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Cobalt-60 adalah salah satu modalitas teleterapi yang paling tua, namun masih digunakan di beberapa negara berkembang. Modifikasi bisa dilakukan untuk mengoptimalkan kemampuan pesawat Cobalt-60 dalam pengobatan kanker nasofaring. Penulis mengembangkan teknik field-in-field pada pesawat Cobalt-60. Beberapa penyulit / keterbatasan berusaha disesuaikan dengan cara mengubah pemberian dosis, peletakan isosenter, collimator, dan blok. Teknik penyinaran ini menggunakan 12-15 lapangan dalam menggunakan 7-9 blok, yang diletakkan dalam 3-5 trays. Teknik ini mampu mencapai kriteria yang ditetapkan untuk planning approval. Sembilan pasien yang telah menjalani terapi mengalami efek samping akut yang dapat diterima, dengan tingkat complete response 71%. Teknik Forward planning field-in-field bisa digunakan untuk membantu mengatasi beberapa keterbatasan pesawat Cobalt-60 dan menunjukkan hasil yang baik.

The three-dimensional field-in-field (3-D FIF) technique for radiotherapy is an advanced, state-of-the-art method that uses multileaf collimators to generate a homogeneous and conformal dose distribution via segmental subfields. The purpose of this study is to evaluate the dosimetric reproducibility of 3-D FIF plans using the original simulation computed tomography (iCT) scans and re-simulation CT (rCT) scans for whole breast irradiation (WBI) schedule. This study enrolled a total of 34 patients. The study population underwent iCT scans for standard WBI and took rCT scans after 45 Gy of WBI for cone down boost plans. The dosimetric parameters (V105%, V103%, V100%, V98%, V95%, V90%, V50%), plan quality indices (conformity index, homogeneity index) and clinical parameters (isocenter-breast axis, isocenter-lung axis, soft tissue volumes within radiation field, lung volumes within radiation field) were assessed. The median time interval from surgery to iCT was 33 days and from iCT to rCT was 35 days. All dosimetric parameters exhibited statistically significant differences between iCT and rCT among cohorts with a surgery-iCT interval of p = 0.001) and isocenter-breast axis (p = 0.032) exhibited statistically significant differences among cohorts with surgery-iCT interval

Purpose: The study is aimed to establish the dosimetric characteristics of field-in-field (FiF) technique for carcinoma of breast treatment in Nepal. We assumed that FIF technique may result in improved dose distribution and reduced acute toxicity in these patients. Methods: Forty breast cancer patients participated in this study. A total dose of 50 Gy in 25 fractions was prescribed to the planning target volume. FiF plan was generated in treatment planning system. Dose volume histograms were evaluated for PTV and organs at risks. Several parameters were analyzed for the PTVs and organ at risks (OARs) together with the Conformity index (CI), and the Homogeneity index (HI). Results: The dose coverage of breast volume was achieved. The V95% (volume of 95%) of PTV covered D95% (Dose of 95%). The PTV dose was covered to 49.98 ± 0.9 Gy and 49.81 ± 1.1 Gy for the left and right breast, respectively. The mean lung dose was 14.87 ± 0.91 Gy. The homogeneity index (0.26 ± 0.17 and 0.22 ± 0.13) and conformity index (1.59 ± 0.75 and 1.36 ± 0.45) were analyzed for left and right breast, respectively. Conclusion: The study supports the viability of FiF technique in the treatment of breast cancer in Nepal. The FIF technique enables better dose distribution in the PTV and reduces dose to OARs. The FiF technique provides dosimetric advantages and requires less planning time.

Purpose:This study compared the plan dosimetry between the intensity-modulated radiation therapy (IMRT) and field-in-field (FIF) technique for head-and-neck cancer using the Elekta Monaco treatment planning system (TPS).Materials and methods:A total of 20 head-and-neck cancer patients were selected in this study. IMRT and FIF plans for the patients were created on the Monaco TPS (ver. 5.11.02) using the 6-MV photon beam generated by the Elekta Synergy linear accelerator. The dose–volume histograms, maximum doses, minimum doses, mean doses of the target volumes and organs-at-risk (OARs), conformity index (CI), homogeneity index (HI) and monitor units (MUs) were determined for each IMRT and FIF plan. All IMRT plans passed the patient-specific quality assurance tests from the 2D diode array measurements (MatriXX Evolution System, IBA Dosimetry, Germany).Results:The results showed that the dose distribution to the target volumes of IMRT plans was better than FIF plans, while the dose (mean or max dose) to the OAR was significantly lower than FIF plan, respectively. IMRT and FIF resulted in planning target volume coverage with mean dose of 71·32 ± 0·76 and 73·12 ± 0·62 Gy, respectively, and HI values of 0·08 ± 0·01 (IMRT) and 0·19 ± 0·06 (FIF). The CI for IMRT was 0·98 ± 0·01 and FIF was 0·97 ± 0·01. For the spinal cord tolerance (maximum dose < 45 Gy), IMRT resulted in 39·85 ± 2·04 Gy compared to 41·37 ± 2·42 Gy for FIF. In addition, the mean doses to the parotid grand were 27·27 ± 7·48 and 48·68 ± 1·62 Gy for the IMRT and FIF plans, respectively. Significantly more MUs were required in IMRT plans than FIF plans (on average, 846 ± 100 MU in IMRT and 467 ± 41 MU in FIF).Conclusions:It is concluded that the IMRT technique could provide a better plan dosimetry than the FIF technique for head-and-neck patients.

Decreasing radiotoxicity to the heart, lungs, and contralateral breast has proven to lower the risk of secondary malignancy and improve overall outcomes when treating chest wall (CW) and regional lymph nodes in postmastectomy breast cancer patients. In this retrospective study, 11 postmastectomy patients were selected and planned with a novel hybrid treatment method and a traditional volumetric arc therapy (VMAT) approach for comparison. This hybrid technique was able to optimize tangential beams to minimize heart dose and the VMAT contribution to improve dose conformity around the planning target volume (PTV). Overall, this hybrid technique produced more homogenous target dose coverage and demonstrated a decrease of integral dose to organs at risk (OAR), while the VMAT technique demonstrated a higher affinity for maintaining dose conformity. Further observation of dose distributions also revealed that the hybrid plans were more effective in sparing low-dose spread to healthy tissue in both right- and left-sided cases. This observation was made evident by the reduction in heart V5 and Dmean, decreases in all parameters regarding the contralateral lung, as well as all values other than the V20 of the ipsilateral lung. This unique hybrid planning technique could present an alternative to standard intensity-modulated radiation therapy (IMRT) planning when treating postmastectomy CW and regional lymph nodes, as it has shown the capacity to decrease cardiac, lung, and contralateral breast toxicity while maintaining quality PTV coverage.

To compare the dosimetric characteristics of helical tomotherapy (HT), volumetric-modulated arc therapy (VMAT), intensity-modulated radiotherapy (IMRT), and tangential field-in-field technique (FIF) for the treatment of synchronous bilateral breast cancer (SBBC).Ten patients with early-stage unilateral breast cancer were selected for simulating the patients with SBBC in this retrospective analysis. Treatment plans with HT, VMAT, IMRT, and FIF were generated for each patient with a total dose of 50.4 Gy in 28 fractions to the target. Plan quality, namely conformity index (CI), homogeneity index (HI), dose-volume statistics of organs at risk (OARs), and beam-on time (BOT), were evaluated.HT plans showed a lower mean heart dose (3.53 ± 0.31Gy) compared with the other plans (VMAT = 5.6 ± 1.36 Gy, IMRT = 3.80 ± 0.76 Gy, and FIF = 4.84 ± 2.13 Gy). Moreover, HT plans showed a significantly lower mean lung dose (p0.01) compared with the other plans: mean right lung doses were 6.81 ± 0.67, 10.32 ± 1.04, 9.07 ± 1.21, and 10.03 ± 1.22 Gy and mean left lung doses were 6.33 ± 0.87, 8.82 ± 0.91, 7.84 ± 1.07, and 8.64 ± 0.99 Gy for HT, VMAT, IMRT, and FIF plans, respectively. The mean dose to the left anterior descending artery was significantly lower in HT plans (p0.01) than in the other plans: HT = 19.41 ± 0.51 Gy, VMAT = 25.77 ± 7.23 Gy, IMRT = 27.87 ± 6.48 Gy, and FIF = 30.95 ± 10.17 Gy. FIF plans showed a worse CI and HI compared with the other plans. VMAT plans showed shorter BOT (average, 3.9 ± 0.2 minutes) than did HT (average, 11.0 ± 3.0 minutes), IMRT (average, 6.1 ± 0.5 minutes), and FIF (average, 4.6 ± 0.7 minutes) plans.In a dosimetric comparison for SBBC, HT provided the most favorable dose sparing of OARs. However, HT with longer BOT may increase patient discomfort and treatment uncertainty. VMAT enabled shorter BOT with acceptable doses to OARs and had a better CI than did FIF and IMRT.

Aims: This study compares data between the Field in Field planning and Wedge planning techniques to figure out which technique has better dose coverage and distribution for PTV, and, if using FiF technique for whole brain treatment, how many beams will have better plan. Methods: 56 patients, who need to radiate whole brain with 30 Gy/10 fractions, have been selected for this study. Four plans have been made for each patient (FiF1—one subfield per field plan, FiF2—two subfields per field plan, FiF3—three subfields per field plan, and a Wedge plan). Results: The results of Field in Field plans including Compare dose distribution on the transverse CT slice, plan evaluation using DVH, number MU of plan, Dmax, HI, HTCI, DmaxPTV, DmeanPTV. Volume of PTV with the dose over 105% prescribed dose, dose of organ at risk, and Quality Assurance (QA) plan, are better than those of Wedge plan. Conclusions: Plans using Field in Field technique has better coverage, is more homogeneous in dose distribution than plan using Wedge technique. When using Field in Field technique for whole brain radiotherapy, using three subfields per field has better result than two subfields per field and one subfield per field.

Introduction The radiotherapy of left-sided breast cancers is challenging because of neighboring critical organs, posing an increased risk of complications. Various radiation delivery techniques have been used to deliver the desired dose of radiation to the target area while keeping the doses to nearby structures within constraints. The main aim of this study is to quantify doses delivered to the organs at risk (OARs) including heart, left lung, spinal cord, and contralateral breast, and to the planning target volume (PTV) using Field-in-Field (FIF) and Volumetric Modulated Arc Therapy (VMAT). Patients and methods A retrospective review of 15 left-sided breast cancer patients was done. All the patients underwent breast-conserving surgery and adjuvant radiation. For every patient, two different radiation treatment plans were formulated and compared for the PTV coverage and doses to OARs, including heart, ipsilateral lung, spinal cord, and contralateral breast. The radiation treatment techniques utilized for this purpose were FIF and VMAT. The homogeneity index (HI), and conformity index (CI) required for the treatment planning were also calculated. Data was analyzed using Statistical Package for the Social Sciences (IBM Corp., Armonk, USA). An Independent T-test was used for statistical analysis. Results The mean age was 41 years and the majority of them were stage II. Total nine patients were given 4005centi Gray (cGy) in 15 fractions (fr) followed by 10Gy boost, hence receiving a total dose of 5005cGy in 20fr. While remaining six patients were given a total dose 4005cGy in 15fr without any boost. All patients were hypofractionated and the dose was delivered at a rate of 267cGy per fr. The FIF technique utilized in breast cancer radiation significantly reduced the mean doses to OARs: mean heart dose (3.81cGy), ipsilateral lung dose (V16- 15cGy), mean contralateral breast dose (0.03cGy), and maximum spinal cord dose (0.18cGy); as compared to VMAT technique which delivered comparatively higher doses: mean heart dose (8.85cGy), ipsilateral lung dose (V16- 19.82cGy), mean contralateral breast dose (4.59cGy), and maximum spinal cord dose (7.14cGy). There was a significant mean difference between doses of OARs and all p-values were statistically significant (p

Background: Planning craniospinal irradiation (CSI) with ‘‘field-in-field’’ (FIF) homogenization technique in combination with daily, intrafractional modulation of the field junctions is needed to avoid spinal cord overdose. Photon-based techniques for CSI may result in dose inhomogeneity within the treatment volume and usually require a weekly manual shift of the field junctions to minimize the possibility of spinal cord overdose. Nowadays, FIF technique is used to feather out the dose inhomogeneity caused by multiple fields. We have started using this technique after acquiring advanced technology machines in recent years. Methods and Materials: Sixteen patients treated with three-dimensional conformal radiation therapy (3D-CRT) for CSI were retrospectively chosen for analysis. These patients were treated during 2019-2020. Contouring of planning target volume (PTV) and organs at risk (OAR) was done, and planning was done on Varian EclipseTM Treatment Planning System (TPS) (Varian Medical Systems, Palo Alto, CA). These patients were planned with lateral craniocervical fields and posterior spinal fields using a forward-planned FIF technique. Field junctions were automatically modulated and custom-weighted for maximal homogeneity within each treatment fraction. Dose-volume histogram (DVH) was used for analysis of results. A corresponding plan without FIF technique was planned; then maximum dose at the junction was noted for each patient with both plans, and the readings were evaluated. Paired sample t-test was used to compute the p-values for the inferential statistics. Results: Without FIF technique, the volume receiving 110% of the prescribed dose ranged from 39% to 74% (mean: 62.12%) and volume receiving 120% dose ranged from 8% to 28% (mean: 17.68%), whereas with FIF technique, the thecal sac volume receiving 110% of dose ranged from 2% to 18% (mean: 11%) and volume receiving 120% ranged from 0% to 2%. Volume receiving 100% of the dose was also calculated in both techniques; mean values of this dose range was almost similar in both groups. Later p-value was calculated, and in both dose ranges of thecal sac volume receiving 110% and 120%, the difference in values was statistically significant. Therefore, it proved that plan inhomogeneity improved with FIF technique. This technique provided consistent dose delivery during each fraction of treatment across the junctions. The maximum doses calculated at the junction were higher in the CSI plans without FIF compared to those with FIF technique. Conclusion: This study concludes that better dose homogeneity is achieved with FIF technique as compared to non-FIF technique, and the difference in values was statistically significant.

Aim: To check the feasibility of simultaneous integrated boost (SIB) using a forward planned field in field (FIF) conformal technique for the treatment of carcinoma of the cervix IIIB and compare it dosimetrically with other advanced inverse planning techniques. Methods: In our study 33 patients of carcinoma of the cervix IIIB were planned for SIB using conformal FIF technique and they were compared with retrospectively planned IMRT and VMAT techniques. SIB using conformal FIF was planned by two different methods. Results: The results of our study indicate that forward planned Conformal SIB techniques are comparable with inverse planned techniques dosimetrically, in terms of conformity Index, Homogeneity Index, Maximum dose, etc. The ability of FIF SIB plans to produce dose contrast in differential dose accumulation was compared and analyzed and the results were encouraging. To treat an advanced/bulky disease like Carcinoma of the Cervix IIIB in centers with large patient load, utilizing advanced techniques such as IMRT and VMAT is both technically and practically difficult. Despite VMAT’s shorter delivery time, the procedures involved are time-consuming. Conclusion: Hence forward planned SIB techniques may be used to achieve similar dosimetric effects of IMRT and VMAT techniques without much compromise in plan quality and patient throughput for treating bulky carcinoma of the cervix IIIB cases. However, the clinical results need to be carefully compared and evaluated and reported.

Purpose This study investigates planned and measured dose differences for 3 dimensional conformal radiotherapy (3DCRT), Field in Field (FinF) and Intensity-Modulated Radiation Therapy (IMRT) techniques for breast cancer radiotherapy. Material and Method Breast shaped phantom (BSP) was fabricated with water equevelent bolus material and BSP was placed on Alderson rando phantom, then planning computerized tomography (CT) images were obtained. Target volume andnormal tissues were delineated on these images. Treatment planning was performed for 3DCRT, FinF and IMRT techniques (Varian, Eclipse 8,6, PencilBeam). EBT2 films were placed into sagittal and transverse planes of BSP which intersect with the isocenter. After thatfilms were irradiated for each calculated plans in two times. The measured doses with film from the isocenter and from the axes passing 1 cm anterior-posterior, superior – inferior and right-left of the isocenter were compared with the doses read from the treatment planning system (TPS) on the same axes. Results Among applied techniques, the maximum and minimum dose differences for measured and calculated doses were 4.5 % and 0.05 % for FinF and IMRT techniques, respectively. Measured doses were higher than calculated doses for 66.6% of all points; however 93% of total points had a difference less than 3 %. Dose differences were minimum on axes that intersect with the isocenter and were directly correlated with the distance from the isocenter. There was no relation between dose differences and directions on axes. Conclusion Dose distributions calculated in TPS were found to be compatible for all three techniques when compared to dose distributions measured by film on rando Phantom. The best compliance was found for IMRT technique.

Background To plan craniospinal irradiation (CSI) with ‘‘field-in-field’’ (FIF) homogenization technique in combination with daily, intra-fractional modulation of the field junctions, to minimize the possibility of spinal cord overdose. Photon-based techniques for CSI may result in dose inhomogeneity within the treatment volume and usually require a weekly manual shift of the field junctions to minimize the possibility of spinal cord overdose. Nowadays FIF technique is used to feather out the dose inhomogeneity caused by multiple fields. We have started using this technique after acquiring advanced technology machines in recent years. Methods and Materials: 16 patients treated with 3D-CRT for CSI were retrospectively chosen for analysis. These patients were treated during 2016–2017. Contouring of PTV and OAR were done and planning done on Eclipse TM TPS (Varian). These patients were planned with Lateral cranio-cervical fields and posterior spinal fields using a forward-planned, FIF technique. Field junctions were automatically modulated and custom-weighted for maximal homogeneity within each treatment fraction. Dose volume histogram (DVH) was used for analysis of results. A corresponding plan without FIF technique was planned and maximum dose at the junction was noted for each patient with both plans and the readings were evaluated. Results Plan inhomogeneity improved with FIF technique. It provided consistent dose delivery during each fraction of treatment across the junctions. The maximum doses calculated at the junction were higher in the CSI plans without FIF compared to those with FIF technique. Conclusion This paper hence proves that FIF technique is better in planning CSI.

Background To implement a tangential treatment technique for whole breast irradiation using the Varian Halcyon and to compare it with Elekta Synergy Agility plans. Methods For 20 patients two comparable treatment plans with respect to dose coverage and normal tissue sparing were generated. Tangential field-in-field treatment plans (Pinnacle/Synergy) were replanned using the sliding window technique (Eclipse/Halcyon). Plan specific QA was performed using the portal Dosimetry and the ArcCHECK phantom. Imaging and treatment dose were evaluated for treatment delivery on both systems using a modified CIRS Phantom. Results The mean number of monitor units for a fraction dose of 2.67 Gy was 515 MUs and 260 MUs for Halcyon and Synergy Agility plans, respectively. The homogeneity index and dose coverage were similar for both treatment units. The plan specific QA showed good agreement between measured and calculated plans. All Halcyon plans passed portal dosimetry QA (3%/2 mm) with 100% points passing and ArcCheck QA (3%/2 mm) with 99.5%. Measurement of the cumulated treatment and imaging dose with the CIRS phantom resulted in lower dose to the contralateral breast for the Halcyon plans. Conclusions For the Varian Halcyon a plan quality similar to the Elekta Synergy device was achieved. For the Halcyon plans the dose contribution from the treatment fields to the contralateral breast was even lower due to less interleaf transmission of the Halcyon MLC and a lower contribution of scattered dose from the collimator system.

Heart diseases and cardiovascular events are well-known side effects in left-sided breast irradiation. Deep inspiration breath hold (BH) combined with fast delivery techniques such as volumetric modulated arc therapy (VMAT) or tangential field-in-field (TFiF) can serve as a valuable solution to reduce the dose to the heart. This study aims to compare the impact of positioning errors in VMAT and TFiF plans for BH left-sided breast treatments. Fifteen left-sided breast patients treated in BH with TFiF technique were included in this retrospective study. For each patient, a second plan with VMAT technique was optimized. Eighteen setup variations were introduced in each of these VMAT and TFiF reference plans, shifting the isocenter along six different directions by 3, 5, and 10 mm. A total of 540 perturbed plans, 270 for each technique, were recalculated and analyzed. The dose distributions on the target and organs at risk obtained in the different perturbed scenarios were compared with the reference scenarios, using as dosimetric endpoints the dose-volume histograms (DVH). The results were compared using the Wilcoxon test. Comparable plan quality was obtained for the reference VMAT and TFiF plans, except for low doses to organs at risk for which higher values (p

The usefulness of the field‑in‑field with two reference points (FIF w/ 2RP) method, in which the dose reference points are set simultaneously at two positions in the irradiation field and the high‑dose range is completely eliminated, was examined in the present study with the aim of decreasing acute skin toxicity in adjuvant breast radiotherapy (RT). A total of 573 patients with breast cancer who underwent postoperative whole breast RT were classified into 178 cases with wedge (W) method, 142 cases with field‑in‑field without 2 reference points (FIF w/o 2RP) method and 253 cases with FIF w/ 2RP method. Using the FIF w/ 2RP method, the high‑dose range was the lowest among the three irradiation methods. The planning target volume (PTV) V105% and the breast PTV for evaluation (BPe) V105% decreased to 0.09 and 0.10%, respectively. The FIF w/ 2RP method vs. the FIF w/o 2RP method had a strong association (η) with PTV V105% (η=0.79; P

The aim of this work is using multi-segmented conformal radiotherapy, field in field (FIF) for large breast cancer treatment, the dose coverage of the planning target volume (PTV) and evaluation the radiation load on the organs at risk (OARs). Ten patients with large breast of mean PTV was 1489 ± 335 Cm3 were included. Many parameters used in the dose evaluations in the planning target volume (PTV) and the organs at risk (OARs) volume including ipsi lateral lung, heart, and the contralateral breast, Dose homogeneity index (DHI) and conformity index (PITV). The FIF technique for all patients improved the homogeneity and conformity of the PTV, where the mean values of maximum dose of the PTV was 107%, the volumes over the prescription dose in irradiated volumes received very low doses. For each dosimetry of the organs at risk, the FIF technique reduced the dose received to theses organs. In conclude the FIF technique provided better dose distribution in the PTV and reduced the doses in the OARs and improving homogeneity and conformity of the planning volume.

Background and Purpose: To examine the feasibility of improving breast-conserving radiotherapy with simultaneous integrated boost (SIB) and analyzing the efficiency of forward versus inverse intensity-modulated radiotherapy (IMRT) techniques in providing the same. Materials and Methods: Three-dimensional conformal radiotherapy (3DCRT) field-in-field (FIF) plans with simultaneous and sequential boost and IMRT SIB plans were generated for the datasets of 20 patients who had undergone breast-conserving surgery. The 3 plans were compared dosimetrically for efficiency in terms of planning target volume (PTV) coverage (PTV 95%), homogeneity and conformity, dose delivered to ipsilateral/contralateral lungs (I/L: V10, V20, C/L: Vmean, V5), heart and contralateral breast (Vmean, V30 for heart and Vmean, V1, V5 for C/L breast). Results: The FIF 3DCRT plan with SIB (PLAN B) was more homogeneous than the classical technique with sequential boost (PLAN A). There were less hot spots in terms of Dmax (63.7 ± 1.3) versus Dmax (68.9 ± 1), P < 0.001 and boost V107%, B (0.3 ± 0.7) versus A (3.5 ± 5.99), P = 0.001. The IMRT SIB (PLAN C) did not provide any significant dosimetric advantage over the 3DCRT SIB technique. IMRT SIB plan C was associated with increased dose to contralateral lung in-terms of V5 (10.35 +/- 18.23) vs. (1.13 +/- 4.24), P = 0.04 and Vmean (2.12 ± 2.18) versus Vmean (0.595 ± 0.89), P = 0.008. There was 3-fold greater exposure in terms of Monitor Unit (MU) (1024.9 ± 298.32 versus 281.05 ± 20.23, P < 0.001) and treatment delivery time. Conclusions: FIF 3DCRT SIB provides a dosimetrically acceptable and technically feasible alternative to the classical 3DCRT plan with sequential boost for breast-conserving radiotherapy. It reduces treatment time by 2 weeks. IMRT SIB does not appear to have any dosimetric advantage; it is associated with significantly higher doses to contralateral lung and heart and radiation exposure in terms of MU.

Hypofractionated whole-breast irradiation has emerged as a viable alternative to conventional fractionation. In the field-in-field forward planning technique, a merged plan with 2 to 4 segmental fields is the final plan delivered to the machine. As per the ASTRO guidelines for the hypofractionation regimen, the volume of breast tissue receiving V105% of the prescription dose should be less than 200 cc. However, we have noticed substantial changes to this volume (change in V105% between -55 cc and + 47.1 cc) after merging the subfields. This study compares the V105% of 29 breast plans before and after merging the subfields.

We performed a dosimetric study to evaluate the benefits of using a flattening-filter-free (FFF) beam with the deep inspiration breath-hold (DIBH) method for left-breast cancer. We used data from 30 previous patients with treatment plans that included DIBH for left-breast cancer with a flattened beam. FFF beam plans were calculated from previous treatment plan images and compared to the original plans in terms of monitor units (MU), number of segments, beam-on time, and breath-holds. Beam-on time was calculated by adding the traveling time of 1.5 second between segments to the time calculated from the MU and dose rate. Breath-holds were calculated based on the beam-on time, assuming 15 s per hold. The FFF beam had increased MU in all cases (mean ± SD: flattened beam, 122.4 ± 9.8 MU; FFF beam, 160.2 ± 17.5 MU). Furthermore, the number of segments increased with the FFF beam in all cases (median [range]: flattened beam, 2 [1 to 3]; FFF beam, 5 [3 to 7]). However, in most cases, the beam-on time was reduced using the FFF beam (mean ± SD: flattened beam, 27.8 ± 7.4 seconds; FFF beam, 13.2 ± 1.7 seconds), although when a 6 MV flattened beam was used there was not a large increase. There were fewer breath-holds in most cases with the FFF beam. Cases using a 4 MV flattened beam also had fewer breath-holds; however, the number of breath-holds was consistent or increased in cases that used a 6 MV flattened beam (median [range]: flattened beam, 3 [1 to 3]; FFF beam, 1 [1 to 2]).

Background: Breast cancer is the most prevalent cancer in women all over the world. The most common and effective treatment for the early stage of breast cancer patients is breast conserving surgery (BCS) followed by radiotherapy. Objectives: The aim of this study is to evaluate and compare the dosimetric parameters of three-dimensional conformal radiation therapy (3D-CRT), using virtual wedge and field in field (FIF) techniques for patients having left breast cancer in early stages. Methods: Twenty-four patients with left breast cancer participated in this study. They were divided into thr3ee categories (small, medium, and large) based on breast volume: ≤ 1500 cc small, 1500 - 2000 cc medium, and > 2000 cc large. Two treatment planning techniques were generated for each patient by prowess treatment planning system. The following parameters were compared: Maximum, minimum, and mean dose in planning target volume (PTV), homogeneity (HI) and conformity indexes (CI), percentage of volume receiving greater than 107% of the prescribed dose (hot spots) and less than 95% of the prescribed dose (cold spots), and total monitor unit (MU) and doses received to organs at risks (OARs) such as heart and left lung. The mean values were compared using student’s t-test. Results: The FIF technique reduced either the maximum dose in PTV or hot spots in all groups significantly (P 0.05). Conclusions: It is recommended that two techniques can be combined and used together to cover their weak points. Also, it seems that if there is no equipment of intensity modulated radiation therapy (IMRT) techniques such as FIF in some centers, conformal technique by using virtual wedge is a proper alternative.

Introduction: Field-in-Field (FIF) and Intensity Modulated Radiation Therapy (IMRT) are two advanced radiation therapy planning techniques. Both of them are being used to achieve the same two related aims which are, to expose the targeted tumor to the full radiation dose and to spare the nearby normal tissues (or organs) from being exposed to high amounts of radiation more than its tolerance dose limits. FIF is a forward planning while IMRT is an inverse planning and FIF is a forward IMRT. Aim: The purpose of this study was to compare between Field-in-Field and IMRT techniques in prostate cancer radiotherapy. Method: A treatment planning system supporting both inverse and forward planning facilities is used. Ten prostate cancer patients were planned with both FIF and IMRT planning techniques. Doses received by the Planning Target Volume (PTV) and Organs at Risk (OARs) were compared in the two methods quantitatively from Dose Volume Histograms (DVHs) and qualitatively from (axial cuts). Results: The results showed that the IMRT planning technique achieved better dose coverage to the PTV than the FIF planning technique but, except RT and LT Femoral Heads, FIF achieved a better protection to the Rectum and the Bladder (OARs) than IMRT. Conclusions: The results showed that the inverse planning based IMRT technique is better and recommended in the prostate cancer radiotherapy than the FIF technique.

In the field-in-field (FIF) technique in breast tangential radiotherapy, the energy of the subfield is usually the same as the energy of the main field. However, some studies have applied 10–18 MV to subfields in patients with large breasts. We compared two FIF plans in 66 breast cancer patients: in one, the energy of the subfield was the same as that of the main field (the mono energy plan); in the other, it was higher (the dual energy plan). The photon energy of the subfield was 6 MV in the mono energy plan and 10 MV in the dual energy plan. The percentage of the planning target volume (PTV) receiving at least 105, 100, and 95 % of the prescribed dose (V105, V100, and V95, respectively) was calculated, as were the maximum and mean doses delivered to the PTV (Dmax and Dmean, respectively). Clinical target volumes (CTVs) and the thickness of the breast between the chest wall and skin surface at the level of the nipple were measured. V95 % was significantly higher in the dual energy plan than in the mono energy plan in patients with CTVs or breast thickness in the highest quartile. There were no significant differences in the other parameters of the two plans in these patients. These findings demonstrate the usefulness of the dual energy FIF technique in patients with large breasts receiving breast tangential radiotherapy.

Purpose: To plan craniospinal irradiation with ‘‘field-in-field'' (FIF) homogenization technique in combination with daily, intra-fractional modulation of the field junctions, to minimize the possibility of spinal cord overdose. Photon-based techniques for craniospinal irradiation (CSI) may result in dose inhomogeneity within the treatment volume and usually require a weekly manual shift of the field junctions to minimize the possibility of spinal cord overdose. Nowadays field-in-field technique is used to feather out the dose inhomogeneity caused by multiple fields. We have started using this technique after acquiring advanced technology machines in recent years. Methods and Materials: 16 patients (2 adults, 14 children) treated with 3D-CRT for craniospinal irradiation were retrospectively chosen for this analysis. These patients were planned and treated during 2016-2017. Contouring of Brain and Spine Cord and organ at risk were already done and planning done on Eclipse TM Treatment Planning System (Varian). All of these patients were planned Lateral cranio-cervical fields and posterior spinal fields were planned using a forward-planned, FIF technique. Field junctions were automatically modulated and custom-weighted for maximal homogeneity within each treatment fraction. Dose volume histogram (DVH) was used for analysis of results. A corresponding plan without FIF technique was planned and maximum dose (in terms of volume of the PTV covering >110 % and >120 %) at the junction was noted for each patient with both plans and the readings were evaluated. Results: Plan inhomogeneity improved with FIF technique. Planning with daily-modulated junction shifts provided consistent dose delivery during each fraction of treatment across the junctions. Without FIF or modulated junctions, the thecal sac volume receiving 110% of the prescribed dose ranged from 12% to 25.8% (mean: 15%) and volume receiving 120% dose ranged from 0% to 8% (mean: 4%). Whereas with FIF and modulated junctions, the thecal sac volume receiving 110% of dose ranged from 0.59% to 3% and volume receiving 120% was 0%. Conclusion: Without FIF or modulated junctions, the thecal sac volume receiving 110% of the prescribed dose ranged from 12% to 25.8% (mean: 15%) and volume receiving 120% dose ranged from 0% to 8% (mean: 4%). Whereas with FIF and modulated junctions, the thecal sac volume receiving 110% of dose ranged from 0.59% to 3% and volume receiving 120% was 0%. Therefore it was concluded that Field-in-field technique improved dose conformality and reduced inhomogeneity. Citation Format: Shabbir Hussain A. Ali, Rahim Gohar, Hira Nazim, Jawaid Mallick. Field-in-field technique with intra-fractionally modulated junction shifts for craniospinal irradiation (CSI) planning with 3D-CRT [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6504.

OBJECTIVE

Volumetric modulated arc therapy (VMAT) has been implemented for left breast irradiation to reduce prescription dose to the heart and improve dose homogeneity across the targeted breast. Our in‐house method requires application of a bolus during the optimization process with a target outside of the body, then removing the bolus during the final calculation in order to incorporate skin flash in VMAT plans. To quantify the dosimetric trade‐offs between traditional 3D field‐in‐field tangents and VMAT with integrated skin flash for these patients, we compared nine consecutive patients who recently received radiation to their entire left breast but not their regional lymphatics. Tangent plans used non‐divergent tangents of mixed energies and VMAT plans utilized four 6 MV arcs of roughly 260°. Mean dose to the heart, contralateral lung, and contralateral breast and their volume receiving 5%, 10%, and 20% of the prescription dose were higher in all nine VMAT plans than in the static tangential beam plans. For all critical structures, the mean VMAT DVH was higher in the low‐dose region and crossed the 3D field‐in‐field DVH between 23.13% and 34.18% of the prescription dose (984.75‐1454.70 cGy). However, the volume of the contralateral breast and heart receiving the prescription dose was slightly lower in the VMAT plans, but not statistically significant. VMAT provided superior homogeneity, with a mean homogeneity index of 9.41 ± 1.64 compared to 11.05 ± 1.82 for 3D tangents. Results indicate that VMAT spares the heart, contralateral lung, and contralateral breast from prescription dose at the cost of increasing their mean and low‐dose volume and delivers a more homogenous dose distribution to the breast. For these reasons, VMAT is selectively applied at the request of the physician for left breast radiation without respiratory gating to spare the heart from prescription dose in cases of poor anatomical geometry.

Purpose To compare 3D-CRT, Field-in-Field (FIF) and VMAT for adjuvant radiotherapy of breast cancer. Methods 26 patients (13 with left-sided breast cancer, 13 with right-sided) treated to a prescribed dose of 40 Gy (2.667 Gy/fraction; normalized to the target mean) were considered. For all patients a 3D-CRT and a VMAT plan were simulated. 3D-CRTs were planned with 2 primary tangential fields with physical wedges and 2 additional low weighted segments. VMAT plans were performed with a Rapid Arc (RA) technique using 2 partial arc. In a subgroup of 15 patients FIF technique was implemented, combining two open fields with 2–3 segments in two tangential beam directions, without using wedges. Comparisons were performed in terms of PTV coverage and OARs dose-volume histogram (DVH) parameters, considering optimal/acceptable constraints of RTOG-1005 protocol. The dosimetric value of omolateral (lung/heart) OARs were related to the OARs volume included in the chest concavity and to OAR’s inclusion maximum depth. Results Concerning PTV, coverage was similar for the three techniques. The mean dose to OARs are summarized in the table. RA was sub-optimal for all contralateral OARs because mean doses were significantly (p Conclusions The FIF (3D-CRT) technique is similar to RA for PTV data and presents the best results all contralateral OARs. Only when (omolateral) lung and heart have an inclusion in chest concavity >1.5 cm, RA significantly reduces dose in the high DVH region.

Purpose Field-in-Field (FIF) is an advanced radiation therapy planning technique [1] . We studied the effectiveness of this technique for breast radiotherapy, with respect to 3D standard technique, in terms of dosimetric benefits and treatment reproducibility. PTV volume dependence on both techniques was also investigated. Methods Two endpoints were analysed. For the first endpoint, dosimetric benefits were studied on 230 breast cancer patients from Macerata hospital who received whole breast radiotherapy with either 3D standard or FIF technique. The second endpoint was a reproducibility study: 28 patients from Macerata and Rieti hospitals were included. For each patient, a 3D standard plan and a FIF plan were prepared on the first simulation CT. All patients underwent other two CT scans on which the original plans were recalculated. Comparisons between techniques were made using V95%, D95%, Dmean, Dmax, HI and CI. Results The FIF technique significantly reduced the PTV Dmax, increased Dmean, allowed better dose coverage and more homogenous dose distribution (Fig. 1). When the irradiated OAR values were compared, the results were slightly higher for the FIF technique, but still within the tolerance limits (p Differences between plans calculated on the repeated CT scans ( Δ 1/2 and Δ 1/3) were not statistically significant between the two techniques (p V PTV > 1000 cc ) (Table 1). Conclusions The FIF technique provided better dose distribution in terms of coverage and homogeneity, also for larger PTVs, both techniques respected OAR dose-volume limits and FIF reproducibility was equivalent to 3D standard technique reproducibility. Download : Download high-res image (436KB) Download : Download full-size image

Techniques, using physical wedge filter and using dynamic wedge filter and FIF(Field in Field) and ISCT(Irregular Surface Compensating Technique), have been developed according to progress of radiation therapy of breast cancer. Measurement of dose was done to judge the usefulness of technique using three cases, non tissue loss after breast conserving operating and tissue loss after breast conserving operating and mastectomy. Dose indexes of breast tissue, CI (Conformity Index), HI (Homogeneity Index) and QOC (Quality of Coverage), dose index of skin, or dose indexes of lung, volume of 50 percent dose and 20 percent dose were estimated and compared. Using dynamic wedge filter is useful plan at non tissue loss allowing for high dose of lung. FIF and ISCT are useful plan at tissue loss. ISCT is useful plan at mastectomy. Henceforth, we need to apply to valid plan and body type and thorax size.

Objective: Technological advances have enabled clinicians to explore dose escalation strategies in various tumor sites. Intermediate and high risk oropharyngeal cancers have poor 5 year outcomes. This study aimed to assess the feasibility and dosimetric safety of 9% dose escalation in these tumors and compare the dose received by organs at risk (OAR) in escalated plans (67.2 Gy/28 fractions) versus (65 Gy/30 fractions) standard dose plans. Materials and Methods: FDG-PET fused datasets were used to delineate gross, clinical and planning target volumes. Standard dose plans were created using two non IMRT techniques (conventional and field in field plans) whilst the patient was treated using a helical tomotherapy plan. A fourth dose escalation plan was obtained allowing comparison between the 20 plans of oropharyngeal cancer patients. Results: It was feasible to escalate dose to the FDG-PET avid tumor within the set constraints to that of planning target volume and OAR. Comparison of the escalated dose to that of standard plans showed a statistically significant (P < 0.05) sparing of the mastication apparatus (MA) with escalated plans. Dose to the other critical and functional organs were comparable between the four plans. Conclusion: Hypofractionated, slightly accelerated dose escalation in oropharyngeal cancers is likely to be safe and the chance of trismus is not any higher than when standard dose radiotherapy is used. Active measures to reduce dose to the MA achieves acceptable dose volume parameters even at escalated doses.

Volumetric modulated arc therapy (VMAT) has been implemented for left breast irradiation to reduce prescription dose to the heart and improve dose homogeneity across the targeted breast. Our in-house method requires application of a bolus during the optimization process with a target outside of the body, then removing the bolus during the final calculation in order to incorporate skin flash in VMAT plans. To quantify the dosimetric trade-offs between traditional 3D field-in-field tangents and VMAT with integrated skin flash for these patients, we compared nine consecutive patients who recently received radiation to their entire left breast but not their regional lymphatics. Tangent plans used non-divergent tangents of mixed energies and VMAT plans utilized four 6 MV arcs of roughly 260°. Mean dose to the heart, contralateral lung, and contralateral breast and their volume receiving 5%, 10%, and 20% of the prescription dose were higher in all nine VMAT plans than in the static tangential beam plans. For all critical structures, the mean VMAT DVH was higher in the low-dose region and crossed the 3D field-in-field DVH between 23.13% and 34.18% of the prescription dose (984.75-1454.70 cGy). However, the volume of the contralateral breast and heart receiving the prescription dose was slightly lower in the VMAT plans, but not statistically significant. VMAT provided superior homogeneity, with a mean homogeneity index of 9.41 ± 1.64 compared to 11.05 ± 1.82 for 3D tangents. Results indicate that VMAT spares the heart, contralateral lung, and contralateral breast from prescription dose at the cost of increasing their mean and low-dose volume and delivers a more homogenous dose distribution to the breast. For these reasons, VMAT is selectively applied at the request of the physician for left breast radiation without respiratory gating to spare the heart from prescription dose in cases of poor anatomical geometry.

new gamma evaluation algorithm was created to improve ability of gamma criterion to determine, whenever field – in field plan two dose distributions are acceptable for further therapy. New parameter, dose gradient, was introduced to differentiate high dose gradient regions from low and use only those with high dose gradient. The aim of this article is to determine whether the new gamma criterion algorithm evaluation principle is suitable for FIF plans verification. For this study a 17 x 12 cm rectangular 6MV photon beam was used. Rectangular fields, sized 5 x 12, 6 x 8,5 and 3 x 4,3 cm were added as segments for each 17 x 12 cm base field in center. Dose distribution was calculated using treatment-planning system (TPS) to be used as a starting point to make distorted plans with segments displaced in superior, inferior, lateral left and lateral right directions to simulate patient movement or positioning errors during irradiation. Dose distributions for the distorted plans were measured using pixel ionization chambers detector array. The resulting dose distributions were compared to the reference one provided by TPS using gamma criterion. For acceptance criteria ΔDM=3% dose-difference, ΔdM=3 mm distance-to-agreement (DTA) and dose gradient 5% were used and 95% of all pixels should be within this criterion. For all the plans, considered in the present paper, 95% threshold was exceeded before the displacement reached clinically significant values of 3 mm. New algorithm show steep decrease of “pass” pixels at 3 mm even for segments with 3 x 4, 3 cm size. One has to conclude, that created algorithm should be investigated at comparison of dose distribution plans of clinical field in field conformal radiotherapy.

Background: The study aimed to evaluate and compare the dosimetric parameters of incidental irradiation to internal mammary node (IMN) from inverse intensity-modulated radiotherapy (I-IMRT) and field-in-field IMRT (F-IMRT), and 3-dimensional conformal radiotherapy (3D-CRT) in patients after breast-conservation surgery (BCS). Methods: Eighty-four patients with BCS were selected. The breast, tumor bed, and IMN, including intercostal spaces (ICS) 1 to 3, were contoured. Three plans were generated. The prescription doses for the breast and tumor bed were 50.4 Gy/28 F and 60.2 Gy/28 F, respectively. If there was no tumor bed boost, patient was treated with 50 Gy/25 F for the whole breast only. The IMN was not included in planning target volume. Results: The median mean dose (Dmean) of the IMNtotal (ICS 1–3) was 2740.2 cGy, 2973.9 cGy, and 2951.4 cGy for I-IMRT, F-IMRT, and 3D-CRT, respectively. Differences were not detected between any of the plans. After separating ICS 1 to 3 for further analysis, neither of the Dmean of ICS 1 to 2 was significantly different between the plans. However, for ICS 3, the median Dmean was highest for I-IMRT, and those for 3D-CRT and F-IMRT were not significantly different. After separating the 3 techniques for further analysis, the median Dmean was highest in ICS 3 and lowest in ICS 1 for all the 3 techniques. Conclusion: All 3 techniques failed to attain an adequate dose to cure subclinical disease, and there were no significant differences among the 3 techniques. It is risky to avoid IMN irradiation (IMNI) using any of the 3 techniques during whole-breast radiotherapy in women with indications for elective IMNI. However, in era of systematic therapy, whether the incidental dose could meet clinical acquirements needs further follow-up.

A radioterapia constitui a modalidade clínica mais utilizada para tratar mestástases cerebrais, tipo mais comum de tumores secundários de mama, pulmão e melanomas. Os protocolos frequentemente utilizam doses diárias elevadas e, dependendo da técnica de irradiação empregada há elevada probabilidade de complicações em tecidos saudáveis. Com o propósito de minimizar os efeitos adversos, é importante a interpretação dosimétrica do planejamento radioterápico tridimensional por meio de imagens tomográficas ou, no caso de simulações 2D, pelo emprego de técnicas que otimizam a distribuição de dose aumentando a homogeneidade. O estudo objetivou comparar os planejamento 2D e conformacional 3D para a irradiação total de cérebro e verificar a evolução desses planejamentos através das técnica “field-in-field”. A metodologia consistiu em simular o planejamento bidimensional, reproduzi-lo em um conjunto de imagens tomográficas e compará-lo com o plano conformacional, tanto para técnica de dois campos quanto para a de quatro campos “field-in-field”. Os resultados mostraram que não há diferenças significativas entre planejamentos 2D e 3D para irradiação de cérebro total, e que a “técnica field in field” melhora sensivelmente a distribuição de dose no volume cerebral comparada à técnica de dois campos. Concluiu-se que a custo efetividade do tratamento é ótima para os 4 campos descritos e que a tomografia de planejamento não é essencial para o caso clinico abordado.

For reaction-diffusion processes with at most bimolecular reactants, we derive well-behaved, numerically tractable, exact Langevin equations that govern a stochastic variable related to the response field in field theory. Using duality relations, we show how the particle number and other quantities of interest can be computed. Our work clarifies long-standing conceptual issues encountered in field-theoretical approaches and paves the way for systematic numerical and theoretical analyses of reaction-diffusion problems., Comment: 5 pages + 6 pages supplemental material