The aim of this work was to investigate the dosimetric characteristics of radiophotoluminescent glass dosimeter (RPLGD) for high energy photon beams in both flattening filter mode and flattening filter free (FFF) mode. The dosimetric characteristics of RPLGD model GD-302M were studied in 6 MV photon beams for the reproducibility of dosimeter reader, uniformity and reproducibility of RPLGD, dose linearity (range from 1 to 20 Gy), repetition rate, and angular dependence. In addition, the energy responses were observed in flattening filter mode (6 MV, 10 MV, and 15 MV) from Varian Clinac Cseries and FFF mode (6 MV_FFF and 10 MV_FFF) from Varian TrueBEAM system. The FGD-1000 reader system exhibited stable readout. The entire number of 100 RPLGDs showed good uniformity and reproducibility within ±1.5%. Furthermore, the signal from RPLGD demonstrated a linear proportion to the radiation dose (r = 0.999), and no energy dependence was observed. For repetition rate response of flattening filter mode and FFF mode, the maximum error of relative response to 400 MU/min were 0.977 ±0.006 and 0.986±0.017, respectively. The response of RPLGD reached 1.00 at ±30°g antry angle while at +90°gantry angle, the RPLGD response was 8% lower compared to-90°gantry angle because the attenuation effect was more pronounced. We conclude that the RPLGD is capable to measure radiation dose since it provides desirable dosimetric properties such as good uniformity and reproducibility of RPLGD including the reader system. Besides, RPLGD is available with small active readout area which adds benefit for clinical implementation in radiotherapy, especially for advanced techniques.

PurposeTo observe the effectiveness of the practical instruction sheet and the educational video for left-sided breast treatment in a patient receiving deep inspiration breath hold (DIBH) technique. Two parameters, simulation time and patient satisfaction, were assessed through the questionnaire.MethodsTwo different approaches, which were the instruction sheet and educational video, were combinedly used to assist patients during DIBH procedures. The guideline was assigned at least 1 week before the simulation date. On the simulation day, patients would fill the questionnaire regarding their satisfaction with the DIBH instruction. The questionnaire was categorized into five levels: extremely satisfied to dissatisfied, sequentially. The patients were divided into four groups: not DIBH technique, DIBH without instruction materials, the DIBH with instruction sheet or educational video, and DIBH with both of instruction sheet and educational video.ResultsTotal number of 112 cases of left-sided breast cancer were analyzed. The simulation time during DIBH procedure significantly reduced when patients followed the instruction. There was no significant difference in simulation time on the DIBH procedures between patient compliance via instruction sheet or educational video or even following both of them. The excellent level was found at 4.6 ± 0.1 and 4.5 ± 0.1, for patients coaching via instruction sheet as well as on the educational video, respectively.ConclusionPatient coaching before simulation could potentially reduce the lengthy time in the simulation process for DIBH technique. Practicing the DIBH technique before treatment is strongly advised.

Radiation protection in the scrotum to reduce the risk of genetic effect in the future is very important. This study aimed to measure the scrotal dose outside the treatment fields by using the radio-photoluminescence glass dosimeter (RPLGD). The characteristics of RPLGD model GD-302M were studied. Scattered dose to scrotum was measured in one liposarcoma case with the prescribed dose of 60 Gy. RPLGDs were placed in three different locations: one RPLGD was positioned at the posterior area which closer to the scrotum, and the other two RPLGDs were placed between the penis and the scrotum. Three RPLGDs were employed in each location. The scattered doses were measured in every fraction during the whole course of treatment. The entire number of 100 RPLGDs showed the uniformity within ±2%. The signal from RPLGD demonstrated linear proportion to the radiation dose (r = 0.999). The relative energy response correction factor was 1.05. The average scrotal dose was 4.1 ± 0.9 cGy per fraction. The results presented a wide range since there was a high uncertainty during RPLGD placement. The total scrotal dose for the whole course of treatment was 101.9 cGy (1.7% of the prescribed dose). The RPLGD model GD-302M could be used to measure scattered dose after applying the relative energy correction factor.

BackgroundWhole breast irradiation is an essential treatment after breast-conserving surgery (BCS). However, there are some adverse effects from inhomogeneity and dose to adjacent normal tissues.ObjectiveAim of this study was to compare dosimetry among standard technique, three-dimensional conformal radiotherapy (3D-CRT), and advanced techniques, electronic compensator (ECOMP), inverse intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT).MethodsWhole breast irradiation treatment plans of patients who had underwent BCS and whole breast irradiation were re-planned with all four techniques. Clinical target volume was contoured according to the Radiation Therapy Oncology Group atlas for breast only in patients who had negative node or ductal carcinoma in situ and breast with chest wall for patients with positive node. Planning target volume was non-uniformly expanded. Dose prescription was 50 Gy in 25 fractions with 6 MV photon energy.ResultsIn total, 25 patients underwent whole breast irradiation with computed tomography simulation from November 2013 to November 2014 were included. Six patients with positive nodes were re-planned for breast with chest wall irradiation and 19 patients with negative nodes were re-planned for breast only irradiation. Primary outcome, radical dose homogeneity index (HI) of 3D-CRT, ECOMP, IMRT and VMAT were 0·865, 0·889, 0·890 and 0·866, respectively. ECOMP and IMRT showed significant higher HI than 3D-CRT (p-value<0·001). Secondary outcome, conformity index (CI) of advanced technique were significantly better than 3D-CRT. Lung V20, mean ipsilateral lung dose (MILD), mean heart dose (MHD), heart V25, heart V30 of advanced techniques were also lower than 3D-CRT. ECOMP had better mean lung dose (MLD), mean contralateral lung dose (MCLD) and mean contralateral breast dose (MCBD) when compared with 3D-CRT. Monitor units of advanced techniques were significantly higher than 3D-CRT.ConclusionsHI of ECOMP and IMRT were significantly higher than 3D-CRT technique. All advanced techniques showed statistically better in CI. Lung V20, MILD, heart V25 and heart V30 of advanced techniques were lower than 3D-CRT. However, only ECOMP showed decreased MLD, MHD, MCLD and MCBD when compared with 3D-CRT.

Introduction:The well-being of breast cancer patients is essential, especially fertility in patients of reproductive age. The objective of this study was to estimate the radiation doses to the ovaries and uterus for different treatment techniques of breast cancer irradiation using radio-photoluminescent glass dosimeters (RPLDs). Methods: A Farmer-type ionisation chamber (IBA FC-65G) and RPLDs were used to measure in-and out-of-field radiation doses in a solid water phantom. The field sizes were set to 10 9 10 cm 2 and 8 9 17 cm 2 with the central axis at out-of-field measurement distances of 30 or 50 cm. The Rando phantom's left breast was planned using four different techniques: two tangential standard fields with and without electronic tissue compensator (E-comp) techniques, intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT). The radiation doses in the ipsilateral ovary, contralateral ovary and uterus were measured using RPLDs. Results: The percentage ratio of out of field to in field was affected by distance from the central axis to the point of measurement, in addition to the field sizes associated with collimator scatter. Advanced techniques such as IMRT and VMAT produced higher doses to the ovaries and uterus. The estimated results of the worst-case scenario for the ipsilateral ovary, contralateral ovary and uterus were 0.84% (42 cGy), 0.62% (31 cGy) and 0.76% (38 cGy), respectively, for a 5000 cGy prescription dose. Conclusion:The lowest to highest out-of-field radiation doses to the ovarian and uterine organs from breast irradiation were the two tangential field techniques, VMAT and IMRT. These advanced techniques yielded higher radiation leakage, which potentially contributed to the out-of-field radiation dose.

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Background Ultrahypofractionation can shorten the irradiation period. This study is the first dosimetric investigation comparing ultrahypofractionation using volumetric arc radiation therapy (VMAT) and intensity-modulated proton radiation therapy (IMPT) techniques in postmastectomy treatment planning. Materials and methods Twenty postmastectomy patients (10-left and 10-right sided) were replanned with both VMAT and IMPT techniques. There were four scenarios: left chest wall, left chest wall including regional nodes, right chest wall, and right chest wall including regional nodes. The prescribed dose was 26 Gy(RBE) in 5 fractions. For VMAT, a 1-cm bolus was added for 2 in 5 fractions. For IMPT, robust optimization was performed on the CTV structure with a 3-mm setup uncertainty and a 3.5% range uncertainty. This study aimed to compare the dosimetric parameters of the PTV, ipsilateral lung, contralateral lung, heart, skin, esophageal, and thyroid doses. Results The PTV-D95 was kept above 24.7 Gy(RBE) in both VMAT and IMPT plans. The ipsilateral lung mean dose of the IMPT plans was comparable to that of the VMAT plans. In three of four scenarios, the V5 of the ipsilateral lung in IMPT plans was lower than in VMAT plans. The Dmean and V5 of heart dose were reduced by a factor of 4 in the IMPT plans of the left side. For the right side, the Dmean of the heart was less than 1 Gy(RBE) for IMPT, while the VMAT delivered approximately 3 Gy(RBE). The IMPT plans showed a significantly higher skin dose owing to the lack of a skin-sparing effect in the proton beam. The IMPT plans provided lower esophageal and thyroid mean dose. Conclusion Despite the higher skin dose with the proton plan, IMPT significantly reduced the dose to adjacent organs at risk, which might translate into the reduction of late toxicities when compared with the photon plan.

Background: Alanine dosimeters are generally used in high-dose industrial applications (kGy). Later, research into employing alanine as a dosimeter in radiotherapy (1-20 Gy) has increased, since alanine may be an alternative transfer dosimeter for quality control, postal audit, and intercomparison between laboratories. However, several factors such as the dosimeter’s characteristic should be investigated while utilizing alanine in radiotherapy. In addition, the optimal electron paramagnetic resonance (EPR) reader should be configured to match the absorbed dose range. Objectives: This study aims to optimize the EPR setting parameters, study the characteristics of alanine dosimeters, and estimate the uncertainty of the 6MV-FFF linear accelerator in a dose ranging from 1 to 20 Gy. The output measurements from different facilities were also investigated. Materials and methods: The alanine dosimeters were irradiated with a 6MV-FFF beam using linear accelerator, Varian TrueBeam (Varian Medical Systems, Inc, CA, USA), 100 cm SSD, with a field size of 10x10 cm2 at 1 to 30 Gy. The EPR operation parameter has been optimized for these dose ranges. The characteristics of alanine dosimeters were then investigated, along with the estimation of uncertainty in using alanine. Finally, the alanine dosimeter proficiency was validated using 9 distinct linear accelerator machines. Results: The EPR parameters were found to be optimized at 1.589 mW of MP, 7.018 G of MA, and 40.96 ms of TC. The expanded uncertainty (k=2) was reported at 2.68% in the 1-20 Gy dose range. The alanine dosimeters’ characteristics were found to have good uniformity and reproducibility, low fading, and angle-and dose-independence. Although the investigation was performed in 9 different linear accelerator machines, the difference of delivered dose output was measured and reported with difference percentages within ±1%. Conclusion: This study reports the feasibility of using alanine dosimeters in radiotherapy. The important EPR parameter setting, and alanine dosimetry characteristics were investigated, whose results suggest that alanine can be used at a dose range of 1-30 Gy. This especially benefits the SRS treatment which uses a high dose per fraction, and this dosimeter can be an alternative transfer dosimeter. Nonetheless, various factors should be explored using an appropriate phantom prior to clinical application.