Aim: This study aims to compare conventional simultaneous integrated boost (SIB) planning technique with a hybrid SIB intensity-modulated radiation therapy (IMRT) technique with varying open tangent to IMRT field dose ratios. Furthermore, we investigated which of the dose ratios proves the most favourable as a class solution across a sample. Methods:In total, 15 patients with conventional SIB treatment plans were re-planned with hybrid SIB IMRT technique using three differing open field:IMRT dose ratios, that is, 80:20, 70:30 and 60:40. Plans were compared using dosimetric comparison of organs at risk (OARs) and homogeneity and conformity indexes across target structures.Results: All hybrid plans reduced dose maximums and showed a reduction of high doses to both lungs but increased lower doses, that is, V5, with similar results discovered for the heart. Contralateral breast dose was shown to decrease V5 and V1 measures by hybrid arms, whereas increasing the V2. Left anterior descending artery dose and non-irradiated structures were reduced by all hybrid arms. The homogeneity and conformity increased across all hybrid arms. Qualitative assessment of all plans also favoured hybrid plans.Findings: Hybrid plans produced superior dose conformity, homogeneity, reduced dose maximums and showed an improvement in most OAR parameters. The 70:30 hybrid technique exhibited greater benefits as a class solution to the sample than conventional plans due to superior dose conformity and homogeneity to target volumes.

Deep Inspiration Breath-Hold (DIBH) techniques for breast cancer radiation therapy (RT) have reduced cardiac dose compared to Free Breathing (FB). Recently, a voluntary deep inspiration breath-hold (vDIBH) technique was established using in-room lasers and skin tattoos to monitor breath-hold. An in-house quality assessment of positional reproducibility during RT delivery with vDIBH in patients with left-sided breast cancer was evaluated. The electronic portal imaging device (EPID) was used in cinematographic (CINE) mode to capture a sequence of images during beam delivery. Weekly CINE images were retrospectively assessed for 20 left-sided breast cancer patients receiving RT in vDIBH, and compared with CINE images of 20 patients treated in FB. The intra-beam motion was assessed and the distance from the beam central axis (CA) to the internal chest wall (ICW) was measured on each CINE image. These were then compared to the planned distance on digitally reconstructed radiograph (DRR). The maximum intra-beam motion for any one patient measurement was 0.30 cm for vDIBH and 0.20 cm for FB. The mean difference between the distance from the CA to ICW on DRR and the equivalent distance on CINE imaging (as treated) was 0.28 cm (SD 0.17) for vDIBH patients and 0.25 cm (SD 0.14) for FB patients (P = 0.458). The measured values were comparable for patients undergoing RT in vDIBH, and for those in FB. This quality assessment showed that using in-room lasers and skin tattoos to independently monitor breath-hold in vDIBH as detected by 'on-treatment' CINE imaging is safe and effective.

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Introduction: Irregular breathing motion exacerbates uncertainties throughout a course of radiation therapy. Breathing guidance has demonstrated to improve breathing motion consistency. This was the first clinical implementation of audiovisual biofeedback (AVB) breathing guidance over a course of liver stereotactic body radiotherapy (SBRT) investigating interfraction reproducibility. Methods: Five liver cancer patients underwent a screening procedure prior to CT sim during which patients underwent breathing conditions (i) AVB, or (ii) free breathing (FB). Whichever breathing condition was more regular was utilised for the patient's subsequent course of SBRT. Respiratory motion was obtained from the Varian respiratory position monitoring (RPM) system (Varian Medical Systems). Breathing motion reproducibility was assessed by the variance of displacement across 10 phase-based respiratory bins over each patient's course of SBRT. Results: The screening procedure yielded the decision to utilise AVB for three patients and FB for two patients. Over the course of SBRT, AVB significantly improved the relative interfraction motion by 32%, from 22% displacement difference for FB patients to 15% difference for AVB patients. Further to this, AVB facilitated sub-millimetre interfraction reproducibility for two AVB patients. Conclusion: There was significantly less interfraction motion with AVB than FB. These findings demonstrate that AVB is potentially a valuable tool in ensuring reproducible interfraction motion.