Total Body Irradiation using VMAT (RapidArc): A Planning Study of a novel treatment delivery method

Purpose: To evaluate the feasibility of using volumetric modulated arc therapy (VMAT) using RapidArc to deliver total body irradiation (TBI) treatment. Methods: VMAT planning was performed a whole body computed tomography (CT) data set using Rapid Arc. The planning target volumes included entire body trimmed to 3 mm below the skin. The organs at risk included the lungs and kidneys. A dose of 12 Gy in 10 fractions was prescribed to the target volume. The VMAT-TBI technique consisted of three isocentres and three overlapping arcs: the head and neck, the chest, and the pelvis. The plans were prescribed to ensure, at a minimum, 95% planning target volume dose coverage with the prescription dose (percentage of volume receiving dose of 12 Gy was 95%) and maximum dose of 109.8%. Mean dose to lung was restricted at 8.6Gy. Results: The total body volume in the study was 15469cm3 and the PTV volume was 11322cm3. The mean dose to PTV was 104%. The homogeneity index was 0.09. Sparing of normal tissues with adequate coverage of skeletal bones was shown to be feasible with Rapid Arc. The study demonstrates that VMAT is feasible for TBI treatment. Unlike conventional TBI chest wall boost with electrons was not required. Conclusion: The technique for total body irradiation using RapidArc VMAT was found feasible and is undergoing further studies prior to clinical use.</p

Total Body Irradiation using VMAT (RapidArc): A Planning Study of a novel treatment delivery method

Purpose: To evaluate the feasibility of using volumetric modulated arc therapy (VMAT) using RapidArc to deliver total body irradiation (TBI) treatment. Methods: VMAT planning was performed a whole body computed tomography (CT) data set using Rapid Arc. The planning target volumes included entire body trimmed to 3 mm below the skin. The organs at risk included the lungs and kidneys. A dose of 12 Gy in 10 fractions was prescribed to the target volume. The VMAT-TBI technique consisted of three isocentres and three overlapping arcs: the head and neck, the chest, and the pelvis. The plans were prescribed to ensure, at a minimum, 95% planning target volume dose coverage with the prescription dose (percentage of volume receiving dose of 12 Gy was 95%) and maximum dose of 109.8%. Mean dose to lung was restricted at 8.6Gy. Results: The total body volume in the study was 15469cm3 and the PTV volume was 11322cm3. The mean dose to PTV was 104%. The homogeneity index was 0.09. Sparing of normal tissues with adequate coverage of skeletal bones was shown to be feasible with Rapid Arc. The study demonstrates that VMAT is feasible for TBI treatment. Unlike conventional TBI chest wall boost with electrons was not required. Conclusion: The technique for total body irradiation using RapidArc VMAT was found feasible and is undergoing further studies prior to clinical use

Nuclear envelope, chromatin organizers, histones, and DNA: The many achilles heels exploited across cancers

In eukaryotic cells, the genome is organized in the form of chromatin composed of DNA and histones that organize and regulate gene expression. The dysregulation of chromatin remodeling, including the aberrant incorporation of histone variants and their consequent post-translational modifications, is prevalent across cancers. Additionally, nuclear envelope proteins are often deregulated in cancers, which impacts the 3D organization of the genome. Altered nuclear morphology, genome organization, and gene expression are defining features of cancers. With advances in single-cell sequencing, imaging technologies, and high-end data mining approaches, we are now at the forefront of designing appropriate small molecules to selectively inhibit the growth and proliferation of cancer cells in a genome- and epigenome-specific manner. Here, we review recent advances and the emerging significance of aberrations in nuclear envelope proteins, histone variants, and oncohistones in deregulating chromatin organization and gene expression in oncogenesis

Shielding in whole brain irradiation in the multileaf collimator era: Dosimetric evaluation of coverage using SFOP guidelines against in-house guidelines

Aim : Compare the planning target volume (PTV) coverage in three different shielding techniques in cranial irradiation. Settings and Design : Tertiary care center, prospective study. Materials and Methods : The whole brain and meninges were contoured in ten planning CT scans, and expanded by 5 mm for the PTV. Shielding was designed using the French Society of Pediatric Oncology (SFOP) guidelines (SFOP plan), in-house recommendation (with 1 cm margin from the orbital roof and sphenoid wing) on a igitally Reconstructed Radiograph (DRR) and a third plan was generated using a 3D conformal radiation technique (3DCRT). The coverage of the PTV was noted using the isodose covering 95% of the PTV(D95), minimum dose within the PTV(D min ), and maximum dose within the PTV(D max ). The location of PTV not covered by the 95% isodose curve was noted. The median dose and maximum dose (D max ) to both eyes and maximum dose D max for the lens were noted. Statistical Analysis : General linear model method repeated the measure of analysis of variance test (ANOVA). Results : PTV coverage was significantly poorer in the SFOP and in-house plans as compared to 3DCRT plan (P=0.04). Median volume of PTV not covered by 95% isodose curve was 4.18 cc, 1.01 cc, and 0 cc in SFOP, in-house, and 3DCRT plan, respectively. Conclusions : In the absence of volumetric planning techniques, SFOP guidelines lead to inadequate coverage and the in-house method is recommended