Quality assurance in radiation oncology. A study of feasibility and impact on action levels of an in vivo dosimetry program during breast cancer irradiation

The study was aimed to check the radiotherapy treatment accuracy and definition of action levels during implementation of in vivo dosimetry as a part of quality assurance program. The calibration and correction factors for in vivo entrance dose measurements for six n-type Isorad semiconductor diodes were determined as recommended by the European Society for Radiotherapy and Oncology Booklet No. 5. The patients for in vivo measurements have been divided in groups, according to the treatment site/techique, in order to investigate and detect the groups where the uncertainty was larger or where a systematic error occurred. The tolerance/action levels for all groups were also defined and checked. In this study, the entrance dose measurements were performed for total of 451 treatment fields, and 338 patients over one year period. The mean value and the standard deviation for different groups were: breast +1.0% ? 2.89%(1 SD), brain, and head and neck - +0.74% ? 2.04%(1 SD), and isocentric pelvis and abdomen - +0.1% ? 2.86%(1 SD). All measurements - +0.72% ? 2.64%(1 SD). In our experience, systematic in vivo dosimetry proved to be a very useful tool for quality assurance of patient's plan and treatment, both in detecting systematic errors and for estimating the accuracy of radiotherapy treatment delivery.

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Image-guided in vivo dosimetry for quality assurance of IMRT treatment for prostate cancer

International Journal of Radiation Oncology*Biology*Physics ◽

10.1016/j.ijrobp.2006.09.008 ◽

2007 ◽

Vol 67 (1) ◽

pp. 288-295 ◽

Cited By ~ 16

Author(s):

Hansjoerg Wertz ◽

Judit Boda-Heggemann ◽

Cornelia Walter ◽

Barbara Dobler ◽

Sabine Mai ◽

...

Keyword(s):

Prostate Cancer ◽

Quality Assurance ◽

In Vivo Dosimetry ◽

Image Guided

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Implementation of an in vivo radiochromic film QA procedure

10.32469/10355/57273 ◽

2016 ◽

Author(s):

◽

Jason Stanford

Keyword(s):

Quality Assurance ◽

Radiation Treatment ◽

Radiochromic Film ◽

In Vivo Dosimetry ◽

Patient Specific ◽

Attractive Alternative ◽

Quality Assurance Procedure ◽

Imaging Device ◽

Treatment Techniques

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Advance treatment techniques, such as IMRT and dynamic conformal arc delivery, are novel radiation treatment procedures at the forefront of accurate and precise radiotherapy. However, the risk of suboptimal treatment resulting in injury is far greater with these techniques due to their complexity. An in vivo quality assurance system is the most appropriate validation of the delivered dose to the patient from these techniques. The intent of this research is to propose an in vivo dosimetry quality assurance procedure using radiochromic film. This research proved that radiochromic in vivo dosimetry is a viable method of detecting spatial patient specific errors in radiotherapy; however, the process is time consuming and not sensitive enough for dosimetric errors associated with weight change. Although time consuming, in vivo radiochromic dosimetry is an attractive alternative for small cancer centers and developing countries without the large startup capital to acquire the electronic portal imaging device necessary for EPID in vivo dosimetry.

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Systematic in vivo dosimetry for quality assurance using diodes 2: Assessing radiotherapy techniques and developing an appropriate action protocol

Journal of Radiotherapy in Practice ◽

10.1017/s1460396905000208 ◽

2004 ◽

Vol 4 (4) ◽

pp. 143-154 ◽

Cited By ~ 5

Author(s):

R. Appleyard ◽

K. Ball ◽

F. E. Hughes ◽

W. Kilby ◽

R. Nicholls ◽

...

Keyword(s):

Head And Neck ◽

In Vivo Dosimetry ◽

Entrance Dose ◽

Treatment Category ◽

P Type ◽

Dose Measurements ◽

Action Levels

Purpose: Having previously reviewed the implementation of systematic in vivo dosimetry at the Norfolk and Norwich Hospital this paper examines the results of entrance dose measurements for specific sites/techniques and determines whether different action/alert protocols are required for these different categories.Methods and materials: Entrance dose measurements using p-type diodes were analysed for the following treatment categories: Breast, head and neck in beam direction shell, abdomino-pelvic and intrathoracic. A 4% tolerance was applied.Results: Mean deviations from expected dose and proportion of measurements exceeding tolerance were: Breast: +1.15%±3.04% (1SD), 238/1073≥4%; Head and neck: +0.35%±2.20% (1SD), 21/326≥4%; Abdomino-pelvic: +0.52%±2.75% (1SD), 93/712≥4%; Intrathoracic: −0.01%±2.75% (1SD), 22/119≥4%. Significant improvements in results for breast patients were noted following the introduction of a commercial breast board. The results for abdomino-pelvic patients confirmed a substantial variation in diode response under short FSD, wedged fields at 16MV (that had not been corrected for). The statistical uncertainty in dose measurement for each treatment category was calculated in order to assist determination of appropriate tolerance levels.Conclusions: A blanket tolerance of 4% was generally too low given the extent of measurement uncertainty. The relatively high number of readings outside tolerance where identification of errors was difficult/impossible resulted in inconsistent application of the action protocol. Some widening of tolerances is likely to improve quality of procedure and treatment. Appropriate action levels are recommended for each treatment category.

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