The normal tissue objective (NTO) is a tool used in inverse-planned intensity-modulated radiation therapy (IMRT) to minimize dose dispersion to surrounding tissues. The current study focuses on the NTO’s impact on RapidArc treatment plans for cervical cancer patients or its role in reducing doses to healthy surrounding tissues.

This study included 11 cervical cancer patients who underwent RapidArc treatment. We assessed plans both with and without the NTO objective by evaluating parameters such as homogeneity, conformity, gradient index (GI), IMRT factor, integral dose and the volume of normal tissues receiving low doses of 40, 30, 20 and 10 Gy. Further, differences between automatic NTO and manual NTO were evaluated using Wilcoxon signed-rank test.

There were no significant differences in the conformity index, homogeneity index, IMRT factor and integral dose between plans with automatic NTO and those with manual NTO RapidArc plans. However, we did observe a clear advantage in using manual NTO for controlling low-dose exposure to normal tissues. The comparisons between automatic and manual NTO resulted in a GI of 3·1 ± 0·3 versus 2·7 ± 0·68 (p = 0·008). Furthermore, we noticed a significant reduction in the volumes receiving low doses (V10, V20, V30 and V40) with the manual NTO settings.

The NTO plays a crucial role in optimizing RapidArc plans for treating cervical cancer. Based on the findings of this study, manual NTO settings of distance from PTV border xstart = 0·5 mm, start dose f0 = 105%, end dose f∞ = an average of 40%, dose fall-off 0·2 mm–1 were optimal. Further research involving a larger sample size and exploration of various NTO parameters is necessary to validate our results.

Haematological toxicities are seen in rectal cancer patients receiving concurrent chemoradiotherapy (CRT) with capecitabine.

To compare dose volume histogram (DVH) parameters and acute haematological toxicities using RapidArc with or without bone marrow constraints for rectal cancer patients receiving pelvic chemoradiation as part of curative treatment.

This is a prospective randomised controlled study including patients with rectal cancer initiated on chemoradiation. Patients were stratified into two arms, bone marrow sparing (BMS) arm and non-bone marrow sparing arm (NBMS).

DVH parameters and weekly toxicity data were collected. Grade 2 or more anaemia, leucopenia, neutropenia, or thrombocytopenia, any blood transfusions, colony-stimulating factor injection, platelet transfusions were considered as an event in acute haematological toxicity (HT).

Independent t-test was used to compare quantitative parameters, and Mann–Whitney U-test was used for ordinal parameters between groups.

A total of 43 patients were enrolled. Bone marrow constraints were achieved without compromising the target coverage. There was a significant reduction in the bone marrow dose with BMS technique (p < 0·05). A 16·7% reduction in the HT (33·3% versus 50%) and a 21·9% reduction in the grade 2 or more anaemia (19% versus 40·9%) were noted in the BMS arm when compared to NBMS arm, though not statistically significant. However, in the preoperative setting, a significant reduction in grade 2/more anaemia (7·1% versus 41·1%, p = 0·035) was noticed in the BMS arm.

Pelvic BMS radiotherapy may benefit patients receiving chemoradiation for locally advanced carcinoma rectum as part of curative treatment.

To report a single-institution experience of intensity-modulated radiotherapy (IMRT) and RapidArc treatment plans for the patients treated with low grade mucoepidermoid carcinoma (MEC) of the salivary gland while sparing the organs at risk (OARs) within tolerance limits.

Twenty-five patients with MEC were selected to develop and analyse the treatment plans using both of the techniques. Dose distributions were calculated using Eclipse treatment planning system (Varian Medical Systems, Palo Alto, CA). Plans were generated to deliver the dose of 6000 cGy in 30 fractions. For IMRT, seven angle plans were used and for RapidArc, two half arcs were used with the same 6 MV photon beam. Quality of treatment plans was evaluated by using parameters such as, coverage, conformity index (CI), homogeneity index (HI), gradient index (GI), unified dosimetry index (UDI), dose volume histogram, delivery time and OARs sparing for IMRT and RapidArc plans.

The analysis revealed that IMRT and RapidArc coverages are 0·90 and 0·94, respectively; CIs are 1·15 and 1·10, respectively; HIs are 1·12 and 1·07, respectively; GIs are 0·94 and 0·98, respectively. Average UDI values for RapidArc and IMRT are 1·09 and 1·11, respectively. Integral dose comparison shows better OAR sparing for RapidArc. RapidArc plans have the shorter beam on time (45%) in comparison with IMRT plans.

Planning constraints were achieved in both techniques. However, RapidArc showed better quality treatment plan, OARs sparing and shorter delivery time as compared to IMRT.

Comparison of the integral dose (ID) delivered to organs at risk (OAR), non-target body and target body by using different techniques of craniospinal irradiation (CSI).

Ten CSI patients (medulloblastoma) already planned and treated either with linear accelerator three-dimensional conformal radiation therapy (Linac-3DCRT) technique or with linear accelerator RapidArc (Linac-RapidArc) technique by Novalis-Tx Linac machine have been analysed. Retrospectively, these patients are again planned on Radixact-X9 Linac with Helical, Direct-3DCRT and Direct-intensity-modulated radiation therapy (Direct-IMRT) techniques. The dose prescription to planning target volume brain (PTV-Brain) and PTV-Spine is 36 Gy in 20 fractions and is kept the same for all techniques. The target body, non-target body, OARs and total body dose are compared.

ID is lowest in the RapidArc plan for every patient in comparison to Helical and Direct-IMRT. The ID for Body-PTV was found slightly higher in the RapidArc plan in comparison to 3DCRT plans. But there is better normal tissue sparing for most of the OARs in RapidArc plans if it compares with 3DCRT plans.

RapidArc is a better alternative for the treatment of CSI. It provides better target coverage and better OARs sparing from any other treatment techniques.

To compare the dosimetric results regarding the sparing effect on normal tissue between RapidArc (RA) and helical tomotherapy (HT) plans for nasopharyngeal carcinoma (NPC) patients in cases of the equal target dose controls utilising two techniques.

Thirteen NPC patients treated with HT were replanned using the Varian Eclipse treatment planning system (TPS) for the RA plan. The target dose of the RA plan was optimised equally to the HT plan in terms of target coverage, dose conformity (CI) and dose homogeneity (HI) for assessing the normal tissue sparing between two techniques. All dose–volume parameters monitor units (MUs) and delivery time were also investigated.

All dosimetric parameter comparisons of organs-at-risk (OARs) between the RA and HT plans were not significantly different for brain stem, spinal cord and cochlea. However, the RA plan showed a significantly lower dose to the left parotid gland. The mean and median dose were significantly lower in the RA plan versus the HT plan by p-value 0·005 and 0·039, respectively. The MUs and delivery time were also significantly lower in the RA plan with a p-value of 0·00.

With the same planning target volume coverage, homogeneity and conformity, almost all of RA and HT treatment planning met the planning goal for normal tissue sparing. There were no significant differences between the two techniques except in the left parotid gland. The RA plans were superior to HT plans by effectively reducing the MUs and treatment time.

Radiation therapy (RT) remains a common and effective treatment modality for patients with locally advanced prostate cancer. Technological advancements over the past decade have resulted in the introduction of intensity-modulated radiation therapy (IMRT) planning and delivery techniques that maximise the dose of radiation delivered to the prostate while sparing organs at risk (OAR). A more recent and evolving IMRT technique, called volumetric-modulated arc therapy (VMAT), involves a continuous irradiation at a constant or variable dose rate when the gantry rotates around the prostate using one or more arcs.

This paper reports on a dosimetric evaluation of our implementation of VMAT technique for prostate cancer treatment. A retrospective analysis of VMAT plans was performed for 300 prostate cancer patients treated during the period of January 2013 to December 2014. Two prescription cohorts of patients treated to a dose of 78 Gy in 39 fractions as the primary radiation therapy treatment (XRT) and 66 Gy in 33 fractions as a post-op or salvage XRT were considered.

The mean and maximal doses, dose inhomogeneities and conformity indexes for the planning target volumes were evaluated for each prescription cohort of patients. Similarly, the doses to OAR such as rectum, bladder and femoral heads were also assessed for various dose levels.

This study shows that highly conformal radiation dose distribution for the treatment of prostate cancer is achievable with the VMAT technique. It provides evidence to support the adoption of such conformal technology in many disease sites such as the prostate. We believe that our experience reported here could help form the foundation for individual institutions to evaluate and develop the most suitable planning criteria tailored to their own needs and priority. This endeavour hopefully will provide further improvement in the planning process and, therefore, help achieve an effective and efficient delivery of radiotherapy for prostate cancer.

This study compared the acute toxicities reported during radiotherapy treatment using either intensity-modulated radiation therapy (IMRT) or volumetric-modulated arc therapy (VMAT) to deliver a moderate hypo-fractionated treatment for early-stage prostate cancer.

Acute toxicities are routinely reported at the clinical site for all patients using the Common Terminology Criteria for Adverse Events. Toxicity assessment is performed on day 1 of treatment, then once weekly thereafter. The recorded toxicities of 40 cases treated with five-field IMRT, and 32 cases treated using VMAT were retrospectively compared. All cases were prescribed 73·68 Gy in 28 fractions. Eight symptoms were assessed; diarrhoea, proctitis, fatigue, pain, dermatitis, urinary frequency, urinary retention and urinary tract pain.

In terms of the overall toxicity recorded, VMAT was shown to reduce the toxicities of dermatitis, fatigue, pain and urinary frequency (p<0·05). Using IMRT, grade 2 toxicities were reported for proctitis, pain, urinary frequency, urinary retention and urinary tract pain. Using VMAT, grade 2 toxicities were reported for urinary frequency and urinary retention.

The research reported here is one of the first publications to demonstrate that VMAT is associated with decreased toxicities compared with IMRT for the treatment of early-stage prostate cancer.