학술논문
New strategy of a lung compensating technique with STR for total body irradiation
Document Type
Report
Source
Journal of Applied Clinical Medical Physics. October 2022, Vol. 23 Issue 10
Subject
Language
English
Abstract
INTRODUCTION Total body irradiation (TBI) is used before hematopoietic stem cell transplants for leukemia to restrain immunity and control tumors.[sup.1,2] Although the target volume of TBI is the whole body, [...]
: Purpose: To determine the thickness of a soft variable shape tungsten rubber (STR) as a lung compensating filter in total body irradiation. Methods: A tough water (TW) phantom and tough lung (TL) phantom were used as water and lung‐equivalent phantoms. The TW with a thickness of 3 cm simulating the thoracic wall was used (upper layer). The TW or TL with a thickness from 1 to 15 cm (1 cm increments) was placed beneath the upper layer (middle layer). The TW with a thickness of 5 cm simulating the mediastinum was placed beneath the middle layer (lower layer), and a farmer ionization chamber was placed beneath this layer. The relative doses of a 10 MV X‐rays were then measured. The TL was compensated in 1 mm increments from 1 to 11 mm of the STR, and the thickness of the STR at the same dose of TW (water equivalent) was obtained. Results: The compensating ability of STR increased as the thickness of the TL increased, and an STR with a thickness of 1 mm reduced the dose by 2%–4%, depending on the thickness of lung. The STR thickness as an equivalent dose of TW per cm of TL was approximately linear, and the thickness was 0.62 mm/cm of TL. Conclusion: The STR can be used as a lung compensating filter for a water equivalent dose with 0.62 mm of STR per cm of lung.
: Purpose: To determine the thickness of a soft variable shape tungsten rubber (STR) as a lung compensating filter in total body irradiation. Methods: A tough water (TW) phantom and tough lung (TL) phantom were used as water and lung‐equivalent phantoms. The TW with a thickness of 3 cm simulating the thoracic wall was used (upper layer). The TW or TL with a thickness from 1 to 15 cm (1 cm increments) was placed beneath the upper layer (middle layer). The TW with a thickness of 5 cm simulating the mediastinum was placed beneath the middle layer (lower layer), and a farmer ionization chamber was placed beneath this layer. The relative doses of a 10 MV X‐rays were then measured. The TL was compensated in 1 mm increments from 1 to 11 mm of the STR, and the thickness of the STR at the same dose of TW (water equivalent) was obtained. Results: The compensating ability of STR increased as the thickness of the TL increased, and an STR with a thickness of 1 mm reduced the dose by 2%–4%, depending on the thickness of lung. The STR thickness as an equivalent dose of TW per cm of TL was approximately linear, and the thickness was 0.62 mm/cm of TL. Conclusion: The STR can be used as a lung compensating filter for a water equivalent dose with 0.62 mm of STR per cm of lung.