scholarly journals Dose compensation based on biological effectiveness due to interruption time for photon radiation therapy

2020 ◽  
Vol 93 (1111) ◽  
pp. 20200125 ◽  
Author(s):  
Daisuke Kawahara ◽  
Hisashi Nakano ◽  
Akito Saito ◽  
Shuichi Ozawa ◽  
Yasushi Nagata
Keyword(s):  
Radiation Therapy ◽  
Dose Rate ◽  
Salivary Gland Tumor ◽  
High Dose Rate ◽  
Compensation Method ◽  
Photon Radiation ◽  
High Dose ◽  
Biological Effectiveness ◽  
The Difference ◽  
Dose Per Fraction

Objective: To evaluate the biological effectiveness of dose associated with interruption time; and propose the dose compensation method based on biological effectiveness when an interruption occurs during photon radiation therapy. Methods: The lineal energy distribution for human salivary gland tumor was calculated by Monte Carlo simulation using a photon beam. The biological dose (Dbio) was estimated using the microdosimetric kinetic model. The dose compensating factor with the physical dose for the difference of the Dbio with and without interruption (Δ) was derived. The interruption time (τ) was varied to 0.1, 0.2, 0.3, 0.4, 0.5, 1, 2, 3, 4, 5, 10, 20, 30, 40, 50, 75, and 120 min. The dose per fraction and dose rate varied from 2 to 8 Gy and 0.1 to 24 Gy/min, respectively. Results: The maximum Δ with 1 Gy/min occurred when the interruption occurred at half the dose. The Δ with 1 Gy/min at half of the dose was over 3% for τ >= 20 min for 2 Gy, τ = 10 min for 5 Gy, and τ = 10 min for 8 Gy. The maximum difference of the Δ due to the dose rate was within 3% for 2 and 5 Gy, and achieving values of 4.0% for 8 Gy. The dose compensating factor was larger with a high dose per fraction and high-dose rate beams. Conclusion: A loss of biological effectiveness occurs due to interruption. Our proposal method could correct for the unexpected decrease of the biological effectiveness caused by interruption time. Advances in knowledge: For photon radiotherapy, the interruption causes the sublethal damage repair. The current study proposed the dose compensation method for the decrease of the biological effect by the interruption.

PET Image-guided Dose Escalation in High-dose Rate Radiation Therapy

2010 ◽  
Vol 78 (3) ◽  
pp. S415
Author(s):  
E.K. Lee ◽  
F. Yuan ◽  
A. Templeton ◽  
R. Yao ◽  
J.C. Chu
Keyword(s):  
Radiation Therapy ◽  
Dose Rate ◽  
Dose Escalation ◽  
High Dose Rate ◽  
High Dose ◽  
Image Guided

scholarly journals Implementation of High Dose Rate Brachytherapy in Cancer Treatment

2021 ◽  
Vol 1 (3) ◽  
pp. 77-106
Author(s):  
Amir Shahabaz ◽  
Muhammad Afzal
Keyword(s):  
Radiation Therapy ◽  
Side Effects ◽  
Dose Rate ◽  
Radiation Source ◽  
Cancer Recurrence ◽  
High Dose Rate ◽  
High Dose ◽  
Hdr Brachytherapy ◽  
Short Treatment ◽  
High Dose Rate Brachytherapy

A technique of radiation therapy delivery in which the radioactive sources are placed very close or even inside the target volume is called Brachytherapy (BT). Brachytherapy is a type of radiation therapy. It destroys cancer cells by making it hard for them to multiply. In this technique, a radiation source is placed directly into or near a tumour. High dose-rate brachytherapy is also known as HDR brachytherapy, or temporary brachytherapy. It is a type of internal radiotherapy. HDR was developed to reduce the risk of cancer recurrence while shortening the amount of time it takes to get radiation treatment. HDR also limits the dose of radiation (associated side effects) to surrounding normal tissue. The important benefits of HDR brachytherapy include extremely precise radiation therapy delivered internally, used alone or after surgery to help prevent cancer recurrence, convenient treatments that are usually pain-free, and a reduction in the risk of common short- and long-term side effects. Currently, tumour dose, as well as doses of the surrounding normal structures, can be evaluated accurately, and high-dose-rate brachytherapy enables three-dimensional image guidance. The biological disadvantages of high-dose-rate were overcome by fractional irradiation. In the definitive radiation therapy of cervical cancer, high-dose-rate brachytherapy is most necessary. Most patients feel little discomfort during brachytherapy. There is no residual radioactivity when the treatment is completed. A patient may be able to go home shortly after the procedure, resuming his normal activities with few restrictions. An advantage of brachytherapy is to deliver a high dose to the tumour during treatment and save the surrounding normal tissues. High-dose-rate (HDR) brachytherapy has great promise with respect to proper case selection and delivery technique because it eliminates radiation exposure, can be performed on an outpatient basis and allows short treatment times. Additionally, by varying the dwell time at each dwell position, the use of a single-stepping source allows optimization of dose distribution. As the short treatment times do not allow any time for correction of errors, and mistakes can result in harm to patients, so the treatments must be executed carefully by using HDR brachytherapy. Refinements will occur primarily in the integration of imaging (computed tomography, magnetic resonance imaging, intraoperative ultrasonography) and optimization of dose distribution and it is expected that the use of HDR brachytherapy will greatly expand over the next decade. Various factors in the development of well-controlled randomized trials addressing issues of efficacy, quality of life, toxicity and costs-versus-benefits will ultimately define the role of HDR brachytherapy in the therapeutic armamentarium. Surrounding healthy tissues are not affected by the radiation due to the ability to target radiation therapy at high dose rates directly to the tumour. Treatment to be delivered as an outpatient in as few as one to five sessions is also allowed by this targeted high dose approach. HDR brachytherapy is the most precision radiation therapy, even better than carbon ion therapy. At the time of invasive placement of the radiation source into the tumour area, brachytherapy requires the skills and techniques of radiation oncologists.

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