Dosimetric Study of an Indigenous and Heterogeneous Pelvic Phantom for Radiotherapy Quality Assurance

Document Type : Original Paper


1 University Department of Physics, Ranchi University, Ranchi- 834008, Jharkhand State, India.

2 Ranchi university, Ranchi

3 All India Institute of Medical Sciences (AIIMS), Bhopal


Introduction: In vitro dosimetric verification prior to patient treatment plays a key role in accurate and precision radiotherapy treatment delivery. Since the human body is a heterogeneous medium, the aim of this study was to design a heterogeneous pelvic phantom for radiotherapy quality assurance.
Material and Methods: A pelvic phantom was designed using wax, pelvic bone, borax powder, and water mimicking different biological tissues. Hounsfield units and relative electron densities were measured. Various intensity-modulated radiotherapy (IMRT) plans were imported to the pelvic phantom for verification and implemented on the Delta 4 phantom. The quantitative evaluation was performed in terms of dose deviation, distance to agreement, and gamma index passing rate.
Results: According to the results of the CT images of an actual patient, relative electron densities for bone, fat, air cavity, bladder, and rectum were 1.335, 0.955, 0.158, 1.039, and 1.054, respectively. Moreover, the CT images of a heterogeneous pelvic phantom showed the relative electron densities for bone, fat (wax), air cavity, bladder (water), and rectum (borax powder) as 1.632, 0.896, 0.159, 1.037, and 1.051, respectively.The mean percentage variation between planned and measured doses was found to be 2.13% within the tolerance limit (< ±3%) .In all test cases, the gamma index passing rate was greater than 90%.
Conclusion: The findings showed the suitability of the materials used in the design of the heterogeneous phantom. Therefore, it can be concluded that the designed phantom can be used for regular radiotherapy quality assurance


Main Subjects

  1. References


    1. Bentzen SM, Overgaard J. Patient-to-Patient Variability in the Expression of Radiation-Induced Normal Tissue Injury.SeminRadiatOncol.1994;4(2):68-80.
    2. Brahme A. Dosimetric precision requirements in radiation therapy.ActaRadiolOncol. 1984;23(5):379-91.
    3. Brahme A. Design principles and clinical possibilities with a new generation of radiation therapy equipment. A review. ActaOncol. 1987;26(6):403–12.
    4. Bouchard H, Seuntjens J. Ionization chamber‑based reference dosimetryof intensity modulated radiation beams. Med Phys. 2004;31:2454‑65.
    5. Fraser D, Parker W, Seuntjens J. Characterization of cylindricalionization chamber for patient specific IMRT QA. J ApplClin MedPhys. 2009;10(4):241-51.
    6. Nijsten SM, Mijnheer BJ, Dekkar AL, Lambin P, Minken AW. Routineindividualised patient dosimetry using electronic portal imagingdevices. RadiotherOncol. 2007;83:65‑75.
    7. Huang YC, Yeh CY, YehJH, Lo CJ, Tsai PF, Hung CH, et al. Clinicalpractice and evaluation of electronic portal imaging device for VMATquality assurance. Med Dosim. 2013;38:35‑41.
    8. Gurjar OP, Mishra SP, Bhandari V, Pathak P, Patel P, Shrivastav G. Radiation dose verification using real tissue phantom in modern radiotherapy techniques. J Med Phys. 2014;39(1):44-9.
    9. IAEA.Absorbeddose determination in photon and electron beams,An International Code of Practice.Series No. 277. Vienna; 1997.
    10. IAEA.An International Code of Practice for Dosimetry based onabsorbed dose to water: Series No. 398,absorbed dosedetermination in external beam radiotherapy. Vienna; 2000.
    11. Van Dyk J, Barnett RB, Cygler JE, Shragge PC. Commissioning and quality assurance of treatment planning computers. Int J RadiatOncolBiol Phys. 1993; 26:261-73.
    12. Harms WBSr, Low DA, WongWJ,Purdy JA. A software tool for the quantitative evaluation of 3D dose calculation algorithms. Med Phys. 1998;25(10):1830-6.
    13. Avgousti R, Armpilia C, Floros I, Antypas C. Evaluation of intensity modulated radiation therapy delivery system using a volumetric phantom on the basis of the task group 119 report of american association of physicists in medicine. J Med Phys. 2017;42:33-41.
    14. Gurjar OP, Paliwal RK, Mishra SP. A dosimetric study on slab-pinewood-slab phantom for developing the heterogeneous chest phantom mimicking actual human chest. J Med Phys. 2017;42(2):80‑5.
    15. Schaly B, Varchena V, Au P, Pang G.Evaluation of an anthropomorphic male pelvic phantom for image-guided radiotherapy. Reports in Medical Imaging. 2009; 2:69-78.
    16. .Zhang F, Zhang H, Zhao H, He Z, Shi L, He Y, et al. Design and fabrication of a personalized anthropomorphic phantom using 3D printing and tissue equivalent materials.Quant Imaging Med Surg. 2019;9(1):94-100.
    17. Shrotriya D, Yadav RS, Srivastava RNL, Verma TR. Design and Development of an Indigenous In-house Tissue-equivalent Female Pelvic Phantom for Radiological Dosimetric Applications. Iran J Med Phys. 2018; 15:200-5.
    18. Akpochafor MO, Madu CB, Habeebu MY,Omojola AD, Adeneye SO, Aweda MA. Development of pelvisphantom for verification of treatment planning system usingconvolution, fast superposition, and superposition algorithms. J ClinSci. 2017; 14:74-80.