Dosimetric Validation of Treatment Planning System for Volumetric Modulated Arc Therapy Using AAPM Medical Physics Practice Guideline 5.b.

AIM: To assess the precision of dose calculations for Volumetric Modulated Arc Therapy (VMAT) using megavoltage (MV) photon beams, we validated the accuracy of two algorithms: AUROS XB and Analytical Anisotropic Algorithm (AAA). This validation will encompass both flattening filter (FF) and flattening filter-free beam (FFF) modes, using AAPM Medical Physics Practice Guideline (MPPG 5b). MATERIALS AND METHODS: VMAT validation tests were generated for 6 MV FF and 6 MV FFF beams using the AAA and AXB algorithms in the Eclipse V.15.1 treatment planning system (TPS). Corresponding measurements were performed on a linear accelerator using a diode detector and a radiation field analyzer. Point dose (PD) and in-vivo measurements were conducted using an A1SL ion chamber and (TLD) from Thermofisher, respectively. The Rando Phantom was employed for end-to-end (E2E) tests. RESULTS: The mean difference (MD) between the TPS-calculated values and the measured values for the PDD and output factors were within 1% and 0.5%, respectively, for both 6 MV FF and 6 MV FFF. In the TG 119 sets, the MD for PD with both AAA and AXB was <0.9%. For the TG 244 sets, the minimum, maximum, and mean deviations in PD for both 6 MV FF and 6 MV FFF beams were 0.3%, 1.4% and 0.8% respectively. In the E2E test, using the Rando Phantom, the MD between the TLD dose and the TPS dose was within 0.08% for both 6 MV FF (p=1.0) and 6 MV FFF (0.018) beams. CONCLUSION: The accuracy of the TPS and its algorithms (AAA and AXB) has been successfully validated. The recommended tests included in the VMAT/IMRT validation section proved invaluable for verifying the PDD, output factors, and the feasibility of complex clinical cases. E2E tests were instrumental in validating the entire workflow from CT simulation to treatment delivery.

A scoping review to evaluate occupational controls and their effectiveness when handling engineered nanomaterials in workplaces.

Research has shown that controlling worker exposure to engineered nanomaterials (ENMs) helps to reduce the exposure risk to employees in workplaces. This study aimed to identify the available evidence on the effectiveness of various control methods used in the workplace to reduce worker exposure to ENMs. The search was conducted in databases-Medline, OVID, Scopus, Science Direct, Web of Science, and Cochrane and the gray literature published from January 2010 to December 2022. The search keywords included ENM controls and their efficiency in workplace environments. Of the 152 studies retrieved, 22 were included in the review. The control measures in the review included (1) substitution controls; (2) engineering measures (i.e., isolation, direct source extraction, and wetting technologies); (3) personal protective equipment; and (4) administrative and work practices. The study results indicate that the above-mentioned control measures were effective in reducing ENM exposures. This information can be used to help employers choose the most effective controls for their workplaces.

Definitive chemoradiation for oropharyngeal squamous carcinomas: Outcomes with intensity-modulated radiation therapy using simultaneous integrated boost, in a majorly p16 negative cohort.

BACKGROUND: The literature on modern-era outcomes of oropharyngeal squamous carcinoma (OPSCC) in India is limited. MATERIALS AND METHODS: We analyzed records of consecutive patients with OPSCC treated using a curative SIB IMRT regimen of 66 Gy/30#/6 weeks. RESULTS: One hundred fifteen patients from July 2011 to December 2018 were analyzed. Twenty of 69 patients tested positive for p16. In p16 positive patients, the K-M probability of being disease free and alive at 2 years, with at least one follow-up 3 months after treatment, was 83% (median not reached) compared with 48% if p16 was unknown/negative. Patients staged as IVB p16 negative had a 2-year DFS of 25%. Patients unfit for cisplatin and consequently received other agents had 2-year DFS estimated at 20%. CONCLUSIONS: Intensity-modulated radiation therapy (IMRT) with simultaneous integrated boost (SIB) and concurrent chemotherapy was feasible, with toxicity and disease control comparable to available literature. AJCC Stage IVB p16 negative disease had notably poor outcome.

Xerostomia quality of life and resource requirements following parotid sparing adaptive radiotherapy in head and neck cancers: Results of a prospective cohort study (Study ID CTRI/2017/11/010683).

BACKGROUND AND PURPOSE: Parotid sparing adaptive radiotherapy (PSART) is resource intensive to implement. Selection criteria for using ART and its impact on quality of life (QoL) is poorly reported. This has been addressed in our study. MATERIALS AND METHODS: Patients planned for curative radiotherapy for Head Neck Cancers were recruited following informed consent in a prospective cohort study. PSART was planned if the mean dose to index parotid(s) increased by 2% from the baseline approved plan. To assess the resource requirements of PSART manpower and time required for treatment planning both for initial as well as PSART was documented. Patient reported QoL using QualiXeQLS and EORTC QLQ C30 and HN35 were obtained pre radiotherapy, and at 3 and 9 months post radiotherapy. RESULTS: Of the ninety patients accrued, 87 were evaluable. 45 (51%) received PSART based on the prespecified criteria. The average time spent in contouring (276 min versus 133 min) and treatment planning (293 min versus 108 min) were almost doubled when PSART was implemented. XeQoL scores at 3 months were significantly worse in those receiving PSART (mean 2.3 vs 1.2, p 0.002). Despite this, xerostomia related QoL recovered to near baseline scores by 9 months after receiving PSART. CONCLUSION: Implementation of PSART is resource intensive. The proposed cutoff for implementing PSART identifies a higher risk population that have worse xerostomia related quality of life. This study lays the foundation for a randomized trial to determine the efficacy of PSART on xerostomia related QoL.

Prioritizing Delivery of Cancer Treatment During a COVID-19 Lockdown: The Experience of a Clinical Oncology Service in India.

PURPOSE: A COVID-19 lockdown in India posed significant challenges to the continuation of radiotherapy (RT) and systemic therapy services. Although several COVID-19 service guidelines have been promulgated, implementation data are yet unavailable. We performed a comprehensive audit of the implementation of services in a clinical oncology department. METHODS: A departmental protocol of priority-based treatment guidance was developed, and a departmental staff rotation policy was implemented. Data were collected for the period of lockdown on outpatient visits, starting, and delivery of RT and systemic therapy. Adherence to protocol was audited, and factors affecting change from pre-COVID standards analyzed by multivariate logistic regression. RESULTS: Outpatient consults dropped by 58%. Planned RT starts were implemented in 90%, 100%, 92%, 90%, and 75% of priority level 1-5 patients. Although 17% had a deferred start, the median time to start of adjuvant RT and overall treatment times were maintained. Concurrent chemotherapy was administered in 89% of those eligible. Systemic therapy was administered to 84.5% of planned patients. However, 33% and 57% of curative and palliative patients had modifications in cycle duration or deferrals. The patient's inability to come was the most common reason for RT or ST deviation. Factors independently associated with a change from pre-COVID practice was priority-level allocation for RT and age and palliative intent for systemic therapy. CONCLUSION: Despite significant access limitations, a planned priority-based system of delivery of treatment could be implemented.

Setting up a lung stereotactic body radiotherapy service in a tertiary center in Eastern India: The process, quality assurance, and early experience.

CONTEXT: Stereotactic body radiotherapy (SBRT) is increasingly being used for early-stage lung cancer and lung oligometastases. AIMS: To report our experience of setting up lung SBRT and early clinical outcomes. SETTINGS AND DESIGN: This was a retrospective, interventional, cohort study. SUBJECTS AND METHODS: Patients were identified from multidisciplinary tumor board meetings. They underwent four-dimensional computed tomography-based planning. The ROSEL trial protocol, the Radiation Therapy Oncology Group (RTOG) 0236, and the UK-Stereotactic Ablative Body Radiotherapy Consortium guidelines were used for target volume and organs-at-risks (OARs) delineation, dosimetry, and plan quality assessment. Each SBRT plan underwent patient-specific quality assurance (QA). Daily online image guidance using KVCT or MVCT was done to ensure accurate treatment delivery. STATISTICAL ANALYSIS USED: Microsoft Excel 2010 was used for data analysis. RESULTS: Fifteen patients were treated to one or more lung tumors. One patient received helical tomotherapy in view of bilateral lung oligometastases at similar axial levels. All the remaining patients received volumetric modulated arc therapy (VMAT)-based treatment. The prescription dose varied from 40 to 60 Gy in 5-8 fractions with alternate-day treatment. The mean and median lung V20 was 5.24% and 5.16%, respectively (range, 1.66%-9.10%). The mean and median conformity indexes were 1.02 and 1.06, respectively (range, 0.70-1.18). After a median follow-up of 17 months, the locoregional control rate was 93.3%. CONCLUSIONS: SBRT was implemented using careful evaluation of OAR dose constraints, dosimetric accuracy and plan quality, patient-specific QA, and online image guidance for accurate treatment delivery. It was safe and effective for early-stage nonsmall cell lung cancer and lung metastases. Prospective data were collected to audit our outcomes.

Is using nanosilver mattresses/pillows safe? A review of potential health implications of silver nanoparticles on human health.

Human exposure to engineered nanoparticles has become inevitable in today's extensive commercial use and large-scale production of engineered nanoparticles. Even though several studies have characterised the exposure to nanomaterials during wakeful state (related to occupational exposures and exposures from commercially available particles), very few studies on human exposure during sleep exist. As the study of exposure to all possible nanomaterials during sleep is extensive, this study focuses on exposure to specifically silver nanoparticles which are present in beddings and mattresses. The reasoning behind the use of silver nanoparticles in bedding and related materials, possible routes of entry to various population groups in several sleep positions, exposure characterisation and toxicity potential of such silver nanoparticles are reviewed in this study. The toxicity potential of silver nanoparticles in vivo tests with relation to mammals and in vitro tests on human cells has been tabulated to understand the risks associated during oral, dermal and inhalation exposure to silver nanoparticles. The exposure to humans with regard to dermal absorption and oral intake has been summarised. Although potential inhalation exposure to silver nanoparticles is increasing, only a few studies address the possible toxic effect of inhaled silver particles. Determination of exposure to silver nanoparticles in beddings is a topic that has been less researched, and this review aims to provide background information for future research and help establish a comprehensive risk assessment during sleep in the times of increasing usage of nanoparticles in our daily activities. Despite the current limitations of our understanding, risk assessments must utilise the available data and apply extrapolation procedures in the face of uncertainty, in order to address the needs of regulatory programs. This would enable safe use of the antimicrobial properties of silver nanoparticles without negatively impacting human health. Until then, it would be better to adopt a conservative approach on the usage of silver nanoparticles in daily used commercial items.

Development and validation of a decision support tool to select IMRT as radiotherapy treatment planning modality for patients with locoregionally advanced non-small cell lung cancers (NSCLC).

OBJECTIVE:: Radiation planning for locally-advanced non-small cell lung cancer (NSCLC) can be time-consuming and iterative. Many cases cannot be planned satisfactorily using multisegment three-dimensional conformal radiotherapy (3DCRT). We sought to develop and validate a predictive model which could estimate the probability that acceptable target volume coverage would need intensity modulated radiotherapy (IMRT). METHODS:: Variables related to the planning target volume (PTV) and topography were identified heuristically. These included the PTV, it's craniocaudal extent, the ratio of PTV to total lung volume, distance of the centroid of the PTV from the spinal canal, and the extent PTV crossed the midline. Metrics were chosen such that they could be measured objectively, quickly and reproducibly. A logistic regression model was trained and validated on 202 patients with NSCLC. A group of patients who had both complex 3DCRT and IMRT planned was then used to derive the utility of the use of such a model in the clinic based on the time taken for planning such complex 3DCRT. RESULTS:: Of the 202 patients, 93 received IMRT, as they had larger volumes crossing midline. The final model showed a good rank discrimination (Harrell's C-index 0.84) and low calibration error (mean absolute error of 0.014). Predictive accuracy in an external dataset was 92%. The final model was presented as a nomogram. Using this model, the dosimetrist can save a median planning time of 168 min per case. CONCLUSION:: We developed and validated a data-driven, decision aid which can reproducibly determine the best planning technique for locally-advanced NSCLC. ADVANCES IN KNOWLEDGE:: Our validated, data-driven decision aid can help the planner to determine the need for IMRT in locally advanced NSCLC saving significant planning time in the process.

Impact of modern radiotherapy techniques on survival outcomes for unselected patients with large volume non-small cell lung cancer.

OBJECTIVE:: Intensity modulated radiotherapy (IMRT) is used, where necessary, for bulky or complex-shaped, locally advanced, non-small cell lung cancer (NSCLC). We evaluate our real-world experience with radical radiotherapy including concurrent chemoradiation (CCRT), and analyse the impact of IMRT on survival outcomes in patients with larger volume disease. METHODS:: All patients treated between May 2011 and December 2017 were included. Analyses were conducted for factors affecting survival, including large volume disease that was defined as planning target volume (PTV) > 500 cc. RESULTS:: In 184 patients with large volume disease, the median overall survival was 19.2 months, compared to 22 months seen with the overall cohort of 251 patients who received radical radiotherapy. PTV and using CCRT were significant predictors for survival. IMRT was used in 93 (50.5%) of 184 patients with large PTV. The patients treated using IMRT had significantly larger disease volume (median PTV = 859 vs 716 cc; p-value = 0.009) and more advanced stage (proportion of Stage IIIB: 56 vs 29%; p-value = 0.003) compared to patients treated with three-dimensional conformal radiotherapy. Yet, the outcomes with IMRT were non-inferior to those treated with 3DCRT. CCRT was used in 103 (56%) patients with large volume disease and resulted in a significantly better median survival of 24.9 months. The proportional benefit from CCRT was also greater than in the overall cohort. CONCLUSION:: Despite being used for larger volume and more advanced NSCLC, inverse-planned IMRT resulted in non-inferior survival. ADVANCES IN KNOWLEDGE:: IMRT enables the safe use of curative CCRT for large-volume, locally-advanced NSCLC.

Radical radiotherapy or chemoradiotherapy for inoperable, locally advanced, non-small cell lung cancer: Analysis of patient profile, treatment approaches, and outcomes for 213 patients at a tertiary cancer center.

INTRODUCTION: Radical radiotherapy (RT) with curative intent, with or without chemotherapy, is the standard treatment for inoperable, locally advanced nonsmall cell lung cancer (NSCLC). MATERIALS AND METHODS: We retrospectively reviewed the data for all 288 patients who presented with inoperable, locally advanced NSCLC at our institution, between May 2011 and December 2016. RESULTS: RT alone or sequential chemoradiotherapy (SCRT) or concurrent chemoradiotherapy (CCRT) was used for 213 patients. Median age was 64 years (range: 27-88 years). Stage-III was the biggest stage group with 189 (88.7%) patients. Most patients with performance status (PS) 0 or 1 received CCRT, whereas most patients with PS 2 received RT alone (P < 0.001). CCRT, SCRT, and RT alone were used for 120 (56.3%), 24 (11.3%), and 69 (32.4%) patients, respectively. A third of all patients (32.4%) required either volumetric-modulated arc radiotherapy (VMAT) or tomotherapy. Median follow-up was 16 months. The median progression-free survival and median overall survival (OS) were 11 and 20 months, respectively. One-year OS and 2-year OS were 67.9% and 40.7%, respectively. Patients treated using CCRT lived significantly longer with a median survival of 28 months, compared with 13 months using SCRT and RT alone (P < 0.001). On multivariate analysis, OS was significantly affected by age, stage group, treatment approach, and response to treatment. CONCLUSION: RT including CCRT is feasible, safe, and well tolerated in our patient population and results in survival benefits comparable with published literature. CCRT should be considered for all patients with inoperable, locally advanced NSCLC, who are fit and have good PS.

Acute toxicity and its dosimetric correlates for high-risk prostate cancer treated with moderately hypofractionated radiotherapy.

AIMS: To report the acute toxicity and the dosimetric correlates after moderately hypofractionated radiotherapy for localized prostate cancer. METHODS: A total of 101 patients with localized prostate cancer were treated with image-guided intensity-modulated radiation therapy. Patients were treated to 65Gy/25Fr/5 weeks (n = 18), or 60Gy/20Fr/4 weeks (n = 83). Most (82.2%) had high-risk or pelvic node-positive disease. Acute toxicity was assessed using Radiation Therapy Oncology Group (RTOG) acute morbidity scoring criteria. Dose thresholds for acute rectal and bladder toxicity were identified. RESULTS: The incidence of acute grade 2 GI toxicity was 20.8%, and grade 2 genitourinary (GU) toxicity was 6.9%. No Grade 3 to 4 toxicity occurred. Small bowel toxicity was uncommon (Gr 2 = 4%). The 2Gy equivalent doses (EQD2) to the rectum and bladder (α/ß = 3) calculated showed that the absolute doses were more consistent predictors of acute toxicities than the relative volumes. Those with grade 2 or more GI symptoms had significantly higher VEQD2-60Gy (13.2 vs 9.9cc, p = 0.007) and VEQD2-50Gy (20.6 vs 15.4cc, p = 0.005). Those with grade 2 or more GU symptoms had significantly higher VEQD2-70Gy (30.4 vs 18.4cc, p = 0.001) and VEQD2-65Gy (44.0 vs 28.8cc, p = 0.001). The optimal cutoff value for predicting grade 2 acute proctitis, for VEQD2-60Gy was 9.7cc and for VEQD2-50Gy was 15.9cc. For grade 2 GU symptoms, the threshold values were 23.6cc for VEQD2-70Gy and 38.1cc for VEQD2-65Gy. CONCLUSIONS: Hypofractionated radiotherapy for prostate cancer is well tolerated and associated with manageable acute side effects. The absolute dose-volume parameters of rectum and bladder predict for acute toxicities.

Carotid sparing hypofractionated tomotherapy in early glottic cancers: Refining image guided IMRT to improve morbidity.

OBJECTIVE: Carotid artery damage has been reported secondary to radiotherapy. We report the feasibility of implementing hypofractionated laryngeal irradiation using carotid sparing tomotherapy (HT) and analyze the image guidance (IG) policy. MATERIALS AND METHODS: Five patients with early glottic cancer (EGC) had radiotherapy using 3D conformal technique (conf) while repeat treatment plans were produced with helical tomotherapy using carotid sparing techniques (cstomo). Inverse and forward planned dose volume histograms were analyzed. Three hundred and sixty four daily images of 14 patients having daily Megavoltage head and neck CT imaging prior to irradiation were analyzed to assess errors. RESULTS: There was no significant difference in the maximum and mean dose to the PTV (P = 0.058, 0.66). The left / right carotid median doses were significantly less in the cstomo plans as compared to conf plans (P = 0.0001/ 0.026). Cstomo plans had significantly better PTV Conformity Index (CI) (P = 0.0006) with comparable Homogeneity Index. A CTV-PTV margin of 5.3, 4, 5.3 cm in the 3 axes were calculated using Van Herks formula. After average shifts from imaging for first 5 fractions (AS5) were applied to remaining fractions, the residual shifts in the calculated CTV-PTV margins reduced to 2.9, and 2.1 in the X, Y axes respectively allowing further adaptation of PTV margin from fraction 6. CONCLUSIONS: Carotid sparing was possible using cstomo plans with significantly better conformity. Applying AS5 could enable us to reduce the PTV (3 mm) margin in X, Y axes for the remaining 15 fractions.