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 Table of Contents  
Year : 2022  |  Volume : 8  |  Issue : 2  |  Page : 117-120

Immobilization devices used to treat unusual sites for better radiation delivery: A single institutional experience

1 Department of Medical Physics, State Cancer Institute, Indira Gandhi Institute of Medical Sciences, Patna, Bihar, India
2 Department of Nuclear Medicine, Indira Gandhi Institute of Medical Sciences, Patna, Bihar, India
3 Netaji Subhash Chandra Bose Cancer Hospital, Kolkata, West Bengal, India
4 Department of Radiation Oncology, Indira Gandhi Institute of Medical Sciences, Patna, Bihar, India

Date of Submission07-Feb-2022
Date of Decision07-Jun-2022
Date of Acceptance13-Jun-2022
Date of Web Publication2-Sep-2022

Correspondence Address:
Santosh Kumar
Department of Medical Physics, State Cancer Institute, Indira Gandhi Institute of Medical Sciences, Sheikhpura, Bihar
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jigims.jigims_15_22

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The present article illustrates an attempt to design and test the reproducibility of low-cost patient positioning devices prepared in-house in the radiotherapy department. A rigid wood-polymer composite material stands with angulations, scales, and support was designed as a new method for immobilization of the mobile target using a thermoplastic mask and a carbon fiber base plate. The lower mobile target, i.e., the penis of a patient, was immobilized by this method. A computed tomography simulation was performed for the patient. This device fit was suitable, comfortable, and had good reproducibility and repeatability, which was proven in daily radiotherapy. Reproducibility and accuracy were tested by serial electronic portal imaging detectors. The positioning devices showed variations within 2–3 mm on consecutive treatment days which were within acceptable limits. It is therefore concluded that low-cost patient positioning devices for the mobile target can be fabricated from available materials in-house. With the help of these in-house available materials, we can also fabricate other types of immobilization devices for particular techniques. It is considerably cheaper than commercially available products.

Keywords: Electronic portal imaging detectors, immobilization, mobile target, radiotherapy, wood-polymer composite material

How to cite this article:
Kumar S, Kumar R, Kumar S, Roy B, Singh RK, Kumar A. Immobilization devices used to treat unusual sites for better radiation delivery: A single institutional experience. J Indira Gandhi Inst Med Sci 2022;8:117-20

How to cite this URL:
Kumar S, Kumar R, Kumar S, Roy B, Singh RK, Kumar A. Immobilization devices used to treat unusual sites for better radiation delivery: A single institutional experience. J Indira Gandhi Inst Med Sci [serial online] 2022 [cited 2023 Mar 27];8:117-20. Available from: http://www.jigims.co.in/text.asp?2022/8/2/117/355313

  Introduction Top

Penile cancer is a rare clinical entity that contributes to significant patient morbidity and mortality. Historically, in this treatment, it consisted of radical surgery with partial or total penectomy. As an alternative or adjunct to surgical resection, radiation therapy can be used for organ preservation strategies successfully in up to 70% of patients.

In the management of penile squamous cell carcinoma using modern radiation therapy treatment techniques, it is expected that clinical outcomes for organ preservation as well as the management of side effects and toxicities, the immobilization devices play a great role in delivering accurate radiation to increase the therapeutic ratio. Intensity-modulated radiation therapy (IMRT), image-guided radiation therapy, and volumetric-modulated arc therapy are related to precisely delivering radiation therapy techniques.[1] It is a challenging job, especially when the target is a flexible body part (for example, penis). The most common radiation therapy is from carefully focused beams of radiation aimed at the tumor from a machine. The setup is generally time-consuming. Treatments are generally given 5 days a week for 6 weeks. Previously, wax/plastic block/molds were used to hold the penis in the same position for each treatment. Verifying patient setup uncertainty before treatment is important for accurate delivery and increase treatment-related effects.[2] Many techniques are available after partial penectomy, which may vary from institute to institute but the key task is to immobilize it and give an accurate radiation delivery to sustain the treatment of the mobile target. Intra- and inter-fraction motion can be minimized with such an immobilization device.[3]

With the development of conformal radiotherapy, particularly IMRT (an advanced type of radiation therapy used to treat cancer and noncancerous tumors), radiation oncologists, and radiotherapy technologists require new immobilization methods. That provides a good reproducibility to the target, especially when the target is a mobile, for example, penis. Till now, no standard method has been established for this organ, so most methods involve the use of alpha cradles, ankle casts, customized immobilization devices, or negative pressure vacuum air cushions. This is a new method for immobilizing the mobile target with improved reproducibility and patient comfort.

  Materials and Methods Top

This device includes a thermoplastic mask (Guangzhou Renfu Medical Equipment Co., Ltd.), a carbon fiber base plate (MedTec, USA), a customized stand made of tissue-equivalent wood-polymer composite (WPC) material of 4 mm × 35 mm × 35 mm dimension of L type corner with an adjustable fixing clamp (Guangzhou Renfu Medical Equipment Co., Ltd.), Fevikwik, and a syringe as per measured diameter of the patient's penis. The thermoplastic mask was remolded before use. The present implementation is mainly concerned with a device for immobilizing body parts for more effective and repeatable medical treatments. First, the measurement has been taken for each side of the device and cut L type WPC material as per the size of the carbon fiber base plate [Figure 1] in rectangular-shaped as per the model diagram and measurement taken [Figure 2]. By attaching the used thermoplastic clamp on both sides of the indigenous stand to fix the stand with the carbon fiber base plate. The upper cover holder of an indigenous penile immobilization device frame has been made by cutting a piece of thermoplastic sheet with L shape edge and fixed it on the upper portion of the device frame. A syringe has been fixed in the middle of the device frame by reversing the plunger inside the syringe [Figure 3]. Finally, with this immobilization device, the patient's penis was immobilized.
Figure 1: Carbon fiber base plate

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Figure 2: Device model

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Figure 3: Customized indigenous penile immobilization device

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Anatomical contouring and planning

DICOM image of the patient from CT unit send to treatment planning system (TPS- Make-Elekta, Model: Monaco). The image was contoured in TPS.[Figure 4]. A four-field three-dimensional conformal radiotherapy (3DCRT) plan has been prepared. The acceptable dose at organ at risk (OAR) were maintained by giving the dose constraints. The acceptable dose was within the range according to the criteria adopted. The dose uniformity within acceptable level also achieved in planning target volume (PTV) [Figure 5].
Figure 4: CT simulator image. CT: Computed tomography

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Figure 5: 3DCRT plan. 3DCRT: Three-dimensional conformal radiotherapy

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A cone-beam computed tomography image has been taken for patient positioning setup and it shows a good result [Figure 6] with our desire for patient benefit.
Figure 6: CB CT image. CB: Cone beam, CT: Computed tomography

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  Results Top

The designed immobilization of the penis is the most suitable immobilization. Hence, holding/immobilization device of the penis is crucial in fractionation radiotherapy (long treatment days). The maximum positional inaccuracy of movement is within 2 mm in either direction (left/right). On the other hand, it is cost-effective and easy to prepare in any common mold room of the radiotherapy department.

  Discussion Top

The hospital medical research ethics committee approved our research following the laws and regulations in India, and the concerned patient gave oral and written informed consent before the start of the study.

3DCRT and IMRT plans show radiation dose distribution that is highly conformal to the target volume. The successful clinical implementation of these radiotherapy modalities requires precise positioning of the target to avoid a geographical miss. Effective reduction in target positional inaccuracies can be achieved with the proper use of immobilization devices.[4] In this execution, our main aim was to deliver the radiation dose precisely and ease of treatment setup. In this study, the daily setup-related errors were also targeted. This study shows that the tumor control probability (TCP) has a close relation to immobilization. The significance of immobilization errors on the TCP has been studied in detail by applying theoretical models.[5] The effect of different immobilization systems in radiation oncology has been reported for various sites.[6],[7] The need for accurate positioning of the patient is a prerequisite for successful radiotherapy.[8],[9] At present, different techniques have also been used lower limb irradiation. The present implementation, solve the problems outlined above and provides a significantly improved body part immobilization device. The execution of this device is to perform shape-retaining material of a selected body part to be immobilized and is configured for holding the body part. With this newly developed indigenous penile immobilization device, a case of carcinoma penis were treated after partial penectomy. From simulation to treatment delivery, the repeatability of the device was always the same position and very easy. Treatment verification has been done once a week, which was good with less acute toxicities. Due to its excellent positioning and mechanism, postpartial penectomy having a small stump, using this device, the patient was able to treat with highly conformal radiotherapy.

Previously, we were using readymade immobilization devices, but in that case, either patients or their relatives have to go to the supplier. Most of the time materials were not available from the supplier side and they were cost-effective too. Many centers suggested it will cost approximately 80 thousand which was unbearable for the poor patients. That is why this idea came to our mind. The total cost of the patients was approximately 100 rupees. This was a great help to the poor patients. If this type of indigenous device is prepared, in-house will help the patients financially as well as easily.

  Conclusion Top

The developed new method is for immobilizing the mobile PTV for radiotherapy. The present developed indigenous device solves the problems that arise during radiotherapy and provides a greatly improved body part immobilization device. The device includes a section of preformed, shape-retaining material that presents a concavity substantially conforming to a selected body part to be immobilized and is configured for receiving and holding the body part. There is a need to immobilize the body parts of patients undergoing some medical treatment, but the patients suffering from carcinoma penis tumors require fractionated radiation therapy. A common problem with such types of patients is to need for the patient's penis in the same position so that radiation can be applied only to the area of the internal PTV. It is very difficult to fully immobilize the patient's penis during the treatment and using this indigenous device immobilization of the mobile penis is possible.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Yartsev S, Kron T, Van Dyk J. Tomotherapy as a tool in image-guided radiation therapy (IGRT): Theoretical and technological aspects. Biomed Imaging Interv J 2007;3:e16.  Back to cited text no. 1
Schubert LK, Westerly DC, Tomé WA, Mehta MP, Soisson ET, Mackie TR, et al. A comprehensive assessment by tumor site of patient setup using daily MVCT imaging from more than 3,800 helical tomotherapy treatments. Int J Radiat Oncol Biol Phys 2009;73:1260-9.  Back to cited text no. 2
Engelsman M, Rosenthal SJ, Michaud SL, Adams JA, Schneider RJ, Bradley SG, et al. Intra- and interfractional patient motion for a variety of immobilization devices. Med Phys 2005;32:3468-74.  Back to cited text no. 3
Saw CB, Yakoob R, Enke CA, Lau TP, Ayyangar KM. Immobilization devices for intensity-modulated radiation therapy (IMRT). Med Dosim 2001;26:71-7.  Back to cited text no. 4
Goitein M, Busse J. Immobilization error: Some theoretical considerations. Radiology 1975;117:407-12.  Back to cited text no. 5
Bentel GC, Marks LB, Krishnamurthy R. Impact of cradle immobilization on setup reproducibility during external beam radiation therapy for lung cancer. Int J Radiat Oncol Biol Phys 1997;38:527-31.  Back to cited text no. 6
Bentel GC, Marks LB, Hendren K, Brizel DM. Comparison of two head and neck immobilization systems. Int J Radiat Oncol Biol Phys 1997;38:867-73.  Back to cited text no. 7
Babu NK, Singh B, Namrata S, Mohanti BK, Ravichandran R, Ghamrawy KE. Development of patient support devices for execution of clinical radiotherapy for cancer patients: A preliminary report. J Med Phys 2006;31:255-61.  Back to cited text no. 8
[PUBMED]  [Full text]  
Bentel GC, Marks LB, Sherouse GW, Spencer DP, Anscher MS. The effectiveness of immobilization during prostate irradiation. Int J Radiat Oncol Biol Phys 1995;31:143-8.  Back to cited text no. 9


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