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Sakai Y, Tanooka M, Okada W, Sano K, Nakamura K, Shibata M, Ueda Y, Mizuno H, Tanaka M. Characteristics of a bolus created using thermoplastic sheets for postmastectomy radiation therapy. Radiol Phys Technol 2021; 14:179-185. [PMID: 33837911 DOI: 10.1007/s12194-021-00618-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 03/19/2021] [Accepted: 04/06/2021] [Indexed: 10/21/2022]
Abstract
This study applied a "shell bolus," an immobilizing thermoplastic shell locally thickened with extra layers over the radiation target, during postmastectomy radiation therapy (PMRT). We performed ion chamber and film measurements for a solid water phantom for thermoplastic sheets and a gel bolus for dosimetric characterization using a 6-MV X-ray flattening-filter-free (FFF) beam. The air gaps between the body surface for the gel and shell bolus were measured using computed tomography (CT) images in patients who underwent PMRT. This included seven and 13 patients treated with the gel and shell boluses, respectively. A comparison of the dose differences between a 10-mm gel bolus and a 9.6-mm-thick thermoplastic sheet at the surface and 5 cm below the surface showed a 4.2% higher surface dose and 0.5% lower dose at 5-cm depth for the thermoplastic sheet compared to those for the gel bolus. The mean (p = 0.029) and maximum (p < 0.001) air gaps of the shell bolus were significantly thinner than those of the gel bolus. Thus, the shell bolus provided a close fit and robust bolus effect. In addition, the shell bolus reduced respiratory motion and eliminated the need for skin marking. Therefore, this system can be effectively used as a bolus for PMRT.
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Affiliation(s)
- Yusuke Sakai
- Radiation Therapy Center, Takarazuka City Hospital, 4-5-1 Kohama, Takarazuka, Hyogo, 665-0827, Japan.
| | - Masao Tanooka
- Radiation Therapy Center, Takarazuka City Hospital, 4-5-1 Kohama, Takarazuka, Hyogo, 665-0827, Japan
| | - Wataru Okada
- Radiation Therapy Center, Takarazuka City Hospital, 4-5-1 Kohama, Takarazuka, Hyogo, 665-0827, Japan
| | - Keisuke Sano
- Radiation Therapy Center, Takarazuka City Hospital, 4-5-1 Kohama, Takarazuka, Hyogo, 665-0827, Japan
| | - Kenji Nakamura
- Radiation Therapy Center, Takarazuka City Hospital, 4-5-1 Kohama, Takarazuka, Hyogo, 665-0827, Japan
| | - Mayuri Shibata
- Radiation Therapy Center, Takarazuka City Hospital, 4-5-1 Kohama, Takarazuka, Hyogo, 665-0827, Japan
| | - Yoshihiro Ueda
- Department of Radiation Oncology, Osaka International Cancer Institute, 3-1-69 Otemae, Chuo-ku, Osaka, 537-8567, Japan
| | - Hirokazu Mizuno
- Division of Central Radiology, Osaka Rosai Hospital, 1179-3 Nagasone-cho, Kita-ku, Sakai, Osaka, 591-8025, Japan
| | - Masahiro Tanaka
- Radiation Therapy Center, Takarazuka City Hospital, 4-5-1 Kohama, Takarazuka, Hyogo, 665-0827, Japan
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Evaluation of thermoplastic Klarity mask use during intensity-modulated radiation therapy for head and neck carcinoma. JOURNAL OF RADIOTHERAPY IN PRACTICE 2018. [DOI: 10.1017/s1460396917000632] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractAimTo evaluate the Klarity® Mask with respect to skin doses and toxicity secondary to head and neck cancer radiation treatment.Materials and methodsThis 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.ResultsThe 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.ConclusionsKlarity immobilisation mask increases skin doses, as a consequence, surface dose measurements should be monitored and must be taken into account.
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