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BackroundRadiotherapy techniques have evolved rapidly over the last decade with the introduction of Intensity Modulated RadioTherapy (IMRT) in different forms. It is not clear which of the IMRT techniques is superior in the treatment of head and neck cancer patients in terms of coverage of the planning target volumes (PTVs), sparing the organs at risk (OARs), dose to the normal tissue, number of monitor units needed and delivery time.The present paper aims to compare Step and Shoot (SS) IMRT, Sliding Window (SW) IMRT, RapidArc (RA) planned with Eclipse, Elekta VMAT planned with SmartArc (SA) and helical TomoHDTM (HT).MethodsTarget volumes and organs at risk (OARs) of five patients with oropharyngeal cancer were delineated on contrast enhanced CT-scans, then treatment plans were generated on five different IMRT systems. In 32 fractions, 69.12 Gy and 56 Gy were planned to the therapeutic and prophylactic PTVs, respectively. For the PTVs and 26 OARs ICRU 83 reporting guidelines were followed. Differences in the studied parameters between treatment planning systems were analysed using repeated measures ANOVA.ResultsMean Homogeneity Index of PTVtherapeutic is better with HT(.06) followed by SA(.08), RA(.10), SW(.10) and SS(.11). PTVprophylactic is most homogeneous with RA. Parotid glands prescribed mean doses are only obtained by SA and HT, 20.6 Gy and 21.7 Gy for the contralateral and 25.6 Gy and 24.1 Gy for the ipsilateral, against 25.6 Gy and 32.0 Gy for RA, 26.4 Gy and 34.6 Gy for SW, and 28.2 Gy and 34.0 Gy for SS. RA uses the least monitor units, HT the most. Treatment times are 3.05 min for RA, and 5.9 min for SA and HT.ConclusionsIn the treatment of oropharyngeal cancer, we consider rotational IMRT techniques preferable to fixed gantry techniques due to faster fraction delivery and better sparing of OARs without a higher integral dose. TomoHD gives most homogeneous target coverage with more sparing of spinal cord, brainstem, parotids and the lower swallowing apparatus than most of the other systems. Between RA and SA, SA gives a more homogeneous PTVtherapeutic while sparing the parotids more, but the delivery of RA is twice as fast with less overdose to the PTVelective.

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A decade after its first introduction into the clinic, little is known about the clinical impact of helical tomotherapy (HT) on head and neck cancer (HNC) treatment. Therefore, we analyzed the basics of this technique and reviewed the literature regarding HT's potential benefit in HNC. The past two decades have been characterized by a huge technological evolution in photon beam radiotherapy (RT). In HNC, static beam intensitymodulated radiotherapy (IMRT) has shown superiority over three-dimensional conformal RT in terms of xerostomia and is considered the standard of care. However, the next-generation IMRT, the rotational IMRT, has been introduced into the clinic without any evidence of superiority over static beam IMRT other than being substantially faster. Of these rotational techniques, HT is the first system especially developed for IMRT in combination with image-guided RT. HT is particularly promising for the treatment of HNC because its sharp dose gradients maximally spare the many radiosensitive organs at risk nearby. In addition, HT's integrated computed tomography scan assures a very precise dose administration and allows for some adaptive RT. Because HT is specifically developed for IMRT in combination with (integrated) imageguidance, it allows for precise dose distribution ("dose painting"), patient setup, and dose delivery. As such, it is an excellent tool for difficult HNC irradiation. The literature on the clinical results of HT in HNC all show excellent short-term (Յ2 years) results with acceptable toxicity profiles. However, properly designed trials are still warranted to further substantiate these results. The Oncologist 2013;18:697-706 Implications for Practice: This article highlights the advantages of helical tomotherapy in the treatment of head and neck cancer as it combines three recent evolutions and challenges in radiotherapy in an integrated system. (1) A rotational IMRT technique that is very efficient in generating homogeneous dose distributions to the target volume while sparing the organs at risk more precisely than conventional IMRT approaches. (2) Three-dimensional image guidance permits a more precise administration of the radiation than the classical two-dimensional imaging. This allows for reduction of the safety margins, which in turn, reduces toxicity. (3) Adaptive radiotherapy is still very labor intensive and no software is able to provide daily online adaptation. Tomotherapy offers a platform that allows for pioneering attempts at adaptive radiotherapy with the possibility of recalculating the administered treatment based on the daily CT scan. Properly designed trials are still warranted to further substantiate the results of this promising treatment modality. INTRODUCTIONDespite major progress in locoregional control, the treatment outcomes of locoregionally advanced head and neck cancer (HNC) remain poor, with a 5-year survival rate of approximately 35% due to the development of distant metastases, locoregional failures, second primaries, and/or comorbidities [1][...

Following the TG-148 report, beam output measurements in water at the reference depth using a local protocol, as developed at different centers, was verified. The measurements were found in good agreement with alanine∕EPR dosimetry. The presented methodology may provide a good concept for reference dosimetry.