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An adenoid cystic carcinoma (T3N0M0) of the tongue, with the tongue requiring depression. The primary tumor was located in the left palate and protruded into the oral cavity. Carbon ion radiation therapy consisted of 64 Gy (RBE) in 16 fractions via 4 portals. Treatment course was uneventful. (A) Mouthpiece with tongue depressor (arrow). (B) Depressed tongue position with custom-made mouthpiece. (C) Clinical results of dose distribution. (D) Mucosal finding after carbon ion radiation therapy.
Source publication
Here, we introduce a custom-made mouthpiece for carbon-ion radiotherapy for head and neck malignancy. The mouthpiece incorporates either a tongue depressor or elevator depending on tumor location. The risk of tongue mucositis may be reduced without compromising therapeutic efficacy through mouthpiece shaping.
Contexts in source publication
Context 1
... To accomplish this, a splint is set, and a heated EVA wedge is placed into the patient's open mouth. Finally, a tongue depressor (Fig 1A) or elevator (Fig 2A) is applied to the mouthpiece according to the tumor position, completing the device, with a total construction time of approximately 100 minutes. ...
Context 2
... function of the tongue depressor is to keep the tongue in a more recessed than usual position ( Fig 1B). In contrast, the function of the tongue elevator is to keep the tongue raised out of the treatment target area (Fig 2B). ...
Context 3
... maxillary tumors, the tongue is depressed caudally to spare it from irradiation ( Fig 1C). During CIRT, grade 3 mucositis appeared in the palatal mucosa, but no mucositis was observed on the dorsal side of the tongue (Fig 1D). ...
Context 4
... maxillary tumors, the tongue is depressed caudally to spare it from irradiation ( Fig 1C). During CIRT, grade 3 mucositis appeared in the palatal mucosa, but no mucositis was observed on the dorsal side of the tongue (Fig 1D). DVH analysis demonstrated reduced dose to the tongue with mouthpiece usage compared with nonusage (Fig 3). ...
Citations
... Intraoral stents (IOS) have been used to prevent oral adverse events, such as OM, dysgeusia, xerostomia, and osteoradionecrosis, by moving normal tissues (such as oral mucosa, tongue, and jawbone) away from the irradiated field or low-dose area and attenuating the effects of radiation [7][8][9][10][11][12][13][14]. Several clinical studies have demonstrated the usefulness of IOSs for malignant tumors of the tongue or floor of the mouth [7][8][9]. ...
... Several clinical studies have demonstrated the usefulness of IOSs for malignant tumors of the tongue or floor of the mouth [7][8][9]. In contrast, for malignant tumors of the maxilla or nasal cavity, an IOS is effective in moving normal tissue away from the irradiated field by maintaining an open mouth [10,12,13]. However, few clinical studies have demonstrated that IOSs have contributed to the prevention of oral adverse events [14]. ...
Purpose
Many patients experience oral adverse events during head and neck cancer radiotherapy (RT). The methods of management of such events are under debate. One such technique is the intraoral stent (IOS) technique, which removes normal tissue from the irradiation field. This retrospective study examined the factors associated with the occurrence of oral mucositis (OM) and dysgeusia and the efficacy of IOSs in preventing them.
Methods
Twenty-nine patients who underwent RT in the maxilla or nasal cavity between 2016 and 2022 were included. They were investigated for background characteristics, treatment factors (IOS and dose-volume histogram), and oral adverse events (OM and dysgeusia).
Results
Significant risk factors for the incidence of grade ≥ 2 (Common Terminology Criteria for Adverse Events v5.0) OM were the non-use of IOSs (p = 0.004) and diabetes (p = 0.025). A significant risk factor for the incidence of grade ≥ 1 dysgeusia was concomitant chemotherapy (p = 0.019). The radiation dose to the tongue was significantly lower in the IOS group than in the non-IOS group.
Conclusion
Our findings suggest that the use of an IOS during RT reduces the severity of OM by reducing irradiation to the tongue. Therefore, the use of an IOS is recommended during RT performed in the maxilla or nasal cavity.
... Various tongue positioning devices have been used in clinics. The dosimetric evaluations of conventional tongue bite or tongue depressor have been evaluated [4][5][6][7][8]. The conventional method includes tongue-positioning device made of paraffin wax as well as the tongue-positioning device made of silicone material using mold and casting method [9][10][11]. ...
This study aimed to assess the performance of a tongue-positioning device in interfractional tongue position reproducibility by cone-beam computed tomography (CBCT). Fifty-two patients treated with radiation therapy (RT) while using a tongue positioning device were included in the study. All patients were treated with 28 or 30 fractions using the volumetric modulated arc therapy technique. CBCT images were acquired at the 1 st , 7 th , 11 th , 15 th , 19 th , 23 th , and 27 th fractions. Tongues on planning computed tomography (pCT) and CBCT images were contoured in the treatment planning system. Geometric differences in the tongue between pCT and CBCT were assessed by the Dice similarity coefficient (DSC) and averaged Hausdorff distance (AHD). Two-dimensional in vivo measurements using radiochromic films were performed in 13 patients once a week during sessions. The planned dose distributions were compared with the measured dose distributions using gamma analysis with criteria of 3%/3 mm. In all patients, the mean DSC at the 1 st fraction (pCT versus 1 st CBCT) was 0.80 while the mean DSC at the 27 th fraction (pCT versus 27 th CBCT) was 0.77 with statistical significance ( p -value = 0.015). There was no statistically significant difference in DSC between the 1 st fraction and any other fraction, except for the 27 th fraction. There was statistically significant difference in AHD between the 1 st fraction and the 19 th , 23 th , and 27 th fractions ( p -value < 0.05). In vivo measurements showed an average gamma passing rate of 90.54%. There was no significant difference between measurements at the 1 st week and those at other weeks. The tongue geometry during RT was compared between pCT and CBCT. In conclusion, the novel tongue-positioning device was found to minimize interfractional variations in position and shape of the tongue.
... Regard, the intraoral stents have been used to decrease the potentially adverse effect of the irradiation in the normal tissues outside the planned target volume by increasing the distance between the maxilla and mandible or depressing to the healthy tissues such as the tongue (24). This method can set apart the healthy tissues from the irradiation field. ...
... An intraoral positioning stent effectively preserves the healthy tissue in HNC patients undergoing radiotherapy [3]. By limiting the radiation field, the intraoral stent reduces the radiation dose to the normal tissue, which substantially decreases the radiation-induced toxicity [4][5][6][7][8][9]. However, positioning stent use remains limited because the process of stent fabrication requires an interprofessional team of a radiologist, dentist, and dental laboratory. ...
... The design of intraoral appliances is customized based on the tumor location. For tongue cancer, we designed a lingual plate to depress the tongue while displacing the hard palate, soft palate, and maxillary alveolar bone from the radiation field that resulted in a minimal radiation dose and toxicity to the normal tissue [6]. Additionally, the minimal occlusal engagement design allowed the appliance to be easily inserted while precisely maintaining the appliance in position during radiotherapy. ...
Introduction:
The radiotherapy received by head and neck cancer patients commonly has adverse effects on oral tissue and the muscles of mastication. This short communication describes the digital fabrication of intraoral appliances for radiotherapy and muscle exercises.
Methods:
Three patients diagnosed with tongue squamous carcinoma were treatment-planned for radiotherapy using different radiation techniques. The patients were referred for oral scanning and digital bite records, and the appliance was collaboratively designed by a radiation oncologist, dentist, and laboratory technician. The appliance covered the occlusal surface of the remaining teeth with a 1-mm engagement. The lingual plate was 2-mm below the occlusal plane, and extended 4-mm distally, and the jaws were opened by 20-mm. The appliances were printed overnight using a rigid and biocompatible 3D printing material.
Results:
Requiring minimal chair-time, the appliance was easily inserted and adjusted to comfortably fit in the mouth. The patients were trained to insert it themselves. The tongue was at a pre-determined position during daily radiotherapy, and the healthy tissues were separated from the radiation field. The patients had mild adverse effects on their oral mucosa. Additionally, the appliances were used for muscle exercises after the radiation courses to prevent trismus.
Conclusions:
The interprofessional collaboration to fabricate customized intraoral appliances using digital workflow to maximize patients' benefits is feasible.
Clinical significance:
The use of intraoral appliances is potentially increased when the fabrication process is facilitated. Using an intraoral appliance precisely targets the tumor are for better treatment outcomes, and the healthy adjacent tissues will be preserved to maintain the patient's quality of life.
... A custom-made mouthpiece is created in our institution for all head and neck cancer patients, as described previously. 6,7 The mouthpiece is constructed using a thermoplastic ethylene-vinyl acetate (EVA) copolymer suitable for use in charged-particle therapy. 8 For lip tumors, the maxilla is incorporated into the PTV because of its anatomical adjacency to the usual lip position. ...
Purpose
A custom mouthpiece with lip bumper for carbon-ion radiotherapy (CIRT) of tumors of the lip was developed with the goal of reducing the incidental exposure of the maxilla.
Methods and Materials
The mouthpiece was manufactured using a thermoplastic ethylene-vinyl acetate copolymer. This was employed in a patient with primary adenoid cystic carcinoma of the right lip without invasion of the maxilla. To evaluate spacer utility, the volume of maxilla receiving more than 50 Gy (relative biological effectiveness, V50) with and without the spacer was calculated using dose-volume histogram (DVH) analysis in a simulation study and subsequently treated.
Results
In the simulation study, DVH analysis demonstrated a 46% dose reduction in the high-dose area of the maxilla with mouthpiece usage (V50 = 2.21 mL) compared to non-usage (V50 = 4.11 mL). The mouthpiece was well-tolerated. Eight years after CIRT, no late dermatitis, oral mucositis, or osteoradionecrosis was observed.
Conclusions
A custom-made mouthpiece with a lip bumper successfully reduced the incidental exposure of the maxilla during CIRT.
... It has been noted that in radiotherapy of the head and neck region, it is necessary to reduce the dose to the organ at risk in the oral cavity and to reduce the risk of side effects, which is also important from the viewpoint of improving patients' quality of life [14][15][16][17]. Thus, reducing the oral-tissue side effects that occur during radiotherapy is of great benefit to patients. ...
We evaluated the basic characteristics and efficacy of our newly developed patient fixation system for head and neck radiotherapy that uses a dedicated mouthpiece and dental impression materials. The present investigation demonstrated that with this system, the changes in the absorbed dose to water depending on the material of the mouthpiece were small, with a maximum of 0.32% for a 10-MV photon beam. For the dental impression material, we selected a silicone material with the lowest Hounsfield unit (HU) value that had little effect on the generation of artifacts and the quality of the X-ray beam. Multiphase magnetic resonance imaging (MRI) revealed that the head-up and -down motions in the thermoplastic shell without the mouthpiece were 5.76 ± 1.54 mm, whereas the motion with the mouthpiece decreased significantly to 1.72 ± 0.92 mm (P = 0.006). Similarly, the head-left and -right motion displacement decreased from 6.32 ± 1.86 mm without the mouthpiece to 1.80 ± 0.42 mm with the mouthpiece (P = 0.003). Regarding the tongue depressor function of the mouthpiece, the median distance from the hard palate to the surface of the tongue was 28.42 mm. The present results indicate that the new immobilization device developed herein that uses a mouthpiece and a thermoplastic shell is useful for suppressing patients’ head motions and tongue positions.
... The use of carbon ion radiation therapy in medical practice is anchored on the accurate energy of carbon ion beam for having desired dose deposited at the tumor to preserve human organs and tissues [8]. Few years ago, it was impossible to directly control the dose distribution in patients treated with the carbon ion beam [9]. Nowadays, positron emission tomography (PET) and prompt gamma imaging (PGI) are two promising modalities for range verification [10,11]. ...
Due to the shortage of data regarding range and water equivalent ratio (WER), in this work, firstly, depth-dose profiles and range were evaluated in liquid water, Polyethylene (PE), Aluminium, Bone, Polymethyl methacrylate (PMMA), and Lead for carbon ion energies ranging 100–300 MeV/n using Fluka Mc code. Afterwards, persuing the repeated use of the above mentioned materials in dosimetric studies in the domain of hadrontherapy, we came up to calculate the water equivalent ratio of only three dosimetric materials (polyethylene (PE), polymethyl methacrylate (PMMA) and lead). Then, we made the remark that the closest and farthest WER values are 1.0016 and 5.7939 respectively, they were obtained for the PE and the lead. The calculated WER values were compared with the values from MCNPX code, and those from the previous analytical methods (NM, BK, BB, EBB). Good agreement was obtained between the results of the MC codes and the previous analytical methods. The largest discrepancy between the two MC codes was 4.2% for PE at 100 MeV/n and was about 1.52% between Fluka and the analytical method (BB) for Lead at 270.83 MeV/n. Among the materials explored, PE stayed the nearest to water with an average WER of 1.0038 for carbon ion energy ranging 100 to 300 MeV/n.
... The use of carbon ion radiation therapy in medical practice is anchored on appropriate calibration to preserve human organs and tissues. Few years ago, it was impossible to directly control the dose distribution in patients treated with any type of radiation [4]. Nowadays, positron emission tomography (PET) and prompt gamma imaging (PGI) are two promising modalities for range verification. ...
... For PMMA and PE, due to their low density, we chose to calculate this factor only for thicknesses of 5 cm and 10 cm, but for the lead, which has a high density, this thickness has been reduced a little to 2.5 cm. All these calculations are presented in table 4. ...
Due to the shortage of data regarding range, WER and WET values for carbon ion beams in a vast range of energies as well as for relevant dosimetric materials, in this work, firstly, depth-dose profiles and range were evaluated in liquid water, polyethylene (PE), aluminium, bone, polymethyl methacrylate (PMMA), and lead for carbon ion energies ranging 100-300 MeV using Fluka Mc code. Afterwards, following their most frequent use in dosimetric studies in hadrontherapy, we decided to calculate the WER and WET of only 3 dosimetric materials (PE, PMMA and lead). Then, we made the remark that the PE and the lead represent the least and the most difference to water with calculated mean WER values of 0.998 and 5.684, respectively. The calculated WER values were compared with MCNPX Mc code as well as the previous analytical results (NM, BK, BB, EBB). Good agreement was reached between Fluka, MCNPX and the previous analytical results. The largest discrepancy between the two Mc codes was 2.29% for lead at 250 MeV carbon ion energy and was about 2.06% between Fluka and the BB method for Lead at 270.83 MeV carbon ion energy. Based on the materials explored, the PE stayed the nearest to water with an average WER of 0.9983 for carbon ion energy ranging 100 to 300 MeV. KeysWords: WER, WET, carbon ion, hadrontherapy, Fluka, MCNPX
... The mouthpiece should effectively reduce setup errors in charged-particle head and neck cancer treatments. Moreover, the mouthpiece should reduce the side effects of external beam RT [3][4][5][6][7][8][9][10]. Verrone et al. [7] reported that the use of a mouthpiece during intensity-modulated RT for oral cancer effectively reduced the dose delivered to the healthy tissues such as the maxilla and parotid gland. ...
... Moreover, the mouthpiece should reduce the side effects of external beam RT [3][4][5][6][7][8][9][10]. Verrone et al. [7] reported that the use of a mouthpiece during intensity-modulated RT for oral cancer effectively reduced the dose delivered to the healthy tissues such as the maxilla and parotid gland. The reduced side effects of custom-made mouthpieces have also been reported for proton [11] and carbon-ion (C-ion) RT [3,4,12]. ...
... In photon and charged-particle therapy for head and neck cancer, the effectiveness of the mouthpiece as a spacer to reduce the dose delivered to the healthy tissues has been reported [3][4][5][6][7][8][9][10]12]. In charged-particle therapy, the beam may unavoidably pass through the mouthpiece or be stopped on the mouthpiece to spare the surrounding normal tissue. ...
In this study, the stopping-power ratios (SPRs) of mouthpiece materials were measured and the errors in the predicted SPRs based on conversion table values were further investigated. The SPRs of the five mouthpiece materials were predicted from their computed tomography (CT) numbers using a calibrated conversion table. Independently, the SPRs of the materials were measured from the Bragg peak shift of a carbon-ion beam passing through the materials. The errors in the SPRs of the materials were determined as the difference between the predicted and measured values. The measured SPRs (errors) of the Nipoflex 710™ and Bioplast™ ethylene–vinyl acetate copolymers (EVAs) were 0.997 (0.023) and 0.982 (0.007), respectively. The SPRs of the vinyl silicon impression material, light-curable resin, and bis-acrylic resin were 1.517 (0.134), 1.161 (0.068), and 1.26 (0.101), respectively. Among the five tested materials, the EVAs had the lowest SPR errors, indicating the highest human-tissue equivalency.
... In the radiation therapy for head and neck cancer, mouthpieces are sometimes used to protect normal tissue and to improve the accuracy of xation, and many papers have reported the usefulness of a mouthpiece [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Most of the mouthpieces were fabricated with dental materials. ...
... In this study, we investigated six dental materials. Among these six dental materials, vinyl polysiloxane and thermoplastic ethylene vinyl acetate copolymer splint, have been investigated for particle therapy in the past [4,5,15], but there are no previous reports examining the other four materials as mouthpiece materials for particle therapy. Kawamura et al. used vinyl polysiloxane as a stopper in proton therapy, and reported on its safety and accuracy in proton therapy [5]. ...
... Kawamura et al. used vinyl polysiloxane as a stopper in proton therapy, and reported on its safety and accuracy in proton therapy [5]. Ikawa et al. used thermoplastic ethylene vinyl acetate copolymer as a mouthpiece splint in carbon-ion radiation therapy and reported that it helped to protect normal tissue [4,15]. However, these reports did not investigate multiple materials in proton therapy together. ...
Purpose: To investigate how the materials of mouthpieces used for proton therapy of head and neck cancer affect the dose distribution in surrounding normal tissue by focusing on the CT values of the materials.
Methods: Six dental materials were used to measure CT values: temporary relining resin, tissue conditioner, vinyl polysiloxane, thermoplastic ethylene vinyl acetate copolymer splint, silicone rubber impression material, and a composite impression material. Among these materials, three of the dental materials were investigated further: one material with the CT value closest to water, and the materials with the highest and lowest CT values. Based on these results, we investigated the effect of the CT value of the mouthpiece on the dose distribution in 17 cases in which a mouthpiece was used during proton therapy for head and neck cancers, the treatment plans were recalculated by changing the CT values of the mouthpiece to that of the three identified dental materials. For each cancer case, the irradiation dose to normal tissue was calculated for the treatment plans. The evaluation indices were set to the mandible max dose (GyE), the mandible mean dose (GyE), the volume of the mandible irradiated above 60 GyE (mandible V-60GyE), the parotid affected side mean dose (GyE), the parotid unaffected side mean dose (GyE), and the oral mean dose (GyE). The Wilcoxon’s rank sum test was used to analyze the significance of the differences between treatment plans.
Results: The temporary relining resin with the CT value closest to water was 36.9 HU, the vinyl polysiloxane with the highest CT value was 985 HU, and the thermoplastic ethylene vinyl acetate copolymer splint with the lowest CT value was -89.7 HU. The maximum absolute difference among the treatment plans per case was 4.18 GyE for the oral mean dose. The radiation dose for the evaluation indices did not differ significantly among the treatment plans.
Conclusion: In the range of CT values from -89.7 HU to 985.0 HU covered in this study, the effect of the CT value of the mouthpiece on the dose distribution may be considered to have no clinical impact.
