VMAT in the management of patients with ESFC +/- KC at Australian facilities. Methods: Two hundred and twenty-four fields for 194 patients with ESFC +/- KC have been prescribed widefield VMAT and prospectively enrolled in the National (Australian) Dermatology Radiation Oncology Registry (NDROR). One hundred and six fields are now beyond 24-months post-treatment. Over 80% of patients had received up to 4 prior non-radiotherapy interventions. Fields included lower and upper limb, face, scalp, or trunk regions. 3-, 6-, 12-, 18-, and 24-month follow-up assessments rated the percentage of field clearance, lesion response, new lesion events, cosmesis using the Lovett’s scale, toxicity based on CTCAE, and quality of life as assessed using a EQ-5D-5L visual analogue scale (VAS). Results: Median dose delivered to ESFC-only and ESFC + KC fields were 45 Gy (16.2-60 Gy) and 47 Gy (22-60 Gy), respectively, in 25 daily fractions (7-30) across 7 weeks (2-13). At 24-month follow-up of 106 fields, 96% and 94% of ESFC-only and ESFC + KC fields, respectively had clinical success, defined as &gt; 90% field clearance. Cosmesis was graded excellent or good in 98% of fields. The incidence of new KC within the field out to 24-months was 11%. Grade 1-2 radiation dermatitis was induced in all fields during treatment, but resolved by 3-month follow-up. Six percent of fields exhibited grade 3 dermatitis. Twelve percent of patients discontinued treatment due to acute toxicities (Median 88% dose delivered). The most common persistent toxicity at 24-month follow-up was localized grade 1-2 xerosis (51%), alopecia (43%), and/or pruritis (8%). Quality of life was sustainably improved in patients at 24-month follow-up (3.67; p= 0.026). Conclusions: Widefield VMAT has a promising profile of clinical efficacy, safety, and cosmesis in patients with ESFC +/- KC for whom other therapies had failed. Treatment was also associated with significant and durable improvements in quality of life. While long-term follow-up of patients continues, these results provide further support for widefield VMAT as a suitable option for patients with increasingly unmanageable presentations of ESFC and locally-advanced KC. Clinical trial information: ACTRN12618000627257 .

The Longitudinal Course of Prospectively Recorded Patient-reported Outcomes in Prostate Cancer Patients Treated with Surgery and Salvage Radiotherapy

BackgroundPatient-reported outcome measures (PROMs) after prostate cancer (PC) treatment, including both radical prostatectomy (RP) and salvage radiation therapy (SRT), are under-reported. ObjectiveTo investigate PROMs longitudinally from before SRT until 18 mo after SRT for men treated with contemporary treatment modalities. Design, setting, and participantsThis prospective, longitudinal cohort study included 120 men (whole cohort) treated with SRT administered with volumetric modulated arc radiotherapy from 2016 to 2021 at the University Hospital of North Norway. The whole cohort was followed from before SRT until 18 mo after SRT. A subcohort of 48 men was followed from before RP until 18 mo after SRT. Outcome measurements and statistical analysisPROMs were collected with the Expanded Prostate Cancer Index-26 (EPIC-26), covering symptoms of urinary incontinence, urinary irritative, bowel, sexual, and hormonal domains. The domain scores were inquired before RP, 3 mo after RP, before SRT, at SRT termination, and 3 and 18 mo after SRT. We used linear mixed models with repeated measurements design to assess changes in PROMs throughout the treatment period. Results and limitationsThe median age before SRT was 63 yr. For the whole cohort, all five domains worsened at 3 and 18 mo after SRT compared with those before SRT. The estimated mean changes from before SRT to 18 mo after SRT are as follows: urinary incontinence –13.1, urinary irritative function –10.4, bowel –16.8, sexual function –9.1, and hormonal function –20.2 (at clinically important levels for all domains but sexual). For the subcohort, the mean urinary incontinence, bowel, sexual, and hormonal functions were significantly worsened 3 and 18 mo after SRT compared with those before RP at clinically important levels. ConclusionsMen treated for PC report particular increased severity of urinary, bowel, sexual, and hormonal symptoms after SRT compared with baseline status. Patient summaryFor men with prostate cancer, the treatment combination of surgery and salvage radiotherapy worsens urinary incontinence and bowel, sexual, and hormonal functions.

Prognostic factors in radiotherapy of anaplastic thyroid carcinoma: a single center study over 31 years

BackgroundAnaplastic thyroid carcinoma has a very poor prognosis. We analyzed the effect of surgery, radiotherapy and chemotherapy on survival time and side effects in patients with ATC.MethodsWe retrospectively analyzed all patients (n = 63) with histologically confirmed ATC who presented at our clinic between 1989 and 2020. We analyzed the survival with Kaplan–Meier curves and cox proportional hazard models and acute toxicities with logistic regression models.ResultsOut of 63 patients, 62 received radiotherapy, 74% underwent surgery and 24% received combined chemotherapy. A median radiation dose of 49 Gy (range 4–66 Gy) was applied. In 32% of the cases opposing-field technique was used, in 18% 3D-conformal, in 27% a combination of opposing field and 3D-conformal technique and 21% obtained IMRT (intensity modulated radiotherapy) or VMAT (volumetric modulated arc radiotherapy). Median overall survival (OS) was 6 months. We identified five predictive factors relevant for survival: absence of distant metastases at the time of diagnosis (OS 8 months), surgery (OS 9.8 months), resection status R0 (OS 14 months), radiation dose of 50 Gy or higher (OS 13 months) and multimodal therapy (surgery, radiotherapy and chemotherapy) with a median OS of 9.7 months.ConclusionIn spite of the dismal outcome, longer survival can be achieved in some patients with ATC using surgery and radiotherapy with a high radiation dose. Compared to our previous study, there are no significant advantages in overall survival.Trial registration Retrospectively registered.

Split X-Jaw techniques of volumetric modulated arc radiotherapy in nasopharyngeal cancer: A dosimetric comparison.

The current study aims to compare the split x-jaw planning technique of volumetric modulated arc radiotherapy (VMAT) with the traditional open and limited jaw techniques of VAMT in nasopharyngeal carcinoma treatment. The multi-leaf collimators on the varian linear accelerator move on a carriage with a maximum leaf span of 15 cm. Therefore, treatment of larger planning target volumes, such as in nasopharyngeal cancer with traditional open and limited jaw technique, yields compromised dose distribution. Computed tomography data sets of 10 nasopharynx cancer patients were enrolled for the study. For each case, three separate treatment plans were generated viz. open, limited, and split x-jaw planning techniques with similar planning objectives. Only PTVs requiring a field size larger than 18 cm in the x-jaw position were considered. Comparable results were obtained regarding organs at risk (OAR) sparing in all the techniques. The target dose coverage with split x-jaw VMAT was superior to both open and limited jaw planning techniques, with a statistically significant difference in the intermediate dose planning target volumes (PTVs) (PTV59.4), P < 0.05. However, the split technique's dose to the spinal cord and larynx was significantly lower (P < 0.05). The split x-jaw planning technique of VMAT can be adapted for larger PTVs requiring an x-jaw of more than 15 cm. The only concern with this technique is the increased MU.

Can knowledge based treatment planning of VMAT for post-mastectomy locoregional radiotherapy involving internal mammary chain and supraclavicular fossa improve performance efficiency?

To validate and evaluate the performance of knowledge-based treatment planning for Volumetric Modulated Arc Radiotherapy for post-mastectomy loco-regional radiotherapy. Two knowledge-based planning (KBP) models for different dose prescriptions were built using the Eclipse RapidPlanTM v 16.1 (Varian Medical Systems, Palo Alto, USA) utilising the plans of previously treated patients with left-sided breast cancer who had undergone irradiation of the left chest wall, internal mammary nodal (IMN) region and supra-clavicular fossa (SCF). Plans of 60 and 73 patients were used to generate the KBP models for the prescriptions of 40 Gy in 15 fractions and 26 Gy in 5 fractions, respectively. A blinded review of all the clinical plans (CLI) and KBPs was done by two experienced radiation oncology consultants. Statistical analysis of the two groups was also done using the standard two-tailed paired t-test or Wilcoxon signed rank test, and p<0.05 was considered significant. A total of 20 metrics were compared. The KBPs were found to be either better (6/20) or comparable (10/20) to the CLIs for both the regimens. Dose to heart, contralateral breast,contralateral lung were either better or comparable in the KBP plans except of ipsilateral lung. Mean dose (Gy) for the ipsilateral lung are significantly (p˂0.001) higher in KBP though the values were acceptable clinically. Plans were of similar quality as per the result of the blinded review which was conducted by slice-by-slice evaluation of dose distribution for target coverage, overdose volume and dose to the OARs. However, it was also observed that treatment times in terms of monitoring units (MUs) and complexity indices are more in CLIs as compared with KBPs (p<0.001). KBP models for left-sided post-mastectomy loco-regional radiotherapy were developed and validated for clinical use. These models improved the efficiency of treatment delivery as well as work flow for VMAT planning involving both moderately hypo fractionated and ultra-hypo fractionated radiotherapy regimens.

A Scalp Dose Threshold for Preventing Permanent Alopecia in Scalp-Avoidance Whole-Brain Irradiation With Volumetric Modulated Arc Radiation Therapy for Pediatric Patients With Medulloblastomas

Although the overall survival of patients with medulloblastoma has dramatically improved, permanent alopecia significantly affects their quality of life. Therefore, we performed scalp-avoidance whole-brain irradiation with volumetric-modulated arc therapy (SAWB-VMAT) as a component of craniospinal irradiation (CSI). We retrospectively estimated the cutoff dose to prevent permanent alopecia in patients treated with SAWB-VMAT according to the St. Jude Medulloblastoma-96 protocol. Eight pediatric patients (median age 8.0 years, range 4.7-12.8 years) with medulloblastoma at our institution who we could take photographs following completion of the St. Jude Medulloblastoma-96 protocol treatment from May 2011 to August 2018 were enrolled in this study. All patients underwent CSI and boost radiotherapy followed by four cycles of dose-intensive chemotherapy. We defined permanent alopecia as hair loss persisting for 1 year after radiotherapy completion and 9 months after chemotherapy completion, as graded by two reviewers for each patient using the Severity of Alopecia Tool (SALT) score. Grades 3 and 4 alopecia were considered severe. Equivalent doses in 2-Gy fractions (assuming α/β = 2) to 50༅ of the scalp (EQD 50%) of SAWB-VMAT was significantly reduced compared to conventional WBRT (16.6 ± 3.6 vs. 20.2 ± 5.5 Gy, P = 0.038). The optimal EQD 50% cutoff was 19.9 Gy for severe permanent alopecia (area under the curve, 84%; sensitivity, 88%; specificity, 78%). The severe alopecia area was markedly reduced based on a 19.9 Gy cutoff (15.7 vs. 84.6 %, P = 0.0001). None of the patients who received SAWB-VMAT showed disease progression 5 years after starting radiotherapy. SAWB-VMAT significantly reduced the scalp EQD 50% and the estimated cutoff EQD 50% was 19.9 Gy. Scalp-avoidance whole-brain irradiation with volumetric-modulated arc therapy (SAWB-VMAT) remarkedly reduced equivalent doses in 2-Gy fractions (assuming α/β = 2) to 50༅ of the scalp (EQD 50%) comparing with conventional WBRT. None of the patients who received SAWB-VMAT showed disease progression 5 years after starting radiotherapy. The optimal EQD 50% cutoff was 19.9 Gy for severe permanent alopecia.

A planning-based feasibility study of MR-Linac treatment for anal cancer radiation therapy.

The hybrid magnetic resonance image (MRI) scanner and radiation therapy linear accelerator (MR-Linac) has the potential to enhance clinical outcomes for anal cancer (AC) patients with improved soft tissue visualization and daily plan adaption but has planning and delivery limitations due to the incorporation of MRI. We aimed to identify if Elekta Unity MR-Linac-based radiation therapy is feasible for anal cancer. Ten prospectively enrolled AC patients treated with radical chemoradiotherapy were replanned for MR-Linac treatment using departmental planning criteria. For comparison, and to reduce interobserver variability, volumetric modulated arc radiation therapy (VMAT) plans were also created for each patient by the same single senior radiation therapist. Plans were compared using departmental dosimetric plan criteria, as well as conformity and homogeneity indices, monitor units (MUs) and measured plan delivery (beam-on) time. Results were deemed clinically acceptable. Target and organ at risk (OAR) doses were comparable between MR-Linac plans and VMAT plans, although PTV45Gy D98% coverage was compromised in 3 of 10 MR-Linac plans due to caudocranial length exceeding the limits of the MR-Linac. MR-Linac plans had lower MUs, median of 689.1 vs 849.65 (p = 0.002), but took over twice as long to deliver, 529.5s vs 224s (p = <0.0001) as VMAT plans. MR-Linac planning and treatment of AC is feasible for a subset of patients. The current physical limitations of the Elekta Unity system mean patients with large caudocranial elective PTV45Gy target volumes may not be covered dosimetrically to the required clinical standard. Longer image verification and treatment delivery times of the MR-Linac also mean patient selection and intrafractional IGRT are likely to be integral to ensuring high quality clinical outcomes in this rare cancer.