Few studies claimed that dynamic jaw (DJ) mode in Helical TomoTherapy® (HT) could improve the cranio-caudal dose distribution without prolonging the treatment time in treating different types of cancer. Also, studies suggested that DJ with a wider 5 cm field width (FW) could replace fixed jaws (FJ) with 2.5 cm FW to reduce the delivery time with the sustainable plan quality. Yet, the study on breast cancer with supraclavicular fossa (SCF) nodal involvement using DJ mode in HT is limited. This study aims to evaluate the DJ mode retrospectively by comparing their dosimetric quality with normal tissue complication probability (NTCP) of organs at risk and treatment delivery time with FJ mode on treating left-side breast with SCF nodal involvement.

All post-mastectomy patients, who had been irradiated for left-side breast with SCF nodal involvement were selected retrospectively in this study. With the same dose constraint and prescription as the treated DJ2.5 plan, two extra plans using DJ mode with 5 cm FW(DJ5.0) and FJ mode with 2.5 cm FW (FJ2.5) were computed for plan comparison.

No statistical significance was found in all the parameters of PTV and OARs, except for V20 of whole lung. DJ5.0 received V20 in ipsilateral left lung than FJ2.5 and DJ2.5. However, the average delivery time of DJ5.0 was significantly lower than that of DJ2.5 and FJ2.5 by almost 40%.

No statistical significance was found in those dosimetric and radiobiological parameters among three modes while the delivery time has greatly reduced by using DJ5.0. A shorter treatment time can minimise intra-fractional error and better the patient’s experience during treatment.

To evaluate the efficacy of concurrent chemotherapy and high-dose (≥55 Gy) intensity-modulated radiotherapy (CCIMRT) in comparison with chemotherapy alone and intensity-modulated radiotherapy (IMRT) alone for unresectable locally advanced or metastatic pancreatic cancer.

Forty-six patients with pancreatic cancer undergoing CCIMRT (n = 17), chemotherapy alone (n = 16) or IMRT alone (n = 13) were analysed. Overall survival (OS), locoregional progression-free survival (LRPFS) and gastrointestinal toxicities were evaluated. The median radiation dose was 60 Gy (range, 55–60) delivered in a median of 25 fractions (range, 24–30). Gemcitabine (GEM) alone, GEM + S-1, S-1 alone, FOLFIRINOX and GEM + nab-paclitaxel were used in CCIMRT and chemo-monotherapy.

The 1-year OS rate was 69% in the CCIMRT group, 27% in the chemotherapy group and 38% in the IMRT group (p = 0·12). The 1-year LRPFS rate was 73, 0 and 40% in the 3 groups, respectively (p = 0·012). Acute Grade ≥ 2 gastrointestinal toxicity (nausea, diarrhea) was observed in 12% (2/17) in the CCIMRT group, 25% (4/16) in the chemotherapy group and 7·7% (1/13) in the IMRT group (p = 0·38). Late Grade 3 gastrointestinal bleeding was observed in 6·3% (1/16) in the chemotherapy group.

High-dose CCIMRT yielded acceptable toxicity and favorable OS and LRPFS.

To modify the final dose delivered to superficial tissues and to modulate dose distribution near irradiated surface, different boluses are used. Air gaps often form under the bolus affecting dose distribution. This study aimed to evaluate the effect of an air gap under the bolus radiation on dose delivery.

To evaluate the impact of the air gap, both helical tomotherapy (HT) and direct tomotherapy (DT) were performed in a simulation study.

The maximum dose to bolus in DT plans was bigger than that used in HT plans. The maximum dose delivered to the bolus depended on the air gap size. However, the maximum dose to bolus in all HT plans was within the acceptable value range. Acceptable value was set to up to 107% of the prescription dose. In the simulation performed in this study, the acceptable air gap under bolus was up to 15 mm and below 5 mm in HT and DT plans, respectively.

HT technique is a good choice, but DT technique can be also used if the bolus position can be reproduced accurately. Thus, the reproducibility of the bolus position between planning and treatment is very important.

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.

This is a phantom study to evaluate the dosimetry effects of using virtual bolus (VB) in TomoTherapy Treatment Planning System (TPS) optimisation for superficial planning target volume (PTV) that extends to the body surface. Without VB, the inverse-planning TPS will continuously boost the photon fluence at the surface of the superficial PTV due to lack of build-up region. VB is used during TPS optimisation only and will not be present in actual treatment delivery.

In this study, a dummy planning target was contoured on a cylindrical phantom which extends to the phantom surface, and VB of various combinations of thickness and density was used in treatment planning optimisation with TomoTherapy TPS. The plans were then delivered with the treatment modality TomoTherapy. Radiochromic films (Gafchromic EBT3) were calibrated and used for dose profiles measurements. TomoTherapy Planned-Adaptive software was used to analyse the delivered Dose-Volume Histograms (DVHs).

The use of 2 mm VB was not providing adequate build-up area and was unable to reduce the hot spots during treatment planning and actual delivery. The use of 4 mm VB was able to negate the photon fluence boosting effect by the TPS, and the actual delivery showed relatively small deviations from the treatment plan. The use of 6 mm VB caused significant dose overestimation by the TPS in the superficial regions resulting in insufficient dose coverage delivered.

VB with the combination of 4 mm thickness and 1·0 g/cc density provides the most robust solution for the TomoTherapy TPS optimisation of superficial PTV.

Re-planning mid-treatment, with the adjustment of target volumes, has been performed as part of the normal workflow at our institution. We sought to quantify the benefit of this approach and identify factors to optimise plan adaptive strategies.

Patients with locally advanced oropharyngeal cancer treated to 70 Gy with concurrent chemoradiation (CCRT) on TomoTherapy® who underwent re-planning during the treatment were eligible. Survival and prognostic factors were evaluated with Kaplan–Meier and Cox proportional hazards, two-side p-value <0·05 significant.

Forty-two patients were identified with Stage III (n = 5), IVA (n = 34) and IVB (n = 3) [AJCC 7th] disease. Median re-planning dose was 40 Gy (14–60 Gy). Median change in mean total parotid dose was reduction of 1 Gy (range –7·5 Gy to +13·9 Gy). The volume of PTV70 and PTV60 receiving 99% of the prescribed (V99) dose was increased by 2·2% (–3·3 to +16·6%) and 1·9% (–11·5 to +12·6%) by re-planning. As a continuous variable, increasing per cent nodal regression was associated with the improved disease control in a multivariate model including stage, pack years smoking and human papilloma viral (HPV) status (HR: 0·85, 0·71–0·99, p = 0·05).

Adaptive planning generates a superior plan for the majority of patients, but there is modest overall parotid gland sparing.

The aim of this study is to compare three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT) and tomotherapy techniques used in the treatment of prostate cancer with target and critical organ doses to be included.

The target dose was studied with 4-and 6-field 3D-CRT, 7-field IMRT and tomotherapy techniques used to treat ten patients for prostate cancer and the dose volume histograms of critical organs were analyzed. The same target volumes, critical organs doses prescribed and treatment times for the three techniques were compared. Total dose of 76 Gy was given using 6 MV and 18 MV for 3D-CRT, 6 MV for IMRT and tomotherapy techniques.

When we compare the three techniques, for rectum V35(p:0·001), V65(p:0·001), D50(p:0·020) and D25(p:0·002), for bladder V50(p:0·027), V65(p:0·006), V100(p:0·006) and for femoral head, the V50(p:0·001) dose was found to be significantly different and more favourable in the tomotherapy technique. Significant differences were found with IMRT planning in 50% of bladder volume (p:0·002). There is no significant difference between the three techniques for doses of 100% volume of rectum and 25% of volume of bladder. The minimum dose that healthy tissue received which was outside the tumour volume was investigated.

Doses to critical organs were lower using the tomotherapy technique. However, the minimum doses that healthy tissue received were higher for the tomotherapy technique. When the beam on times were compared for all three techniques, a significant difference was found in favor of tomotherapy.

The purpose of this study was to investigate whether significant difference exists on radiation dose delivered to organs at risks in megavoltage computed tomography (MVCT) verification using three predefined scanning modes, namely fine (2 mm), normal (4 mm) and coarse (6 mm). This will provide information for the imaging protocol of tomotherapy for the left breast.

Organ doses were measured using thermoluminescent dosimeters (TLD-100) placed within a female Rando phantom for MVCT imaging. Kruskal–Wallis test was conducted with p<0·05 to evaluate the significant difference between the three MVCT scanning modes.

Statistically significant difference existed in organ absorbed dose between different scan mode selections (p<0·001). Relative to the normal scan selection (4 mm), the absorbed dose to the organs of interests can be scaled down by 0·7 and scaled up by 2·1 for coarse (6 mm) and fine scans (2 mm) respectively.

Optimisation of imaging protocols is of paramount importance to keep the radiation exposure ‘as low as reasonably achievable’. The recommendation of undergoing daily coarse mode for MVCT verification in breast tomotherapy not only mitigates the radiation exposure to normal tissues, but also trims the scan-acquisition time.

The purpose of this study was to dosimetrically compare TomoDirect, TomoHelical and linear accelerator-based 3D-conformal radiotherapy (Linac-3DCRT) for craniospinal irradiation (CSI) in the treatment of medulloblastoma.

Five CSI patients were replanned with Linac-3DCRT, TomoHelical, TomoDirect-3DCRT and TomoDirect-intensity-modulated radiotherapy (IMRT). Dose of 36 Gy in 20 fractions was prescribed to the planning target volume (PTV). Homogeneity index (HI), non-target integral dose (NTID), dose–volume histograms, organs-at-risk (OARs) Dmax, Dmean and treatment times were compared.

TomoHelical achieved the best PTV homogeneity compared with Linac-3DCRT, TomoDirect-3DCRT and TomoDirect-IMRT (HI of 3·6 versus 20·9, 8·7 and 9·4%, respectively). TomoDirect-IMRT achieved the lowest NTID compared with TomoDirect-3DCRT, TomoHelical and Linac-3DCRT (141 J versus 151 J, 181 J and 250 J), indicating least biological damage to normal tissues. TomoHelical plans achieved the lowest Dmax in all organs except the breasts, and lowest Dmean for most OARs, except in laterally situated OARs, where TomoDirect triumphed. Beam-on time was longest for TomoHelical, followed by TomoDirect and Linac-3DCRT.

TomoDirect has the potential to lower NTID and shorten treatment times compared with TomoHelical. It reduces PTV inhomogeneity and better spares OARs compared with Linac-3DCRT. Therefore, TomoDirect may be a CSI treatment alternative to TomoHelical and in place of Linac-3DCRT.

The aim of this study was to compare the dosimetric parameters and effects of simultaneous integrated boost (SIB) and traditional sequential electron boost, after helical tomotherapy, because of the lack of studies in this field in the current literature.

Computed tomographic data of 14 patients who received SIB in 2012–2015 were collected from Hong Kong Sanatorium & Hospital. New tomotherapy with SIB plans and tomotherapy with sequential boost plans were generated for each patient, and results were compared.

Conformation number, mean dose, dose received by 95% volume (both sides), ipsilateral lung volume receiving 20 Gy (V20) and skin dose (right side) were found to be significantly better for SIB (p<0·05), however coverage index and gross target volume dose showed no significant difference, and heart dose was significantly higher for SIB on the right side.

Tomotherapy with SIB may be able to offer less organ at risk dose (except for the heart), while maintaining the ability to deliver adequate dose coverage.

Desmoid tumour is a rare neoplasm occurring intra- and extra-abdominally.

In this study, a lower extremity desmoid tumour located close to the ovaries was irradiated with tomotherapy after surgery in a 16-year-old female patient. 30 fractions defined for delivery of 54 Gy were administered to the patient.

The planning target volume and organs at risk doses were evaluated and the ovary doses were discussed for fertility.

The patient tolerated the radiotherapy well. During radiotherapy, only grade 1 skin toxicity occurred.