A data-driven method to predict achievability of clinical objectives in IMRT

When specifying a clinical objective for a target volume and normal organs/tissues in IMRT planning, the user may not be sure if the defined clinical objective could be achieved by the optimizer. To this end, we propose a novel method to predict the achievability of clinical objectives upfront before invoking the optimization. A new metric called “Geometric Complexity (GC)” is used to estimate the achievability of clinical objectives. Essentially GC is the measure of the number of “unmodulated” beamlets or rays that intersect the Region-of-interest (ROI) and the target volume. We first compute the geometric complexity ratio (GCratio) between the GC of a ROI in a reference plan and the GC of the same ROI in a given plan. The GCratio of a ROI indicates the relative geometric complexity of the ROI as compared to the same ROI in the reference plan. Hence GCratio can be used to predict if a defined clinical objective associated with the ROI can be met by the optimizer for a given case. We have evaluated the proposed method on six Head and Neck cases using Pinnacle3 (version 9.10.0) Treatment Planning System (TPS). Out of total of 42 clinical objectives from six cases accounted in the study, 37 were in agreement with the prediction, which implies an agreement of about 88% between predicted and obtained results. The results indicate the feasibility of using the proposed method in head and neck cases for predicting the achievability of clinical objectives.

COMBINED IRRADIATION OF PELVIS AND INGUINALNODAL REGIONS USING MODIFIED SEGMENTAL BOOST TECHNIQUE: A PROSPECTIVE STUDY.

AIM: To describe a novel Modied Segmental Boost Technique (MSBT) for combined irradiation of pelvis and inguinal nodes and to compare the dosimetry of the new method with that of other traditional methods of radiation treatment and IMRT. Total 30 patients who required combined irradiation of pelvis and inguinal regi METHODS AND MATERIALS: ons are included in our study to illustrate details and advantages of MSBT. Conventional photons with enface electrons design was created rst with two opposing parallel elds and four eld box. MSBT plans are generated and patient is treated with this technique to TD 45-50Gy for 5-6 weeks duration. A step-and-shoot inverse IMRT planning was subsequently generated. For dosimetric comparison, these treatment techniques were evaluated by dose-volume histogram (DVH) of PTV and OARs. Dose proles at different depths from each treatment planning were generated for comparison. Comparing the modied segmental boost technique with conventional two oppos RESULTS: ing and four eld box technique, we have found out that the target coverage, dose homogeneity index (DHI) and femoral head sparing is superior in modied segmental boost technique compared to other conventional approaches. And also the patients had better clinical response of both primary and the nodes with minimal skin morbidity when compared with conventionally treated patients data. DHI and target coverage of MSBT was comparable with that of IMRT. CONCLUSION: To cover pelvis and inguinal/femoral nodes, MSBT is technically simple to simulate, plan, and execute. Dosimetric study has demonstrated that it achieves comparable PTV coverage compared with other approaches while at the same time signicantly sparing the surrounding OAR .It also has dose homogeneity comparable with IMRT and can be a nearer alternative for IMRT, in centers which are not having the facility and where the patient load is higher.

Provider-Level Variation in Treatment Planning of Radiation Oncology Procedures in the United States

PURPOSE: Variation in the use of radiation oncology procedures and technologies is poorly characterized. We sought to identify associations between the treatment planning codes used to bill for radiotherapy procedures and the demographic characteristics of the radiation oncologists submitting them. METHODS: The Physician and Other Supplier Public Use File was linked to the Physician Compare database by using the physician National Provider Identifier for the year 2016. Analysis was stratified by practice setting, considering both the freestanding non–facility-based (NFB) setting and the facility-based (FB) setting. Multivariable logistic regression was used to determine provider characteristics (gender, practice rurality, and years since graduation) that predicted for the use of 3D-conformal RT (3DCRT) planning, intensity-modulated RT (IMRT) planning, and brachytherapy planning in the Medicare population. RESULTS: Three thousand twenty-nine physicians were linked for analysis. In both the FB and NFB settings together, male gender predicted for decreased likelihood of 3DCRT planning (OR, 0.70, 95% CI, 0.62 to 0.80, P < .001) and increased likelihood of IMRT planning (OR, 1.35, 95% CI, 1.19 to 1.54, P < .001). Brachytherapy planning was also more likely with increasing years since medical school graduation (OR, 1.03, 95% CI, 1.01 to 1.04, P < .001) in the combined FB and NFB settings. These significant associations persisted when examining the NFB and FB settings individually. In both settings overall, brachytherapy planning was more likely in male providers (OR, 1.75, 95% CI, 1.10 to 2.76, P = .02) and also more likely for providers practicing in metropolitan regions compared with those practicing in rural areas (OR, 3.01, 95% CI, 1.23 to 7.39, P = .02). CONCLUSION: Male gender predicts for utilization of IMRT planning, whereas female gender predicts for utilization of 3DCRT planning. Future research is warranted to better understand the role that provider gender and rurality play in the selection of radiation planning techniques for Medicare patients.

Plan quality assessment of modern radiotherapy delivery techniques in left-sided breast cancer: an analysis stratified by target delineation guidelines

Objective: This study compares planning techniques stratified by consensus delineation guidelines in patients undergoing whole-breast radiotherapy based on an objective plan quality assessment scale. Methods: 10 patients with left-sided breast cancer were randomly selected, and target delineation for intact breast was performed using Tangent (RTOG 0413), ESTRO, and RTOG guidelines. Consensus Plan Quality Metric (PQM) scoring was defined and communicated to the physicist before commencing treatment planning. Field-in-field IMRT (FiF), inverse IMRT (IMRT) and volumetric modulated arc therapy (VMAT) plans were created for each delineation. Statistical analyses utilised a two-way repeated measures analysis of variance, after applying a Bonferroni correction. Results: Total PQM score of plans for Tangent and ESTRO were comparable for FiF and IMRT techniques (FiF vs IMRT for Tangent, p = 0.637; FiF vs IMRT for ESTRO, p = 0.304), and were also significantly higher compared to VMAT. Total PQM score of plans for RTOG revealed that IMRT planning achieved a significantly higher score compared to both FiF and VMAT (IMRT vs FiF, p < 0.001; IMRT vs VMAT, p < 0.001). Conclusions: Total PQM scores were equivalent for FiF and IMRT for both Tangent and ESTRO delineations, whereas IMRT was best suited for RTOG delineation. Advances in knowledge: FiF and IMRT planning techniques are best suited for ESTRO or Tangent delineations. IMRT also yields better results with RTOG delineation.