Dosimetric Comparison of Helical Tomotherapy and HyperArc Treatment Plans for Angiosarcoma of the Scalp.

BACKGROUND/AIM: Angiosarcoma of the scalp (AS) is a rare tumor that has often been treated by total scalp irradiation (TSI). TSI has technical and dosimetric challenges. This study aimed to compare the dosimetric performance of helical tomotherapy (HT) plans with that of HyperArc (HA) plans for TSI in AS. PATIENTS AND METHODS: A planning study was conducted for 11 patients with AS (70 Gy/35 fr). HT and HA planning was performed using TomoHDA and TrueBeam Edge systems, respectively. The performance of three different plans were compared: HT, HA, and HA with half-field beams (HF-HA). The dose distribution and dosimetric parameters for each plan were evaluated. RESULTS: All constraint parameters for the target and organs at risk (OARs) met the goals within acceptable limits for the three techniques. The HA and HF-HA plans provided significantly lower mean brain dose (12.46±2.48 Gy and 8.02±1.48 Gy) than did the HT plan (17.59±3.47 Gy). The doses receiving 0.1 cc of the volume for brainstem and chiasm were significantly lower in the HA and HF-HA plans than those in the HT plan. The HA and HF-HA plans provided a shorter beam-on time (155±3 s and 181±14 s) than did the HT plan (962±221 s). CONCLUSION: The HA plan provided significantly better OARs sparing than the HT plan for TSI in AS and had an advantage to using half-field beams.

Low-Dose Volumetric Modulated Arc Therapy for a Patient With Head and Neck Involvement of Mycosis Fungoides: A Case Report With a Review of Literature.

Mycosis fungoides (MF) is the most common type of cutaneous T-cell lymphoma that slowly progresses over a period of years to decades. In some cases, lesions that spread to the scalp, neck, or facial skin can have a significant impact on cosmetic appearance and a patient's quality of life. Among the various treatments, radiation therapy is one of the most effective treatment modalities for patients with symptomatic cutaneous lesions. We report on an MF patient who had gradually increasing patches and plaques on the scalp, face, and neck and who underwent irradiation with 20 Gy administered in 10 fractions using volumetric modulated arc therapy. After undergoing this highly conformal technique, the patient obtained prolonged local control and significant alleviation of symptoms with acceptable adverse events. This technique constitutes a promising approach for treating a complex target due to its ability to provide homogeneous coverage of irregularly shaped target volumes along with its ability to preserve organs at risk. In addition, we systematically reviewed clinical reports on the management of extensive cutaneous lesions in MF patients undergoing other irradiation techniques.

Development of a transparent and flexible patient-specific bolus for total scalp irradiation.

A commercially available flat bolus (commercial bolus) would not fully fit the irregular surfaces of the scalp. We developed a transparent and flexible material with good fitting properties, analyzed its physical characteristics, and evaluated the clinical feasibility of the bolus fabricated using a three-dimensional (3D) printer (3D bolus). To evaluate the physical characteristics of the new material, treatment plans with virtual, 3D, and commercial boluses were created for water-equivalent phantoms using a radiation treatment planning system (RTPS). Using a head phantom and the dose volume histogram calculated with RTPS, dose distributions for total scalp irradiation were compared between the three treatment plans. To evaluate the clinical feasibility, the fitness and reproducibility of the 3D bolus were compared with the head phantom and clinical cases using dice similarity coefficient (DSC) measurements. A good agreement was observed between the percentage depth dose (PDD) curves for the virtual, 3D, and commercial boluses. The homogeneity indexes of the planning target volume (PTV) for the 3D and commercial boluses were 0.083 and 0.153, respectively, proving that the former achieved a better dose uniformity of PTV than the latter. Good fitness and reproducibility with the 3D bolus were observed in both the head phantom and two clinical cases, with mean DSC values of 0.854, 0.829, and 0.843, respectively. These results successfully demonstrated and verified the utility of the 3D bolus for total scalp irradiation.

Novel strategy with the automatic non-coplanar volumetric-modulated arc therapy for angiosarcoma of the scalp.

BACKGROUND: Total scalp irradiation presents technical and dosimetric challenges. While reports suggest that HyperArc, a new stereotactic radiosurgery planning technique applied to non-coplanar volumetric-modulated arc therapy (VMAT) technique, is associated with high conformity and rapid dose fall-off, the performance of HyperArc for total scalp irradiation has not been explored. The current study aimed to compare the dosimetric performance of HyperArc plans with those of non-coplanar VMAT plans in angiosarcoma of the scalp. METHODS: Ten patients with angiosarcoma of the scalp were included in this study. The performance of three different plans administered using TrueBeam Edge were compared: non-coplanar VMAT using flattening filter (FF) beams (VMAT-FF), HyperArc using FF beams (HyperArc-FF), and HyperArc using flattening filter free (FFF) beams (HyperArc-FFF). The dose distribution, dosimetric parameters, and dosimetric accuracy for each of these plans were evaluated. RESULTS: The three plans showed no statistically significant differences in target volume coverage, conformity, and homogeneity. The HyperArc-FF and HyperArc-FFF plans provided significantly lower mean brain doses (12.63 ± 3.31 Gy and 12.71 ± 3.40 Gy) than did the VMAT-FF plans (17.11 ± 5.25 Gy). There were almost no differences in sparing the organs at risk between the HyperArc-FF and HyperArc-FFF plans. The HyperArc-FF and HyperArc-FFF plans provided a shorter beam-on time than did the VMAT-FF plan. The 3%/2 mm gamma test pass rates were above 95% for all three plans. CONCLUSIONS: Our results suggest that the HyperArc plan can be potentially used for radiation therapy of target regions with large and complicated shapes, such as the scalp, and that there are no advantages of using FFF beams.

Proton Versus Intensity-Modulated Radiation Therapy: First Dosimetric Comparison for Total Scalp Irradiation.

PURPOSE: Total scalp irradiation (TSI) is used to treat malignancies of the scalp and face, including angiosarcomas, nonmelanoma skin cancers, and cutaneous lymphomas. Owing to the irregularity of the scalp contour and the presence of underlying critical organs at risk (OARs), radiation planning is challenging and technically difficult. To address these complexities, several different radiation therapy techniques have been used. These include the combined lateral photon-electron technique (3DRT), intensity-modulated radiation therapy (IMRT)/volumetric arc therapy (VMAT), helical tomotherapy (HT), and mold-based high-dose-rate brachytherapy (HDR BT). However, the use of proton radiation therapy (PRT) has never been documented. MATERIALS AND METHODS: A 71-year-old, immunosuppressed man presented with recurrent nonmelanoma skin cancer of the scalp. He was successfully treated at our center with PRT to deliver TSI. A comparative VMAT treatment plan was generated and dose to critical OARs was compared. RESULTS: We present the first clinical case report of PRT for TSI and dosimetric comparison to a VMAT plan. The PRT and VMAT plans provided equivalent target volume coverage; however, the PRT plan significantly reduced dose to the brain, hippocampi, and optical apparatus. CONCLUSION: TSI planned with PRT is relatively straightforward from a planning perspective and does not require a bolus. It also has the potential to decrease radiation therapy-related toxicity. However, PRT is relatively expensive and not universally available. The uncertainty surrounding the end-range of the proton beam is a consideration. Although there are potential disadvantages to using PRT for TSI, its use should be considered by treating radiation oncologists and referring physicians.

Development and validation of a 3D-printed bolus cap for total scalp irradiation.

PURPOSE: The goal of total scalp irradiation (TSI) is to deliver a uniform dose to the scalp, which requires the use of a bolus cap. Most current methods for fabricating bolus caps are laborious, yet still result in nonconformity and low reproducibility, which can lead to nonuniform irradiation of the scalp. We developed and validated patient-specific bolus caps for TSI using three-dimensional (3D) printing. METHODS AND MATERIALS: 3D-printing materials were radiologically analyzed to identify a material with properties suitable for use as a bolus cap. A Python script was developed within a commercial treatment planning system to automate the creation of a ready-to-print, patient-specific 3D bolus cap model. A bolus cap was printed for an anthropomorphic head phantom using a commercial vendor and a computed tomography simulation of the anthropomorphic head phantom and bolus cap was used to create a volumetric-modulated arc therapy TSI treatment plan. The planned treatment was delivered to the head phantom and dosimetric validation was performed using thermoluminescent dosimeters (TLD). The developed procedure was used to create a bolus cap for a clinical TSI patient, and in vivo TLD measurements were acquired for several fractions. RESULTS: Agilus-60 was validated as a new 3D-printing material suitable for use as bolus. A 3D-printed Agilus-60 bolus cap had excellent conformality to the phantom scalp, with a maximum air gap of 4 mm. TLD measurements showed that the bolus cap generated a uniform dose to the scalp within a 2.7% standard deviation, and the delivered doses agreed with calculated doses to within 2.4% on average. The patient bolus was conformal and the average difference between TLD measured and planned doses was 5.3%. CONCLUSIONS: We have developed a workflow to 3D-print highly conformal bolus caps for TSI and demonstrated these caps can reproducibly generate a uniform dose to the scalp.

Radiation Therapy for Angiosarcoma of the Scalp: Total Scalp Irradiation and Local Irradiation.

Angiosarcoma, a rare cutaneous malignancy, frequently arises in the scalp of older individuals. Because it characteristically initially mimics benign disease, such as a bruise, definitive diagnosis in the early stages is difficult. Angiosarcoma of the scalp is highly malignant and often accompanied by lung metastases that cause hemopneumothorax. Although surgery has been the standard and most reliable curative treatment for angiosarcoma of the scalp, there is a high probability of local recurrence, even after wide surgical excision. Therefore, postoperative radiation therapy has been administered in an attempt to minimize local recurrence. However, surgery is contraindicated in many older patients because of severe comorbidities or age. Definitive radiation therapy has been administered to such patients and has achieved good local control. In particular, total scalp irradiation may be a promising option for curative treatment of angiosarcoma of the scalp. Recent reports suggest that chemotherapy, particularly with taxanes, can prolong survival by reducing the rate of distant failure after radiation therapy. Thus, radiation therapy along with chemotherapy is now recommended for curative treatment of patients with inoperable disease and even some patients with operable disease. Technological developments in radiation therapy, such as intensity-modulated radiation therapy, will contribute to enhanced efficacy and reduced toxicities in the treatment of patients with angiosarcoma of the scalp.

Volumetric arc therapy for total scalp irradiation: case report for a recurrent basal cell carcinoma of the scalp.

Total scalp irradiation may be used to treat numerous conditions including squamous and basal cell carcinomas. These conditions are relatively uncommon and patients are frequently treated with palliative intent. In this report, we describe a volumetric arc therapy technique using photon beams for curative intent in an 84 years old patient with recurrent basal cell carcinoma of the scalp. Dose was 50Gy (2Gy per session) to the planning target volume (PTV) followed by a 10 Gy boost to the macroscopic disease on the forehead. A custom made 1 cm superflab bolus helmet was used. Toxicities only consisted of Grade-1 transient radiation dermatitis and alopecia. A sustained clinical response was observed at 6 months follow-up. Volumetric arc therapy (VMAT) may offer an effective alternative modality to treat patients with very extensive scalp lesions as described in this case report.

Dosimetric comparison of intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) in total scalp irradiation: a single institutional experience.

PURPOSE: Total scalp irradiation (TSI) is a rare but challenging indication. We previously reported that non-coplanar intensity-modulated radiotherapy (IMRT) was superior to coplanar IMRT in organ-at-risk (OAR) protection and target dose distribution. This consecutive treatment planning study compared IMRT with volumetric-modulated arc therapy (VMAT). MATERIALS AND METHODS: A retrospective treatment plan databank search was performed and 5 patient cases were randomly selected. Cranial imaging was restored from the initial planning computed tomography (CT) and target volumes and OAR were redelineated. For each patients, three treatment plans were calculated (coplanar/non-coplanar IMRT, VMAT; prescribed dose 50 Gy, single dose 2 Gy). Conformity, homogeneity and dose volume histograms were used for plan. RESULTS: VMAT featured the lowest monitor units and the sharpest dose gradient (1.6 Gy/mm). Planning target volume (PTV) coverage and homogeneity was better in VMAT (coverage, 0.95; homogeneity index [HI], 0.118) compared to IMRT (coverage, 0.94; HI, 0.119) but coplanar IMRT produced the most conformal plans (conformity index [CI], 0.43). Minimum PTV dose range was 66.8% -88.4% in coplanar, 77.5%-88.2% in non-coplanar IMRT and 82.8%-90.3% in VMAT. Mean dose to the brain, brain stem, optic system (maximum dose) and lenses were 18.6, 13.2, 9.1, and 5.2 Gy for VMAT, 21.9, 13.4, 14.5, and 6.3 Gy for non-coplanar and 22.8, 16.5, 11.5, and 5.9 Gy for coplanar IMRT. Maximum optic chiasm dose was 7.7, 8.4, and 11.1 Gy (non-coplanar IMRT, VMAT, and coplanar IMRT). CONCLUSION: Target coverage, homogeneity and OAR protection, was slightly superior in VMAT plans which also produced the sharpest dose gradient towards healthy tissue.

Dosimetric comparison of three different treatment modalities for total scalp irradiation: the conventional lateral photon-electron technique, helical tomotherapy, and volumetric-modulated arc therapy.

The aim of this study was to compare lateral photon-electron (LPE), helical tomotherapy (HT), and volumetric-modulated arc therapy (VMAT) plans for total scalp irradiation. We selected a single adult model case and compared the dosimetric results for the three plans. All plans mainly used 6-MV photon beams, and the prescription dose was 60 Gy in 30 fractions. First, we compared the LPE, HT and VMAT plans, with all plans including a 1-cm bolus. We also compared HT plans with and without the bolus. The conformity indices for LPE, HT and VMAT were 1.73, 1.35 and 1.49, respectively. The HT plan showed the best conformity and the LPE plan showed the worst. However, the plans had similar homogeneity indexes. The dose to the hippocampus was the highest in the VMAT plan, with a mean of 6.7 Gy, compared with 3.5 Gy in the LPE plan and 4.8 Gy in the HT plan. The doses to the optical structures were all within the clinically acceptable range. The beam-on time and monitor units were highest in the HT plan. The HT plans with and without a bolus showed similar target coverage and organ-at-risk (OAR) sparing. The HT plan showed the best target coverage and conformity, with low doses to the brain and hippocampus. This plan also had the advantage of not necessarily requiring a bolus. Although the VMAT plan showed better conformity than the LPE plan and acceptable OAR sparing, the dose to the hippocampus should be considered when high doses are prescribed.