Dosimetric and radiobiological advantages from deep inspiration breath-hold and free breath technique for left-sided breast radiation using 3DCRT, IMRT and Rapid Arc methods-a complete assessment.

The verification and use of the best treatment approach using 3D conformal radiation therapy (3DCRT), intensity modulated radiation therapy (IMRT) and Rapid Arc methods for left breast radiation with dosimetric and radiobiological characteristics. The use of custom-built Python software for the estimation and comparison of volume, mean dose, maximum dose, monitor units and normal tissue integral dose along with radiobiological parameters such as NTCP, tumor control probability, equivalent uniform dose and LKB's effective volume from 3DCRT, IMRT and Rapid Arc planning with deep inspiration with breath holding (DIBH) and free breadth (FB) techniques. Volume growth of three-fourth in DIBH compared with FB causes a decrease in cardiac doses and complications because the left lung expands, pulling the heart away from the chest wall and the treatment area. A tiny area of the left lung was exposed during treatment, which reduced the mean dose. There was little difference in the treatment approaches because the spinal cord was immobile in both techniques. Rapid Arc is the unmatched modality for left-sided breast irradiation with significant patient breath-hold, as shown by the comparison of dosimetric and radiobiological parameters from treatment techniques with a deep inspiration breath-hold approach.

Assessment of the Dosimetric Index from IMRT and Rapid arc Plan for Oropharyngeal Cancer with Simultaneous Integrated Boost (SIB) Technique in Combination with EUD-based NTCP and TCP Radiobiological Models.

PURPOSE: The current research compared radiobiological and dosimetric results for simultaneous integrated boost (SIB) plans employing RapidArc and IMRT planning procedures in oropharyngeal cancer from head-and-neck cancer (HNC) patients. MATERIALS AND METHODS: The indigenously developed Python-based software was used in this study for generation and analysis. Twelve patients with forty-eight total plans with SIB were planned using Rapid arc (2 and 3 arcs) and IMRT (7 and 9 fields) and compared with radiobiological models Lyman, Kutcher, Burman (LKB) and EUD (Equivalent Uniform Dose) along with physical index such as homogeneity index(HI), conformity index(CI) of target volumes. RESULTS: These models' inputs are the dose-volume histograms (DVHs) calculated by the treatment planning system (TPS). The values obtained vary from one model to the other for the same technique and patient. The maximum dose to the brainstem and spinal cord and the mean dose to the parotids were analysed both dosimetrically and radiobiologically, such as the LKB model effective volume, equivalent uniform dose, EUD-based normal tissue complication probability, and normal tissue integral dose. The mean and max dose to target volume with conformity, homogeneity index, tumor control probability compared with treatment times, and monitor units. CONCLUSION: Rapid arc (3 arcs) resulted in significantly better OAR sparing, dose homogeneity, and conformity. The findings indicate that the rapid arc plan has improved dose distribution in the target volume compared with IMRT, but the tumor control probability obtained for the two planning methods, Rapid arc (3 arcs) and IMRT (7 fields), are similar. The treatment time and monitor units for the Rapid arc (3 arcs) were superior to other planning methods and considered to be standard in head & neck radiotherapy.

Evaluation of liver segmental dose threshold for hepatocyte regeneration following liver stereotactic body radiation therapy.

BACKGROUND OBJECTIVES: There is limited evidence studying the relationship of liver segmental dose and segmental volume changes. The segmental dose thresholds could potentially allow for segmental regeneration after liver stereotactic body radiation therapy (SBRT). Given improved survival in hepatocellular cancer (HCC) and liver metastases and more salvage therapy options, this has become an important clinical question to explore. This study assesses the impact of liver segmental dose on segmental volume changes (gain or loss) after SBRT. METHODS: Liver segmental contours were delineated on baseline and serial follow up triphasic computed tomography scans. The volumes of total liver and doses to total liver, uninvolved liver and individual segments were noted. A correlation was evaluated between liver/segmental volume and dose using Pearson's correlation. Furthermore, receiver operator's curve (ROC) analysis was performed to find the segmental dose, i.e . predictive for liver volume loss. RESULTS: A total of 140 non-tumour liver segments were available for analysis in 21 participants. Overall, 13 participants showed loss of overall liver volume and eight showed gain of overall liver volume. The median dose in segments reporting an increase in volume was 9.1 Gy (7-36 Gy). The median dose in segments losing volume was 15.5 Gy (1-49 Gy). On ROC analysis, segmental dose >11 Gy was associated with volume loss. On univariate analysis, only liver segmental dose contributed to a significant segmental volume loss. INTERPRETATION CONCLUSIONS: We propose from the findings of this study that in SBRT for large hepatocellular cancer or liver metastases, liver segments should be individually delineated. Furthermore, 3-5 liver segments may be preferentially subjected to <9 Gy to facilitate hepatocyte regeneration. Preferential sparing of uninvolved liver segments may improve outcomes in liver stereotaxyas lower segmental doses were associated with liver regeneration. This may have implications on future liver SBRT planning where segmental doses may be as important as the mean dose.

Validation of esophageal cancer treatment methods from 3D-CRT, IMRT, and Rapid Arc plans using custom Python software to compare radiobiological plans to normal tissue integral dosage.

Background: The aim was to develop in-house software that is able to calculate and generate the biological plan evaluation of the esophagus treatment plan using the Niemierko model for normal tissue complication probability and tumor control probability. The Niemierko model can be applied for esophagus cancer treatment plan to estimate the tumor control probability (TCP) and the normal tissue complication probability (NTCP) using different planning techniques. The equivalent uniform dose (EUD) and effective volume parameters were compared with organ at risk. Subsequently, EUD and TCP parameter were compared with tumor volume for all five different planning techniques. Materials and methods: Ten cases for esophageal cancer were included in this study. For each patient, five treatment plans were generated. The Anisotropic analytical algorithms (AAA) were used for dose calculation for the three-dimensional conformal radiation therapy (3D-CRT), intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) techniques. The in-house developed radiobiological plan evaluation software using python programming is used for this study which takes a dose volume histogram (DVH) text file as an input file for biological plan evaluation. Results and Conclusion: EUD, NTCP, TCP and effective volume were calculated from the Niemierko model using the in-house developed python based software and compared with treatment monitor units (MU) with all five different treatment plan. The best technique is quantified as benchmarked out of other different qualities of treatment. The four field 3D-CRT treatment plan is found to be the best suited from the perspective of biological plan index evaluation among the other planning techniques.

Closing the Cancer Care Gap in India.

Cancer burden in India is increasing. Cancer treatment today is multi-disciplinary requiring the coordination of many specialists for best outcomes. Bringing such expertise together to the district level is the greatest challenge for cancer care in any country, moreover in India. This article focuses on the step-wise journey to make comprehensive cancer care center in a small city.

Stereotactic body radio therapy for inoperable large hepatocellular cancers: results from a clinical audit.

OBJECTIVES: To evaluate the outcomes of stereotactic radiotherapy (SBRT) in the treatment of inoperable hepatocellular carcinomas (HCC) that are unsuitable for, or refractory to other liver-directed therapies. METHODS: Between March 2015 and June 2018, patients with primary HCCs refractory to or unsuitable for treatment with other liver-directed therapies were treated with SBRT. Patients of Child status A5-B7 and with normal liver reserve ≥ 700 cc were preferred. Local control (LC), overall survival (OS), progression free survival (PFS) and effect of prognostic factors were analysed. RESULTS: 21 patients with inoperable HCCs were treated. The median tumour diameter was 9.6 cm (5-21) and median tumour volume was 350 cc (32.9 - 2541). The median SBRT dose prescription was 42 Gy/6 fractions (25 - 54 Gy/6#). The 1- and 2-year LC rate was 88 and 43 % respectively. Overall rate of > grade III toxicity was 14 %. Patients with Child A5 liver function had a better median OS than A6 and B7 patients [21 vs 11 vs 8 months]. Also, tumours with GTV < 350 cc volumes had a better OS compared to GTV of greater than 350 cc [24 months vs 8 months, p value = 0.004]. CONCLUSIONS: This study showed that SBRT can be used safely and effectively to treat inoperable HCCs with or without prior loco-regional therapies, resulting in good local control and survival with acceptable toxicity. ADVANCES IN KNOWLEDGE: Use of SBRT in inoperable HCC is safe and effective.