Statistical Analysis on Impact of Image Preprocessing of CT Texture Patterns and Its CT Radiomic Feature Stability: A Phantom Study.

AIM: To examine computed tomography (CT) radiomic feature stability on various texture patterns during pre-processing utilizing the Credence Cartridge Radiomics (CCR) phantom textures. MATERIALS AND METHODS: Imaging Biomarker Explorer (IBEX) expansion for the abbreviation IBEX extracted 51 radiomic features of 4 categories from 11 textures image regions of interest (ROI) of the phantom. 19 software pre-processing algorithms processed each CCR phantom ROI. All ROI texture processed image features were retrieved. Pre-processed CT image radiomic features were compared to non-processed features to measure its textural influence. Wilcoxon T-tests measured the pre-processing relevance of CT radiomic features on various textures. Hierarchical cluster analysis (HCA) was performed to cluster processer potency and texture impression likeness. RESULTS: The pre-processing filter, CT texture Cartridge, and feature category affect the CCR phantom CT image's radiomic properties. Pre-processing is statistically unaltered by Gray Level Run Length Matrix (GLRLM ) expansion  for the abbreviation GLRLM and Neighborhood Intensity Difference matrix (NID) expansion for the abbreviation NID feature categories. The 30%, 40%, and 50% honeycomb are regular directional textures and smooth 3D-printed plaster resin, most of the image pre-processing feature alterations exhibited significant p-values in the histogram feature category. The Laplacian Filter, Log Filter, Resample, and Bit Depth Rescale Range pre-processing algorithms hugely influenced histogram and Gray Level Co-occurrence Matrix (GLCM) image features. CONCLUSION: We found that homogenous intensity phantom inserts, CT radiomic feature, are less sensitive to feature swaps during pre-processing than normal directed honeycomb and regular projected smooth 3D-printed plaster resin CT image textures. Because they lose fewer information during image enhancement, This feature concentration empowerment of the images also enhances texture pattern recognition.

A Dosimetric Analysis of Modified Volumetric Modulated Arc Therapy for Bone Marrow Sparing Radiotherapy in Cervical Cancer-An alternative Approach to Conventional VMAT.

BACKGROUND: External beam radiotherapy remains the primary treatment modality in cervical cancer. Nowadays Intensity Modulated Radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) are increasingly being used to reduce normal tissue toxicity. The drawback of conventional  VMAT is that a considerable volume of pelvic bone marrow receives a low dose. AIM: We analyzed whether there was a way to reduce the volume of the low dose regions of bone marrow, and assessed the potential benefit of conventional-4Arc (C-4Arc VMAT), and Modified-4Arc (M-4Arc VMAT) over the conventional 2 ARC VMAT. MATERIALS AND METHODS: Twelve clinically proven locally advanced cervical cancer patients treated with concurrent chemo-radiotherapy by Conventional VMAT (RapidArc) in dual rotation mode (C-2Arc VMAT) were selected for this study.C-4Arc VMAT and M-4Arc VMAT dose plans were generated for these twelve patients and these three different types of plans were evaluated for the quality and compared dosimetrically. RESULTS: M-4Arc VMAT designs exhibited a greater bone marrow sparing when compared with conventional VMATs with respect to volume receiving 5Gy to 35Gy without compromising PTV dose coverage. M-4Arc VMAT plans, the bone marrow volume receiving 30 Gy (V30Gy),40Gy (V40Gy), and mean doses were lower than the C- 4 Arc plan and a similar result was observed for V50(Gy) also when comparing with the standard 2 Arc plan. In modified VMAT plans, the rectum and bladder dose volumes were lower than standard VMAT. Similarly, the bowel bag V35(Gy), V40(Gy), V50(Gy), mean doses. The right and left femoral head doses were reduced significantly when compared to conventional VMAT plans. CONCLUSION: The M-4Arc VMAT plans are better than the C-2Arc and C-4Arc VMAT plans for reducing the dose to bone marrow by limiting the MLC field width travel.

Second malignant neoplasm risk after craniospinal irradiation in X-ray-based techniques compared to proton therapy.

Cranio-spinal irradiation (CSI) is widely used for treating medulloblastoma cases in children. Radiation-induced second malignancy is of grave concern; especially in children due to their long-life expectancy and higher radiosensitivity of tissues at young age. Several techniques can be employed for CSI including 3DCRT, IMRT, VMAT and tomotherapy. However, these techniques are associated with higher risk of second malignancy due to the physical characteristics of photon irradiation which deliver moderately higher doses to normal tissues. On the other hand, proton beam therapy delivers substantially lesser dose to normal tissues due to the sharp dose fall off beyond Bragg peak compared to photon therapy. The aim of this work is to quantify the relative decrease in the risk with proton therapy compared to other photon treatments for CSI. Ten anonymized patient DICOM datasets treated previously were selected for this study. 3DCRT, IMRT, VMAT, tomotherapy and proton therapy with pencil beam scanning (PBS) plans were generated. The prescription dose was 36 Gy in 20 fractions. PBS was chosen due to substantially lesser neutron dose compared to passive scattering. The age of the patients ranged from 3 to 12 with a median age of eight with six male and four female patients. Commonly used linear and a mechanistic doseresponse models (DRM) were used for the analyses. Dose-volume histograms (DVH) were calculated for critical structures to calculate organ equivalent doses (OED) to obtain excess absolute risk (EAR), life-time attributable risk (LAR) and other risk relevant parameters. A α' value of 0.018 Gy-1 and a repopulation factor R of 0.93 was used in the mechanistic model for carcinoma induction. Gender specific correction factor of 0.17 and - 0.17 for females and males were used for the EAR calculation. The relative integral dose of all critical structures averaged were 6.3, 4.8, 4.5 and 4.7 times higher in 3DCRT, IMRT, VMAT and tomotherapy respectively compared to proton therapy. The mean relative LAR calculated from the mean EAR of all organs with linear DRM were 4.0, 2.9, 2.9, 2.7 higher for male and 4.0, 2.9, 2.8 and 2.7 times higher for female patients compared to proton therapy. The same values with the mechanistic model were 2.2, 3.6, 3.2, 3.8 and 2.2, 3.5, 3.2, 3.8 times higher compared to proton therapy for male and female patients respectively. All critical structures except lungs and kidneys considered in this study had a substantially lower OED in proton plans. Risk of radiation-induced second malignancy in Proton PBS compared to conventional photon treatments were up to three and four times lesser for male and female patients respectively with the linear DRM. Using the mechanistic DRM these were up to two and three times lesser in proton plans for male and female patients respectively.