Squamous Cell Carcinoma of the Scalp After Radiotherapy for Tinea Capitis

Planning study of flattening filter free beams for volumetric modulated arc therapy in squamous cell carcinoma of the scalp

Purpose

Flattening filter free (FFF) beams show the potential for a higher dose rate and lower peripheral dose. We investigated the planning study of FFF beams with their role for volumetric modulated arc therapy (VMAT) in squamous cell carcinoma of the scalp.

Methods and Materials

One patient with squamous cell carcinoma which had involvement of entire scalp was subjected to VMAT using TrueBeam linear accelerator. As it was a rare skin malignancy, CT data of 7 patients with brain tumors were also included in this study, and their entire scalps were outlined as target volumes. Three VMAT plans were employed with RapidArc form: two half-field full-arcs VMAT using 6 MV standard beams (HFF-VMAT-FF), eight half-field quarter-arcs VMAT using 6 MV standard beams (HFQ-VMAT-FF), and HFQ-VMAT using FFF beams (HFQ-VMAT-FFF). Prescribed dose was 25×2 Gy (50 Gy). Plan quality and efficiency were assessed for all plans.

Results

There were no statistically significant differences among the three VMAT plans in target volume coverage, conformity, and homogeneity. For HFQ-VMAT-FF plans, there was a significant decrease by 12.6% in the mean dose to the brain compared with HFF-VMAT-FF. By the use of FFF beams, the mean dose to brain in HFQ-VMAT-FFF plans was further decreased by 7.4% compared with HFQ-VMAT-FF. Beam delivery times were similar for each technique.

Conclusions

The HFQ-VMAT-FF plans showed the superiority in dose distributions compared with HFF-VMAT-FF. HFQ-VMAT-FFF plans might provide further normal tissue sparing, particularly in the brain, showing their potential for radiation therapy in squamous cell carcinoma of the scalp.

Modern external beam radiation therapy for refractory dissecting cellulitis of the scalp

BACKGROUND

Dissecting cellulitis of the scalp can be an extremely painful and disfiguring dermatological condition. The associated pain can be severe enough in some cases to require opioid analgesics, and this pain in conjunction with the disfigurement can induce significant emotional distress. Conservative treatments often fail to provide relief. Radiation therapy has been successfully used in the past but with outdated equipment and techniques.

OBJECTIVES

To evaluate the efficacy and toxicity of modern external beam radiation therapy techniques for the treatment of dissecting cellulitis of the scalp.

METHODS

Four patients with intractable dissecting cellulitis of the scalp were treated with electrons or a combination of electrons and photons to the entire scalp. Daily fraction sizes were 2.5 or 3 Gy and initially prescribed to 15-21 Gy. Patients were re-evaluated 3-4 weeks after completion of therapy. Any residual hair growth was treated with additional radiation treatments to ensure full epilation, up to a maximum dose of 35 Gy.

RESULTS

Rapid resolution of pain was seen in all patients with pain. Regression of nodules and decreased discharge was seen in all patients following treatment and cosmesis was subjectively improved. No long-term toxicity has been observed.

CONCLUSIONS

Using modern techniques and equipment, radiation therapy appears to be a reasonable option for patients with severe/refractory dissecting cellulitis of the scalp. Acute effects are mild and well tolerated. Aside from alopecia, which was present to some extent in all patients before treatment, no long-term complications have been observed.