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A study on rectal dose measurement in phantom and in vivo using Gafchromic EBT3 film in IMRT and CyberKnife treatments of carcinoma of prostate.

Ganapathy K, Kurup PG, Murali V, Muthukumaran M, Subramanian SB, Velmurugan J - J Med Phys (2013)

Bottom Line: The measured doses using EBT3 films were compared with the TPS-calculated dose along the anterior rectal wall at multiple points.Gafchromic EBT3 film is a suitable detector for in vivo rectal dose measurements as it offers the possibility of analyzing the dose at multiple points.In addition, the method of extending this in vivo rectal dose measurement technique as a tool for patient-specific quality assurance check is also analyzed.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiotherapy, Apollo Specialty Hospital, Chennai, Tamil Nadu, India.

ABSTRACT
The objective of this study is to check the feasibility of in vivo rectal dose measurement in intensity-modulated radiotherapy (IMRT) and CyberKnife treatments for carcinoma prostate. An in-house pelvis phantom made with bee's wax was used in this study. Two cylindrical bone equivalent materials were used to simulate the femur. Target and other critical structures associated with carcinoma prostate were delineated on the treatment planning images by the radiation oncologist. IMRT treatment plan was generated in Oncentra Master Plan treatment planning system and CyberKnife treatment plan was generated in Multiplan treatment planning system. Dose measurements were carried out in phantom and in patient using Gafchromic EBT3 films. RIT software was used to analyze the dose measured by EBT3 films. The measured doses using EBT3 films were compared with the TPS-calculated dose along the anterior rectal wall at multiple points. From the in-phantom measurements, it is observed that the difference between calculated and measured dose was mostly within 5%, except for a few measurement points. The difference between calculated and measured dose in the in-patient measurements was higher than 5% in regions which were away from the target. Gafchromic EBT3 film is a suitable detector for in vivo rectal dose measurements as it offers the possibility of analyzing the dose at multiple points. In addition, the method of extending this in vivo rectal dose measurement technique as a tool for patient-specific quality assurance check is also analyzed.

No MeSH data available.


Related in: MedlinePlus

Dose distribution in-patient images for IMRT plan in axial and sagittal views
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Figure 5: Dose distribution in-patient images for IMRT plan in axial and sagittal views

Mentions: After analyzing the results of the phantom-based rectal dose measurements, the study was extended to in vivo measurement. Rectal dose measurements were carried out on a patient treated with IMRT for carcinoma prostate. Treatment plan was generated with prescription doses of 180 cGy and 200 cGy to the contoured volumes of CTV and GTV, respectively [Figure 5]. EBT3 film pieces of 1 cm width by 10 cm length were used to measure the anterior rectal wall dose in the patient. Transrectal ultrasound based localization of the prostate was done by radiation oncologists during imaging and treatment execution. The ultrasound probe was then removed from its holder and EBT3 film with the rod was kept inside the holder. The insertion of the plastic rod was ensured to be straight using a line drawn on the surface of the rod to avoid rotation of the film while inserting the rod into the holder. CBCT images were obtained to verify the local geometry comprising prostate, ultrasound probe holder, and the isocenter. IMRT treatments were executed after alignment of the patient using CBCT images and planning CT images. EBT3 film was removed from the rectum after treatment and scanned after a 24-h wait time interval. In vivo rectal dose measurement in the patient was done for 10 treatment fractions. The measured dose from the film was then compared with the TPS calculated dose for multiple points at a uniform interval of 1 cm distance along the length of the film. The maximum dose delivered to the anterior rectal wall was obtained from the film profile generated along the length of the film.


A study on rectal dose measurement in phantom and in vivo using Gafchromic EBT3 film in IMRT and CyberKnife treatments of carcinoma of prostate.

Ganapathy K, Kurup PG, Murali V, Muthukumaran M, Subramanian SB, Velmurugan J - J Med Phys (2013)

Dose distribution in-patient images for IMRT plan in axial and sagittal views
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3775037&req=5

Figure 5: Dose distribution in-patient images for IMRT plan in axial and sagittal views
Mentions: After analyzing the results of the phantom-based rectal dose measurements, the study was extended to in vivo measurement. Rectal dose measurements were carried out on a patient treated with IMRT for carcinoma prostate. Treatment plan was generated with prescription doses of 180 cGy and 200 cGy to the contoured volumes of CTV and GTV, respectively [Figure 5]. EBT3 film pieces of 1 cm width by 10 cm length were used to measure the anterior rectal wall dose in the patient. Transrectal ultrasound based localization of the prostate was done by radiation oncologists during imaging and treatment execution. The ultrasound probe was then removed from its holder and EBT3 film with the rod was kept inside the holder. The insertion of the plastic rod was ensured to be straight using a line drawn on the surface of the rod to avoid rotation of the film while inserting the rod into the holder. CBCT images were obtained to verify the local geometry comprising prostate, ultrasound probe holder, and the isocenter. IMRT treatments were executed after alignment of the patient using CBCT images and planning CT images. EBT3 film was removed from the rectum after treatment and scanned after a 24-h wait time interval. In vivo rectal dose measurement in the patient was done for 10 treatment fractions. The measured dose from the film was then compared with the TPS calculated dose for multiple points at a uniform interval of 1 cm distance along the length of the film. The maximum dose delivered to the anterior rectal wall was obtained from the film profile generated along the length of the film.

Bottom Line: The measured doses using EBT3 films were compared with the TPS-calculated dose along the anterior rectal wall at multiple points.Gafchromic EBT3 film is a suitable detector for in vivo rectal dose measurements as it offers the possibility of analyzing the dose at multiple points.In addition, the method of extending this in vivo rectal dose measurement technique as a tool for patient-specific quality assurance check is also analyzed.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiotherapy, Apollo Specialty Hospital, Chennai, Tamil Nadu, India.

ABSTRACT
The objective of this study is to check the feasibility of in vivo rectal dose measurement in intensity-modulated radiotherapy (IMRT) and CyberKnife treatments for carcinoma prostate. An in-house pelvis phantom made with bee's wax was used in this study. Two cylindrical bone equivalent materials were used to simulate the femur. Target and other critical structures associated with carcinoma prostate were delineated on the treatment planning images by the radiation oncologist. IMRT treatment plan was generated in Oncentra Master Plan treatment planning system and CyberKnife treatment plan was generated in Multiplan treatment planning system. Dose measurements were carried out in phantom and in patient using Gafchromic EBT3 films. RIT software was used to analyze the dose measured by EBT3 films. The measured doses using EBT3 films were compared with the TPS-calculated dose along the anterior rectal wall at multiple points. From the in-phantom measurements, it is observed that the difference between calculated and measured dose was mostly within 5%, except for a few measurement points. The difference between calculated and measured dose in the in-patient measurements was higher than 5% in regions which were away from the target. Gafchromic EBT3 film is a suitable detector for in vivo rectal dose measurements as it offers the possibility of analyzing the dose at multiple points. In addition, the method of extending this in vivo rectal dose measurement technique as a tool for patient-specific quality assurance check is also analyzed.

No MeSH data available.


Related in: MedlinePlus