article · International Journal of Human and Health Sciences (IJHHS)
A retrospective study evaluated out-of-field radiation doses received by normal tissues during modern photon radiotherapy. Using treatment plans from two centres in Nigeria, the research examined 88 patient records comprising 41 pelvic and 47 breast cancer cases treated with Intensity-Modulated Radiation Therapy (IMRT) or Volumetric Modulated Arc Therapy (VMAT). Peripheral doses were evaluated at distances of 2.5 cm, 5 cm, and 10 cm from the edge of the treatment field. Although radiation levels dropped as distance increased, measurable and clinically relevant doses remained even at 10 cm due to scatter and leakage. Treatments using VMAT generally generated higher and more variable out-of-field doses than IMRT, and larger target volumes directly correlated with increased peripheral exposure. The findings indicate that refining beam arrangements, limiting target volumes where possible, and using shielding can help protect healthy tissues.
Radiotherapy is designed to target tumours, but scattered radiation can unintentionally expose healthy organs to harm. By assessing peripheral doses across modern treatment techniques, this work helps medical teams understand how delivery methods and target volume sizes influence stray radiation, supporting safer treatment design and reducing long-term exposure risks for cancer patients.
These findings are directly relevant to radiotherapy clinics, medical physicists, and developers of treatment planning software. Clinical teams can apply the recommendations immediately to refine beam arrangements and protocol selection. For healthcare technology vendors, the data can inform the design of software tools and shielding solutions to better calculate and limit peripheral dose, representing an applied and clinically tested body of evidence.
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A retrospective dosimetric analysis was conducted using treatment planning systems from two radiotherapy centers in Cross River State, Nigeria, equipped with advanced linear accelerators delivering Intensity-Modulated Radiation Therapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT), to investigate the levels of out-of-field radiation doses in modern photon radiotherapy and strategies to minimize exposure to normal tissues. A total of 88 patient treatment plans (41 for pelvic cancer and 47 for breast cancer) were purposively selected from archived records. These plans included a range of clinically approved techniques and varied planning target volumes (PTVs), reflecting typical clinical scenarios. Out-of-field radiation doses were evaluated at fixed distances of 2.5 cm, 5 cm, and 10 cm from the edge of the treatment field. Dose-volume histogram (DVH) data were extracted from the treatment planning system and supplemented by phantom or in vivo measurements when available.The study compared the peripheral dose distributions between treatment modalities and anatomical regions. Results showed that out-of-field doses consistently declined with increasing distance from the treatment field but remained measurable and clinically relevant even at 10 cm, indicating the persistent impact of scatter and leakage radiation. Pelvic treatments exhibited significant modality-based dose differences, particularly at 5 cm, while breast cancer treatments revealed statistically significant differences at all measured distances. VMAT treatments were generally associated with higher and more variable out-of-field doses than IMRT. Larger PTV sizes were directly correlated with increased peripheral radiation exposure. To mitigate out-of-field doses, the study recommends optimizing beam arrangements, minimizing PTV sizes when feasible, and employing shielding. Continuous dose monitoring and quality assurance practices are essential, alongside exploring emerging technologies. This study highlights the importance of treatment planning decisions in reducing unnecessary radiation exposures to the surrounding normal tissues and supports the need for individualized, safety-conscious radiotherapy strategies. International Journal of Human and Health Sciences Vol. 10 No. 04 Oct’26 Page: 263-269
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DOI: 10.31344/ijhhs.v10i4.998
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