Light and shadows of a new technique: is photon total-skin irradiation using helical IMRT feasible, less complex and as toxic as the electrons one?

Abstract

BackgroundRadiotherapy is one of the standard treatments for cutaneous lymphoma and Total Skin Electrons Beam Irradiation (TSEBI) is generally used to treat diffuse cutaneous lymphoma and some cases of localized disease. Helical IMRT (HI) allows to treat complex target with optimal dose distribution and organ at risk sparing, so helical tomotherapy has been proposed as alternative technique to TSEBI but only one preliminary report has been published.MethodsThree patients treated (from May 2013 to December 2014) with Helical IMRT, with a total dose between 24 and 30 Gy, were retrospectively evaluated. Data about dosimetric features, response and acute toxicity were registered and analyzed.Planned target coverage was compared with daily in vivo measures and dose calculation based on volumetric images used for set up evaluation as well.ResultsThe patients had a mean measured surface fraction dose ranging from 1.5 Gy up to 2.0 Gy. A planned target dose ranging from 85 to 120% of prescription doses was obtained. All doses to Organs At Risk were within the required constraints. Particular attention was posed on “whole bone marrow” planned V10Gy, V12Gy and V20Gy values, ranging respectively between 23 and 43%, 20.1 and 38% and 9.8 and 24%. A comparison with the theoretical homologous values obtained with TSEBI has shown much lower values with TSEBI.Even if treatment was given in sequence to the skin of the upper and lower hemi-body, all the patients had anaemia, requiring blood transfusions, leukopenia and thrombocytopenia.ConclusionBased on our limited results TSEBI should still be considered the standard method to treat total skin because of its pattern of acute and late toxicities and the dose distribution. In this particular case the better target coverage obtained with HI can be paid in terms of worse toxicity. Helical IMRT can instead be considered optimal in treating large, convex, cutaneous areas where it is difficult to use multiple electrons fields in relation with the clinical results and the limited and reversible toxicities.

A Helical tomotherapy as a robust low‐dose treatment alternative for total skin irradiation

“…Similar to results reported by Buglione et al . we believe TSI with TT to be a complement to electron treatment and in certain cases where treatment with Tomotherapy could be beneficial.…”

“…The difference in the surface dose found for paired measurements with and without the neoprene bolus was significant, justifying the use of a virtual bolus as well as a physical bolus for total skin delivery, despite the fact that neoprene is not a standard material, and the lack of water equivalence in the material. The results quantify the difference with using neoprene as bolus and stands in contrast to other studies that did not find it necessary to use bolus for skin irradiation . The dosimetric advantage to a non‐bolus treatment is clear, any attempt at optimizing or deliver photons to the skin performs better with bolus added.…”

A case report of total skin photon radiation therapy for cutaneous epitheliotropic lymphoma in a dog

“…Hematological toxicity is uncommon with TSEBT because of the limited depth of penetration of the electrons and minimal photon contamination in the beam. Unexpected hematological toxicity has been reported in humans using a similar technique using a neoprene wetsuit [30, 31]. A Grade 3 hematological toxicity experienced in TSPT by our patient was unexpected but the grade is more than likely an intricate interplay between hematopoietic reserve (how heavily pretreated they were), technique refinement (more modular mold, better ventilation technique, etc.…”

Tomotherapy as an Alternative Irradiative Treatment for Complicated Keloids

“…By using central core complete block to restrict exposure to only obliquely incident photon beams, thereby increasing the superficial dose and reducing the internal organ dose, in the treatment of irregularly shaped cutaneous areas where it is difficult to use multiple electron fields, HT provides impressive uniformity, conformity, and dose distribution with limited damage to critical organs [ 14 , 34 , 35 ]. In the current study, the mean and maximum doses to critical organs were under 1.8 Gy in patients treated by the HT technique.…”

“…It makes electron beams obliquely incident onto the surface with bolus, which results in a decreased surface dose relative to an unbolused surface, but the photon beam does not [ 14 ]. The surface dose delivered by HT for the total skin reportedly ranges from 85% to 150% of the prescribed dose [ 14 , 34 , 35 ]. In the current study, the surface dose delivered to lesions measured by EBT3 film exposure ranged from 103.7% to 112.5% of the prescribed dose in HT.…”