pmp Progress in Medical Physics Progress in Medical Physics 2508-4445 2508-4453 Korean Society of Medical Physics 10.14316/pmp.2017.28.2.39 pmp-28-39 Original Article Evaluation of Dosimetric Effect and Treatment Time by Plan Parameters for Endobronchial Brachytherapy ChoiChang Heon ∗ † ‡ § ParkJong Min ∗ † ‡ § ParkSo-Yeon ∗ † ‡ § KangSungHee ∗ † ‡ ChoJin Dong ∗ † KimJung-in ∗ † ‡ Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea Biomedical Research Institute, Seoul National University Hospital, Seoul, Korea Center for Convergence Research on Robotics, Advance Institutes of Convergence Technology, Suwon, Korea Corresponding author Jung-in Kim (madangin@gmail.com) Tel: 82-2-2072-3573 Fax: 82-2-765-3317 62017 1762017 282 3944 12062017 29062017 30062017 Copyright © 2017 Korean Society of Medical Physics 2017 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract

This study aims to analyze dose distribution and treatment time of endobronchial brachytherapy (EBBT) by changing the position step size of the dwell position. A solid water phantom and an intraluminal catheter were used in the treatment plan. The treatment plans were generated for 3, 5, 7, and 10 cm treatment lengths, respectively. For each treatment length, the source position step sizes were set as 2.5, 5, and 10 mm. Three reference points were set 1 cm away from the central axis of the catheter, along the axis, for uniform dose distribution. Volumetric dose distribution was calculated to evaluate the dosimetric effect. The total radiation delivery time and total dwell time were estimated for treatment efficiency, which were increased with position step sizes. At half-life time, the differences between the position step sizes in the total radiation delivery time were 18.1, 15.4, 18.0, and 24.0 s for 3, 5, 7, and 10 cm treatment lengths, respectively. The dose distributions were more homogenous by increasing the position step sizes. The dose difference of the reference point was less than 10%. In brachytherapy, this difference can be negligible. For EBBT, the treatment time is the key factor while considering the patient status. To reduce the total treatment time, EBBT can be performed with 2.5 mm position step size.

 Endobronchial Brachytherapy Treatment planning Position step size REFERENCES Donovan E Timotin E Farrell T Donde B Puksa S Sur R Endobronchial brachytherapy for metastasis from extrapulmonary malignancies as an effective treatment for palliation of symptoms Brachytherapy. 201716 6308 Nag S Abitbol AA Anderson LL Blasko JC Flores A Harrison LB Consensus guidelines for high dose rate remote brachytherapy in cervical, endometrial, and endobronchial tumors Int J Radiat Oncol Biol Phys. 199327 12414 Bedwinek J Petty A Bruton C Sofield J Lee L The use of high dose rate endobronchial brachytherapy to palliate symptomatic endobronchial recurrence of previously irradiated bronchogenic carcinoma Int J Radiat Oncol Biol Phys. 199222 2330 Kelly JF Delclos ME Morice RC Huaringa A Allen PK Komaki R High-dose-rate endobronchial brachytherapy effectively palliates symptoms due to airway tumors: the 10-year MD Anderson cancer center experience Int J Radiat Oncol Biol Phys. 200048 697702 Perol M Caliandro R Pommier P Malet C Montbarbon X Carrie C Curative irradiation of limited endobronchial carcinomas with high-dose rate brachytherapy: results of a pilot study Chest. 1997111 141723 Taulelle M Chauvet B Vincent P Felix-Faure C Buciarelli B Garcia R High dose rate endobronchial brachy–therapy: results and complications in 189 patients Eur Respir J. 199811 1628 Mendiondo OA Dillon M Beach LJ Endobronchial brac–hytherapy in the treatment of recurrent bronchogenic carcinoma Int J Radiat Oncol Biol Phys. 19839 57982 Huber RM Fischer R Haŭtmann H Pöllinger R Wendt T Müller-Wening D Palliative endobronchial brachytherapy for central lung tumors: a prospective, randomized comparison of two fractionation schedules Chest. 1995107 46370 Hennequin C Tredaniel J Chevret S Durdux C Dray M Manoux D Predictive factors for late toxicity after endobronchial brachytherapy: a multivariate analysis Int J Radiat Oncol Biol Phys. 199842 217 Langendijk H de Jong J Tjwa M Muller M ten Velde G Aaronson N External irradiation versus external irradiation plus endobronchial brachytherapy in inoperable non-small cell lung cancer: a prospective randomized study Radiother Oncol. 200158 25768 Murakami N Kobayashi K Nakamura S Wakita A Okamoto H Tsuchida K A total EQD2 greater than 85 Gy for trachea and main bronchus D2cc being associated with severe late complications after definitive endobronchial brachytherapy Journal of Contemporary Brachytherapy. 20168 164 Moon SY Jeong E Lim YK Chung WK Huh HD Kim DW Feasibility Study of Source Position Verification in HDR Brachytherapy Using Scintillating Fiber Prog Med Phys. 201627 2139 Delclos ME Komaki R Morice RC Allen PK Davis M Garden A Endobronchial brachytherapy with high-dose-rate remote afterloading for recurrent endobronchial lesions Radiology. 1996201 27982 Gustafson G Vicini F Freedman L Johnston E Edmundson G Sherman S High dose rate endobronchial bra–chytherapy in the management of primary and recurrent bronchogenic malignancies Cancer. 199575 234550 Hosni A Bezjak A Rink A Czarnecka K McPartlin A Patterson S High Dose Rate Brachytherapy as a Treatment Option in Endobronchial Tumors Lung Cancer Int. 20162016 3086148 Rogus RD Smith MJ Kubo HD An equation to QA check the total treatment time for single-catheter HDR brachytherapy Int J Radiat Oncol Biol Phys. 199840 2458 Wong T Wallace S Fernando W Schumer W Quong G Dose errors in the near field of an HDR brachytherapy stepping source Phys Med Biol. 199944 357 Nath R Anderson LL Luxton G Weaver KA Williamson JF Meigooni AS Dosimetry of interstitial brachytherapy sources: recommendations of the AAPM Radiation Therapy Committee Task Group No. 43 Med Phys. 199522 20934 Fonseca GP Viana RS Podesta M Rubo RA Sales CP Reniers B HDR 192Ir source speed measurements using a high speed video camera Med Phys. 201542 4125 Minamisawa R Rubo R Seraide R Rocha J Almeida A Direct measurement of instantaneous source speed for a HDR brachytherapy unit using an optical fiber based detector Med Phys. 201037 540711 Figures and Tables

Dose distribution in coronal view for each position step size and treatment length. (a-1): Position step size=2.5 mm, treatment length=3 cm; (a-2): position step size=5 mm, treatment length=3 cm; (a-3): position step size=10 mm, treatment length=3 cm; (b-1): position step size=2.5 mm, treatment length=5 cm; (b-2): position step size=5 mm, treatment length=5 cm; (b-3): position step size=10 mm, treatment length=5 cm; (c1): position step size=2.5 mm, treatment length=7 cm; (c-2): position step size=5 mm, treatment length=7 cm; (c-3): position step size=10 mm, treatment length=7 cm; (d-1): position step size=2.5 mm, treatment length=10 cm; (d-2): position step size=5 mm, treatment length=10 cm; (d-3): position step size=10 mm, treatment length=10 cm.

Dwell time and the number of active positions for various treatment lengths and position steps.

Treatment length (cm) Source position step (mm) Total dwell time (sec) Dwell time per Number of active
Planning Calibration Half life position (s) positions
3 2.5 118.3 75.9 151.8 9.1 13
  5 123.9 79.5 159.0 17.7 7
  10 133.2 85.5 171.0 33.3 4
5 2.5 172.2 110.5 221.1 8.2 21
  5 176 112.9 225.9 16.0 11
  10 184.8 118.6 237.2 30.8 6
7 2.5 226.2 145.2 290.4 7.8 29
  5 231 148.2 296.5 15.4 15
  10 238.4 153.0 306.1 29.8 8
10 2.5 311.6 200.0 400.0 7.6 41
  5 315 202.2 404.4 15.0 21
  10 319 204.7 409.5 29.0 11

Radiation delivery time and secondary time recoded on the treatment control system for various treatment lengths and positiosteps.

Treatment length (cm) Source position step (mm) Radiation time (s) Secondary
Planning Calibration Half life time (s)
3 2.5 120.9 77.6 155.2 131.4
  5 126.0 80.9 161.8 136.4
  10 135.0 86.7 173.3 141.6
5 2.5 176.4 113.2 226.5 186.8
  5 179.3 115.1 230.2 189.7
  10 188.4 121.0 241.9 198.8
7 2.5 229.2 147.1 294.3 239.4
  5 235.5 151.2 302.4 245.8
  10 243.2 156.1 312.3 253.5
10 2.5 315.8 202.7 405.5 326
  5 324.1 208.1 416.1 331.6
  10 334.5 214.7 429.5 334.8

Doses at three reference points for various treatment lengths and position steps.

Treatment length (cm) Source position step (mm) Reference point dose
Point 1 Point 2 Point 3
3 2.5 98.91 102.15 98.93
  5 99.11 101.76 99.13
  10 99.72 100.54 99.74
5 2.5 96.49 106.95 96.56
  5 97.02 105.88 97.09
  10 98.15 103.62 98.22
7 2.5 95.14 109.61 95.25
  5 95.81 108.28 95.91
  10 97.16 105.58 97.26
10 2.5 94.06 111.73 94.21
  5 94.80 110.25 94.94
  10 96.02 107.83 96.15