The purpose of this study was to investigate variations in surface dose, with and without the use of a Klarity® Mask (Orfit Industries America, Wijnegem, Belgium), using intensity-modulated radiotherapy (IMRT) and 3-D conventional radiotherapy (3D-CRT).

Thermoluminescent dosimeters (TLDs) together with a phantom were used to examine acute skin toxicity during nasopharyngeal cancer treatment. These plans were sequentially delivered to the perspex phantom. Dosimeters were placed in five fixed regions over the skin. A Klarity mask for immobilization was used for covering the head, neck, and shoulder. The phantom was irradiated with and without a Klarity Mask, using IMRT and 3D-CRT, respectively.

The Klarity mask increased the skin doses for IMRT and 3D-CRT approximately 18·6% and 8·6%, respectively, from the prescribed maximum skin dose using treatment planning system (TPS). Additionally, the average percentage dose between IMRT and 3D-CRT received on the surface region was 30·9%, 24·9% with and without Klarity mask respectively. The average percentage dose received on surfaces from the total therapeutic dose 70 Gy, without using the mask was 7·7% and 5·7%, for IMRT and 3D-CRT, respectively. The TPS overestimated the skin dose for IMRT planning by 20%, and for 3D-CRT by 16·6%, compared with TLD measurements.

The results of this study revealed that IMRT significantly increases acute skin toxicity, compared with CRT. Although it is recommended to use Klarity mask as a sparing tool of normal tissue, it increases the risk of skin toxicity. In conclusion, skin dose is an important issue of focus during radiotherapy.

To evaluate the Klarity® Mask with respect to skin doses and toxicity secondary to head and neck cancer radiation treatment.

This prospective study included five nasopharyngeal cancer patients who underwent intensity-modulated radiation therapy and monitored for skin toxicity. An anatomical Perspex head and neck phantom was designed and used. All patients’ treatment plans were separately transferred to the phantom. Dosimetric measurements were performed using chip-shaped thermoluminescent dosimeters (LiF:Mg,Ti TLDs) which were distributed at certain target points on the phantom. Phantom was irradiated twicely with and without a Klarity® Mask. Three fractions for each patient plan were obtained and compared with treatment planning system (TPS) doses as guided by computed tomography.

The Klarity mask used for patient immobilisation increased the surface dose by 10·83% more than that without the mask. The average variations between skin dose measurements with and without the Klarity mask for all patients’ plans ranged from 10·26 to 11·83%. TPS overestimated the surface dose by 19·13% when compared with thermoluminescent dosimeters that measured the direct skin dose.

Klarity immobilisation mask increases skin doses, as a consequence, surface dose measurements should be monitored and must be taken into account.

Exposure of skin to high doses of radiation may lead to the development of erythematous skin changes. The aims of this study were to measure skin doses and to identify potential factors that may contribute to skin reactions in nasopharyngeal cancer patients undergoing intensity-modulated radiation therapy (IMRT).

This study was a prospective study with 21 nasopharyngeal cancer patients treated by IMRT. Personal data were collected and in vivo skin dose measurements were performed using Thermoluminescent dosimeters. All patients were monitored clinically and skin reactions were classified according to the Radiation Therapy Oncology Group criteria. Univariate and multivariate logistic regression was conducted using Statistical Package for Social Sciences Software to identify skin toxicity risk factors.

Grade 1 toxicity was observed in eight patients, Grade 2 in 11 patients and Grade 3 in two patients towards the end of treatment. It was found that accumulative skin doses >7 Gy (p<0·05) was a risk factor for skin toxicity. However, previous or concomitant chemotherapy with radiotherapy and stage of cancer were not significant factors for the severity of skin reactions.

The neck skin should be identified as a sensitive structure for dose optimisation. Skin dose measurement and skin-sparing techniques are highly recommended for head and neck patients treated with IMRT.